The global regulator LaeA controls biosynthesis of host-specific toxins, pathogenicity and development of Alternaria alternata pathotypes
The global regulator LaeA controls biosynthesis of host-specific toxins, pathogenicity and development of Alternaria alternata pathotypes
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DOI：
10.1007/s10327-016-0656-9
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发表时间：
2016-05-01
影响因子：
1.2
通讯作者：
Kodama, Motoichiro
中科院分区：
文献类型：
--
作者：
Takao, Kazumi;Akagi, Yasunori;Kodama, Motoichiro
在丝状真菌中，次生代谢物的生物合成基因的表达需要全局调控因子LaeA，例如尼杜拉曲霉。互隔交链孢菌至少有7个致病变异体(致病类型)，可产生寄主特异性毒素(HST)并在寄主植物上引起严重病害。为了进一步了解这些基因的调控，我们在番茄、草莓和苹果的致病类型中鉴定了编码甲基转移酶的LaeA同源基因，分别命名为AtLAE1、AsLAE1和AaLAE1。在番茄致病型突变体(Delta AtLAE1)中，AAL毒素生物合成基因ALT1的表达水平低于野生型。相应地，突变株的AAL毒素产量和致病力显著降低，产孢量和菌丝生长也显著降低。同样，草莓致病类型的AsLAE1缺失突变体(Delta AsLAE1)和苹果致病类型的缺失突变体(Delta AaLAE1)产生的寄主特异性毒素(分别为AF-和AM-毒素)较少，对寄主植物的毒力降低，菌丝生长和产孢量下降。因此，全局调控基因laeA对赤霉菌致病类型的HST合成、致病性、生长和分化具有正向调节作用。
The global regulator LaeA is required for the expression of biosynthetic genes for secondary metabolites in filamentous fungi such as Aspergillus nidulans. To learn more about the regulation of these genes in Alternaria alternata, which has at least seven pathogenic variants (pathotypes) that produce host-specific toxins (HSTs) and cause severe diseases in their host plants, we identified LaeA homologs encoding methyltransferase in tomato, strawberry and apple pathotypes of A. alternata, designating them AtLAE1, AsLAE1 and AaLAE1, respectively. In the AtLAE1-deleted mutant of the tomato pathotype (Delta AtLAE1), expression of the AAL-toxin biosynthetic gene ALT1 was lower than that in the wild type. Correspondingly, AAL-toxin production and virulence of the mutant were significantly lower as were spore production and hyphal growth. Similarly, the AsLAE1-deleted mutant of the strawberry pathotype (Delta AsLAE1) and the AaLAE1-deleted mutant of the apple pathotype (Delta AaLAE1) produced less of their host-specific toxin (AF- and AM-toxin, respectively), had reduced virulence on the host plant, and hyphal growth and sporulation were defective. Thus, the global regulator gene LaeA positively regulates HST biosynthesis, pathogenicity, growth and differentiation in A. alternata pathotypes.