December 2012
Articles
December 2012 [6(12) 2012]
Table of Contents
December 2012 [6(12) 2012]
Table of Contents
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Differential growth response of rice genotypes based on quiescence mechanism under flash flooding stress Salah El-Hendawy, Chiharu Sone, Osamu Ito and Jun-Ichi Sakagami Abstract The main strategies enabling rice plants to cope with flash flooding stress require growth regulation during submergence and subsequent rapid growth recovery after de-submergence. The objective of this study was to characterize the response of 56 diverse contrasting rice genotypes to submergence and their recovery following de-submergence. Among these genotypes, nine lines had been developed for anaerobic germination and submergence tolerance (AG + Sub1) by IRRI. Fourteen-day-old plants were submerged completely in water for 7 days. Subsequently, the plants were kept under normal rice-cultivation conditions as the control for a further period of 5 days. The tested genotypes were generally classified into three clusters based on shoot elongation rate of submerged to non-submerged treatments (ratio) during submergence period and chlorophyll contents during recovery period using Ward’s method. The genotypes in clusters I include most of AG + Sub1 lines and tolerant genotype FR13A adapted to submergence stress, which get the benefits of quiescence mechanism during submergence coupled with maintenance of higher chlorophyll content during recovery period. In contrast, the cluster III spanned most of intolerant genotypes such as IR42 by enhancing shoot elongation through escape mechanism in response to submergence. This mechanism negatively affected the plant growth recovery due to a great reduction of chlorophyll contents during the recovery period. The genotypes placed in cluster II followed the similar trend as cluster I during the submergence and recovery periods in addition of increases in shoot fresh weight during submergence period. This finding suggests that other mechanisms along with quiescence might be associated with submergence stress in the genotypes placed in cluster II. In conclusion, the contrasting rice genotypes expressed differential growth responses in genotypes with lower shoot elongation ratio using different quiescence strategies during submergence period. Pages 1587-1597 | Full Text PDF |
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Transgenic corn plants with modified ribosomal protein L3 show decreased ear rot disease after inoculation with Fusarium graminearum Pragya Kant, Anju Gulati, Linda Harris, Steve Gleddie, Jas Singh and K Peter Pauls Abstract Cereal crops are susceptible to various Fusarium species worldwide. Fusarium graminearum is a major pathogen of corn that causes ear rot disease and contaminates kernels with mycotoxins such as deoxynivalenol (DON). DON binds with the 60S ribosomal protein L3 (RPL3), blocking the translational machinery in the eukaryotic cells. Previously, the modified rice Rpl3 gene (resulting in a change in amino acid residue at 258 from tryptophan to cysteine) was transformed into tobacco and resulted in increased resistance to DON. In the present study, the same modified Rpl3 gene was used to develop two types of transgenic corn plants in which the modified Rpl3 gene was controlled by a constitutive 35S CaMV promoter or a silk-specific ZmGRP5 promoter. The transgenic lines were evaluated for the ear rot disease in the field by inoculating F. graminearum spores in silk and kernel tissues. The overall disease symptoms in the transgenic lines were significantly lower than wild type plants. Transgenic plants having the Rpl3 gene with 35S CaMV promoter showed a 23 to 58% decrease in disease scores whereas the transgenic plants expressing the modified Rpl3 gene under silk specific promoter showed a 27 to 62% decrease in disease scores compared to wild type plants. The kernel inoculation gave lesser disease symptoms in both types of transgenic plants compared to silk inoculation. The maximum decrease in disease scores was observed (up to 62%) in transgenic plants expressing modified Rpl3 gene with silk specific promoter when inoculations were done through kernels. The present report is the first field study of transgenic corn plants developed to reduce F. graminearum infection. Taken together, the results suggest that the modified Rpl3 gene is effective in reducing ear rot disease in corn. Pages 1598-1605 | Full Text PDF |
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Variability and correlation analysis between area of single seedling occupancy (ASSO) and rice individual characters under non-uniformity spatial distribution Y. Huang, D. C. Chen, W. Zhou, W. J. Ren, W.Y. Yang Abstract In order to study the individual characters under non-uniformity spatial distribution, the variation characteristics of the area of single seedling occupancy (ASSO) were used as a control group to study morphological variability of rice. Different mathematical models were applied to combine the yield component of rice and some of its morphological index. Manfred Hühn's mathematical statistical model was used to analyze the possibility of increasing yield by non-regular spatial distribution. The plot models were constructed by inlaying individual unit area designed by computer simulation methods. A different ASSO was designed under non-regular horizontal distribution, Thiessen polygons