【作者】 Tauqeer Ahmad Yasir；

【导师】 胡银岗；

【作者基本信息】 西北农林科技大学 ， 作物遗传育种， 2013， 博士

【摘要】 干旱是影响作物产量的一个重要因素。增加旱区作物产量和水分利用效率对提高粮食总产非常重要。为了明确小麦碳同位素分辨率在小麦抗旱节水育种中的利用价值，本研究以49份小麦品种为材料，在两个水平的水分处理条件下（W120and W200），对碳同位素分辨率（Δ）与气孔导度、产量性状以及叶绿素含量的相关性进行了分析。实验于2010年-2011年在西北农林科技大学旱区研究院抗旱大棚内进行，灌浆期进行水分胁迫，重度水分胁迫处理比适度水分胁迫处理少浇40％的水。并对碳同位素分辨率候选基因TaER在各种质间的SNP进行了检测，分析了其与抗旱性相关指标的关联性。取得的主要结果如下：研究发现，小麦Δ与光合速率、气孔导度（gs）、蒸腾速率（E）、胞间CO₂浓度与大气CO₂浓度比（Ci/Ca）呈显著正相关；而与内源水分利用效率（iWUE）呈显著负相关。在两个水分处理下，Δ与产量（GY）、生物量（BM）和收获系数（HI）都呈显著正相关，而与叶绿素含量没有显著相关性。以Δ为标准，分别以五个Δ值高的材料和五个Δ值低的材料为研究对象，计算相关指标的平均值。发现在两个水分处理下，除了iWUE外，高Δ值材料的各性状指标的平均值均高于低Δ值的材料。结果表明，Δ可以作为一个水分胁迫下相关性状选择的一个间接指标。小麦Δ被认为是提高小麦抗旱性和产量的一个有力的辅助选择性状。本研究分析了2011-2012生长周期收获的小麦籽粒的灰分含量、微量元素含量（Ca, K, Mg, Fe and Mn），并分析了其与籽粒Δ及产量的关系，以评价其作为Δ的替代指标的可行性。结果表明，叶绿素含量（Chl）与籽粒Δ和产量在中度水分胁迫下（W200）极显著相关。在两个处理中，灰分含量（AC）、钾浓度（K）与籽粒Δ呈显著负相关，灰分含量（AC）与产量也呈负相关。然而，在W120处理下，锰含量与籽粒Δ呈负相关、镁含量在W200处理下与籽粒Δ呈负相关。在两个处理下，籽粒Δ与光合速率（A）、气孔导度（gs）、产量（GY）呈显著正相关，和内源水分利用效率（iWUE）成负相关。在中度水分胁迫下，叶绿素含量可以作为产量选择的一个有力指标。籽粒灰分含量和钾含量可以作为干旱条件下衡量产量潜力差异、评价籽粒Δ的可用替代指标。采用基于产量的抗旱相关指标（MP, GMP, STI, SSI, TOL, YI and YSI），分析评价了水分胁迫（Ys）和充分供水（Yp）环境下不同小麦品种的形态、产量相关性状和气孔特性等性状，以筛选适应指标和筛选抗旱材料。水分胁迫下所有性状的平均值都下降，生物量和产量受水分胁迫最明显，较充分灌水降低了25％。气孔性状和穗长对水分胁迫最不明显，下降幅度不到10％。在重度水分胁迫（Ys）和中度水分胁迫（Yp）下，产量和抗旱相关指标MP、GMP和STI呈显著正相关，与抗旱相关指标TOL、SSI和YSI相比，能较好地反映小麦品种的抗旱性和产量潜力。主成分分析可将供试材料分为三类。第一类包含对干旱高敏感的材料；第二类包含高抗旱性材料；第三类主要为产量很低的材料。聚类分析把供试材料分为两大类，一类为抗旱性好产量稳定的材料；一类为干旱敏感但产量较高的材料。抗旱相关指标MP、GMP和STI在抗旱性筛选中具有较好的利用价值，可以应用到育种中。对TaER基因的一个片段（1.1Kb）（TaER-1位于D染色体组；TaER-2位于B染色体组）在供试材料中的SNP进行了分析，并对其与碳同位素分辨率、光合效率、气孔导度、蒸腾速率、内源水分利用效率、株高叶长、气孔密度和表皮细胞密度等性状的相关性进行了分析。结果表明，在33份材料中，TaER-1基因的一段编码区（1105bp）中共检测到39个SNP，其中24个SNP引起错义突变，15个SNP引起同义突变。在26份材料中， TaER-2基因的一段编码区（1108bp）中共检测到32个SNP，其中18个SNP引起错义突变，13个SNP引起同义突变。同时，在TaER-1和TaER-2的非编码区还分别检测到35个和9个SNP。候选基因关联分析表明部分SNP与碳同位素分辨率、光合效率、气孔导度、蒸腾速率、内源水分利用效率、株高叶长、气孔密度、表皮细胞密度等性状存在相关性。更多还原

