Drought Response and Genetic Diversity in Pisum fulvum, a Wild Relative of Domesticated Pea

Productivity of grain crops in semi-arid environments is often affected by drought, which is likely to increase due to predicted climate changes. Wild pea (Pisum fulvum Sibth. & Smith, Pf) accessions sampled across its ecological amplitude in Israel (350-850 mm annual precipitation) were used to assess the genetic diversity for drought responses. We hypothesized that native species evolving under Eastern Mediterranean climate carry adaptive traits to cope with drought stress. Accessions were classified according to single-nucleotide polymorphism variation pattern and habitat ecogeographic parameters. Significant differences were found between the accession groups, but grouping in both systems did not match. Subsequently, 52 Pf accessions and three domesticated pea (P. sativum L.) genotypes were evaluated during 2 yr under well-watered (similar to 580 mm) and water-limited (similar to 340 mm) treatments. Total dry matter, grain yield, harvest index, and average grain weight were higher in domesticated pea than wild Pf; however several Pf accessions exhibited lower drought susceptibility indices (i.e., greater stability across environments) than domesticated genotypes. Of special interest are a number of Pf genotypes in which low susceptibility to water stress was coupled with relatively high productivity. The sampling habitats of those low susceptibility-high productivity accessions are characterized by mild (400-530 mm) annual precipitation. Further sampling and evaluation of Pf from such locations may improve our understanding of pea drought adaptation and yield physiology.