Exploration of Phaseolus Germplasm for Heat and Drought Tolerance

This presentation will discuss the potential of identifying Phaseolus accessions with potential tolerance to heat and drought. The genus Phaseolus consists of some 70-80 species, five of which have been domesticated. The most important of these domesticated species is the common bean (P. vulgaris), which has a mesic adaptation, i.e., it thrives in intermediate temperature and rainfall. Experiments are under way to develop advanced lines with potential mechanisms of tolerance to drought in common bean, including introgression from wild beans and recombination in a multi-parent (MAGIC) population resulting from crosses among diverse, but related parents. Concurrently, a GBS analysis of wild P. vulgaris diversity is coupled with a GIS analysis to identify key climatic factors differentiating these wild populations and establish correlations between these environmental variables and DNA sequence variation, as a first step towards marker-assisted and genomic selection. In contrast, two other domesticated Phaseolus species - lima bean (P. lunatus) and tepary bean (P. acutifolius) - are adapted to hotter and/or drier environments. (Two other species are adapted to cooler and wetter environments and will not be discussed here.) Physiological studies are being conducted to compare the behavior of the three species when faced with soil water deficit. These studies will hopefully lead to the development of bean cultivars with more robust growth patterns and performance in light of existing global climate change.