橡胶草萌发期耐盐碱性鉴定评价及优异种质挖掘

Identification and evaluation of saline-alkali tolerance at germination stage and elite germplasm screening of Taraxacum kok-saghyz Rodin

    摘要
  • 摘要: 【目的】 对橡胶草种质资源萌发期耐盐碱性进行鉴定评价，建立耐盐碱性鉴定评价体系，并筛选耐盐碱性种质，为挖掘橡胶草耐盐碱基因及选育耐盐碱品种提供理论参考。【方法】 以36份橡胶草种质资源为材料，采用NaCl∶Na2SO4∶NaHCO3=3∶1∶1（物质的量比）溶液模拟盐碱胁迫，设置0、50、100、150、200和250 mmol/L 6个混合盐碱浓度梯度，分析3份橡胶草种质（K445、TK30和TK37）的发芽势和发芽率，筛选橡胶草萌发期耐盐碱性鉴定评价最适胁迫浓度。根据筛选出的最适胁迫浓度，对36份橡胶草种质萌发期进行盐碱胁迫试验，以蒸馏水处理作为对照组（CK），根据橡胶草种质的相对发芽势、相对发芽率、相对发芽指数、伤害率、相对芽长和相对根长等耐盐碱相关性状比值，对其进行相关分析、主成分分析、综合评价和聚类分析。【结果】 在不同浓度盐碱胁迫条件下，K445、TK30和TK37的发芽势和发芽率均随混合盐碱溶液浓度升高而降低。当胁迫浓度为150 mmol/L时，供试橡胶草具有丰富的遗传变异，故以150 mmol/L作为橡胶草耐盐碱性评价的最适浓度。在150 mmol/L盐碱溶液胁迫处理下，处理组的发芽势、发芽率、发芽指数、芽长和根长均低于CK。6个耐盐碱相关性状变异系数为6.64%~54.37%，其排序为相对根长<相对芽长<伤害率<相对发芽指数<相对发芽率<相对发芽势。相对发芽势与相对发芽率和相对发芽指数均呈极显著正相关（P<0.01，下同），与伤害率呈极显著负相关；相对发芽率与相对发芽指数呈极显著正相关，与伤害率呈极显著负相关；相对发芽指数与伤害率呈极显著负相关；相对芽长与相对根长呈显著正相关（P<0.05）。6个指标转化为2个主成分的累计贡献率达84.276%。36份橡胶草种质可分为四大类群，分别鉴定出1份高度耐盐碱种质、15份中度耐盐碱种质、13份耐盐碱种质和7份盐碱敏感种质。依据D值建立橡胶草耐盐碱鉴定评价回归方程：D=-0.527+0.236X1+0.758X2+0.412X3+0.493X4+0.224X5-0.244X6，该回归方程拟合效果较好，可用于橡胶草种质资源耐盐碱性鉴定评价。【结论】 橡胶草萌发期耐盐碱性最适胁迫浓度为150 mmol/L，该盐碱胁迫浓度对橡胶草萌发期6个耐盐碱相关性状均起抑制作用。从36份橡胶草种质中分别鉴定出1份高度耐盐碱种质和7份盐碱敏感种质。相对发芽率、相对根长、相对芽长、相对发芽指数、相对发芽势和伤害率6个耐盐碱相关性状，可作为橡胶草种质萌发期耐盐碱性鉴定评价指标。

     

    Abstract: 【Objective】 This study aimed to evaluate the saline-alkali tolerance of Taraxacum kok-saghyz Rodin germplasm resources at germination stage， and establish an evaluation system of saline-alkali tolerance，so as to provide theoretical references for screening saline-alkali tolerance genes and breeding saline-alkali tolerant cultivars. 【Method】 Thirty-six germplasm resources of Taraxacum kok-saghyz Rodin were as materials， and a solution with NaCl∶Na2SO4∶NaHCO3=3∶1∶1 （molar ratio） was used to simulate saline-alkali tolerance. Six mixed saline-alkali concentration gradients were set at 0， 50， 100， 150， 200， and 250 mmol/L. The germination potential and germination rate of three Taraxacum kok-saghyz Rodin germplasms （K445， TK30， and TK37） were analyzed to screen the optimal tolerance concentration for identifying and evaluating saline-alkali tolerance at germination stage. Under the screened optimal tolerance concentration， a saline-alkali tolerance experiment was conducted on 36 Taraxacum kok-saghyz Rodin germplasms at germination stage， with distilled water treatment as the control group （CK）. Based on trait ratios related to saline-alkali tolerance such as relative germination potential， relative germination rate， relative germination index， damage rate， relative bud length， and relative root length， correlation analysis， principal component analysis， comprehensive evaluation， and cluster analysis were performed. 【Result】 Under conditions of different concentrations of saline-alkali stress， the germination potential and germination rate of K445， TK30， and TK37 all decreased as the concentration of mixed saline-alkali solution increased. At the stress concentration reached 150 mmol/L， the tested Taraxacum kok-saghyz Rodin exhibited rich genetic variation， so 150 mmol/L was identified as the suitable concentration for evaluating the saline-alkali tolerance. Under stress treatment with 150 mmol/L saline-alkali solution， the germination potential， germination rate， germination index， bud length， and root length of the treatment group were all lower than those of CK. The coefficients of variation for the six saline-alkali tolerance-related traits ranged from 6.64% to 54.37%， ranked as relative root length<relative bud length<damage rate<relative germination index<relative germination rate<relative germination potential. Relative germination potential showed an extremely significant positive correlation （P<0.01， the same below） with both relative germination rate and relative germination index， and an extremely significant negative correlation with the damage rate. Relative germination rate showed an extremely significant positive correlation with relative germination index， and showed an extremely significant negative correlation with the damage rate. Relative germination index showed an extremely significant negative correlation with the damage rate. Relative bud length showed a significant positive correlation with relative root length （P<0.05）. The cumulative contribution rate of the two principal components transformed from the six indexes reached 84.276%. The 36 Taraxacum kok-saghyz Rodin germplasms could be classified into four clusters： one was identified as highly saline-alkali tolerant germplasm， 15 as moderately saline-alkali tolerant germplasms， 13 as saline-alkali tolerant germplasms， and seven as saline-alkali sensitive germplasms. Based on the D value， a regression equation for the identification and evaluation of saline-alkali tolerance was established： D=-0.527+0.236X1+0.758X2+0.412X3+0.493X4+0.224X5-0.244X6. This regression equation demonstrated a good fit and could be used for the identification and evaluation of saline-alkali tolerance of Taraxacum kok-saghyz Rodin germplasm resources. 【Conclusion】 The optimal saline-alkali stress concentration for evaluating salt-alkali tolerance of Taraxacum kok-saghyz Rodin at germination stage is 150 mmol/L. This concentration inhibits six traits related to saline-alkali tolerance measured at germination stage. Among the 36 Taraxacum kok-saghyz Rodin germplasms， one highly saline-alkali tolerant germplasm and seven saline-alkali sensitive germplasms are identified. The six traits related to saline-alkali tolerance （relative germination rate， relative bud length， relative root length， relative germination index， relative germination potential， and damage rate） could serve as effective indexes for identif-ying and evaluating saline-alkali tolerance of Taraxacum kok-saghyz Rodin germplasms at germination stage.

     

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