were used to determine the ASSO. The result showed that, coefficients of variation of yield components were all less than those of ASSO, the effects of ASSO variability on effective panicles per plant and filled grain number of per panicle were the greatest; except flag leaf, the variation coefficient of most of the individual plant characters were greater than that of ASSO, and the variation coefficient of empty-shrivel grain number (0.3637) was the greatest. Most of individual plant characters suited the power function model, the setting percentage and filled grain number of per panicle kept steady after a quick increase as ASSO was increased, the spikelet number of per panicle peaked slowly and decreased slowly. The spikelet number of individual plants had linear relationships with individual bio-mass of single plant and dry matter of stem leaf in different degrees. The economic coefficient had linear relationships with setting percentage, had non-linear relationships with ASSO, yield of unit area, grain number of per panicle, filled grain number of per panicle, and average length of flag leaf. The effects of ASSO variability on 1000-grain weight and average length of flag leaf were small. It was possible to increase rice grain yield under non-regular spatial distribution which was proven by the mathematic statistical model with the condition of the ratio between the variation coefficient of ASSO and yield was greater than the correlation coefficient of the two (vA/vS> rSA). Pages 1606-1612 | Full Text PDF |
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A view on the role of metabolites in enhanced stem reserves remobilization in wheat under drought during grain filling Mitra Mohammadi Bazargani Mohammad-Reza Hajirezaei, Ghasem Hosseini Salekdeh, Ali-Akbar Shahnejat Bushehri, Mohsen Falahati-Anbaran, Foad Moradi, Mohammad-Reza Naghavi, Bahman Ehdaie Abstract Terminal drought is one of the major factors limiting the yield of wheat (Triticum aestivum L.). Remobilization of pre-stored carbohydrates from stem to grain during grain filling is one of the drought tolerance mechanisms. To investigate the enhanced stem reserves remobilization under drought condition, we compared metabolome pattern of two contrasting wheat landraces (NO.49 and NO.14) during days after anthesis (DAA) under drought stress. Wheat genotypes were cultivated in a greenhouse and drought stress initiated just after anthesis and peduncle, penultimate and lower internodes samples were collected from well-watered and drought-stressed plants at 0, 10, 20 and 30 DAA. The peduncle of NO.49 showed remarkably higher stem reserves remobilization efficiency compared with NO.14 during this period. The higher content of fructan in peduncle of NO.49 genotype under drought stress suggesting a higher oxidative stress defense response and a faster fructan remobilization supports grain filling under stress. A positive correlation observed between the fructan and sucrose:sucrose fructosyltransferase (SST) activity (r2=0.77) in No.49, whereas this was not the case in NO.14 genotype. A higher Invertase (INV) activity in NO.49 genotype under drought stress compared with control during 20 DAA revealed an increase in sucrose degradation during fructan remobilization. The decrease in arginine and increase in proline content in NO.49 under drought stress only during 10 DAA could be considered as the index of senescence initiation. Increase accumulation of arginine and ACC amino acids in NO.49 peduncle in after anthesis period, suggesting enhancement of senescence during grain filling. Our results indicate that carbon remobilization in NO.49 increases from the stem to the grains by a good coordination between enhancing senescence and oxidative stress defense to protect stem cells from premature cell death. Pages 1613-1623 | Full Text PDF | Supplementary data |
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Effects of nitrogen fertilisation rate on the accumulation of high-molecular-weight glutenin subunits and distribution of glutenin macropolymer size in strong gluten wheat (Triticum aestivum L.) Juan Liu, Taibo Liang, Shuping Xiong, Jing Wang, Yanfeng Wang, Yang Yang, Qingyun Zhai Abstract The high-molecular-weight glutenin subunits (HMW-GS) and glutenin macropolymer (GMP) in wheat grain significantly affect the wheat quality. The role of nitrogen in determining grain yield and quality has been extensively studied. However, the effects of nitrogen application on HMW-GS accumulation and GMP particle distribution are rarely reported. In the present study, the strong gluten wheat cultivar Shannong 12 was used in a field experiment to examine the effects of the nitrogen fertilisation rate on HMW-GS accumulation and GMP size distribution. The total and individual HMW-GS contents both increased with nitrogen application 14 days after anthesis. The responses of individual HMW-GS contents to nitrogen application varied; subunits 5 and 10 were more sensitive to nitrogen application than subunit 15. The diameter of the GMP particles in wheat grain ranged from 0.37 µm to 245 µm. The distribution of number percentage exhibited a one-peak curve at 1 µm, which indicated that most of the GMP particles in the wheat grains had small diameters. The distributions of volume percentage and surface area percentage of GMP exhibited two-peak curves. The number and volume arcsine square roots of GMP particles larger than 100 µm increased with nitrogen application, whereas those of GMP particles smaller than 10 µm decreased. The HMW-GS and GMP contents were significantly positively correlated with GMP particles larger than 100 µm. These results suggested that nitrogen application promoted the development of GMP and increased the percentage of larger GMP particles, thereby enhancing wheat quality. Page 1624-1629 | Full Text PDF |
