基底硬度对玉米大斑病菌主要侵染结构和黑色素沉积的影响

 基底硬度是调控植物病原真菌侵染结构形成的重要物理信号。为探讨基底硬度对玉米大斑病菌(Setosphaeria turcica)侵染能力的影响,本研究利用不同硬度的PDA培养基进行模拟试验,并在不同叶龄的玉米叶片上进一步验证,结果表明,基底硬度越大,气生菌丝越少,菌丝分枝越多;硬基底上,病菌的分生孢子产量高,是软基底和适中硬度基底上的29.93和6.82倍,且硬基底上病菌附着胞形成率显著高于软基底。研究发现,在硬基底上生长的大斑病菌菌落颜色较深,菌丝中黑色素含量高。利用实时荧光定量PCR技术分析病菌黑色素合成途径中相关基因的表达情况,发现在硬基底上StMR1、StPKS、St4HNR、StSCD、St3HNR、StLAC1、StLAC2和StLAC4基因的相对表达量均高于软基底。上述结果说明,基底硬度影响了病菌形态结构的发育,导致了与侵染相关的黑色素含量的变化和侵染结构的形成,研究结果为探究植物病原真菌的侵染机制和病害防控提供了理论依据。

Effects of matrix stiffness on main infection structure and melanin deposition of Setosphaeria turcica

Matrix stiffness is an important physical signal for the formation of infection structures in plant pathogenic fungi. In order to explore effects of matrix stiffness on the infecting ability of Setosphaeria turcica, PDA media with different stiffness was used to mimic the simulation. The results were further verified on corn leaves with different developmental ages. There are less aerial hyphae and more hyphal branches on hard matrix than those on soft one. On the hard matrix, the number of conidia was the highest, which was 29.93 and 6.82 folds of the soft one and the moderate one, respectively. The rate of appressorium formation on the hard matrix was significantly higher than that on the soft one. Moreover, the colony color was deeper and the melanin content of the hyphae was higher on the hard matrix. Real-time fluorescence quantitative PCR was used to analyze expression levels of genes involved in the melanin synthesis pathway of S. turcica. The results showed that the expression levels of StMR1, StPKS, St4HNR, StSCD, St3HNR, StLAC1, StLAC2 and StLAC4 were higher on the hard matrix than that on the soft one. The above results indicated that the matrix stiffness affected the morphological structure of S. turcica, which led to the change of melanin content and the development of infection structures. It also provided a theoretical basis for the research on infection mechanism of S. turcica and the prevention and control of this disease.