Genetic analysis of resistance to root-lesion nematode (Pratylenchus thornei) in wheat

The inheritance of resistance to root-lesion nematode was investigated in five synthetic hexaploid wheat lines and two bread wheat lines using a half-diallel design of F-1 and F-2 crosses. The combining ability of resistance genes in the synthetic hexaploid wheat lines was compared with the performance of the bread wheat line 'GS50a', the source of resistance to Pratylenchus thornei used in Australian wheat breeding programmes. Replicated glasshouse trials identified P. thornei resistance as polygenic and additive in gene action. General combining ability (GCA) of the parents was more important than specific combining ability (SCA) effects in the inheritance of P. thornei resistance in both F-1 and F-2 populations. The synthetic hexaploid wheat line 'CPI133872' was identified as the best general combiner, however, all five synthetic hexaploid wheat lines possessed better GCA than 'GS50a'. The synthetic hexaploid wheat lines contain novel sources of P. thornei resistance that will provide alternative and more effective sources of resistance to be utilized in wheat breeding programmes.

Effect of environment and genotype on bread-making quality of spring-sown spring wheat cultivars in China

Improvement of end-use quality in bread wheat depends on a thorough understanding of current wheat quality and the influences of genotype (G), environment (E), and genotype by environment interaction (G x E) on quality traits. Thirty-nine spring-sown spring wheat (SSSW) cultivars and advanced lines from China were grown in four agro-ecological zones comprising seven locations during the 1998 and 1999 cropping seasons. Data on 12 major bread-making quality traits were used to investigate the effect of G, E, and G x E on these traits. Wide range variability for protein quantity and quality, starch quality parameters and milling quality in Chinese SSSW was observed. Genotype and environment were found to significantly influence all quality parameters as major effects. Kernel hardness, flour yield, Zeleny sedimentation value and mixograph properties were mainly influenced by the genetic variance components, while thousand kernel weight, test weight, and falling number were mostly influenced by the environmental variance components. Genotype, environment, and their interaction had important effects on test weight, mixing development time and RVA parameters. Cultivars originating from Zone VI (northeast) generally expressed high kernel hardness, good starch quality, but poor milling and medium to weak mixograph performance; those from Zone VII (north) medium to good gluten and starch quality, but low milling quality; those from Zone VIII (central northwest) medium milling and starch quality, and medium to strong mixograph performance; those from Zone IX (western/southwestern Qinghai-Tibetan Plateau) medium milling quality, but poor gluten strength and starch parameters; and those from Zone X (northwest) high milling quality, strong mixograph properties, but low protein content. Samples from Harbin are characterized by good gluten and starch quality, but medium to poor milling quality; those from Hongxinglong by strong mixograph properties, medium to high milling quality, but medium to poor starch quality and medium to low protein content; those from Hohhot by good gluten but poor milling quality; those from Linhe by weak gluten quality, medium to poor milling quality; those from Lanzhou by poor bread-making and starch quality; those from Yongning by acceptable bread-making and starch quality and good milling quality; and those from Urumqi by good milling quality, medium gluten quality and good starch pasting parameters. Our findings suggest that Chinese SSSW quality could be greatly enhanced through genetic improvement for targeted well-characterized production environments.

Pattern analysis on grain yield performance of Chinese and CIMMYT spring wheat cultivars sown in China and CIMMYT