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Grain yield and dry matter accumulation response to enhanced panicle nitrogen application under different planting methods (Oryza sativa L.) Song Chen, Xiufu Zhang, Guoping Zhang, Dangying Wang, Chunmei Xu Abstract A four-year field experiment (2006-2009) was conducted to assess the effect of enhanced panicle nitrogen application on rice yield and its dry matter accumulation characteristics in direct-seeded (DSR) and transplanted rice (TPR). The field experiment included two planting patterns (TPR and DSR) and four nitrogen treatments: (F1) low panicle nitrogen fertilizer (PNF) with high total nitrogen amount (TNA; 225kg N ha-1); (F2) low PNF with low TNA (150kg N ha-1); (F3) high PNF with high TNA; (F4) high PNF with low TNA. There was little difference in mean yield of planting patterns between F2 and F4. However, the mean yield in F1 was 10.15% greater than in F3. The mean total dry matter in F3 was 12.0% greater than in F1. These results indicated that enhanced PNF might benefit dry-matter accumulation but lead to yield decline. We found that rice yield was linearly correlated with grain filling percentage (R2 = 0.47, p < 0.01) as well as grains m-2 (R2 = 0.55, p < 0.01). Grains m-2 was quadratically correlated with stem dry matter at the heading stage, which suggests that over-accumulated dry matter in the stem before grain filling might play a negative role in grain yield. Grain filling percentage and grain m-2 were found to be linearly correlated with leaf dry matter at the heading stage, which suggests that leaf growth at panicle initiation and heading stage might be critical characteristics in yield performance. Pages 1630-1636 | Full Text PDF |
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Influence of air temperature on the histological characteristics of ginseng (Panax ginseng C. A. Meyer) in six regions of Korea Kwon-Ryeol Ryu, Myeong-Hun Yeom, Sun-Sang Kwon, Ho-Sik Rho, Duck-Hee Kim, Han-Kon Kim, Kyeong Won Yun Abstract Ginseng (Panax ginseng C.A. Meyer) is a well-known oriental traditional herb that grows naturally on the Korean peninsula, in Manchuria (northeast of China), and the Maritime province of Siberia. The quality of ginseng is usually estimated according to its cultivation region in Korea. We analyzed the air temperature of six well-known ginseng cultivation regions and investigated the hardness and crude saponin content of the cultivated ginseng. According to the Korea Meteorological weather reports, the air temperature of Jinan and Ganghwa is lower than that of Geumsan. The cambial growth, tissue density, and xylem hardness of ginseng grown in the cooler regions (i.e., Ganghwa and Jinan) were greater than those in the other four regions. The crude saponin content of ginseng of Ganghwa and Jinan was 1.2 fold higher than that of Gimpo and Geumsan. From these results, we concluded that the lower summer air temperature contributes to the growth of ginseng and enriches its crude saponin content. Pages 1637-1641 | Full Text PDF |
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Bicistronic expression and functional analysis of a novel LMW-m glutenin gene in wheat (Triticum aestivum L.) Wen Zang, Jian Dong, Xiang Gao, Qijiao Chen, Zhoubo Hu, Xiaoyan Li, and Wanchun Zhao Abstract Low-Molecular-Weight Glutenin Subunits (LMW-GS) play the major role in determining the viscoelastic properties of dough. DsbA, an efficient catalyst for disulfide bond formation, could increase the solubility of the co-expressed protein in Escherichia coli. To isolate large amounts of LMW-GS for in vitro functional analysis, the bicistronic expression method was employed in the present study. The lmw-gs and dsbA genes were obtained using gene-specific primers, and joined into lmw/dsbA through splicing by overlapping extension PCR (SOE-PCR). The combination molecule was ligated into pET32a (+) and co-expressed in E.coli BL21 (DE3) host cells. Meanwhile, pET32a-lmw was constructed as a negative control to assess the impact of DsbA on the solubility of LMW-GS. The expression products were confirmed by SDS-PAGE and Western-blot. The solution ability was evaluated by the concentration of LMW-GS in supernatants of pET32a-lmw/dsbA and pET32a-lmw under the same conditions. Small-scale dough testing was conducted using the standard Farinograph test (10-g ?our). Results showed that three lmw-gs genes (from JF439428 to JF439430) were isolated from wheat Shaan253 (Triticum aestivum L.), and that one dsbA gene (JF755399) from E.coli strain DH5a, respectively. Due to owning more typical motifs of LMW-m type than the others, JF439428 was selected for co-expression with JF755399 and further functional analysis. Standard curve analysis revealed that DsbA could increase the solubility of LMW-GS 1.76-fold. Small scale testing suggested that JF439428 belongs to a neutral subunit on the dough quality. We also found the severe bias of each type among LMW-GS in common wheat. Pages 1642-1648 | Full Text PDF |
