Fusarium Wilt Resistance in Pigeonpea: A Combined Phenotypic and ISSR Marker Study

Abstract

Pigeonpea (Cajanus cajan (L.) Millsp.) is a vital leguminous crop with significant nutritional and economic value, particularly in tropical and subtropical regions. However, its productivity is severely constrained by Fusarium wilt, a soil-borne disease caused by Fusarium udum, which can lead to yield losses ranging from 30 to 100%. Traditional breeding for resistance faces challenges due to limited resistant germplasm and environmental variability in phenotypic screening. This study integrates morphological evaluation with Inter Simple Sequence Repeat (ISSR) marker analysis to identify resistant genotypes and assess genetic diversity. Eleven pigeonpea genotypes were screened under controlled greenhouse conditions using artificial inoculation, revealing four resistant (0-6.66% wilt incidence), three moderately resistant (13.33-26%), and four susceptible (46.66-100%) genotypes. Molecular characterization using 13 ISSR primers generated 761 scorable bands, with UBC-818 and UBC-850 showing 100% polymorphism and ISSR-843 exhibiting the highest polymorphism information content (PIC = 0.358). Cluster analysis based on Jaccard’s similarity coefficients (0.54-0.91) distinctly grouped resistant and susceptible genotypes, validating phenotypic results. The study highlights the effectiveness of ISSR markers in identifying resistance-linked genomic regions, providing a reliable tool for marker-assisted breeding. These findings contribute to the development of high-yielding, wilt-resistant pigeonpea varieties, offering a sustainable solution to enhance productivity in disease-prone regions.