Suppression of Defence Signalling and Wound-Healing Responses in Chickpea by Fusarium oxysporum f. sp. ciceris in Salinity-Affected Soil Increases Vulnerability to Wilt Incidence

Abiotic causes contribute to disease severity in several crops. The threat posed by increasing soil salinity to Fusarium wilt severity in chickpea is not thoroughly worked out. To determine the same, chickpea plants were challenged against the wilt pathogen Fusarium oxysporum f. sp. ciceris ( Foc-49 ) in salinity-stressed (FocNaCl) or non-stressed (Foc) soils, and the results were compared with the results from plants grown only in salinity without the pathogen (NaCl) and control (C). The antioxidant activities, G-protein-mediated defence signalling, and expression of defence genes in chickpea were enhanced in the salinity (NaCl) and suppressed in the combined treatment (FocNaCl). The defence genes in chickpea were up-regulated by 2–3 times in NaCl compared to FocNaCl indicating suppression of the defence responses by the pathogen Foc-49 . Similarly, the indicators of wound-healing responses in chickpea roots were also suppressed in FocNaCl that were otherwise up-regulated in NaCl. Additionally, NaCl-mediated tissue damage facilitated Foc-49 colonization on chickpea roots in FocNaCl compared to Foc and resulted in severe root rotting and wilt incidence. From the results, it can be concluded that chickpea plants become more vulnerable to Fusarium wilt due to salinity-induced root tissue damage coupled with suppression of a variety of defence signals such as G-protein-mediated defence signalling and wound-healing responses. The results also highlight the potential threats posed by increasing soil salinity to diseases like Fusarium wilt in crops.