Genetic analyses of reddish-brown polyoxin-resistant mutants of Bipolaris maydis.
Genetic analyses of reddish-brown polyoxin-resistant mutants of Bipolaris maydis.
复制标题
玉米赤霉抗红棕色多抗素突变体的遗传分析。
DOI：
10.1016/j.myc.2017.12.002
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发表时间：
2018
期刊：
影响因子：
1.4
通讯作者：
Tanaka C.
中科院分区：
文献类型：
--
作者：
Chen D;Masumoto H;Kitade Y;Izumitsu K;Tanaka C.
在南方玉米疫病菌中，已报道了5个抗多毒素基因（Pol1 ~ Pol5）。Pol2和Pol5不仅具有多毒素抗性，而且具有红棕色菌落。在这里，我们使用比较基因组学方法在分子遗传学水平上鉴定Pol2和Pol5。我们的分析显示，羟甲基二烷合成酶（HMBS）和铁螯合酶（FECH）基因的核苷酸序列变化分别与Pol2和Pol5的表型有关。在Pol2和Pol5的其他菌株中也发现了这些基因的核苷酸序列的进一步变化。与野生型基因的互补试验证实，这些Hmbs和Fech突变是Pol2和Pol5突变体耐多毒素的原因。这些基因的缺失突变体（DHMBS和DFECH）在没有外源血红素的情况下是有条件致死的。Pol2和Pol5突变体的血红素含量低于野生型，表明hmbs和fech的突变降低了hmbs和fech的功能，尽管两者都没有完全失活。这些结果表明，Pol2和Pol5编码了该真菌血红素生物合成途径中酶成员HMBS和FECH。
In the southern corn blight fungus, Bipolaris maydis, five polyoxin-resistance genes (Pol1 to Pol5) have been reported. Pol2 and Pol5 are pleiotropic for not only polyoxin resistance but also reddish brown colonies. Here, we used a comparative genomics approach to identify Pol2 and Pol5 at a molecular genetics level. Our analysis revealed that nucleotide sequence variations in the genes for hydroxymethylbilane synthase (HMBS) and ferrochelatase (FECH) were linked to the phenotypes of Pol2 and Pol5, respectively. Further variations in the nucleotide sequences of these genes were also found in other strains of Pol2 and Pol5. Complementation tests with the wild type genes confirmed that these mutations at Hmbs and Fech were responsible for the polyoxin resistance in the Pol2 and Pol5 mutants. The deletion mutants of these genes (DHMBS and DFECH) were conditionally lethal without exogenous heme. The heme contents of Pol2 and Pol5 mutants were lower than that in the wild type, suggesting that the mutations in hmbs and fech reduced the functions of HMBS and FECH, although neither was completely inactivated. These results suggested Pol2 and Pol5 encode HMBS and FECH, members of enzymes in the heme-biosynthetic pathway of this fungus.