【Abstract】 Drought is a major issue affecting crop grain yield. Augmenting grain yield and crop wateruse efficiency （WUE） under drought is crucial for enhancing world crop production and foodavailability. Relationships of carbon isotope discrimination （Δ） with gas exchange parameters,yield traits, ash contents, mineral concentrations, and leaf chlorophyll content （Chl） wereexamined on a collection of49-wheat （Triticum aestivum L.） genotypes under two levels ofrestricted irrigation （W120and W200）. Drought tolerance indices were also calculated and analysedto screen wheat genotypes for their drought tolerance. The trial was carried out under controlledirrigation in a rainout shelter. Water stress was applied at grain filling stage. The severe waterdeficit regime received40%less water than the moderate water deficit regime. The SNPs in thecandidate gene TaER were also investigated by sequencing and their correlations with those traitswere also estimated. The main results were as following.Analysis on the correlations between CID and the traits revealed that significant and positivecorrelations were found between Δ and photosynthesis rate （A）, stomatal conductance （gs）,transpiration rate （E）, and the ratio of intercellular CO₂concentration to ambient CO₂concentration （Ci/Ca）, while significant and negative correlations were obtained between Δ andintrinsic water use efficiency （iWUE） under both water regimes. Strong positive correlations of Δwith grain yield （GY）, biomass （BM） and harvest index （HI） were also observed in both waterregimes. Mean values of all other parameters were calculated for the five genotypes based on Δvalue, i.e. which produced the highest Δ and which produced the lowest Δ. It was found thatmean values for all the parameters in the high Δ genotypes were higher that for low Δ genotypesexcept for iWUE in both water regimes. These results suggest that Δ may be a good trait as anindirect selection criterion for genotypic improvement in drought tolerance of wheat underrestricted irrigation, especially in conditions similar to those encountered here where limitedwater was applied during grain filling.Carbon isotope discrimination （Δ） has been recognized as a valuable phenotyping tool in breeding wheat for drought adaptation and yield potential. The associations of ash content,concentrations of individual mineral （Ca, K, Mg, Fe and Mn） with grain Δ and grain yield wereinvestigated to assess the possibility for these traits as an alternative or reciprocal criterion tograin Δ in evaluating yield potential and drought tolerance in wheat. The results revealedsignificant （P <0.01） and negative correlations between ash content （AC） and potassiumconcentration （K） with grain Δ, and between AC and grain yield under both water regimes, whilemanganese concentration （Mn） was negatively correlated with grain Δ under W120regime andmagnesium concentration （Mg） correlated negatively under the W200regime. These resultsconfirmed that ash content and K concentration in grain could be a potentially useful andeconomical alternative criterion to grain Δ in the evaluation of differences in yield potential anddrought resistance in wheat under drought conditions.Drought tolerance indices （MP, GMP, STI, SSI, TOL, YI and YSI） based on the grain yieldunder water-stressed （Ys） and well-watered （Yp） environments were also calculated for thescreening of these genotypes for drought adaptation. The mean values for all the traits decreasedunder water-stressed treatment. Biological yield （BM） and grain yield （GY） were the mostsensitive traits to water stress which reduced by more than25%, while stomata characteristics andspike length were the least affected traits with a decrease of less than10%. Grain yield undersevere-stressed （Ys） and moderate-stressed （Yp） environments were positively and significantlycorrelated with the indices MP, GMP, and STI. So, these indices were considered as a betterpredictor of potential yield Ys and Yp than TOL, SSI and YSI. Principal component analysisclassified the genotypes into three groups. First group contained genotypes with high droughtsusceptibility and only suitable for non-stressed environments. Second group consisted ofdrought tolerant genotypes suitable for stressed environments. Third group included genotypeswith low yielding performance. Cluster analysis classified the genotypes into two groups i.e.,drought resistant with moderate to high yield stability group and drought susceptible with highyield performance group. MP, GMP and STI were found effective in screening genotypes withdifferent levels of drought tolerance. Therefore, these indices could successfully be used as aselection criterion for the screening of genotypes in breeding programs.Candidate gene based association study which involves the identification of causative singlenucleotide polymorphism （SNP） for excellent traits has been proposed as a promising approachto dissect complex traits in plants. The genetic association was identified between SNPs from1.1Kb partial sequence of wheat ERECTA genes （TaER-1and TaER-2from D-genome and B- genome of wheat, respectively） with different morpho-physiological traits （Carbon isotopediscrimination, photosynthesis rate, stomatal conductance, transpiration rate, intrinsic water useefficiency, plant height, leaf length, leaf width, stomatal density, epidermal cell density andstomatal index） in wheat genotypes. Thirty nine SNPs were identified in the coding regions of1105bp sequence of TaER-1gene in33genotypes, of which twenty four SNPs causednonsynonymous mutations and fifteen SNPs caused synonymous mutations. Whereas thirty oneSNPs were located in the coding regions of1108bp sequence of TaER-2gene in26genotypes,of which eighteen SNPs caused nonsynonymous mutations and thirteen SNPs causedsynonymous mutations. In addition, thirty five SNPs in TaER-1and nine SNPs in TaER-2werealso identified in the non-coding regions. The genetic association study revealed that SNPs inboth genes do associated with different morph-physiological properties.更多还原