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Marker-assisted backcrossing (MABC) for improved salinity tolerance in rice (Oryza sativa L.) to cope with climate change in Vietnam Hien Thi Thu Vu, Duc Duy Le, Abdelbagi M. Ismail, Ham Huy Le Abstract Salinity is the most common abiotic stresses leading to the reduction of rice yield in many rice-growing areas of the world. Improvement in salt tolerance of rice for target stress regions is one of the important objectives of many breeding programs. In this study, we are currently applying a MABC (marker-assisted backcrossing) system on foreground selection, recombinant selection followed by background selection for development of Vietnamese rice variety that can tolerate salinity of rised sea water. The highly salt tolerant FL478 was used as a donor to transfer Saltol QTL into Bacthom 7 recipient rice cultivar. A total of 368 SSR markers were conducted to identify 8 markers in Saltol locus and 81 markers in other loci with total of 89 (24%) polymophic markers between the parents, out of which 88 markers were then applied to analyze genotyping of each backross generation with three steps of selection. The results showed that, the best plants of BC3F1 generation carry segments of the donor (11.16 - 12.6 Mb), which had 96.8% - 100 % of the recipient genome. This study revealed that the introgression lines can be directly developed into the salinity tolerance variety, which suitable for cultivating in coastal areas of Vietnamese Deltas. The MABC aids in the transfer of target chromosome segments and may improve the recovery of the recipient genome if background selection is employed. Pages 1649-1654 | Full Text PDF |
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Intraspecific variation of Achyranthes bidentata (Amaranthaceae) in the geo-authentic product area based on internal transcribed spacer sequences of ribosomal DNA Yong Li, Ping Liu, Yonghua Li Abstract Achyranthes bidentata Blume belongs to perennial herbs (Amaranthaceae) and is widely distributed in India, Java, China, and Japan. The population of this plant is rapidly decreasing due to overexploitation for its important medicinal value. In this study, the genetic diversity of A. bidentata was analyzed using an internal transcribed spacer of ribosomal DNA from 58 individuals in the geo-authentic product area. A survey of ribosomal DNA variation revealed relatively low genetic diversity (hT = 0.703) and significant genetic differentiation (?ST = 0.730). Nucleotide diversity (p) among 8 populations ranged from 0 to 4.04×10-3 and haplotype diversity (h) varied between 0 and 0.822. Significant deviation from Hardy-Weinberg expectation (P £ 0.001) was found in the species due to its high homozygosity. The population sampled from Jigong Mountain had the highest nucleotide and haplotype diversity.The isolation-by-distance for ribosomal DNA was detected in plants from the geo-authentic product area was not significant (r = 0.236, P = 0.134), and two major geographic groups were distinguished. Increasing human activity and overexploitation are likely to be the reasons for the observed high differentiation and relatively low genetic diversity. Based on the results of this study, the populations from Jiulian Mountain and Jigong Mountain, which had greater genetic diversity than the other sampled populations, should be the best candidates for ex situ conservation. Pages 1655-1660 | Full Text PDF |
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Identification of heterotic loci for seven yield and yield-related traits in maize with a set of introgression lines Xiaomin Feng, Juan Huang, Huanhuan Qi, Yaqun Huang, Liying Zhu, Yongfeng Zhao, Qi Zheng, Wenzhen Li, Bing Yue Abstract Dissection of the genetic basis of heterosis facilitates hybrid breeding in crops. In this study, heterotic loci (HL) for seven yield and yield-related traits were identified in a set of maize introgression lines (ILs) under two environments (locations) by a backcross population with one of their parents, Zong 3. Middle parent heterosis of seven yield and yield-related traits was calculated based on the field experiments conducted at two locations. A total of 120 significant loci for six traits were identified by calculating marker-trait coefficients with the software Graphical Genotypes (GGT) 2.0, and 48 loci represent for five traits were commonly identified under two environments. This indicates that it is possible to identify HL with the population derived from ILs. Of the 48 significant loci, 13 were found to be associated with more than 2 different traits, indicating strong genetic correlations among these traits. For yield and most of the yield-related traits, the heterozygosity of the markers at the HL were strongly correlated to the performance of middle parent heterosis, suggesting that the HL identified in this study could be used for heterosis prediction and maker-assisted selection in maize hybrid breeding. Pages 1661-1665 | Full Text PDF |