Understanding the relationships among testing environments is essential for better targeting cultivars to production environments. To identify patterns of cultivar, environment, cultivar-by-environment interactions, and opportunities for indirect selection for grain yield, a set of 25 spring wheat cultivars from China and the International Maize and Wheat Improvement Center (CIMMYT) was evaluated in nine environments in China and four management environments at CIMMYT in Cd. Obregon, Mexico, during two wheat seasons. Genetic background and original environment were the main factors influencing grain yield performance of the cultivars. Baviacora M 92, Xinchun 2 and Xinchun 6 showed relatively more stable and higher grain yields, whereas highly photoperiod sensitive cultivars Xinkehan 9, Kefeng 6 and Longmai 19 proved consistently inferior across environments, except in Harbin and Keshan, the two high latitude environments. Longmai 26, also from high latitude environments in the northeastern Heilongjiang province, was however probably not as photoperiodicly sensitive as other cultivars; from that region, and produced much higher grain yield and expressed a broader adaptation. None of the environments reported major diseases. Pattern analyses revealed that photoperiod response and planting option on beds were the two main factors underlying the observed interactions for grain yield. The production environment of planting on the flat in Mexico grouped together with Huhhot and Urumqi in both wheat seasons, indicating an indirect response to selection for grain yield in this CIMMYT managed environment could benefit the two Chinese environments. Both the environment of planting on the flat with Chinese Hejin and Yongning, and the three CIMMYT enviromnents planting on raised beds with Chinese Yongning grouped together only in one season, showing that repeatability may not be stable in this case.

Pattern analysis on protein properties of Chinese and CIMMYT spring wheat cultivars sown in China and CIMMYT

Improvement of processing quality is a very important objective for Chinese wheat breeding programs. Twenty-five CIMMYT and Chinese spring wheat cultivars were grown at four managed conditions by CIMMYT in Cd. Obregon, Sonora, Mexico and in nine environments in China, over two successive wheat seasons from 2000 to 2002. These trials were used to identify patterns of cultivar, environment and cultivar x environment interactions, and to determine opportunities for indirect selection for protein content and the protein-quality related parameter, SDS sedimentation (SDSS) value. The cultivar Inqalab 91 showed low levels of interaction with environments in the 2000-01 crop cycle for protein content, and expressed intermediate levels for both protein content and SDSS value, across most of the environments in both years. Longmai 26 had consistently high protein content and SDSS value across environments in both years, indicating that it is possible to breed cultivars expressing high yields with good protein properties. Cluster analyses revealed that cultivars grouped differently for protein content and SDSS value. Besides photoperiod, water availability appeared to influence the ranking of cultivars for protein content and SDSS value. Temperature and soil type may underlie the observed interactions for protein content, while temperature may also be a factor associated with interactions for SDSS value. The full irrigation managed environment in Mexico, with the cultivars sown on raised beds two months later than optimum and exposing them to late heat, clustered together with the Chinese environments Huhhot, Yongning, and Hejin in the 2000-01 season for SDSS value. This indicates that there is an opportunity to exploit indirect responses to selection in the CIMMYT management environments for SDSS value with relevance for China's spring wheat regions. However, there seemed little chance for positive indirect selection in CIMMYT's managed environments for China in regard to protein content, as environments clustered distinctly. Pattern analyses permitted a sensible and useful summary for this multi environment experiment, helping in understanding natural relationships and variations in cultivar performance among the various environment groups, and assisting in the structuring of environments.

Methyl jasmonate induced gene expression in wheat delays symptom development by the crown rot pathogen Fusarium pseudograminearum

The necrotrophic fungal pathogen Fusarium pseudograminearum (F. pseudograminearum) causes crown rot disease (CR) in wheat. This host-pathogen interaction has not been studied previously at the molecular level. In this study. using real-time quantitative PCR, the expression of 26 selected wheat genes was examined 1, 2 and 4 days after inoculation of wheat seedlings of the CR susceptible cultivar Kennedy and the partially field-resistant cultivar Sunco. Reproducible induction of eight defence genes consisting of PR1.1, PR2 (beta,1-3 glucanase), PR3 (chitinase), PR4 (wheativin), PR5 (thaumatin-like protein). TaPERO (peroxidase), PR10 and TaGLP2a (germin-like) was observed. These genes were induced in both cultivars, however. some genes were induced more rapidly in Sunco than in Kennedy. MJ treatment also induced the above pathogen responsive defence genes in both cultivars while benzo(1,2,3)thiadiazole-7-carbothionic acid S-methyl ester (BTH) treatment weakly induced them in Kennedy only. Similarly. treatment with MJ before inoculation significantly delayed the development of necrotic symptoms for 2 weeks in both wheat cultivars, while BTH pre-treatments delayed symptom development in Kennedy only. The chemically induced protection, therefore, correlated with induction of the F. pseudograminearum-responsive genes. These results support the emerging role of jasmonate signalling in defence against necrotrophic fungal pathogens in monocots and future manipulation of this pathway may improve CR resistance in wheat. (c) 2006 Elsevier Ltd. All rights reserved.

