Sources, Spectrum, Genetics, and Inheritance ofPhaseolus vulgarisResistance AgainstXanthomonas citripv.fuscans

Abstract

Common bean (Phaseolus vulgaris) is one of the most consumed agricultural products in the world. Its production is affected by common bacterial blight (CBB) caused by Xanthomonas citri pv. fuscans and X. phaseoli pv. phaseoli. In this work, we investigated the spectrum, genetics, and inheritance of common bean resistance to X. citri pv. fuscans. Inoculation of nine selected cultivars with an X. citri pv. fuscans strain showed that BRS Radiante and IAPAR 16 were resistant. These two cultivars were also resistant to six X. phaseoli pv. phaseoli strains of different geographic origins, demonstrating their broad-spectrum resistances. BRS Radiante sustained smaller X. citri pv. fuscans populations than two susceptible cultivars. Stomatal densities of IAPAR 16 and BRS Radiante were significantly higher than or not different from susceptible cultivars. BRS Radiante showed the lowest general combining ability values and the combination BRS Radiante × Carioca MG the lowest specific combining ability (SCA) values, revealing the capacity of BRS Radiante to increase resistance to X. citri pv. fuscans. Positive and negative parental SCA values indicated dominant and recessive genes involved in X. citri pv. fuscans resistance. Resistance of the BRS Radiante × Carioca MG cross segregated in a 9:7 ratio in the F2 population, indicating that it is governed by two complementary dominant genes. Maximum likelihood analysis showed that the resistance of BRS Radiante to X. citri pv. fuscans is conferred by a gene of major effect with contribution of additional polygenes. This study contributes with important knowledge on the resistance against CBB in Brazilian common bean cultivars as well as with molecular tools for confirmation of common bean hybrids.

Genome‐wide association study (GWAS) of Phaseolus vulgaris resistance to Xanthomonas citri pv. fuscans

“…The common bean cultivars tested here showed different levels of resistance to Xcf, indicating that it is of quantitative type, which is consistent with results of previous reports for CBB (Monteiro et al, 2020; Paiva et al, 2018; Singh & Muñoz, 1999; Yu et al, 2012). Moreover, the AUDPC estimates varied from 19 to 55, a range that is similar to that reported by Durham (2011), who found a maximum value of 59.9 in a similar study using Xpp strains.…”

“…So far, the vast majority of studies have investigated common bean resistance against Xpp and only a few have addressed resistance to Xcf (Monteiro et al, 2020; Mutlu et al, 2008; Paiva et al, 2018). Nonetheless, it has been shown that some components of plant resistance are more effective against one of the bacterial pathogens, either Xpp or Xcf (Mutlu et al, 2008).…”

“…acutifolius and P . coccineus (Monteiro et al, 2020; Singh & Muñoz, 1999; Yu et al, 2012). Most studies on the resistance of common bean to CBB state that it is of quantitative type (Monteiro et al, 2020; Mutlu et al, 2008; Paiva et al, 2018; Silva et al, 2009; Singh & Muñoz, 1999; Yu et al, 2012), which is generally conferred by several genes that jointly contribute to fighting pathogen attack and, consequently, different levels of disease severity are observed among different plant genotypes.…”

“…coccineus (Monteiro et al, 2020; Singh & Muñoz, 1999; Yu et al, 2012). Most studies on the resistance of common bean to CBB state that it is of quantitative type (Monteiro et al, 2020; Mutlu et al, 2008; Paiva et al, 2018; Silva et al, 2009; Singh & Muñoz, 1999; Yu et al, 2012), which is generally conferred by several genes that jointly contribute to fighting pathogen attack and, consequently, different levels of disease severity are observed among different plant genotypes. Sometimes, these differences in levels of resistance are not easily distinguishable, which makes it important to measure disease progression through estimation of the area under the disease progress curve (AUDPC; Jeger & Viljanen‐Rollinson, 2001).…”

Improving Common Bacterial Blight Phenotyping by Using Rub Inoculation and Machine Learning: Cheaper, Better, Faster, Stronger

“…Different Xpp-Xcf strains may have different levels of pathogenicity regardless of whether they belong to one or the other pathovars (Mkandawire et al, 2004). In addition, common bean resistance to CBB is mediated by numerous quantitative trait loci (Monteiro et al, 2020;Singh and Miklas, 2015;Yu et al, 2012). Differences in aggressiveness combined with the presence of quantitative resistances lead to a wide range of possible disease intensities (Duncan et al, 2011).…”