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Molecular characterization of Jatropha curcas germplasm using inter simple sequence repeat (ISSR) markers in Peninsular Malaysia Ibrahim Wasiu Arolu, M.Y. Rafii, M.M. Hanafi, T.M.M. Mahmud, M. A Latif Abstract Molecular characterization and evaluation of germplasm was carried out using 10 Inter simple sequences repeat (ISSR) on 48 accessions of Jatropha curcas (L) collected from three states (Kelantan, Selangor and Terengganu) in Peninsular Malaysia. The stem cuttings of these J. curcas accessions were collected, raised in the nursery and then transferred to the experimental site at University Agricultural Park. The 48 J. curcas accessions were grouped into three different populations based on the state from where they were collected. Percentage polymorphism in these three populations ranged from 90.75% (Terengganu) to 100% (Kelantan). Analysis of molecular variance (AMOVA) showed that 94 % of the total variation was observed within the populations while variation among the populations accounted for the remaining 6%. A dendrogram produced by Unweighted Pair Group Method with Arithmetic Mean (UPGMA) based on Nei’s genetic distance grouped the whole germplasm into 11 distinct clusters. Based on the information from this dendrogram, accessions that are far from each other by virtue of genetic origin and diversity index are strongly recommended to be use as parent for crossing. This will bring about greater genetic diversity, thus resulting into increase in selection gain. This will also lead to high productive index in terms of increase in fruit yield per hectare, oil yield, seed weight and other yield components. Therefore, accessions, B-01-03, T-01-09, B-04-01 and T-01-01 could be crossed with accessions D-04-02, B-05-05, B-01-04, and D-01-06 for the improvement of J. curcas in future breeding program. Pages 1666-1673 | Full Text PDF |
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Herbicide tolerance and seed survival of grain amaranth (Amaranthus sp.) Per Kudsk, Andreu Taberner, Rosa M. de Troiani, Teresa M. Sànchez, Solvejg K. Mathiassen Abstract Amaranth is receiving increasing attention as an alternative crop to small grain cereals. From a weed control point of view cultivation of amaranth poses two problems. Firstly, amaranth grows slowly after emergence and hence is very susceptible to competition by weeds and secondly, seed losses at harvest are significant due to an uneven maturing and volunteer amaranth plants could potentially become a weed problem in following crops. Nonetheless, no studies are available on the tolerance of amaranth to herbicides or the survival of seeds in the soil. In this study we examined 1) the tolerance of amaranth to a range of herbicides in a series of outdoor pot experiments and in one field experiment and 2) the survival of amaranth seeds buried at 4 depths (2.5, 5, 10 and 25 cm) in 3 countries. The results showed that amaranth is very susceptible to broadleaved weed herbicides. Of the broadleaved herbicides examined only clomazone, clopyralid, phenmedipham and triflusulfuron were tolerated by amaranth. Applying clomazone early post-emergent instead of pre-emergent provided full crop tolerance even at the highest doses (P<0.05). The post-emergence herbicides phenmedipham and triflusulfuron caused less crop damage applied at the 4-6 leaf stage compared to the 2-4 leaf stage while clopyralid was selective at both growth stages. The seed survival studies revealed differences between the countries with higher viability in Spain (up to 18%) than in Argentina and Denmark (up to 6%). Our results showed that chemical weed control in amaranth is possible and despite a significant loss of seeds at harvest problems with volunteer amaranth plants in the following crop should not be a major issue due to a high susceptibility of amaranth to herbicides and the short longevity of amaranth seeds. Pages 1674-1680 | Full Text PDF |
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Research Note Greater differences exist in seed protein, oil, total soluble sugar and sucrose content of vegetable soybean genotypes [Glycine max (L.) Merrill] in Northeast China Yan-sheng LI, Ming DU, Qiu-ying ZHANG, Guang-hua WANG, Masoud Hashemi, and Xiao-bing LIU Abstract Understanding edamame seed compositions at edible stage is fundamental for developing cultivars that are considered as healthier diet. Thirty vegetable soybean genotypes were grown at the rate of 28 plants m-2 in a randomized complete block design with three replications in field condition in Northeast China. Protein, oil, total soluble sugar (TSS) and sucrose contents of the seeds at the edible stage (R6-R7) were determined. Cultivar Tai 292, a commercial vegetable soybean cultivar, was used as a standard cultivar for comparison of genotypes evaluation. The mean values in seed protein, oil, TSS and sucrose of all genotypes were 420 mg g-1, 186 mg g-1, 60 mg g-1 and 43 mg g-1, respectively. Genotype variation in sucrose content was 187% and that of TSS was 163%, while the variations in oil and protein were only 39% and 26%, respectively. Sucrose content constituted 71% of TSS. In fresh seed of vegetable soybean, negative correlations were found between protein and TSS (r=-0.52), protein and sucrose (r=-0.43), while the determination coefficients (R2) were only 0.17 for protein and sucrose. Every 10 mg·g-1 increase in seed protein was accompanied by 4.3 mg·g-1 decrease in sucrose. No significant correlation (p>0.05) was found between oil and TSS, and oil and sucrose. Sixteen out of 30 genotypes and 7 out of 30 genotypes had greater protein and sucrose contents than check cultivar Tai 292. Genotypes L-1, L66 and L-139/19 are the valuable genetic resources in developing vegetable soybean cultivars with higher sucrose, lower oil content without reduced protein content. Pages 1681-1686 | Full Text PDF |