Sowing date reduces the incidence of wheat blast disease.

2016

Comparison of the coat protein, movement protein and RNA polymerase gene sequences of Australian, Chinese, and American isolates of barley yellow dwarf virus transmitted by Rhopalosiphum padi

Barley yellow dwarf luteovirus-GPV (BYDV-GPV) is a common problem in Chinese wheat crops but is unrecorded elsewhere. A defining characteristic of GPV is its capacity to be transmitted efficiently by both Schizaphis graminum and Rhopaloshiphum padi. This dual aphid species transmission contrasts with those of BYDV-RPV and BYDV-SGV, globally distributed viruses, which are efficiently transmitted only by Rhopaloshiphum padi and Schizaphis graminum respectively. The viral RNA sequences encoding the coat protein (22K) gene, the movement protein (17K) gene, the region surrounding the conserved GDD motif of the polymerase gene and the intergenic sequences between these genes were determined for GPV and an Australian isolate of BYDV-RPV (RPVa). In all three genes, the sequences of GPV and RPVa were more similar to those of an American isolate of BYDV-RPV (RPVu) than to any other luteovirus for which there is data available. RPVa and RPVu were very similar, especially their coat proteins which had 97% identity at the amino acid level. The coat protein of GPV had 76% and 78% amino acid identity with RPVa and RPVu respectively. The data suggest that RPVu and RPVa are correctly named as strains of the same serotype and that GPV is sufficiently different from either RPV strain to be considered a distinct BYDV type. The coat protein and movement protein genes of GPV are very dissimilar to SGV. The polymerase sequences of RPVu, RPVa and GPV show close affinities with those of the sobemo-like luteoviruses and little similarity with those of the carmo-like luteoviruses. The sequences of the coat proteins, movement proteins and the polymerase segments of BYDV serotypes, other than RPV and GPV, form a cluster that is separate from their counterpart sequences from dicot-infecting luteoviruses. The RPV and GPV isolates consistently fall within a dicot-infecting cluster. This suggests that RPV and GPV evolved from within this group of viruses. Since these other viruses all infect dicots it seems likely that their common ancestor infected a dicot and that RPV and GPV evolved from a virus that switched hosts from a dicot to a monocot.

Rice ragged stunt oryzavirus genome segment S4 could encode an RNA dependent RNA polymerase and a second protein of unknown function

The complete nucleotide sequence of genome segment S4 of rice ragged stunt oryzavirus (RRSV, Thai-isolate) was determined. The 3823 bp sequence contains two large open reading frames (ORFs). ORF1, spanning nucleotides 12 to 3776, is capable of encoding a protein of M(r) 141,380 (P4a). The P4a amino acid sequence predicted from the nucleotide sequence contains sequence motifs conserved in RNA-dependent RNA polymerases (RDRPs). When compared for evolutionary relationships with RDRPs of other reoviruses using the amino acid sequences around the conserved GDD motif, P4a was shown to be more related to Nilaparvata lugens reovirus and reovirus serotype 3 than to rice dwarf phytoreovirus, bovine rotavirus or bluetongue virus. The ORF2, spanning nucleotides 491 to 1468, is out of frame with ORF1 and is capable of encoding a protein of 36, 920 (P4b). Coupled in vitro transcription-translation from cloned ORF2 in wheat germ extract confirmed the existence of ORF2 but in vivo production and possible function of P4b is yet to be determined.

Resistance to root-lesion nematodes (Pratylenchus thornei and P-neglectus) in synthetic hexaploid wheats and their durum and Aegilops tauschii parents.

