Discovering candidate genes related to flowering time in the spring panel of Camelina sativa

Camelina sativa is a promising oilseed and industrial crop that benefits sustainable food, feed and fuel industries. Early flowering is critical for local adaptation as well as maximizing yield in Camelina sativa. Even though the preliminary data indicated wide variation in flowering time in the spring camelina germplasm, our understanding of underlying genes and their roles in regulating flower development is still limited. The current study combined genotypic data and flowering time from the spring panel, followed by genome-wide association study (GWAS) and whole-genome prediction to identify significant trait-associated markers and evaluate the predictive capability of the entire marker set. The analysis of phenotypic data showed significant genotypic and environmental effects on flowering time. A high heritability of 0.893 in flowering time suggests effectiveness of breeding early flowering camelina varieties. The GWAS analysis identified 20 significant trait-associated single nucleotide polymorphisms (SNPs) that colocalized within/or near a variety of transcription factors (e.g. SUPPRESSOR of PHYA-1/SPA1, BES1-INTERACTING MYC-LIKE 1/BIM1) or protein families containing specific functional domains (e.g. CCCH zinc finger protein family and B3-DNA binding domain containing protein family). These transcription factors were known to interact with key regulatory genes in the four major pathways (i.e. photoperiod, autonomous, vernalization and gibberellic acid pathways) to cooperatively regulate floral transition in arabidopsis. Whole-genome prediction showed a low-to-moderate predictive ability (0.559) to improve early flowering trait in camelina. This study is the first step for future in-depth exploration and genetic improvements of flower development and timing in camelina for breeding.