Screening of cowpea accessions for cowpea aphid resistance

Abstract

<jats:p>ABSTRACT Cowpea (Vigna unguiculata) genotypes may preserve important characteristics of potential use for the genetic breeding of this species. This study aimed to characterize sources of genetic resistance to the cowpea aphid (Aphis craccivora), among accessions maintained at the cowpea germplasm bank of the Universidade Federal do Ceará (Brazil), in order to suggest crossing options for obtaining superior cultivars. Twenty-one local accessions were assessed together with two genotypes as resistant checks and two others as susceptible checks. A randomized complete block design, with four replications, was used. Counts of live adults and nymphs per plant were used to evaluate the genotypic resistance and, based on the ranking of these data, the effective resistance was estimated. The applied approach showed to be effective to discriminate the genetic variability for cowpea aphid resistance, identifying antibiosis as the probable resistance mechanism. Four genotypic groups were identified: resistant, intermediate, susceptible and highly susceptible. Thus, for a short-time cultivar release strategy, backcrosses are suggested between the BRS Guariba cultivar (recurrent parental, with good agronomic traits) and aphid-resistant accessions, such as Enrica Pobre (CE-36), Das Almas (CE-07), CE-51 (selected within CE-13) and Ritinha (CE-08). However, for a long-term breeding strategy, crossings between the most dissimilar accessions are suggested, using resistant genitors (e.g. BRS Guariba, Enrica Pobre, Das Almas, CE-51 and Ritinha) and others with good commercial and agronomic attributes.</jats:p>

Características da transmissão do maize yellow mosaic virus (gênero >i<Polerovirus>/i<) por afídeos (Hemiptera: Aphididae) em milho (>i<Zea mays >/i< L.)

“…Estudos indicam o melhoramento de espécies de plantas como feijão (Phaseolus vulgaris, Lineu) e sorgo a fim de evitar a instalação e multiplicação dos insetos na cultura. Genótipos de feijão apresentaram maior resistência ao ataque de pulgões provavelmente seguindo a via da antibiose (liberação de algum composto que promove maior mortalidade dos afídeos) (Silva e Bleicher, 2010;Ferreira et al, 2020). Como na maioria dos casos, no Brasil, os afídeos se multiplicam por partenogênese vivípara, mesmo os casos em que adultos aparentemente não foram atingidos, sua prole acabou sendo afetada, já que se desenvolve no interior do adulto.…”