Morphological, ultrastructural and molecular variations in susceptible and resistant genotypes of chickpea infected with Botrytis grey mould

Biotic stress due to fungal infection is detrimental to the growth and development of chickpea. In our study, two chickpea genotypes viz Cicer pinnatifidum (resistant) and PBG5 (susceptible) were inoculated with (1 x 10(4) spore mL(-1)) of nectrotrophic fungus Botrytis cinerea at seedling stage. These seedlings were evaluated for morphological, ultrastructural, and molecular differences after 3, 5 and 7 days post inoculation (dpi). Visual symptoms were recorded in terms of water-soaked lesions, rotten pods and twigs with fungal colonies. Light and scanning electron microscopy (SEM) revealed the differences in number of stomata, hyphal network and extent of topographical damage in resistant (C. pinnatifidum) and susceptible (PBG5) genotypes, which were validated by stomatal index studies done by using fluorescence microscopy in the infection process of B. cinerea in leaves of both chickpea genotypes. In case of control (water inoculated) samples, there were differences in PCR analysis done using five primers for screening the genetic variations between two genotypes. The presence of a Botrytis responsive gene (LrWRKY) of size similar to 300 bp was observed in uninoculated resistant genotype which might have a role in resistance against Botrytis grey mould. The present investigation provides information about the variation in the infection process of B. cinerea in two genotypes which can be further exploited to develop robust and effective strategies to manage grey mould disease.

Automated summary

Biotic stress caused by fungal infection has a negative impact on the growth and development of chickpea. This study compared the response of a resistant genotype (C. pinnatifidum) and a susceptible genotype (PBG5) to Botrytis cinerea infection, and found morphological, ultrastructural, and molecular differences between them. Fluorescence microscopy revealed a higher stomatal index in the resistant genotype. PCR analysis also identified a Botrytis responsive gene in the resistant genotype, potentially contributing to its resistance against grey mould.