大豆芽期耐高温评价方法构建及耐高温种质资源筛选

Construction of evaluation method for tolerance to high-temperature and screening of heat-tolerant germplasm resources of bud stage in soybean

极端高温事件频增导致大豆生产接连遭受高温热害,严重影响其产量构成和品质性状。种子在发芽阶段对外界环境变化较为敏感,温度升高及伴随而来的干旱等现象会影响大豆种子出苗。建立一套科学的大豆芽期耐高温评价方法,可以为早期耐高温鉴定、耐高温种质选育以及遗传机制研究提供理论基础。本研究以385份大豆种质资源为材料,利用人工气候培养箱创造高温环境,于芽期进行高温处理3 d(40℃,8 h光照/16 h黑暗)。相较于对照(25℃,8 h光照/16 h黑暗),高温处理后大豆芽期下胚轴长显著下降10.9%(P<0.05);根鲜重、根干重和根冠比等指标分别极显著增加了13.10%、22.20%和16.90%(P<0.01),结果表明,高温处理会显著影响大豆芽期地上部与地下部生物量的分布。对各性状耐高温系数进行主成分分析,将11个指标转换成3个主成分因子,进一步通过隶属函数标准化分析计算获得大豆响应高温胁迫综合评价值(H),并基于H值对参试品种进行聚类分析。最终将385份种质资源芽期耐高温特性划分为5个等级,即:Ⅰ级(耐高温型)、Ⅱ级(较耐高温型)、Ⅲ级(中间型)、Ⅳ级(高温较敏感型)和Ⅴ级(高温敏感型),综合试验中具体表现,筛选出4个芽期耐高温型大豆品种(H245、H070、H268和H216)。对各项指标逐步回归分析后,建立大豆芽期耐高温综合评价(H值)预测模型:H=0.191+0.017X_(1)–0.007X_(2)+0.013X_(7)+0.027X_(8)–0.009X_(10)(R^(2)=0.9752),筛选出下胚轴长(X_(1))、主根长(X_(2))、下胚轴干重(X_(7))、根鲜重(X_(8))和简化活力指数(X_(10))5个指标可以作为大豆芽期耐高温评价指标。

The frequent occurrence of extreme high temperature(HT)events causes continuous heat damage to soybean production,which seriously damages the yield components and quality traits.The seeds are sensitive to the changes of the external environment at germination stage.The rising temperature and the accompanying drought will affect the emergence of soybean seeds.The establishment of a set of scientific evaluation methods for HT tolerance at bud stage can provide a theoretical basis for the early identification of soybean,the breeding of HT tolerance germplasm,and the study of tolerance mechanism.In this study,385 germplasm resources varieties were selected as the experimental materials,which creating a HT environment by artificial climate incubator and subjected to HT-stress for 3 d(40℃,16 h light/8 h darkness)at bud stage of soybean.Compared with the control(25℃,16 h light/8 h darkness),the hypocotyl length of soybean bud stage was significantly decreased 10.9%under HT stress(P<0.05).The indices of fresh root weight,dry root weight,and root-shoot ratio increased by 13.10%,22.20%,and 16.90%,respectively(P<0.01).The results showed that HT-stress significantly affected the surface and underground biomass distribution of bud stage in soybean.Meanwhile,the principal component analysis for the coefficient of HT-tolerance for each trait converted 11 indexes into two principal component factors.The comprehensive evaluation value(H-value)of soybean response to HT-stress was obtained by the standardized analysis of membership function,and cluster analysis was conducted for the tested varieties based on H-value.Ultimately,385 germplasm resources were divided into 5 grades for the HT-tolerance at bud stage in soybean[namely:Grade Ⅰ(tolerance),Grade Ⅱ(strong tolerance),Grade Ⅲ(medium),Grade Ⅳ(strong sensitive),and Grade Ⅴ(sensitive type)]and four HT-resistant varieties based on the specific performance(H245,H070,H268,and H216)were initially selected combined with the actual heat resistance performance.After the stepwise regression analysis of each index,a predictive model for the comprehensive evaluation of HT tolerance(H-value)at bud stage of soybean was established:H=0.191+0.017X_(1)–0.007X_(2)+0.013X_(7)+0.027X_(8)–0.009X_(10)(R^(2)=0.9752).Five indexes main including hypocotyl length(X_(1)),main root length(X_(2)),hypocotyl dry weight(X_(7)),root fresh weight(X_(8)),and simplified vigor index(X_(10))were screened out as the evaluation indexes for HT tolerance at bud stage in soybean.