Root-lesion nematodes (Pratylenchus thornei Sher and Allen and P. neglectus (Rensch) Filipijev and Schuurmans Stekhoven) cause substantial yield loss to wheat crops in the northern grain region of Australia. Resistance to P. thornei for use in wheat breeding programs was sought among synthetic hexaploid wheats (2n= 6x = 42, AABBDD) produced through hybridisations of Triticum turgidum L. subsp. durum (Desf.) Husn (2n= 4x = 28, AABB) with Aegilops tauschii Coss. (2n= 2x = 14, DD). Resistance was determined for the synthetic hexaploid wheats and their durum and Ae. tauschii parents from the numbers of nematodes in the roots of plants grown for 16 weeks in pots of pasteurised soil inoculated with P. thornei. Fifty-nine (32%) of 186 accessions of synthetic hexaploid wheats had lower numbers of nematodes than Gatcher Selection 50a (GS50a), a partially resistant bread wheat. Greater frequencies of partial resistance were present in the durum parents (72% of 39 lines having lower nematode numbers than GS50a) and in the Ae. tauschii parents (55% of 53 lines). The 59 synthetic hexaploids were re-tested in a second experiment along with their parents. In a third experiment, 11 resistant synthetic hexaploid wheats and their F-1 hybrids with Janz, a susceptible bread wheat, were tested and the F(1)s were found to give nematode counts intermediate between the respective two parents. Synthetic hexaploid wheats with higher levels of resistance resulted from hybridisations where both the durum and Ae. tauschii parents were partially resistant, rather than where only one parent was partially resistant. These results suggest that resistance to P. thornei in synthetic hexaploid wheats is polygenic, with resistances located both in the D genome from Ae. tauschii and in the A and/or B genomes from durum. Five synthetic hexaploid wheats were selected for further study on the basis of (1) a high level of resistance to P. thornei of the synthetic hexaploid wheats and of both their durum and Ae. tauschii parents, (2) being representative of both Australian and CIMMYT (International Maize and Wheat Improvement Centre) durums, and (3) being representative of the morphological subspecies and varieties of Ae. tauschii. These 5 synthetic hexaploid wheats were also shown to be resistant to P. neglectus, whereas GS50a and 2 P. thornei-resistant derivatives were quite susceptible. Results of P. thornei resistance of F(1)s and F(2)s from a half diallel of these 5 synthetic hexaploid wheats, GS50a, and Janz from another study indicate polygenic additive resistance and better general combining ability for the synthetic hexaploid wheats than for GS50a. Published molecular marker studies on a doubled haploid population between the synthetic hexaploid wheat with best general combining ability (CPI133872) and Janz have shown quantitative trait loci for resistance located in all 3 genomes. Synthetic hexaploid wheats offer a convenient way of introgressing new resistances to P. thornei and P. neglectus from both durum and Ae. tauschii into commercial bread wheats.