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Effect of elevated boron concentrations on the growth and yield of barley (Hordeum vulgare L.) and alleviation of its toxicity using different plant growth modulators Soad Soliman El-Feky, Fatma Aly El-Shintinawy, Eman Mohamed Shaker and Hassan Aly Shams El-Din Abstract This study was carried out to assess the role of elevated concentration of boron in barley (Hordeum vulgare L. cv. Giza 123) growth and yield as well as to test the involvement of some plant growth modulators in counteracting the boron-mediated retardations to improve its tolerance. Barley grains were treated with B concentrations of 0, 0.5, 1.5, 3.0 and 6.0 mg L-1 (as boric acid). The alleviation of the growth inhibition in the presence of 3.0 mg L-1 B was investigated by adding the following growth modulators: glutamic acid (1 or 3 mM ), glycine (1 or 3 mM), ascorbic acid (2 or 5 mM), salicylic acid (1 or 5 mM) and calcium chloride (1 or 5 mM). Barley grains were cultivated and samples were collected at vegetative (22-day-old), flowering (45-day-old) and harvesting stages (92-day-old). At vegetative stage, the application of 0.5 mg L-1 boron significantly increased (P = 0.05) shoot fresh weight by 1%. The addition of 0.5 and 1.5 mg L-1 boron significantly increased (P = 0.05 and 0.01) growth parameters (shoot and root fresh and dry weights) by 5%, leaf area by 4.5% and 7%, Chl a and Chl b contents by 3% and 7% at vegetative and flowering stages, respectively, and yield by 5.5%, compared to non-boron treated barley. The inhibitory effects of boron on barley growth started at concentrations above 3.0 mg L-1, causing decrease in all the measured parameters. The five tested growth modulators alleviated boron toxicity at 3.0 mg L-1 at the following sequence: salicylic acid (1 mM), calcium chloride 5 mM =, ascorbic acid (2 mM) =, glycine (1 mM) and glutamic acid (3 mM). The boron-alleviating efficiency of either 1 mM salicylic acid or 5 mM calcium chloride recommended their application when cultivating barley in boron contaminated soils. Pages 1687-1695 | Full Text PDF |
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Photosynthetic characteristics and variation of osmoregulatory solutes in two white clover (Trifolium repens L.) genotypes in response to drought and post-drought recovery Zhou Li and Yan Peng Abstract This study was conducted to analyze responses of the small-leafed white clover (SL) and the large-leafed white clover (LL) associated with photosynthetic characteristics and osmoregulatory solutes accumulation under drought stress and rewatering. The plants of two genotypes were subjected to drought stress for 12 days by withholding irrigation and then rewatering for 6 days in a greenhouse. Their relative water content (RWC), electrolyte leakage (EL), malondialdehyde content (MDA), water use efficiency (WUE) in photosynthetic process and osmoregulatory capacity in response to water stress and rewatering were comparatively measured. Results showed that SL plants maintained significantly higher RWC and membrane stability (P = 0.05) expressed as EL level and content of MDA with the increased drought. Following rewatering, SL recovered more rapidly in all parameters than LL. Progressive water deficit induced the decline of net photosynthetic rate (Pn) and stomatal conductance (gs) in both genotypes. However, intercellular CO2 concentration (Ci) of both clovers gradually increased with the decline of RWC and was not affected by a decline of gs. It could be referred that limit photosynthesis of the two white clovers was caused by non-stomatal factors during drought stress. Meanwhile, WUE in the SL was significantly higher (P = 0.05) than that in the LL under drought stress although the WUE trend was totally opposite while being well watered and rewatered. Furthermore, significantly higher (P = 0.05) osmoregulatory solutes, such as free proline, total soluble sugar and betaine, were observed in the SL leaves as compared with that in the LL under treatment conditions. The results suggested that drought tolerance and post-drought recovery in different white clover genotypes were associated with their ability to accumulate the osmoregulatory solutes, which might play an important role in protecting cellular membrane stabilization from water loss and improving water use efficiency in photosynthetic process during drought stress. Pages 1696-1702 | Full Text PDF |
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Pre-germination anaerobic stress tolerance in tropical maize (Zea mays L.) Pervez H. Zaidi, Zerka Rashid, M.T. Vinayan and T. Anil Babu Abstract Pre-germination anaerobic stress caused by temporary soil water-logging at the planting and seedling establishment stage is an important constraint for maize (Zea mays L.) production in the tropics, especially in South and Southeast Asia. Whilst it is commonly accepted that the occurrence of excessive soil moisture following planting adversely affects the establishment and early growth of maize crops, the threshold limit and genotypic variability for pre-germination anaerobic stress tolerance in tropical maize germplasm have not been determined. We aimed to identify the threshold limit for pre-germination anaerobic stress tolerance and available genotypic variability in tropical maize for this stress. A set of 100 elite maize inbred lines selected from a wide genetic background