Análise global da expressão gênica de cultivares de feijão comum desafiadas pela raça 65 de Colletotrichum lindemuthianum e análise genômica ampla da família de genes PvRLK-LRR

Abstract

Anthracnose, caused by the fungus Colletotrichum lindemuthianum, is one of the main diseases that affect the common bean crop, which can drastically reduce production, under conditions suitable for the development of the pathogen. From the perspective of the host, the genetic control of the disease involves the involvement of several independent loci, organized in complex sets, conferring resistance to specific races of the pathogen. However, expanding the knowledge of the genes found at these loci and understanding their mode of action in the response pathways of the host plant to the pathogen is an important strategy in the study of this pathosystem. In view of the above, the objectives of this research consisted of: i) Obtaining and evaluating the transcriptional profiles of bean plants, both in compatible and incompatible interaction with isolate of race 65 of C. lindemuthianum, by means of RNA-seq, in different infection times; and ii) Identify, classify and characterize the RLK-LRR gene family of Phaseolus vulgaris, also evaluating its expression profile in response to infection by C. lindemuthianum, through in silico analyses. To achieve the first objective, 12 RNA libraries were sequenced, and it was possible to observe a transcriptional rearrangement in both cultivars after infection with the pathogen. In resistant, the role of genes related to recognition is highlighted, such as those that encode protein kinases and NB-LRRs; defense-related genes such as MLP pathogenesis genes; and, genes related to the synthesis of new carbohydrates, involved in cell wall remodeling. Glycerolipid, phenylpropanoid and linoleic acid signaling pathways were associated with the resistance response of the resistant genotype. On the other hand, in the susceptible genotype, auxin-mediated signaling and the expression of genes related to the processing and transport of sugars were highlighted. A greater connection between resistance-associated genes can be seen in gene co-expression networks. Therefore, considering the specificity of the genetic control of resistance in pathosystems involving different races, this work presents an overview of the response to race 65, which is so relevant in the economic scenario of bean crop production in Brazil. As for the study of the PvRLK-LRR family, the entire genome of P. vulgaris was analyzed, allowing the identification and classification of 230 PvRLK-LRRs in 15 different subfamilies. Analyzes of gene structures, conserved domains and motifs were performed and suggested a consistent structural organization and composition of proteins from the same subfamily. The PvRLK-LRR genes were distributed among the 11 chromosomes of the species, including regions close to anthracnose resistance markers. One can note the importance of duplication events in the expansion of this gene family, mainly resulting from stabilizing selection. An analysis of the promoter regions was also carried out, which highlighted the cis elements associated with the plant's response to biotic stress. Regarding the expression pattern of PvRLK-LRRs in response to C. lindemuthianum infection, it was possible to highlight several differentially expressed genes in this subfamily. Our analyzes allowed deep structural and functional characterization of PvRLK-LRRs, and their direct participation in the mechanisms of resistance to anthracnose.