小麦SKP1同源基因TSK1的克隆和功能分析

SKP1 (S-phase kinase-associated-protein 1) 家族蛋白是普遍存在于真核生物中的一类小分子量蛋白质，其主要的生物学功能在于参与SCF复合体的形成，从而调控生物体内泛素介导的蛋白质降解，并参与多方面的生物发育过程。SKP1蛋白能够同时和Cullin蛋白以及F-box蛋白结合，形成SCF复合体的核心部分。因此，SKP1正常功能的维持对于SCF复合体功能的实现至关重要。研究显示，植物中尤其是以拟南芥为代表模式植物中已经发现了21个SKP1基因成员，并发现其中的ASK1参与了多个SCF复合体的形成并调控着包括植物雄性减数分裂、生长素、赤霉素、茉莉酸和乙烯等生理和发育进程。但是来自高等植物尤其是小麦和水稻中的SKP1基因还鲜有报道，其功能还不为所知;此外，SKP1基因与ABA的关系还没有任何报道。 　　本文利用筛选小麦减数分裂期小花的cDNA文库结合RT-PCR的方法从小麦中分离到了一个SKP1同源基因，并命名为TSK1 (Triticum aestivum SKP1-Like 1)。序列比较结果显示TSK1与多个植物来源的SKP1基因有较高的同源性，对其推测的编码蛋白序列的分析发现TSK1与包括拟南芥来源的ASK1/ASK2等蛋白的羧基端存在非常高的保守性。 　　在对TSK1表达模式的研究中，本文发现TSK1主要是集中在小麦花序和幼根中表达。利用多种激素对小麦幼苗处理之后，发现TSK1的表达受ABA的抑制，但是当小麦中ABA合成受抑的情况下，TSK1的表达会有所增加，说明TSK1的表达受ABA的调控。RNA原位杂交显示TSK1基因在花顶端分生组织、花药以及幼根等分生较旺盛的组织中有较强的表达，暗示该基因可能参与了与细胞分裂相关的过程。 　　为了研究TSK1可能具有的功能，本文首先在ask1-1突变体背景上超表达TSK1，发现能够部分恢复ask1-1突变体雄性不育的表型，说明TSK1和ASK1在植物减数分裂过程中存在某种保守性。 　　在野生型拟南芥中超表达TSK1造成了拟南芥多个方面的变化，包括萌发和开花推迟，气孔开度减小等。进一步的观察发现，转基因植株的萌发和营养生长都呈现出对ABA的超敏感，后续证据证实这种ABA的超敏感性并不是由于转基因拟南芥中ABA合成途径的改变所造成的，而极有可能是影响了ABA的信号传导过程。RT-PCR的结果显示，转基因植株中多个ABA相关的已知基因表达量的发生了变化。 　　为了提供植物中SKP1家族成员参与调节植物ABA信号传导途径证据，本文对拟南芥ASK1/ask1 ASK12/ask2的杂合双突变体自交后代进行了研究。结果显示，ask1/ask1纯合突变体和ask1/ask1 ASK2/ask2植株表现出对ABA的弱敏感性。该结果从另一个侧面印证了TSK1超表达植株对ABA超敏感表型。 　　此外，TSK1超表达拟南芥也表现出生长素相关表型，也印证了该基因可能与ASK1类似，参与到生长素介导的根发育过程。 　　综上所述，本文认为TSK1参与了植物激素介导的植物发育过程，而且极有可能是形成了目前未知的某种SCF复合体。最重要的是，本文的结果为SCF复合体参与调节植物ABA信号传导途径提供了生理及遗传层面的证据。 　　 　　

