| Peanut plays an important role in oil crops in China,but its growth environment is mostly in arid or semi-arid rain-fed areas.Drought,especially drought at seedling stage,has a serious impact on peanut production,and the varieties with strong drought resistance have been screened.The physiological response of peanut to drought stress and the characteristics of related gene expression are of great significance to the breeding of drought-resistant peanut varieties and the guidance of field production.In this study,the drought resistance of 23 peanut varieties(germplasms)selected and cultivated in Liaoning area were evaluated and identified,and the protective enzyme activities of the drought-resistant and drought-sensitive varieties were evaluated.The differences of physiological and biochemical characteristics,such as the accumulation of osmotic regulators and related hormone contents,and the expression of drought resistance-related genes were analyzed.The results were as follows:1.A comprehensive evaluation system for drought resistance of peanut at seedling stage was established.The proline content,relative water content,relative plant fresh weight,leaf weight change,relative damage rate,water loss rate of leaf and withered index of 23 different cultivars(germplasm)was measured.NH5,HY22,were screened out for strong drought resistant varieties(germplasm),the average membership functions were 0.793 and 0.784.The average membership functions were 0.228 and 0.294 for drought-sensitive varieties(FH18 and NH16),respectively.2.The activities of SOD,POD,APX and CAT of drought-resistant varieties NH5 and HY22 were higher than those of drought-sensitive varieties NH16 and FH18,and the regulation ability of proline and soluble protein of NH5 and HY22 were stronger,the accumulation rate was faster and the range of increase was higher than that of drought-sensitive varieties NH16 and FH18,.Compared with the control treatment,the content of NH5 secondary metabolite flavonoids increased by 2.0 times and 4.2 times respectively,and reached 3.8 mg/g DW,at the peak value.The root activity of drought-resistant varieties was better than that of sensitive varieties after drought stress.The superoxide anion-resistant free radical activity of drought-resistant varieties was stronger than that of sensitive ones.The root systems of NH 5 and HY22 were well developed and the dehydration phenomenon was not obvious after stress.However,the root system of NH16 and FH18 showed local necrosis under stress.3.The two groups of extreme materials selected above were used as test materials to determine the relative expression of Ah PAL1,Ah NCED1,Ah DHN1,Ah DREB1 and Ah NAC2 genes related to drought resistance after drought treatment for 0h,2h,4h,6h,8h,.and the results showed that the relative expression of Ah PAL1,Ah NCED1,Ah DHN1 and Ah NAC2 genes were up-regulated in each variety.The expression of NH5 gene was the highest and reacted quickly after drought stress,while the relative expression of Ah PAL1 and Ah NAC2 genes of HY22 was lower than that of two drought-sensitive varieties.The expression of Ah DREB1 was not detected in NH16,but in the other three varieties,the relative expression was adjusted to varying degrees.The highest upregulation of NH5,was 30 times,followed by 20 times of HY22... |
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