Flowering time is a key trait in breeding and crop evolution, due to its importance for adaptation to different environments and for yield. In the particular case of chickpea, selection for early phenology was essential for the successful transition of this species from a winter to a summer crop. Here, we used genetic and expression analyses in two different inbred populations to examine the genetic control of domestication-related differences in flowering time and growth habit between domesticated chickpea and its wild progenitor Cicer reticulatum . A single major quantitative trait locus for flowering time under short-day conditions [ Days To Flower ( DTF)3A ] was mapped to a 59-gene interval on chromosome three containing a cluster of three FT genes, which collectively showed upregulated expression in domesticated relative to wild parent lines. An equally strong association with growth habit suggests a pleiotropic effect of the region on both traits. These results indicate the likely molecular explanation for the characteristic early flowering of domesticated chickpea, and the previously described growth habit locus Hg . More generally, they point to de-repression of this specific gene cluster as a conserved mechanism for achieving adaptive early phenology in temperate legumes.

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Modern-day domesticated lentil germplasm is generally considered to form three broad adaptation groups: Mediterranean, South Asian and northern temperate, which correspond to the major global production environments. Reproductive phenology plays a key role in lentil adaptation to this diverse ecogeographic variation. Here, we dissect the characteristic earliness of the pilosae ecotype, suited to the typically short cropping season of South Asian environments. We identified two loci, DTF6a and DTF6b, at which dominant alleles confer early flowering, and we show that DTF6a alone is sufficient to confer early flowering under extremely short photoperiods. Genomic synteny confirmed the presence of a conserved cluster of three florigen (FT) gene orthologs among potential candidate genes, and expression analysis in near-isogenic material showed that the early allele is associated with a strong derepression of the FTa1 gene in particular. Sequence analysis revealed a 7.4 kb deletion in the FTa1-FTa2 intergenic region in the pilosae parent, and a wide survey of over 350 accessions with diverse origin showed that the dtf6a allele is predominant in South Asian material. Collectively, these results contribute to understanding the molecular basis of global adaptation in lentil, and further emphasize the importance of this conserved genomic region for adaptation in temperate legumes generally.

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