Legumes were among the first plant species to be domesticated, and accompanied cereals in expansion of agriculture from the Fertile Crescent into diverse environments across the Mediterranean basin, Europe, Central Asia, and the Indian subcontinent. Although several recent studies have outlined the molecular basis for domestication and eco-geographic adaptation in the two main cereals from this region, wheat and barley, similar questions remain largely unexplored in their legume counterparts. Here we identify two major loci controlling differences in photoperiod response between wild and domesticated pea, and show that one of these, HIGH RESPONSE TO PHOTOPERIOD (HR), is an ortholog of EARLY FLOWERING 3 (ELF3), a gene involved in circadian clock function. We found that a significant proportion of flowering time variation in global pea germplasm is controlled by HR, with a single, widespread functional variant conferring altered circadian rhythms and the reduced photoperiod response associated with the spring habit. We also present evidence that ELF3 has a similar role in lentil, another major legume crop, with a distinct functional variant contributing to reduced photoperiod response in cultivars widely deployed in short-season environments. Our results identify the factor likely to have permitted the successful prehistoric expansion of legume cultivation to Northern Europe, and define a conserved genetic basis for major adaptive changes in flowering phenology and growth habit in an important crop group.crop adaptation | Pisum sativum | Lens culinaris M any of the world's earliest agricultural systems were based around crops from two important groups: cereals and legumes. Although molecular and genetic analyses have led to considerable progress in understanding the genetic changes underlying domestication and adaptation in several cereal crops, similar efforts in legumes are in general much less advanced. Among the legumes domesticated in the world's oldest farming culture in the Neolithic Near East, the temperate long-day (LD) species lentil (Lens culinaris Medik.), pea (Pisum sativum L.), and chickpea (Cicer arietinum L.) all persist as crops of global economic importance. Of these crops, pea has the widest distribution, the most diverse phenology, and is the best understood genetically, and offers prospects for a detailed exploration of molecular events important in early cultivation and spread (1, 2).P. sativum is now generally viewed as a complex species that includes a wide variety of cultivated and wild forms with pink, purple, or white flowers (1). Wild P. sativum lines are characterized by dehiscent pods and a rough, thick seed coat, and include both tall, climbing forms distributed around the Mediterranean (P. sativum var. elatius) and shorter forms restricted to the Near East (P. sativum var. humile), which intergrade in their areas of overlap. Cytogenetic differences and analyses of genetic diversity support the view that the majority of cultivated peas originated from a distinct gene pool within var....

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.

Reproductive phenology is well known to be a key feature of crop adaptation to diverse ecogeographic variation and management practices. Lentil is one of the founder pulse crops of middle-eastern Neolithic agriculture, and the modern-day domesticated lentil germplasm is generally considered to form three broad adaptation groups: Mediterranean, South Asian and northern temperate, which correspond approximately to the major global production environments. Understanding the molecular basis of these adaptations is crucial to maximise efficiency of breeding programs. Here, we use a QTL approach to dissect the earliness that is characteristic of the South Asian pilosae ecotype, and that suits it to the typically short winter cropping season. We identified two loci, DTF6a and DTF6b, at which dominant alleles confer early flowering. We show that, although these loci can interact in an additive manner, DTF6a alone is sufficient to confer early flowering even in extremely short photoperiods. Comparisons with closely related legume species confirmed the presence of a conserved cluster of three FT orthologs among potential candidate genes in the region, and expression analysis in near-isogenic material showed that the early dtf6a allele is associated with a strong derepression of the FTa1 gene in particular. Analysis of sequence variation revealed the presence of a 7.4 kb deletion in the FTa1-FTa2 intergenic region in the pilosae parent, and a wide survey of over 400 accessions with diverse origin showed that the dtf6a allele is dominant in South Asia 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.