Shared and tailored common bean transcriptomic responses to combined fusarium wilt and water deficit

Common bean(Phaseolus vulgaris L.),one of the most consumed food legumes worldwide,is threatened by two main constraints that are found frequently together in nature,water deficit(WD)and fusarium wilt(Fop).To understand the shared and unique responses of common bean to Fop and WD,we analyzed the transcriptomic changes and phenotypic responses in two accessions,one resistant and one susceptible to both stresses,exposed to single and combined stresses.Physiological responses(photosynthetic performance and pigments quantification)and disease progression were also assessed.The combined FopWD imposition negatively affected the photosynthetic performance and increased the susceptible accession disease symptoms.The susceptible accession revealed a higher level of transcriptional changes than the resistant one,and WD single stress triggered the highest transcriptional changes.While 89 differentially expressed genes were identified exclusively in combined stresses for the susceptible accession,35 were identified in the resistant one.These genes belong mainly to“stress”,“signaling”,“cell wall”,“hormone metabolism”,and“secondary metabolism”functional categories.Among the up-regulated genes with higher expression in the resistant accession,the cysteine-rich secretory,antigen 5 and Pr-1(CAP)superfamily protein,a ribulose bisphosphate carboxylase family protein,and a chitinase A seem promising targets for multiple stress breeding.

First genetic linkage map of Lathyrus cicera based on RNA sequencing-derived markers: Key tool for genetic mapping of disease resistance

The Lathyrus cicera transcriptome was analysed in response to rust(Uromyces pisi)infection to develop novel molecular breeding tools with potential for genetic mapping of resistance in this robust orphan legume species.One RNA-seq library each was generated from control and rust-inoculated leaves from two L.cicera genotypes with contrasting quantitative resistance,de novo assembled into contigs and sequence polymorphisms were identified.In toto,19,224 SNPs differentiate the susceptible from the partially resistant genotype’s transcriptome.In addition,we developed and tested 341 expressed E-SSR markers from the contigs,of which 60.7%varied between the two L.cicera genotypes.A first L.cicera linkage map was created using part of the developed markers in a RIL population from the cross of the two genotypes.This map contains 307 markers,covered 724.2 cM and is organised in 7 major and 2 minor linkage groups,with an average mapping interval of 2.4 cM.The genic markers also enabled us to compare their position in L.cicera map with the physical position of the same markers mapped on Medicago truncatula genome,highlighting a high macrosyntenic conservation between both species.This study provides a large new set of genic polymorphic molecular markers with potential for mapping rust resistances.It represents the first step towards genomics-assisted precision breeding in L.cicera.