AsSlt2基因对茄链格孢细胞壁完整性的调控

Regulation of the cell wall integrity by AsSlt2 gene in Alternaria solani

摘要:

[背景] 由茄链格孢（Alternaria solani）引起的马铃薯早疫病被普遍认为是马铃薯生产上的第二大叶部病害，在马铃薯各产区普遍发生，给马铃薯生产造成了巨大的经济损失。[目的] 明确AsSlt2基因对茄链格孢细胞壁完整性的影响。[方法] 在含有刚果红、细胞壁降解酶和十二烷基硫酸钠（sodium dodecyl sulfate，SDS）等细胞壁胁迫的培养基上观察ΔAsSlt2缺失突变株的生长情况，计算相对生长抑制率；通过实时荧光定量PCR （RT-qPCR）方法检测ΔAsSlt2菌株中细胞壁合成相关基因的表达情况；进一步检测ΔAsSlt2细胞壁中几丁质的含量及胞外酶活性。[结果] ΔAsSlt2缺失突变株对SDS、刚果红、细胞壁降解酶等细胞壁胁迫的敏感性增强，在加入细胞壁降解酶后突变株原生质体释放量显著增多；ΔAsSlt2对外源氧胁迫更敏感，突变株胞外过氧化物酶和漆酶活性均显著降低；进一步研究发现，ΔAsSlt2细胞壁中几丁质含量减少，几丁质合成相关基因与漆酶合成相关基因的表达量均明显降低。[结论] AsSlt2基因在茄链格孢细胞壁的完整性及抵御外界胁迫方面发挥重要作用。

Abstract:

[Background] Potato early blight caused by Alternaria solani is generally considered to be the second major potato disease in potato production, which occurs in various potato production areas. Serious disease will lead to large-scale production reduction and potato block decay during storage, causing huge economic losses to potato production. [Objective] In order to clarify the effect of AsSlt2 gene on the cell wall integrity of Alternaria solani. [Methods] Congo red, sodium dodecyl sulfate (SDS) and cell wall degrading enzymes were applied to evaluate the cell wall integrity for the mutant strain, and calculate the relative growth inhibition rate. RT-qPCR was used to analyze the transcription of cell wall-related genes. The chitin content and extracellular enzyme activity in the cell wall of ΔAsSlt2 were further detected. [Results] the tolerance of ΔAsSlt2 to cell wall stress factors SDS, Congo red and cell wall degradation enzymes were weaker than that of wild and complementation strain. The protoplast release increased significantly after adding cell wall degrading enzyme. Furthermore, it was found that ΔAsSlt2 was more sensitive to exogenous peroxide stress. The extracellular peroxidase and laccase activity of ΔAsSlt2 mutant were significantly reduced, the chitin content in the cell wall of ΔAsSlt2 mutant were decreased. The expression of laccase related genes and chitin synthase related genes in ΔAsSlt2 mutant were detected by RT-qPCR. [Conclusion] The AsSlt2 plays an important role in cell wall integrity and tolerance to external stress in A. solani.