冬小麦抗寒性和光合作用对增强UV-B辐射与温度交互作用的响应

人类活动产生的氯氟烃化合物破坏了大气臭氧层，导致了到达地球表面的UV-B辐射大幅度增加。UV-B辐射增强可以影响到植物的生长、形态与发育等各个方面，因此有关增强UV-B辐射对植物的影响，及其与许多环境因子复合作用的研究都已经广泛开展。但是增强UV-B辐射与温度，特别是与低温的相互作用的研究报道很少。在北半球的晚秋至早春这段时期里，一些越冬生长的植物将面临着UV-B辐射增强和低温的双重胁迫，因此，迫切需要进行UV-B辐射和低温生长环境下植物的响应及其机制的研究。 以人工气候生长室中生长的冬小麦(Triticum aestivum)幼苗为试验材料，研究了低剂量（4.2 kJ m-2 d-1 UV-BBE，LUVB）和较高剂量（7.0 kJ m-2 d-1 UV-BBE，HUVB）UV-B辐射处理对20/16℃条件下幼苗抗寒力的交叉适应性及其抗氧化系统的反应;同时还研究了在两种生长温度（25/20℃和10/5℃）条件下，低剂量（4.2 kJ m-2 d-1 UV-BBE，LUVB）和超高剂量（10.3 kJ m-2 d-1 UV-BBE，SHUVB）UV-B辐射处理幼苗的生长速率、光合与荧光参数、叶黄素循环色素、抗氧化系统、以及抗寒性和酚类物质等生理反应，以期阐明不同温度条件下生长的冬小麦对UV-B辐射的生长、光合作用以及抗寒性响应与适应机制。主要结果如下： 1.在LUVB辐射处理下，在20/16℃和25/20℃条件下生长的冬小麦幼苗LT50值都显著降低，HUVB辐射处理对在20/16℃条件下生长的幼苗LT50值也可以显著降低，而SHUVB辐射对25/20℃条件下生长的幼苗LT50值没有显著影响。但是，LUVB和SHUVB辐射处理都导致了10/5℃条件下生长的幼苗LT50值的显著增加。表明适当的UV-B辐射能增强较高温度（20/16℃或25/20℃）条件下冬小麦幼苗的抗寒力，即表现出对冷冻低温的交叉适应性，但低温（10/5℃）生长条件却削弱了UV-B辐射下冬小麦的抗寒能力。 2.在20/16℃条件下接受UV-B辐射预处理的幼苗在-6℃条件下冷冻胁迫6 h再缓慢恢复6 h后，与未进行UV-B辐射处理的对照相比，其叶片过氧化氢酶（CAT）、愈创木酚过氧化物酶（GPX）、谷胱甘肽还原酶（GR）活性，谷胱甘肽氧化还原比例（GSH/GSSG）都显著提高，而由硫代巴比妥酸反应物质（TBARS）代表的膜质过氧化程度显著低于对照。此外，UV-B辐射期间处理幼苗的H2O2含量较对照显著增加，而冷冻恢复以后却明显低于对照。表明UV-B辐射诱导的抗寒力的提高应该与冷冻恢复后植株体内抗氧化系统的上调表达有关，H2O2可能参与了UV-B辐射对低温的交叉适应的信号传导。 3.除25/20℃生长条件下的LUVB处理的小麦幼苗外，UV-B辐射显著降低幼苗的相对生长速率（RGR）、净光合速率（Pn）、光系统II最大量子产量（Fv/Fm）、光系统II实际量子产量（(F΄m−Fs)/F΄m）以及光化学淬灭（qP），但是UV-B辐射并不影响叶片胞间CO2浓度（Ci），而且冬小麦幼苗生长和光合作用的抑制被增加的UV-B辐射剂量和降低的温度加强。UV-B辐射引起的光抑制由非气孔限制所导致，而且主要与PS II光化学效率降低有关。 4.UV-B辐射显著增加了两个温度条件（20/16℃或25/20℃）下生长的冬小麦幼苗叶黄素循环过程中紫黄素（V）的合成，但抑制了V向玉米黄质（Z）的转化，从而造成了对照与LUVB辐射处理幼苗之间的叶片中脱环氧化比例（DEPS）和NPQ无显著性差异，但SHUVB辐射处理幼苗叶片中DEPS和NPQ显著降低。因此，在本试验条件下，增强UV-B辐射处理的冬小麦可能并不通过热耗散形式形成光保护机制，光抑制形成的过剩激发能的耗散可能更多地通过代谢途径来实现。 5.UV-B辐射处理提高了在25/20℃条件下幼苗的超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）和GR等活性，以及抗坏血酸氧化还原比例（AsA/DHA）和GSH/GSSG;但是在10/5℃下，UV-B辐射除了导致SOD和CAT活性升高之外，对APX活性和AsA/DHA并不产生明显影响，但GPX和GSH/GSSG则显著降低。说明UV-B辐射幼苗的抗氧化系统在较高生长温度下显著地增强，而在低温10/5℃下被严重地削弱或降低，即低温阻止了代谢途径的光保护机制的正常运转。 6.多酚物质在UV-B辐射或低温10/5℃条件下都能显著地累积，且在UV-B辐射和低温复合作用下增加尤其显著，表明多酚物质在两个温度生长条件下特别是低温条件下都参与了对UV-B辐射幼苗的保护。 7.在高温条件下仅仅SHUVB处理的幼苗TBARS含量显著增加，而低温10/5℃条件下两个UV-B辐射处理都非常显著地上升，说明与高温生长条件相比较，低温加重了UV-B辐射引起的氧化胁迫，低温10/5℃条件下幼苗多酚的增加以及抗氧化系统的部分增强都没有能阻止UV-B辐射对幼苗的伤害。

