Toward the introgression of PvPdh1 for increased resistance to pod shattering in common bean

Abstract

Key message A common bean shattering-resistance allele of PvPdh1 reduces pod twists during dehiscence, shows dominance that varies by phenotyping method, is part of a selective sweep, and can be introgressed using CAPS markers. Abstract Some varieties of common bean (Phaseolus vulgaris L.) sufer from pod shattering, which can severely reduce yields, especially in arid conditions. The PvPdh1 locus on chromosome Pv03 has recently been described as a major locus controlling pod shattering in common bean and could be used to mitigate pod shattering in the future. Despite this, the role of a possible second locus on chromosome Pv08 remains unclear and patterns of dominance and epistasis between alleles of these genes have not been resolved. This information will be vital for eicient selection to decrease pod shattering. Further, the genetic diversity around the PvPdh1 gene has not yet been thoroughly explored, and there are not yet genetic screens that can be used to evaluate pod shattering in segregating populations. Here, we have developed a recombinant inbred population to determine the roles of genes implicated in pod shattering and evaluate the patterns of dominance among the relevant alleles. Our results suggest that a PvPdh1 allele reduces pod valve twisting, and its dominance varies by phenotyping method. This allele is the only genetic variant that provides environmentally stable and widespread resistance to pod shattering in Middle American common beans grown for grain. Further analyses identiied a selective sweep around PvPdh1 with greater nucleotide diversity in individuals with the ancestral, shattering-susceptible allele. Finally, we developed simple, efective CAPS markers to facilitate the introgression of PvPdh1 into new varieties of common bean. These genetic resources will be critical for improving the aridity resilience of a major global staple.

Pod shattering in grain legumes: emerging genetic and environment-related patterns

“…Race Mesoamerica types, which are native to lowland, higher-humidity regions, typically have the wild-type susceptible allele. Market classes in which the shattering-resistant PvPdh1 allele predominates have the lowest levels of shattering found in dry beans (Parker et al, 2020b). This allele is associated with a selection sweep and a reduction in pod twisting, and markers have been developed to facilitate its introgression (Parker et al, 2020b).…”

“…Rau et al (2019) proposed that nonorthologous mechanisms were responsible for the loss of pod shattering in legumes, accurately reflecting the state of research at the time. Since then, an increasing body of evidence suggests that homologous genes can often govern variation in this trait between species (Di Vittori et al, 2020;Parker et al, 2020aParker et al, , 2020bTakahashi et al, 2020;Zhang and Singh 2020), although several genes and mechanisms are responsible for this trait (Lenser and Theißen, 2013).…”

“…(B) A detailed view of the cell-wall-modifying pathway in Arabidopsis, which includes homologs of several candidates for legume shattering. Asterisks indicate genes with relatively well-characterized roles in pod shattering in Glycine max (red asterisks; Dong et al, 2014;Funatsuki et al, 2014;Zhang and Singh, 2020), P. vulgaris (yellow asterisks; Rau et al, 2019;Parker et al, 2020aParker et al, , 2020b, and Vigna spp. (purple asterisks; Lo et al, 2018;Takahashi et al, 2020).…”

Registration of ‘UC Southwest Gold’ heirloom‐like gold and white mottled bean

“…Growers in humid environments are advised to trial UC Southwest Gold under their local conditions before increasing the production scale. Both parents of UC Southwest Gold carry the PvPdh1 mutation leading to resistance to pod shattering, and pod shattering occurred at low levels in UC Southwest Gold even when grown in arid environments (Parker, Berny Mier y Teran, Palkovic, Jernstedt, & Gepts, 2020; Parker, Sousa, Floriani, Palkovic, & Gepts, 2020).…”

Registration of ‘UC Southwest Red’ heirloom‐like red and white mottled bean

“…Producers in humid climates are recommended to trial UC Southwest Red locally before scaling up production to larger acreage. Both parents possess PvPdh1 ‐mediated resistance to pod shattering (Parker, Berny Mier y Teran, Palkovic, Jernstedt, & Gepts, 2020; Parker, Sousa, Floriani, Palkovic, & Gepts, 2020), and UC Southwest Red shows low levels of pod shattering in the field.…”