Genetic Dissection of Heat Stress Tolerance in Faba Bean (Vicia faba L.) Using GWAS

Heat waves are expected to become more frequent and intense, which will impact faba
bean cultivation globally. Conventional breeding methods are effective but take considerable time
to achieve breeding goals, and, therefore, the identification of molecular markers associated with
key genes controlling heat tolerance can facilitate and accelerate efficient variety development.
We phenotyped 134 accessions in six open field experiments during summer seasons at Terbol,
Lebanon, at Hudeiba, Sudan, and at Central Ferry, WA, USA from 2015 to 2018. These accessions
were genotyped using genotyping by sequencing (GBS), and 10,794 high quality single nucleotide
polymorphisms (SNPs) were discovered. These accessions were clustered in one diverse large group,
although several discrete groups may exist surrounding it. Fifteen lines belonging to different
botanical groups were identified as tolerant to heat. SNPs associated with heat tolerance using singletrait
(ST) and multi-trait (MT) genome-wide association studies (GWASs) showed 9 and 11 significant
associations, respectively. Through the annotation of the discovered significant SNPs, we found
that SNPs from transcription factor helix–loop–helix bHLH143-like S-adenosylmethionine carrier,
putative pentatricopeptide repeat-containing protein At5g08310, protein NLP8-like, and photosystem
II reaction center PSB28 proteins are associated with heat tolerance.