小麦高分子量谷蛋白新亚基基因1Dx5’的克隆与分子标记

小麦是世界第一大粮食作物, 而HMW- GS 是直接影响小麦品质的重要因子。我国小麦面粉的烘烤品质普遍较差, 这与我国品种缺少优质的HMW- GS 有关，因此创造与发掘新的优质谷蛋白亚基编码基因，并开展相关生化、农学、分子生物学等方面研究、探讨优质的分子机理，对于培育优质小麦新品种具有重要意义。W958是我们培育的种间远缘杂交（T.durum Desf. ×T.aestivum L���优良品系，该品系在1D染色体上具有父母本没有的新型亚基，由于此亚基在SDS- PAGE电泳中具有和1Dx5亚基一样的电泳迁移率, 因此我们将该亚基命名为1Dx5’亚基。为了进一步从分子水平确证该亚基为新亚基和在育种中利用该亚基，本研究对该亚基的遗传规律、基因分子结构、品质特性和农艺性状等进行了分析。结果表明1Dx5’亚基在品质上与1Dx5亚基一样优质，对于品质的贡献大于1Dx2亚基。1Dx5’亚基具有特异的遗传规律，在分离群体中，此亚基占有极大的比例，该特性十分有利于将其导入高产小麦遗传背景中。此外，本研究扩增出了1Dx5’亚基基因的启动子区域、N－端区域和部分中间重复区域，并比较了1Dx5’和传统的1Dx5、1Dx2亚基在此区域氨基酸序列。结果进一步证明了1Dx5’是一个新的基因。通过蛋白质结构模拟分析，认为1Dx5’亚基的优良特性可能是由于1Dx5’亚基的的中部重复区域能形成分子间较强的氢键，加大了分子间的相互作用，使1Dx5’亚基的面团具有优良的品质，这为1Dx5’亚基的应用提供了理论基础。同时，本研究还设计用于区分1Dx5’和1Dx5等位基因的分子标记，解决了利用SDS-PAGE生化标记难以将二者区分的问题。Wheat is one of the major crops utilized worldwide. Nevertheless, due to the lackof the superior HMW- GS, the wheat quality in China is not satisfying. Therefore,identification and characterization of the superior HMW- GS will lay good foundation to the wheat breeding.W958 is a new bread wheat line developed by interspecific cross (T.durum Desf.×T.aestivum L). It contains a novel HMW- GS. We have designated such subunit as1Dx5’ here for its unique character. To confirm that such subunit is innovative andbeneficial for wheat breeding program on the molecular level, we have investigated itin terms of inheritance, DNA and protein sequence, dough property and agronomictrait associated with it. The result shows that 1Dx5’is as superior as 1Dx5 in terms of dough property.In addition, we have cloned the promoter, N- terminal as well as partial centralrepetitive domain of the allele coding for this subunit. Comparison of the amino acidsequence of 1Dx5’ with that of 1Dx5 and 1Dx2 showed that the superior quality of1Dx5’ subunit may result from the degree of conservation of the repetitive sequencesby which the glutenin polymers interact via inter-chain hydrogen bonds formedbetween the subunit repetitive domains with longer subunits forming more stableinteractions. In addition, we have developed two dominant molecular markers tofacilitate the discrimination of 1Dx5’ and 1Dx5 which could no be achieved by SDS-PAGE.

Reconhecimento oficial de área livre do nematóide Anguina tritici (Steinbuch, 1799) Chitwood, 1935, no estado de Virginia; EUA, para exportação de trigo para o Brasil.

2002

Modelagem molecular da proteína small heat shock de Xylella fastidiosa.

Este documento descreve o modelo molecular da proteína XF2234 e a análise preliminar da sua estrutura. O modelo foi construído por modelagem por homologia (ou modelagem comparativa) com a estrutura cristalográfica de uma proteína small heat shock de Triticum aestivum (trigo). A análise da estrutura tridimensional da proteína XF2234 tem o objetivo de contribuir para aumentar o conhecimento sobre o papel biol��gico das smHSPs, necessário para o combate à CVC.

Trigo Embrapa 41: nova cultivar para Minas Gerais, Goiás e Distrito Federal.

1997