GENETIC-ANALYSIS OF MELANIN-DEFICIENT, NONPATHOGENIC MUTANTS OF MAGNAPORTHE-GRISEA
GENETIC-ANALYSIS OF MELANIN-DEFICIENT, NONPATHOGENIC MUTANTS OF MAGNAPORTHE-GRISEA
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DOI：
10.1094/mpmi-3-135
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发表时间：
1990-05-01
影响因子：
3.5
通讯作者：
VALENT, B
中科院分区：
文献类型：
--
作者：
CHUMLEY, FG;VALENT, B
稻瘟病菌引起水稻稻瘟病和其他牧草的灰斑病。许多不能产生野生型菌丝的深灰色色素的稻瘟病菌突变体已经被分离和分析。根据色素表型可区分出三类突变体：白化(Alb-)、玫瑰色(RSY-)和浅黄色(Buf-)。一些色素突变体在诱变后被回收，另一些则自发出现。自发的buf突变尤其常见。遗传分析表明，这三个突变表型是由于非连锁基因座上的单基因缺陷造成的。基因杂交产生了三种可能的双重突变体。对这两个突变体的分析揭示了上位性关系：alb-rys-和alb-buf-突变体是Alb-，而RSY-buf-突变体是RSY-。这些上位性关系与函数ALB+.fwdarw的顺序一致。RSY+.fwdarw。Buf+在黑色素生物合成中的作用。所有测试的色素突变体都未能感染完整的寄主植物，但相同的突变体成功地感染了因磨损叶表皮而受伤的植物。当将生物合成途径中的中间体scytalone添加到生长介质中时，白化突变株的培养平板培养明显变暗，而RSY或buf突变株则不变。当将scytalone加入到喷洒在未受伤害的寄主植物上的孢子悬浮液中时，对alb-突变体的致病力得到恢复，但对RSY-或buf-突变体的致病力没有恢复。
The fungus Magnaporthe grisea causes rice blast disease and gray leaf spot disease of other grasses. Numerous M. grisea mutants that fail to produce the dark gray pigment typical of wild-type mycelia have been isolated and analyzed. Three classes of mutants have been distinguished based on pigmentation phenotypes: albino (Alb-), rosy (Rsy-), and buff (Buf-). Some pigment mutants were recovered following mutagenesis, and others appeared spontaneously. Spontaneous Buf- mutants have been particularly common. Genetic analysis has shown that the three mutant phenotypes are due to single gene defects at unlinked loci. Genetic crosses have yielded the three possible classes of double mutants. Analysis of the double mutants has revealed epistasis relationships: alb- rys- and alb- buf- mutants are Alb-, whereas rsy- buf- mutants are Rsy-. These epistasis relationships are consistent with the order of function ALB+ .fwdarw. RSY+ .fwdarw. BUF+ in melanin biosynthesis. All the pigment mutants tested failed to infect intact host plants, but the same mutants successfully infected plants that had been wounded by abrading the leaf epidermis. When scytalone, an intermediate in the biosynthetic pathway leading to dihydroxynaphthalene-based fungal melanins, was added to the growth medium, petri plate cultures of alb- mutants, but not rsy- or buf- mutants, darkened noticeably. When scytalone was incorporated in spore suspensions sprayed onto unwounded host plants, pathogenicity was restored to alb-, but not to rsy- or buf- mutants.