were exposed to different durations of pre-germination anaerobic stress (12, 36, 72, 96, and 120 h). Two independent but key traits for crop establishment, germination percentage (> 80%) and delay in coleoptile emergence (<5 days), were compared under normal conditions and anaerobic stress conditions. These traits were used as the basic criteria for identifying the threshold limit of pre-germination anaerobic stress tolerance. By varying the duration of managed anaerobic stress screening, it was observed that 72 h of exposure to the stress resulted in the best identification of available genotypic variability. Any further increase in stress duration (96 and 120 h) masked the genotypic variation as almost all entries were susceptible. After identifying the threshold limit, we tested two different sets of test-cross progenies to identify the available genotypic variability in tropical maize for pre-germination anaerobic stress tolerance. This included 214 entries of test-cross progenies of recombinant inbred lines (developed by crossing vegetative stage water-logging tolerant and susceptible lines) and 296 entries of drought tolerant maize (DTM) association mapping panel, representing a wide genetic background of tropical maize. Our results clearly indicate significant genotypic variability in tropical maize for pre-germination anaerobic stress tolerance, which could be systematically selected for and further improved using a managed anaerobic stress screening technique. This study also showed that test weight (100 seed weight) is significantly (P<0.01) correlated with seedling vigor (shoot and root dry weight) under pre-germination anaerobic stress; however, there was no relationship with the test weight and seed germination or time to seedling emergence. Pages 1703-1711 | Full Text PDF |
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Grain quality evaluations of hybrids between Triticum aestivum and Sorghum bicolor produced by pollen tube pathway method Weiguo Zhang, Liang Jin, Xinglin Li, Xiaolei Jiang, Yafu Wang, Xiaojuan Wang Abstract Distant hybridization makes it possible to transfer the genome of one species to another, and the pollen tube pathway method has been widely used based on the hypothesis that such distant hybridization process provided the opportunity of the recombination of DNA segment. In this study, we carried out a distant hybridization between Triticum aestivum and Sorghum bicolor via pollen tube pathway method, and five new wheat lines including 9122 (S. bicolor 2D + T. aestivum L13), 9141 (S. bicolor 5D + T. aestivum L10), 9144 (S. bicolor 2D + T. aestivum G8), 9145 (S. bicolor 5D + T. aestivum G8) and 0154 (S. bicolor 10D + T. aestivum G8) were selected to determine the grain quality characteristics of these hybrids. Therefore, the properties of their flour mixogram and high molecular weight subunit of hybrids were analyzed. The variations of mixogram peak time, mixogram peak height, mixogram height in the seventh minute and sedimentation value in the five hybrids were observed, while mixogram width at the seventh minute of all the hybrids was improved. The mutation of high molecular weight subunits of glutenin happened including the composition pattern and content of HMW-GS. In hybrid 9144, the high molecular weight glutenin subunits 5+10 were presented instead of subunits 2+12 of its maternal parent G8. The results indicated that distant hybridization between T. aestivum and S. bicolor via pollen tube pathway method improved the wheat grain quality, which will provide more opportunities for the selection of new wheat cultivar with improving grain quality. Pages 1712-1717 | Full Text PDF |
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Combining ability and heritability of selected rice varieties for grain quality traits R. Asfaliza, M.Y. Rafii, G. Saleh, O. Omar and A. Puteh Abstract This study was conducted to determine the combining ability and heritability of rice grain quality traits. Some grain quality traits such as grain length, grain width, milled grain length, milled grain width, length to width ratio, milled rice recovery, head rice recovery, amylose and gel consistency were analyzed using a full diallel mating design in Malaysian rice varieties. This study was commenced by crossing the selected rice varieties based on a full diallel mating design. The F1 was harvested at the end of the season. In the following season, the crossed, reciprocal and parental lines were planted in randomly complete block design with three replications. Analysis of variance indicated that genotypes were significantly different for all traits evaluated except for milled rice recovery. Mean square values for general combining ability were significant for the evaluated grain quality traits which indicated the importance of additive gene effects in inheritance of these traits. The specific combining ability effects were significant for several populations derived from crosses involving MR 263, MR 267, MRQ 74, Q 85 and MRQ 76. Reciprocal effects were significant for eight combinations for grain quality traits. Broad sense heritability showed that the AMYL and GC had the lowest value. The GL showed moderate value while GW, MGL, MGW, LW and HRR were the highest. The narrow sense heritability for grain physical properties was higher than grain chemical properties. The highest heritability was observed for LW, MGL, HRR, MGW, GW and GL. Pages 1718-1723 | Full Text PDF |
