AUTHOR=Oladzad Atena , González Abiezer , Macchiavelli Raul , de Jensen Consuelo Estevez , Beaver James , Porch Tim , McClean Phillip 

TITLE=Genetic Factors Associated With Nodulation and Nitrogen Derived From Atmosphere in a Middle American Common Bean Panel

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.576078

DOI=10.3389/fpls.2020.576078

ISSN=1664-462X

ABSTRACT=<p>Among grain legume crops, common beans (<italic>Phaseolus vulgaris</italic> L.) are considered to have poor biological nitrogen (N<sub>2</sub>) fixation (BNF) capabilities although variation in N<sub>2</sub> fixing capabilities exists within the species. The availability of genetic panel varying in BNF capacity and a large-scale single nucleotide polymorphism (SNP) data set for common bean provided an opportunity to discover genetic factors associated with N<sub>2</sub> fixation among genotypes in the Middle American gene pool. Using nodulation and percentage of N<sub>2</sub>-derived from atmosphere (%NDFA) data collected from field trials, at least 11 genotypes with higher levels of BNF capacity were identified. Genome-wide association studies (GWASs) detected both major and minor effects that control these traits. A major nodulation interval at Pv06:28.0–28.27 Mbp was discovered. In this interval, the peak SNP was located within a small GTPase that positively regulates cellular polarity and growth of root hair tips. Located 20 kb upstream of this peak SNP is an auxin-responsive factor AUX/indole acetic auxin (IAA)-related gene involved in auxin transportation during root nodulation. For %NDFA, nitrate (NO<sub>3</sub><sup>−</sup>) transporters, <italic>NRT1:2</italic> and <italic>NRT1.7</italic> (Pv02:8.64), squamosa promoter binding transcriptome factor (Pv08:28.42), and multi-antimicrobial extrusion protein (MATE) efflux family protein (Pv06:10.91) were identified as candidate genes. Three additional QTLs were identified on chromosomes Pv03:5.24, Pv09:25.89, and Pv11: 32.89 Mbp. These key candidate genes from both traits were integrated with previous results on N<sub>2</sub> fixation to describe a BNF pathway.</p>