Validation of candidate genes for resistance to powdery mildew in grass pea (Lathyrus sativus)

• Main Author: Crespo, Pedro Miguel Sousa
• Publication Date: 2021
• Format: Master thesis
• Language: eng
• Source: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Download full: http://hdl.handle.net/10773/33520
• topic: Lathyrus sativus; Erysiphe pisi; Candidate resistance genes; Gene expression analysis

Lathyrus sativus (grass pea) is a promising grain legume crop for a more sustainable agriculture, combining dietary advantages with exceptional agronomic properties. Among them, L. sativus is an extremely resilient crop to both abiotic and biotic stress, which gives it a great potential to be used in disease resistance studies. Erysiphe pisi is the causal agent of pea (Pisum sativum) powdery mildew, and it has the capability to infect other Leguminosae, such as L. sativus. This disease can be quite severe and infected crops can experience severe yield losses. Although the impact of powdery mildew disease is great and the resistance mechanisms of L. sativus are still not well known, promising resistance mechanisms have already been identified. Candidate resistance genes against E. pisi were recently identified in Lathyrus spp. However, the gene expression analysis and functional validation of those genes in order to verify the genes’ functional reaction in infected plants, is still missing. In this study, 13 candidate resistance genes were selected from studies on Leguminosae–fungi molecular interactions. The main objective was to evaluate the expression dynamics of candidate resistance genes quantified in two partial resistant and two susceptible grass pea accessions, non-inoculated and inoculated, at five time points after infection with E. pisi, by Real-Time quantitative PCR (RT-qPCR). From the starting 13 selected genes, expression patterns of eight candidate resistance genes was analyzed, from which, AT-Hook motif nuclear-localized protein (AT-Hook), the mitochondrial ATP synthase subunit 9 (ATP), L. sativus Mildew Locus O 1 (LsMLO1) and pea disease resistance response protein (Pi49) genes showed the most potential for further functional validation based on the high levels of fold change in partial resistant genotypes compared to the most susceptible non inoculated (0h) genotype. Also, on their previously known biological functions in plant-pathogen interactions, such as ATP synthase, disease response proteins and gene expression regulator proteins. This study provides clues about the putative resistance molecular mechanisms underlying the L. sativus response against E. pisi, which should be useful in gene selection for future development of molecular tools able to assist in breeding L. sativus, and phylogenetically similar species against E. pisi.