小豆种子萌发期耐旱性评价及耐旱种质资源筛选

Evaluation and screening of adzuki bean germplasm resources for drought tolerance during germination stage

【目的】研究80份小豆种质材料萌发期的耐旱性,筛选小豆耐旱种质,为小豆耐旱品种选育、耐旱生理机制及分子机制研究提供理论参考。【方法】采用甘露醇模拟干旱胁迫的方法对80份小豆种质材料种子萌发期耐旱性进行初步鉴定,以相对发芽率作为耐旱性评价的参考指标,从中筛选出3份不同耐旱性的小豆种质材料,对其进行不同浓度梯度甘露醇(0、5.0%、7.5%和10.0%)干旱胁迫试验,以确定小豆萌发期耐旱性鉴定的最适甘露醇浓度。然后用最适浓度的甘露醇溶液对初步鉴定为高耐、耐旱和弱耐的种质资源进行干旱胁迫,以相对发芽率、相对发芽势和相对根鲜重等作为耐旱性评价指标,并采用隶属函数法对小豆萌发期耐旱性进行综合评价。【结果】初步鉴定获得高耐种质3份、耐旱种质9份、中耐种质37份、弱耐种质4份。10.0%甘露醇对种子萌发有明显的抑制作用,达不到发芽标准,而5.0%甘露醇对3份材料种子萌发的影响无明显差异,小豆种子耐旱性鉴定的最适甘露醇浓度为7.5%。用7.5%甘露醇溶液模拟干旱胁迫对初步鉴定获得的16份小豆种质(3份高耐种质、9份耐旱种质和4份弱耐种质)进行萌发期耐旱性等级划分,共发现2份高耐种质、4份耐旱种质、7份中耐种质、2份较敏感种质和1份敏感种质。16份小豆种质耐旱性初步鉴定与隶属函数法鉴定结果存在差异,但二者相关系数为0.63,呈极显著正相关(P<0.01,下同)。【结论】以相对发芽率为参考指标对小豆种质资源的耐旱性进行初步鉴定,可实现在短时间内获取大量小豆种质萌发期耐旱性的基本情况。但利用多项指标综合评价的隶属函数法评价种质资源的耐旱性更全面,鉴定结果更可靠。筛选出的耐旱性强的种质资源可用于小豆抗旱性育种,也可用于开展分子水平的耐旱机制研究。

【Objective】The drought tolerance of 80 adzuki bean materials during seed germination was studied,and drought-tolerant germplasms were screened to provide theoretical reference for breeding of adzuki bean drought-tolerant varieties and studying on physiological and molecular machanism of drought tolerance.【Method】Average relative germination rate was as a reference index to identification of the drought tolerance of 80 adzuki bean germplasms during seed germination with mannitol simulating drought stress,screening out three Adzuki bean germplasm whose tolerance to drought was different. The three germplasm were treated with different concentrations of mannitol(0,5.0%,7.5% and 10.0%)to determine the optimal concentration of mannitol to conduct the identification of drought tolerance. The germplasm resources with high,medium and weak level of drought tolerance were subjected to drought stress with the optimal concentration of mannitol,with comprehensive evaluation indexes including relative germination rate,relative germination potential and relative root fresh weight of seeds,subordinative function method was used to assess the level of drought tolerance.【Result】Three high drought-tolerant germplasms,nine drought-tolerant germplasm,37 medium droughttolerant germplasms and 4 low drought-tolerant germplasms were obtained. 10.0% mannitol had obvious inhibitory effect on seed germination,which could not reach the germination standard,while 5.0% mannitol had no obvious influence on seed germination among three materials. Therefore,7.5%was the optimum concentration of mannitol solution for identifying of drought tolerance. For identification of drought tolerance level of sixteen adzuki bean germplasms(three high droughttolerant level germplasms,nine drought-tolerant germplasms and four low drought-tolerant germplasms),with 7.5% mannitol solution simulated drought stress,two belonged to high drought-tolerant germplasms,four drought-resistant germplasms, seven medium drought-resistant germplasms,two sensitive germplasms,one very sensitive germplasm. There were differences between the results of preliminary identification and subordinative function method identification of 16 samples of Adzuki bean germplasms,but the correlation coefficient(0.63)showing an extremely significant positive correlation between them(P<0.01,the same below).【Conclusion】The drought tolerance of adzuki bean resources is preliminarily identified with the relative germination rate as the reference index,which can obtain the drought tolerance situation at germination period of adzuki bean materials within a short period of time.However,it is more comprehensive and reliable to evaluate drought tolerance of germplasms by subordinative function method with multiple indexes.The selected drought-tolerant germplasms can be used for drought-tolerance breeding of adzuki bean,and the molecular drought-tolerant mechanism can be further studied.