Effects of Different Temperature Treatments on Dormancy Regulation of Konjac Bulbil
In order to explore the effects with different temperatures on the dormancy regulation of konjac bulbil,we used the foliar bulbils as the material.The day/night temperature(24 ℃/9 ℃,24 ℃/13 ℃,24 ℃/17 ℃)and constant temperature(9 ℃,13 ℃,17 ℃,21 ℃)were set during the dormancy period,and the temperature was set at 26 ℃ and 33 ℃ during the germination period.We analyzed the biological phe-notypic changes,endogenous physiological changes and expression of genes related to dormancy regulation after different temperature treatments in dormancy Ⅰ,Ⅱ,early germination,germination of mid,germi-nation of late and terminal germination stage.The results showed that,(1)constant temperature treat-ment during the dormancy stage was beneficial to improve the budding ratio of konjac bulbil.Dormancy was broken by constant temperature treatment at 13 ℃ in the dormancy stage,and germination rate of konjac bulbil reached its peak at 33 ℃ in the germination stage.(2)The content of starch in bulbil at dor-mancy Ⅱ stage was lower than at dormancy Ⅰ stage,the content of soluble sugar in bulbils at dormancyⅡ stage was higher than at dormancy Ⅰ stage.The content of starch in bulbils at 13 ℃ decreased the fas-test,and the content of soluble sugar in bulbils at 13 ℃ was the highest.There were significant difference in starch content and the soluble sugar content of bulbils between early and late stage of germination(P＜0.05).(3)The content of ABA in bulbils increased gradually,and the content of GA3 decreased gradually at dormancy stage Ⅰ and dormancy stage Ⅱ.The ABA content of bulbils in germination period showed a trend of"first rising and then decreasing"and the content of GA3 in bulbils treated at 26 ℃ also showed the same trend in germination period.The GA3 content of bulbils treated with a germination temperature of 33 ℃ showed an overall upward trend.(4)The expression level of NCED gene increased gradually with the deepening of dormancy and decreased gradually during germination;The expression of CYP707A gene decreased gradually with the deepening of dormancy and increased significantly during germination.In con-clusion,we found that the optimal temperature for breaking dormancy was 13 ℃,and the optimal temper-ature for promoting germination was 33℃.As the konjac bulbil broken the dormancy,the starch content in the bulbils decreased and the soluble sugar content increased;ABA content showed a trend of"first ris-ing and then decreasing",GA3 content showed a trend of"first decreasing and then rising".We suggest that the gene NCED and CYP707A may be the key genes in the dormancy regulation of konjac bulbil.
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