Identification of sources of resistance to damping-off and early root/hypocotyl damage from Rhizoctonia solani in common bean (Phaseolus vulgaris L.)

Abstract

Rhizoctonia solani causes economically important root and hypocotyl diseases in common bean throughout the world. Root health is a vital factor in plant development and root diseases would negatively influence water and nutrient uptake as well as cause direct stand reduction and root rot damage to the crop. An efficient common bean screening method to evaluate damping-off and early root/ hypocotyl damage from R. solani was developed and used to identify dry bean lines with levels of resistance to this disease. Two sets of 163 and 111 lines previously evaluated for drought tolerance in Nebraska and Puerto Rico were evaluated for damping-off resistance and early root/hypocotyl damage under greenhouse conditions. Disease severity on plants was identified based on above-ground symptoms, seedling survival and root lesions using a rating scale of 1 (resistant) to 9 (susceptible). In the first set of lines representing commonly grown dry bean cultivars, germplasm and sources of damping-off resistance, the Rhizoctonia mean rating ranged from 1.7 to 3.9; Phaseolus vulgaris lines PI 310668 and PI 533249 had the highest damping-off resistance. In the second set of the best lines from a drought tolerance shuttle breeding program the Rhizoctonia mean rating was between 2.6 and 5.7. The availability of drought tolerant dry bean lines allowed the testing of the hypothesis that there was a correlation between selecting for drought tolerance and R. solani damping-off resistance. No correlation between mean disease rating and drought tolerance was found, but adapted dry bean lines such as NE14-08-176 released as SB-DT1, and NE14-08-225 were identified with moderate damping-off resistance and drought tolerance. Lines with both traits and other attributes will facilitate development of resistant bean cultivars to manage damping-off caused by R. solani.

Fungal Endophyte Diversity and Bioactivity in the Indian Medicinal Plant Ocimum sanctum Linn

“…R . solani causes economically important root and hypocotyl diseases in common bean throughout the world [ 78 ]. Different degrees and types of interactions were observed between phytopathogens and endophytic fungal isolates.…”

Sources of Resistance to Fusarium solani and Associated Genomic Regions in Common Bean Diversity Panels

“…A crucial step in developing resistant varieties is a reproducible protocol to screen for pathogen resistance under controlled conditions. Abiotic factors, including soil moisture content and temperature, can dramatically influence pathogen colonization or root development (Peña et al, 2013), resulting in inconsistent phenotypic evaluations. Improving the phenotypic methods of screening for resistance provides more robust and accurate phenotypic data that increases the power of GWAS to identify and map resistance QTL.…”

Isolation and identification of pathogenic fungi and oomycetes associated with beans and cowpea root diseases in Oman

“…This pathogen caused lesions and root rot symptoms on the hypocotyl, taproot and secondary roots of V. unguiculata inoculated with R. solani but with a non-significant reduction in fresh and dry weight, stem and root length. R. solani is the causal agent of Rhizoctonia root rot on Phaseolus vulgaris and other beans (El-Mohamedy et al, 2017; Peña et al, 2013). It is reported as the causal agent of web blight disease on Vigna unguiculata ( Onesirosan, 1975 ).…”

“…and Alternaria spp . Infection of roots by soilborne pathogens can affect water and nutrient uptake (Peña et al, 2013). Generally, fungal root disease epidemics on plants are influenced by several factors such as soil moisture, soil fertility, and the occurrence of other diseases and pests (Belete, Ayalew & Ahmed, 2013; Degraeve et al, 2016; Li et al, 2016; Naseri & Ansari Hamadani, 2017).…”