The melanin biosynthesis genes of Alternaria alternata can restore pathogenicity of the melanin-deficient mutants of Magnaporthe grisea
The melanin biosynthesis genes of Alternaria alternata can restore pathogenicity of the melanin-deficient mutants of Magnaporthe grisea
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DOI：
10.1094/mpmi.1997.10.4.446
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发表时间：
1997-05-01
影响因子：
3.5
通讯作者：
Tsuge, T
中科院分区：
文献类型：
--
作者：
Kawamura, C;Moriwaki, J;Tsuge, T
稻瘟病菌和链格孢菌通过聚酮生物合成产生黑色素，并且两种真菌都形成黑化菌落。然而，黑色素沉积的部位和黑色素在致病性中的作用在这两种真菌之间是不同的。M.稻瘟病菌在附着胞中积累黑色素，并且它们的黑化对于寄主的侵入是必需的。另一方面，A. alternata产生无色附着胞，黑色素与寄主渗透无关。我们检测了黑色素合成基因是否与A. alternata可以补充A.稻瘟病菌黑色素缺乏的非致病性M.用携带黑色素生物合成基因ALM、BRM 1和BRM 2的粘粒克隆pMBR 1成功地转化了稻瘟病菌、白化病病菌（Alb（-））、玫瑰色病菌（Rsy（-））和浅黄色病菌（Buf（-））。交替这种转化恢复了Alb（-）和Buf（-）突变体的黑色素合成，但不能恢复Rsy（-）突变体的黑色素合成。黑色素恢复的转化子恢复了菌丝黑化、附着胞黑化和对水稻的致病性。此外，分别用亚克隆的ALM和BRM 2基因转化Alb（-）和Buf（-）突变体也产生黑色素恢复的转化体。这些结果表明，链格孢属基因ALM和BRM 2可以分别恢复突变体Alb（-）和Buf（-）的致病性，这是由于它们在M.稻瘟病菌
The phytopathogenic fungi Magnaporthe grisea and Alternaria alternata produce melanin via the polyketide biosynthesis, and both fungi form melanized colonies. However the site of melanin deposition and the role of melanin in pathogenicity differ between these two fungi. M. grisea accumulates melanin in appressoria, and their melanization is essential for host penetration. On the other hand, A. alternata produces colorless appressoria, and melanin is not relevant to host penetration. We examined whether the melanin biosynthesis genes of A. alternata could complement the melanin-deficient mutations of A. grisea. Melanin-deficient, nonpathogenic mutants of M. grisea, albino (Alb(-)), rosy (Rsy(-)), and buff (Buf(-)), were successfully transformed with a cosmid clone pMBR1 that carries melanin biosynthesis genes ALM, BRM1, and BRM2 of A. alternata. This transformation restored the melanin synthesis of the Alb(-) and Buf(-) mutants, but not that of the Rsy(-) mutant. The melanin-restored transformants regained mycelial melanization, appressorium melanization, and pathogenicity to rice. Further, transformation of Alb(-) and Buf(-) mutants with subcloned ALM and BRM2 genes, respectively, also produced melanin-restored transformants. These results indicate that the Alternaria genes ALM and BRM2 can restore pathogenicity to the mutants Alb(-) and Buf(-), respectively, due to their function during appressorium development in M. grisea.