Genômica comparativa e anotação funcional de genes de seis isolados brasileiros de Magnaporthe oryzae de arroz

Abstract

Rice (Oryza sativa) plays a crucial role in global food security. However, rice blast, a disease caused by the fungus Magnaporthe oryzae, is one of the main threats to production. Genetic resistance has been one of the most widely used strategies. Nevertheless, the constant evolution of the pathogen compromises the durability of these resistance genes. During coevolution with the host, M. oryzae races can undergo mutations in avirulence (avr) genes, which then fail to be recognized by rice resistance genes, resulting in increased virulence and evasion of the plant's defense response. The aim of this study was to perform a comparative analysis and functional annotation of six Brazilian isolates of M. oryzae, collected in the states of MG, MT, SC, RS, TO, and MA. After Illumina sequencing, de novo assembly was performed using the SPAdes program. Genome completeness was assessed with BUSCO and gene prediction was carried out using AUGUSTUS. Repetitive elements were identified using RepeatMasker. The search for unique genes was conducted through comparisons with the reference genome using BLASTP and the OrthoFinder software. The completeness analysis revealed that the isolates BRM63294, BRM63295, BRM11219, BRM25023, BRM25027, and BRM25033 presented 1,661 conserved genes. The total number of genes per genome ranged from 10,232 to 10,374. Among the identified genes, notable avirulence genes include Avr-Pita, Avr-Piz-t, Avr-Pi54, and Avr-Pi9. A total of 2,578 LTR retrotransposons were found, including 189 from the Ty1-copia family and 849 from the Ty3/gypsy family, as well as non-LTR elements, including 246 SINEs and 236 LINEs. The comparative analysis revealed that the isolates BRM25027 and BRM25023 had the highest number of unique genes, while BRM63294 and BRM25033 showed the lowest proportions (0.35% and 0.59%, respectively). The functional annotations of these unique genes indicated variations in categories of biological processes, molecular functions, and cellular components. The results provide a relevant basis for understanding the genetic diversity of the pathogen, which may help in disease monitoring.