Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China.
The Ministry of Agriculture and Rural Affairs for Key Laboratory of Crop Pest Monitoring and Green Control, College of Plant Protection, China Agricultural University, Beijing 100193, China.
Int J Mol Sci. 2023 Dec 22;25(1):198. doi: 10.3390/ijms25010198.
spp. are ascomycete fungi and cause anthracnose disease in numerous crops of economic significance. The genomes of these fungi are distributed among ten core chromosomes and two to three minichromosomes. While the core chromosomes regulate fungal growth, development and virulence, the extent to which the minichromosomes are involved in these processes is still uncertain. Here, we discuss the minichromosomes of three hemibiotrophic pathogens, i.e., , and . These minichromosomes are typically less than one megabase in length, characterized by containing higher repetitive DNA elements, lower GC content, higher frequency of repeat-induced point mutations (RIPMs) and sparse gene distribution. Molecular genetics and functional analyses have revealed that these pathogens harbor one conditionally dispensable minichromosome, which is dispensable for fungal growth and development but indispensable for fungal virulence on hosts. They appear to be strain-specific innovations and are highly compartmentalized into AT-rich and GC-rich blocks, resulting from RIPMs, which may help protect the conditionally dispensable minichromosomes from erosion of already scarce genes, thereby helping the pathogens maintain adaptability on hosts. Overall, understanding the mechanisms underlying the conditional dispensability of these minichromosomes could lead to new strategies for controlling anthracnose disease in crops.
种是子囊菌真菌，可引起许多具有经济意义的作物炭疽病。这些真菌的基因组分布在十个核心染色体和两到三个小染色体中。虽然核心染色体调节真菌的生长、发育和毒性，但小染色体在这些过程中的参与程度仍不确定。在这里，我们讨论了三种半活体病原体的小染色体，即 、 和 。这些小染色体通常小于一个兆碱基，其特征是含有更高的重复 DNA 元件、更低的 GC 含量、更高的重复诱导点突变 (RIPMs) 频率和稀疏的基因分布。分子遗传学和功能分析表明，这些病原体携带一个条件性可缺失的小染色体，该小染色体对真菌的生长和发育是可有可无的，但对真菌在宿主上的毒性是必不可少的。它们似乎是菌株特异性的创新，高度分隔成富含 AT 和富含 GC 的块，这是由于 RIPMs 造成的，这可能有助于保护条件性可缺失的小染色体免受已经稀缺基因的侵蚀，从而帮助病原体在宿主上保持适应性。总的来说，了解这些小染色体条件性缺失的机制可能会为控制作物炭疽病提供新的策略。
