3种外源诱导剂预处理对甜瓜抗病特征及其Fom 2和CHT基因表达的影响

该研究选用水杨酸(SA)、茉莉酸甲酯(MeJA)、Ca~(2+)、无菌水(对照)作为外源预处理诱导剂,以抗、感枯萎病甜瓜品种为材料,分别于诱导预处理2d后接种甜瓜枯萎菌,并于接种5、7、9d时观察发病情况,进行病情调查;在接种后1、3、5、7、9d取甜瓜叶片,分析抗病甜瓜(MR-1)和感病甜瓜(M1-15)叶片中甜瓜抗枯萎病基因(Fom-2)、几丁质酶基因(CHT)的表达变化,以探寻提高防治甜瓜枯萎病菌侵染的技术途径。结果显示:(1)外源MeJA和SA预处理接种后2品种的病情指数显著低于对照,但Ca~(2+)处理后的病情指数与对照无显著差异。(2)经外源诱导预处理接种后,MR-1和M1-15品种叶片的Fom-2和CHT基因均出现差异表达,但Ca~(2+)诱导其上调表达的效果微弱。(3)经SA、MeJA诱导预处理接种后,2品种叶片的Fom-2和CHT基因表达总体均显著高于对照;Fom-2基因的表达抗病甜瓜MR-1分别在接种后5d、7d时达到峰值,而感病甜瓜M1-15则均在接种9d时达到峰值;CHT基因的表达抗病甜瓜MR-1则均在接种后7d时达到峰值,而感病甜瓜M1-15分别在接种后7d、9d时达到峰值。(4)Ca~(2+)处理对抗、感甜瓜叶片的Fom-2和CHT基因的表达均无显著影响。(5)相关分析表明,经SA、MeJA诱导预处理接种后,甜瓜枯萎病病情指数与Fom-2和CHT基因表达量有显著的相关性;而Ca~(2+)处理效果不显著。研究表明:SA、MeJA通过诱导Fom-2、CHT基因上调表达,进而使甜瓜的抗病性提高,而Ca~(2+)处理对两基因表达和甜瓜抗病性均无显著影响。

Fom 2 and CHT Gene Expression in Melon under Exogenous Inducers

In this study, salicylic acid (SA), methyl jasmonate (MeJA), Ca²⁺, and sterile water as a control were used as exogenous inducers to pretreat the melons for resistance and susceptibility to fusarium wilt. Two days after the induction of pretreatment, they were inoculated with F. melilocarpa, and the incidence was observed on the 5, 7 and 9 d after inoculation. The disease status was investigated, and melon leaves were taken at 1, 3, 5, 7 and 9 d after inoculation. Expression changes of Fom 2 and CHT in resistant melon (MR 1) and susceptible melon (M1 15) leaves were evaluated in order to check the wilt in control wilt with the technical way of dyeing. The results showed that: (1) the disease indexes of the two varieties after inoculation with exogenous MeJA and SA were significantly lower than that of the control and there was no significant difference between the condition index after Ca²⁺ treatment and the control. (2) After inoculated with exogenously induced pretreatment, the expression of Fom 2 and CHT genes in leaves of MR 1 and M1 15 cultivars was different but the effect of Ca²⁺ on upregulation was not strong. (3) After inoculated with SA and MeJA, the expression of Fom 2 and CHT genes in the leaves of the two cultivars were significantly higher than those of the control, but the expression level of Fom 2 for resistant melon MR 1, the peaks were reached at 5 d and 7 d and all susceptible melon M1 15 were peaked at 9 d after inoculation. The expression of CHT gene for resistant melon MR 1 peaked at 7 d after inoculation. M1 15 showed peak at 7 and 9 days after inoculation, respectively. (4) There was no significant effect of Ca²⁺ treatment on the expression of Fom 2 and CHT genes in muskmelon leaves. (5) The correlation analysis showed that the disease index of Fusarium wilt was correlated with the expression levels of Fom 2 and CHT genes after SA and MeJA induced pretreatment inoculation. The effect of Ca²⁺ treatment is not significant.