Screening soil-borne disease resistance in wild and cultivated eggplant accessions for grafting and rootstock breeding

Abstract

Brinjal (S. melongena L.), a crucial dietary staple in South and Southeast Asia, faces severe yield losses from soil-borne wilt diseases caused by Fusarium oxysporum f. sp. melongenae (Fusarium Wilt), Ralstonia solanacearum (Bacterial Wilt), and Sclerotium rolfsii (Southern Blight), with losses up to 81% in India. To address this, 14 Solanum germplasms, including seven wild species and seven cultivated varieties, were screened for resistance to FW, BW, and SB during Kharif 2024 at the ICAR-Indian Institute of Vegetable Research, Varanasi, India, aiming to identify robust rootstocks for sustainable disease management and also a source for resistance in the rootstock breeding program. Disease severity was evaluated using the disease index at 10, 20, 30, and 40 days after inoculation and quantified cumulatively via the AUDPC under controlled conditions. Among the germplasms, S. torvum exhibited exceptional resistance across all pathogens, recording the lowest disease index at 40 days after inoculation (BW: 9.33%; SB: 53.33%; FW: 32.00%) and AUDPC (BW: 210.0; SB: 500.0; FW: 380.0), highlighting its potential as a superior rootstock. Similarly, S. sisymbrifolium, S. incanum, and accession IC-111056 showed strong resistance, particularly to BW and SB, while cultivars Surya, Solemel, and Zippy were highly susceptible, underscoring their vulnerability. Identifying the susceptibility of Surya through field trials across diverse agro-ecological zones is essential to validate the stability of resistance, as pathogen strains and environmental conditions vary regionally. The present experiment underscores advancements in rootstock breeding, highlighting significant progress in developing bacterial wilt-resistant eggplant through the identification of promising resistant accessions, contributing to global efforts for sustainable cultivation and rootstock breeding program in brinjal.