叶面喷施外源ABA对胡椒抗寒生理生化及ABA信号转导相关基因的影响

Effects of exogenous foliar spraying ABA on genes related to cold resistance physiology,biochemistry and ABA signal transduction of black pepper

【目的】筛选出能提高胡椒抗寒性的脱落酸(ABA)适宜浓度,明确低温胁迫条件下外施适宜浓度ABA对胡椒叶片ABA信号转导相关基因SnRK2和PYL表达的影响,为生产上提高胡椒抗寒技术及揭示ABA信号在胡椒抗寒中的作用机理提供依据。【方法】以热引1号胡椒为试验材料,通过叶面喷施0(CK)、25(T1)、50(T2)、75(T3)、100(T4)mg/L ABA及4℃低温胁迫处理,测定各处理胡椒叶片叶绿素荧光参数、抗氧化酶活性(POD、CAT和SOD)、H2O2和MDA含量。在筛选出适宜ABA喷施浓度的基础上,进一步运用实时荧光定量PCR分析ABA信号转导相关基因的表达情况。【结果】低温胁迫后,不同浓度ABA处理的胡椒POD、CAT和SOD活性与CK相比均显著上升(P<0.05,下同),其中T2处理的POD活性升高最显著,T3处理的CAT和SOD活性升高最显著;随着ABA处理浓度的升高,H2O2和MDA含量呈先下降后上升的变化趋势,以T3处理含量最低,即一定浓度外源ABA处理对胡椒抗寒生理发挥积极作用。低温胁迫0 d时,不同ABA浓度处理的胡椒Fv/Fm和Fv/Fo无显著变化;低温胁迫4d时,其Fv/Fm和Fv/Fo均显著降低,但T3处理缓解Fv/Fm和Fv/Fo下降效果显著,即ABA预处理能够在一定程度上缓解低温对胡椒光系统潜在活性的抑制。低温胁迫0 d时,不同ABA浓度处理胡椒的qP和Yield无显著变化,但qN随着ABA处理浓度的升高明显下降,即正常生长条件下,外施不同浓度ABA对胡椒叶片的qP和Yield无影响,但会减弱胡椒的光保护能力;低温胁迫4 d时,不同ABA浓度处理的胡椒叶片qP、qN和Yield均有不同程度的下降,随着ABA处理浓度的升高,qN呈现下降、上升再下降的变化趋势,qP呈先下降后上升的变化趋势,T3处理成为转折点,即在低温胁迫下外源ABA能够提高胡椒的光保护能力,其中T3处理效果相对较好。低温胁迫条件下,ABA预处理可诱导ABA信号转导相关基因SnRK2和PYL提前并高表达。【结论】外源ABA通过提高胡椒抗氧化酶活性、降低H2O2和MDA含量及缓解低温对其光系统活性的伤害,从而提高胡椒抵抗低温胁迫的能力。外源ABA还能诱导胡椒ABA信号转导相关基因表达,启动和引发植株固有抗冻性基因的表达,进而提高其耐冻性。

【Objective】The optimal abscisic acid(ABA)concentration to improve the cold resistance for black pepper was screened,and the expression changes of SnRK2 and PYL genes of ABA signal transduction related genes in black pepper leaves under low temperature stress were clarified,which could provide basis for further research on the cold resistance mechanism of black pepper and function of ABA signal in cold resistance of black pepper.【Method】Piper nigrum cv.Reyin1 leaves were sprayed with 0(CK),25(T1),50(T2),75(T3),100(T4)mg/L ABA.After 4℃low temperature stress,detected the chlorophyll fluorescence parameters,antioxidant enzyme activities(POD,CAT and SOD),H2O2 and MDA content.Base on the suitable ABA concentration,the expression of ABA transduction related genes was further analyzed by real-time fluorescence quantitative PCR.【Result】The POD,CAT,SOD activities of black pepper were significantly increased under low temperature stress compared with CK(P<0.05,the same below).Furthermore,the POD activity increased the most in T2 treatment,and the CAT and SOD activities in T3 treatment increased the most.With the increase of ABA treatment concentration,the contents of H2O2 and MDA first decreased and then increased.And the value was the lowest in T3 treatment.The results declared that certain concentration of exogenous ABA treatment played a positive role in black pepper resistant to cold stress.Fv/Fm and Fv/Fo values treated by different ABA concentrations did not change significantly under low temperature stress of 0 d,while the values decreased significantly under low temperature stress of 4 d.However,T3 treatment had a significant effect in alleviating the decline of Fv/Fm and Fv/Fo values.The results indicated that ABA pretreated black pepper could alleviate the inhibition on the light system potential activity.Under low temperature stress of 0 d,the q P and yield values treated with different ABA concentrations did not change significantly,but the qN value decreased significantly with the increase of ABA concentration.It showed that different ABA concentrations had no effect on the q P and Yield values of black pepper under normal growth conditions,but the light protection ability was weakened.Under low temperature stress of 4 d,the qP,qN and Yield value were also decreased.With the increase of concentration of ABA treatment,qN value presented a trend of decreased,increased and then decreased,and qP value showed a trend of decreased and then increased.The turning point was T3 treatment.These results showed that exogenous ABA under low temperature could improve the light protection ability of black pepper,and T3 treatment performed the best.Under low temperature stress,ABA pretreatment could induce the early and high expression of SnRK2 and PYL genes.【Conclusion】Exogenous ABA enhances pepper resistance to low-temperature stress moths by increasing pepper antioxidant enzyme activity,reducing H2O2 and MDA contents,and alleviating the damage of low temperature to its light system activity.The exogenous ABA can also induce the expression of pepper ABA signal transduction related genes,initiate and trigger the expression of plant inherent antifreeze genes,and then improve its freezing resistance.