IDENTIFICATION OF COWPEA GENOTYPES RESISTANT TO FUSARIUM WILT1

Rezânio Martins Carvalho ,Anthony Carlos Da Silva,Jonas Alberto Rios,Risoneide De Cássia Zeferino Silva,Antônio Félix Da Costa ,Alessandro Nicoli

doi:10.1590/1983-21252021v34n423rc

Abstract

ABSTRACT Fusarium wilt, caused by soil-borne Fusarium oxysporum f. sp. tracheiphilum (Fot), can reduce cowpea bean yield. Considering that genetic control through resistant genotypes is pivotal for Fusarium wilt control, the aim of the present study was to identify cowpea genotypes that are resistant to Fot from the Germplasm Bank of the Pernambuco Agronomic Institute, Embrapa Middle North, and other producing areas in the North and Northeast regions of Brazil. The cultivar BR-17 Gurguéia was used as a susceptible control and MNC01-649F-2-1 was used as a resistant control. Two experiments were carried out in a completely randomized design in the greenhouse of the Department of Agronomy of the University Federal Rural of Pernambuco. Plants with the first pair of expanded leaves were inoculated with a conidial suspension (106 conidia/mL) using the conidia root-immersion methodology. Fusarium wilt severity in plants was assessed 21 d after inoculation, with the aid of a descriptive scale. In the first experiment, we evaluated the resistance of 38 cowpea genotypes, of which 19 (5 moderately resistant and 14 resistant) were selected for the second experiment. In the first experiment, four genotypes (Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante) did not show any symptoms of Fusarium wilt. In the second, 15 genotypes showed high resistance to Fot, including Canapu PE and Miranda IPA 207, which again had no symptoms of Fusarium wilt. In conclusion, this study identified that the genotypes, Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante have greater resistance to Fusarium wilt.

Highlights

Cowpea seeds (Vigna unguiculata) from 38 genotypes were derived from the Germplasm Bank of the Pernambuco, Embrapa Middle North, and other producing areas in the North and Northeast regions of Brazil (Table 1)
*The values mean: 0 = plant without external symptoms; 1 = less than 10% of foliage with chlorosis and / or wilting; 2 = approximately 25% leaves with chlorosis and / or wilting; 3 = approximately 50% of leaves and branches with chlorosis and / or wilting, with plants showing dwarfism; 4 = approximately 75% or more of withered leaves and branches, severe dwarfism and premature defoliation, often resulting in plant death
Considering that genetic control through resistant cultivars is the most efficient control method for Fusarium wilt, this study shows the importance of exploring genetic variability in cowpea germplasm banks in management practices and for future application in cowpea breeding programs

Summary

Introduction

Walp.) is cultivated in many countries of tropical and subtropical regions (BERGER et al, 2016). The production of cowpea in Brazil is approximately. Fusarium wilt, caused by soil-borne Fusarium oxysporum f. Tracheiphilum (Fot), is one of the most important problems in cowpea (ASSUNÇÃO et al, 2003). The pathogen invades the vascular tissue via the root system, causing wilting and chlorosis of the leaves and sometimes stunting of the plant. Outward symptoms typically become evident at the seedling stage until flowering and early pod development, resulting in high mortality in the affected areas with significant overall yield loss (ARMSTRONG; ARMSTRONG, 1980). Dwarfism, leaf fall, death, and premature death of plants and damage caused by crop yield are commonly observed (ARMSTRONG; ARMSTRONG, 1980)

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