摘要：
Setaria viridis was a new model plant,which meets all the requirements of model plants.It was an excellent model of C4 photosynthesis,and for studying the tolerance of abiotic stress.Based on the efficient genetic transformation of Setaria viridis,the non-transgenic mature seeds of ME34 strain which was Setaria viridis suitable for transformation were choosen as explants to study drought tolerance.According to Mannitol medium culture method,0,200,300,400,500,600 mmol/L 6 gradients were designed.The germination rate,bud length,root length and fresh weight of each gradient were measured and analyzed.The results showed that the 200-300 mmol/L gradient of Mannitol were the key gradients of the Mannitol tolerance for ME34 strain.The germination rate,fresh weight,root length and bud length of seed germination were significant or extremely significant affected.The susceptibility of each growth index to mannitol drought stress was fresh weight＞root length＞bud length＞germination rate.There were significant or extremely significant correlations between the four parameters.The fresh weight was the most sensitive and direct to the mannitol stress and extremely significant reduced at 200 mmol/L gradient,which could be used as the first grade index for drought resistance identification at seed germination stage.The sensitivity of the root length to mannitol stress was also very strong,but as a drought resistance index,only the extremely significant gradient (200 mmol/L) was suitable for identification.In addition,bud length was also sensitive to mannitol,200,300 mmol/L,was the significant and extremely significant reduced gradient,respectively.Root length and bud length could be used as the second grade index for drought resistance identification at seed germination stage.The seed germination rate was not significant at 200 mmol/L,and it showed a extremely significant decrease under the condition of 300 mmol/L.Compared with other growth indexes,the susceptibility was weak,which could be used as the third grade of drought resistance identification index.The study prepared the identification and evaluation index of drought tolerance at seed germination stage for the pattern plant of Setaria viridis under Mannitol Stress.Whether the overexpression of exogenous drought-resistant genes of Setaria viridis,or the knockout of endogenous anti-drought gene,both need the support of these specific evaluation indicators.%狗尾草是一种新型的模式植物,符合作为模式植物的所有要求,是C4光合作用的优秀模型,也是研究非生物胁迫耐受性很好的模型.在狗尾草高效遗传转化技术的基础上,以适宜转化的狗尾草ME34品系非转基因成熟种子为外植体,根据甘露醇高渗培养基培养法,设计了0、200、300、400、500、600 mmol/L 6个梯度,对狗尾草ME34品系种子萌发期的抗旱性进行了鉴定.结果表明:甘露醇200～300 mmol/L的梯度是鉴定狗尾草ME34品系抗旱性的关键梯度,种子萌发期发芽率、鲜重、根长、芽长等各项生长指标都受到显著或极显著的影响,各生长指标对甘露醇干旱胁迫的敏感性依次为鲜重＞根长＞芽长＞发芽率,参数间两两显著或极显著正相关;鲜重对甘露醇的胁迫的反应最敏感和直接,在200 mmol/L梯度下已表现为极显著降低,可作为该品系种子萌发期抗旱性鉴定的一级指标;根长对甘露醇梯度的反应是低浓度促进根的生长,高浓度抑制根的生长,极显著促进生长的梯度(200 mmol/L)适合用作鉴定依据,此外,芽长对甘露醇也敏感,200、300 mmol/L分别显著和极显著抑制芽长,根长和芽长可作为该品系种子萌发期抗旱性鉴定的二级指标;种子发芽率对甘露醇的敏感性稍弱,200 mmol/L条件下发芽率变化不明显,在300 mmol/L条件下才表现为极显著下降,可作为该品系种子萌发期抗旱性鉴定的三级指标.实验为狗尾草作为抗旱模式植物的研究准备了抗旱性评价指标基础,无论是外源抗旱基因在狗尾草内的过表达,还是内源抗旱基因的敲除,都需要这些具体评价指标的支撑.
