Sources of Resistance to Common Bacterial Blight and Charcoal Rot Disease for the Production of Mesoamerican Common Beans in the Southern United States

Abstract

The gene pool of Mesoamerican common beans (Phaseolus vulgaris L.) includes genotypes in the small-to-medium-size seeded dry beans, as well as some snap beans from hotter environments adapted to the Southeastern United States. However, the warm and humid climate of the Southeastern United States is conducive to diseases such as Common Bacterial Blight (CBB) and Charcoal Rot (CR). The pathogens for these two diseases can survive long periods in infested soil or on seeds and are difficult to control through pesticides. Hence, field-level resistance would be the best management strategy for these diseases. The goals of this study were (1) to evaluate field-level resistance from the various commercial classes and subgroups represented in the Mesoamerican gene pool as sources for breeding beans for the region and (2) to evaluate genome-wide marker × trait associations (GWAS) using genetic markers for the genotypes. A total of 300 genotypes from the Mesoamerican Diversity Panel (MDP) were evaluated for CBB and CR in field experiments for three years. CBB resistance was also tested with a field isolate in controlled greenhouse conditions. The analysis of variance revealed the presence of variability in the MDP for the evaluated traits. We also identified adapted common bean genotypes that could be used directly in Southeastern production or that could be good parents in breeding programs for CBB and CR resistance. The GWAS detected 14 significant Single-Nucleotide Polymorphism (SNP) markers associated with CBB resistance distributed on five chromosomes, namely Pv02, Pv04, Pv08, Pv10, and Pv11, but no loci for resistance to CR. A total of 89 candidate genes were identified in close vicinity (±100 kb) to the significant CBB markers, some of which could be directly or indirectly involved in plant defense to diseases. These results provide a basis to further understand the complex inheritance of CBB resistance in Mesoamerican common beans and show that this biotic stress is unrelated to CR resistance, which was evident during a drought period. Genotypes with good yield potential for the Southeastern U.S. growing conditions were found with resistant to infection by the two diseases, as well as adaptation to the hot and humid conditions punctuated by droughts found in this region.

Association mapping for common bacterial blight in carioca beans

“…Zhu et al (2016) revealed two markers, BMp10s174 and BMp10s244, on Pv10 (39,730,677 and 40,002,585 bp in G19833). Ambachew et al (2021) found SNPs with minor effects associated with common bacterial blight resistance on Pv02 (8,541,089 bp), Pv04 (29,756,136 bp),Pv08 (24,383,486;55,730,740;55,730,740;8,738,278 bp),Pv10 (1,437,174 bp),and Pv11 (25,981,923 bp). Among them, Pv08 and Pv10 concentrated most of the CBB resistance genes.…”

“…Wu et al (2017) explored the association mapping of NBS-LRR (nucleotide binding site-leucine CCF Barbosa et al rich repeat) microsatellites and seven of them also mapped by Shi et al (2011). Ambachew et al (2021) detected 14 significant SNPs connected to CBB and over Pv02, Pv04, Pv08, Pv10, and Pv11. Simons et al (2021) identified 8 regions, including 6 previously mapped and two new loci (Pv11 and Pv10).…”

Screening a newly developed common bean germplasm with improved resistance to ashy stem blight in multiple environments

“…However, common bean BL and cultivars with enhanced levels of resistance are not yet available. One of the reasons may be because the breeding against ASB has been focused only on Middle American beans that possess tolerance to heat and drought ( Urrea et al., 2009 ; Beebe et al., 2013 ; Ambachew et al., 2021 ) and the severity of M. phaseolina increases in these environments ( Frahm et al., 2004 ; Mayek et al., 2002 ). In fact, BAT 477 and Negro Tacaná were used as donor parents to improve the resistance to M. phaseolina and tolerance to the aforementioned abiotic stresses in the SEA 5 and TARS-MST1 BL, respectively ( Singh et al., 2001 ; Porch et al., 2012 ).…”

“…Ashy stem blight (ASB) caused by the fungus Macrophomina phaseolina (Tassi) Goidanich is an important disease in the common bean ( Phaseolus vulgaris L.) in tropical and subtropical regions in the Americas and elsewhere ( Singh and Schwartz, 2010 ; Ambachew et al., 2021 ). This plant pathogen affects roots and all aerial plant parts causing damping off, root rots, stem blight, leaf burning, and premature senescence symptoms ( Islam et al., 2012 ; Kaur et al., 2012 ; Marquez et al., 2021 ).…”

Identification of a QTL region for ashy stem blight resistance using genome-wide association and linage analysis in common bean recombinant inbred lines derived from BAT 477 and NY6020-4

“…Ashy stem blight (ASB) is a common disease in the common bean ( Phaseolus vulgaris L.) in tropical and subtropical regions in the Americas and worldwide ( Kaur et al, 2012 ; Ambachew et al., 2021 ). The disease is caused by the seed-transmitted fungus Macrophomina phaseolina (Tassi) Goidanich, and the pathogen can infect the roots and all aerial plant parts during the entire cropping season ( Islam et al., 2012 ; Kaur et al., 2012 ; Viteri and Linares, 2022a ).…”