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A putative protein kinase Femu9p contributes to the iron deficiency-inducible expression of FOX1 gene in Chlamydomonas reinhardtii Yajun Li, Xiaodong Deng, Jinghao Yang, Xiaowen Fei Abstract FOX1 gene encoding a multicopper ferroxidase is vital in iron metabolism in the single-celled green algae Chlamydomonas reinhardtii. Molecular characteristics of this gene have been extensively studied. However, little information is available about its regulatory factors in C. reinhardtii. In this study, we isolated a regulatory mutant of FOX1 gene by using an arylsulfatase gene driven by the FOX1 promoter. The corresponding gene was also identified via thermal asymmetric interlaced polymerase chain reaction and named Femu9p. Gene structure analysis shows that the Femu9p gene encodes a protein of 757 amino acids which was predicted to contain a protein kinase domain. We demonstrate that Femu9p is essential for the regulation of FOX1 gene expression because Femu9p RNAi silencing leads to a significant decrease in FOX1 promoter activity. Moreover, our analysis indicates that Femu9p positively affects total chlorophyll (Ch a+b) content and the regulation of other iron-uptake-related endogenous gene expressions such as FTR1, FEA1, ATX, and NRAMP2 in C. reinhardtii. Pages 1724-1731 | Full Text PDF | Supplementary data PDF |
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Effect of salinity on proximate mineral composition of purslane (Portulca oleracea L.) Md. Kamal Uddin, Abdul Shukor Juraimi, Farooq Anwar, Md. Alamgir Hossain and Md. Amirul Alam Abstract Purslane (Portulaca oleracea) is a drought and salt tolerant annual plant which contains high amounts of beneficial antioxidant vitamins and minerals. The objective of this study was to determine the influence of salt stress on the growth and mineral composition of purslane (Portulaca oleracea L.). Four salinity levels namely 0 (control), 66, 132 and 264 mM NaCl were tested. Full grown leaf and stems of purslane samples were harvested at 10 and 20 days of the saline treatment exposure. Growth of purslane plants was more suppressed under 264 mM compared to 132 mM. Salinity levels and planting harvest time significantly influenced the levels of protein, water content and ash. The protein content of purslane leaves decreased with increasing salinity and time of exposure treatment. However, carbohydrates and mineral residue content increased. The highest mineral residue content was found in leaves exposed to the maximum salinity levels. The mineral composition was also affected by salinity levels, Na+, Mg++ and Cl- uptake and accumulation increased with the increment of salinity. The Ca++, K+ and Zn+ ion levels decreased with increasing salinity. Accumulation of Ca++ and Zn+ in leaves was higher while K+ and Na+ were higher in the stems. The relative ratio of Na+/K+, Na+/ Ca++, Na+/Mg++, Mg++/Ca++ and Mg++/K+ increased with increasing salinity treatment. The findings of this study revealed that purslane can tolerate moderate salinity levels (66 and 132 mM). Therefore, purslane can be a potential to become a key vegetable crop, especially for functional food and nutraceutical applications. Pages 1732-1736 | Full Text PDF |
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QTL analysis of nitrogen content of plant shoot under two nitrogen conditions in rice (Oryza sativa L.) Shi-kai Hu, Da-li Zeng, Yan Su, Zhen-yuan Shi, Wei-jun Ye, Guo-jun Dong, Li Zhu, Jiang Hu, Qian Qian, Long-biao Guo Abstract As an essential macronutrient, nitrogen (N) is one of the most important factors which could limit agricultural productivity and plays an important role in rice yield formation. To investigate the genetic mechanism of N absorption and utilization efficiency and to improve N utilization efficiency in rice a QTL analysis was done. The main-effect quantitative trait loci (QTLs), epistatic QTLs and QTL-by-environment interactions (QEs) for nitrogen content (NC) of plant shoot at heading and mature stages in two N conditions were identified using a double haploid population derived from a cross between a japonica Chun Jiang06 (CJ06) and an indica Taichung Native 1 (TN1). A total of three NC QTLs were detected on chromosomes 5, 6 and 8 in two N conditions. The phenotypic variation explained by individual QTL ranged from 9.73 to 39.50%. Two pairs of digenic epistatic loci were associated with NC. The QTL qNc8-4 was detected in both high nitrogen (HN) and low nitrogen (LN) conditions, and explained phenotypic variation 18.35% and 39.5% in HN and LN conditions, respectively. The analysis revealed that the additive effect of qNc8-4 came from TN1. Then the qNc8-4 was considered as the main effect loci affecting NC of rice shoot. We suggest that QTL markers of qNc8-4, RM4085 and RM1111, expressing in LN conditions, may be used to improve the N absorption and utilization efficiency in low input rice varieties through marker assisted selection (MAS) breeding programs. It is the first time to use a genetic population like this to map the QTLs of NC of plant shoot in rice, and these results will supply references and research forecast for further study on practicable methods of N utilization, cloning the genes which affect NC and improving N utilization efficiency of varieties by MAS. Pages 1737-1744 | Full Text PDF |
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