A novel blight and root rot of chickpea: A new host for Neoscytalidium dimidiatum

Abstract

In the southeastern province of Mardin in Turkey, a severe and novel fungal infection affected all chickpea plant parts, resulting in blight symptoms on stem, petiole, branch, and leaf, defoliation, seed and root rot, and death. Neoscytalidium dimidiatum was identified as the agent responsible for this new blight and root rot using sequence analysis of the ITS, tef1, and tub2 loci as well as morphological data. The pathogen was found in all surveyed districts and fields, with varying incidences of blight and root rot, blight being nearly twice (40%) as common as root rot (21%), and root-rotted and blighted plants co-occurring in the majority of instances. All 92 N. dimidiatum isolates from various tissues induced necrotic lesions on the inoculated plants, indicating they were pathogenic for chickpea. Conidia exhibited germination across a temperature range, with increasing temperatures positively influencing germination rates, and mycelial growth was significantly influenced by temperature, with the optimal growth temperature observed to be 35 °C. The response of 25 Turkish chickpea cultivars and three other genotypes when subjected to inoculation with Ciar 12 and Ciar 78 isolates, representative of phylogenetic clusters, was evaluated based on the severity of blight and root rot. The majority of cultivars and genotypes displayed high susceptibility and suffered mortality when exposed to either soil or spray inoculation with each isolate. Among the assessed cultivars and genotypes, Çağatay had the lowest severity of root rot. This study is the first to report a natural infection of chickpea plants by N. dimidiatum. Under global warming, this may be detrimental to chickpea cultivation and habitat in southeastern Turkey, which is the origin of chickpeas.