Blackgram-Macrophomina phaseolina Interactions and Identification of Novel Sources of Resistance

Macrophomina phaseolina, a fungus that causes dry root rot, is a relatively new threat to blackgram in South Asia. Because this pathogen is a polyphagic necrotroph, it remains viable in the soil for several years, making disease management challenging. One of the most economical methods for managing dry root rot in blackgram is through an integrated approach that uses resistant varieties. This study examined M. phaseolina associated with dry root rot in blackgram and screened 41 blackgram genotypes for dry root rot resistance. The present work also characterized morphological features and internal transcribed sequence regions of the nuclear rDNA operon to identify M. phaseolina from blackgram. Evaluation of the 41 blackgram genotypes against M. phaseolina by the paper towel technique identified two genotypes, CO-5 and IPU 07-3, with dry root rot resistance (disease scores: ≤3) and 18 genotypes with moderate resistance (disease scores: >3 to ≤5). Five genotypes with disease scores <4.0 and two susceptible genotypes were reevaluated using the paper towel method, which revealed moderate resistance reactions of CO-5, IPU 07-3, and MASH 1-1. To confirm dry root rot resistance of these seven genotypes, further screening was done in a greenhouse using the sick pot assay. Results revealed moderate resistance of CO-5, IPU 07-3, and MASH 1-1 genotypes. As compared with susceptible check (VO 2135-B-BL), CO-5 consistently excelled in plant survival with 13.4% disease incidence, followed by IPU 07-3 (16.7%) and MASH 1-1 (19.9%). Therefore, these three genotypes can be used as parents in blackgram breeding programs for developing blackgram cultivars with improved dry root rot resistance.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.