Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China.
Institute of Plant Protection, Liaoning Academy of Agricultural Science, Shenyang 110161, China.
Int J Mol Sci. 2023 Oct 15;24(20):15196. doi: 10.3390/ijms242015196.
Rice false smut (RFS) caused by (anamorph: ) has become one of the most destructive fungal diseases to decrease the yield and quality of rice grains. An albino strain LN02 was isolated from the white RFS balls collected in the Liaoning Province of China in 2019. The strain LN02 was considered as a natural albino mutant of by analyzing its phenotypes, internal transcribed spacer (ITS) conserved sequence, and biosynthesis gene clusters (BGCs) for secondary metabolites. The total assembled genome of strain LN02 was 38.81 Mb, which was comprised of seven nuclear chromosomes and one mitochondrial genome with an N50 value of 6,326,845 bp and 9339 protein-encoding genes. In addition, the genome of strain LN02 encoded 19 gene clusters for biosynthesis of secondary metabolites mainly including polyketides, terpenoids and non-ribosomal peptides (NRPs). Four sorbicillinoid metabolites were isolated from the cultures of strain LN02. It was found that the polyketide synthase (PKS)-encoding gene for ustilaginoidin biosynthesis in strain LN02 was inactivated due to the deletion of four bases in the promoter sequence of . The normal complementary mutant of strain LN02 could restore the ability to synthesize ustilaginoidins. It demonstrated that deficiency of ustilaginoidin biosynthesis is the cause of albinism for RFS albino strain LN02, and should be a non-melanin-producing fungus. This study further confirmed strain LN02 as a white phenotype mutant of . The albino strain LN02 will have a great potential in the development and application of secondary metabolites. The physiological and ecological functions of ustilaginoidins in RFS fungus are needed for further investigation.
稻曲病（RFS）由 （无性型：）引起，已成为降低稻谷产量和质量的最具破坏性的真菌病害之一。2019 年，在中国辽宁省采集的白色稻曲病球中分离到一株白化突变株 LN02。通过分析其表型、内部转录间隔区（ITS）保守序列和次生代谢产物生物合成基因簇（BGCs），认为菌株 LN02是 的天然白化突变体。菌株 LN02 的总组装基因组为 38.81Mb，由 7 条核染色体和 1 条线粒体基因组组成，N50 值为 6,326,845bp 和 9339 个蛋白质编码基因。此外，菌株 LN02 的基因组编码了 19 个次生代谢产物生物合成基因簇，主要包括聚酮化合物、萜类化合物和非核糖体肽（NRPs）。从菌株 LN02 的培养物中分离出 4 种索比尔菌素代谢物。发现菌株 LN02 中 ustilaginoidin 生物合成的聚酮合酶（PKS）编码基因 由于启动子序列中四个碱基的缺失而失活。菌株 LN02 的正常 互补突变体能恢复合成 ustilaginoidin 的能力。这表明 ustilaginoidin 生物合成的缺陷是稻曲病白化突变株 LN02 白化的原因，而 应该是一种不产生黑色素的真菌。本研究进一步证实了菌株 LN02 是 RFS 白化突变株 的白色表型突变体。白化菌株 LN02 在次生代谢产物的开发和应用方面具有巨大的潜力。需要进一步研究稻曲病菌中 ustilaginoidin 的生理和生态功能。
