Severity Evaluation Methods in Common Bean Recurrent Selection Programme for Resistance to Angular Leaf Spot

Abstract

The objectives of this study were to identify which method and period of evaluation of angular leaf spot (ALS) of common bean, caused by the fungal pathogen Pseudocercospora griseola, allow better discrimination among common bean lines derived from seven cycles of recurrent selection for resistance to this pathogen. For that reason, 35 lines of the first seven cycles of the programme were assessed for disease severity on leaves and pods using a rating scale. For leaves, the methods used were severity in field plots (SF), severity in sampled leaflets (SS) and percentage of the sampled leaf area with symptoms (%LAS). Leaf assessments were performed at 7, 14, 21, 28, 33 and 41 days after flowering (DAF), and area under the disease progress curve (AUDPC) was calculated. On pods, severity was evaluated at 41 DAF. It was observed that the SF using a rating scale is the most efficient method for selection of resistant lines, and the best time period for evaluating the disease is around 33 DAF.

Genetic progress estimation strategy for upright common bean plants using recurrent selection

“…The most appropriate in this case is to compare our results to those found in studies that also used scores. For studies on common beans, especially angular leaf spot resistance, the estimates obtained in the present study were similar to those found in the literature (Amaro et al, 2007;Arantes et al, 2010;Rezende et al, 2014).…”

Effet variétal et du traitement fongicide sur la sévérité de la maladie des taches angulaires et le rendement du haricot commun (<i>Phaseolus vulgaris</i> L.) à l’Ouest-Cameroun

“…Ainsi, l'intensité des symptômes plus facile à déterminer que la sévérité pourrait être utilisée comme un indicateur d'évaluation de la sensibilité variétale du haricot commun vis-à-vis de la MTA. Ceci a été confirmé par les travaux récents de Rezende et al (2014) …”

“…L'inoculum qui a réalisé l'infection des plantes provenait de l'environnement. L'échelle d'intensité (de 1 à 9) établie par le CIAT (Rezende et al, 2014) a été utilisée pour mesurer l'intensité des symptômes de la maladie tandis que l'échelle modifiée de Horsfall-Barratt a permis d'estimer la sévérité de la maladie (Campbell et Madden, 1990). Les données de l'aire standardisé sous la courbe de progression de la maladie (ASCPM) ont été estimées selon la formule : où y i est la sévérité de la MTA au temps t i après inoculation (Bergamin et al, 1997).…”

Phenotyping for angular leaf spot severity and its implication in breeding common bean for resistance

“…Evaluation of progenies, that is, ALS severity of plants, is carried out in the field in R7 stage, with natural occurrence of pathogen, in dry season. After 16 recurrent selection cycles, several lines presented resistance to P. griseola and therefore genomic regions responsible for qualitative and quantitative resistance have been established (Arantes, 2010;Rezende et al, 2014;.…”

“…Phenotyping ALS severity in plants is important to identify new resistance sources, select progenies in breeding programs, and identify quantitative trait loci (QTL) for a marker-assisted selection. Reliable phenotyping is a crucial step for accurate disease assessment (Oblessuc et al, 2012;Rezende et al, 2014). Plant phenotyping in the greenhouse has been performed by artificial inoculation of isolates of P. griseola (Silva et al, 2008;Pereira et al, 2013;Jara et al, 2015).…”