Response of Tomato Plant to Abiotic (Heat Stress) and Biotic (Tomato Leaf Curl New Delhi Virus, TOLCNDV) Factors

Abstract

Tomato (Lycopersicon esculentum) is a vital fruit-bearing plant renowned for its nutritional advantages. Subjected to various environmental stresses, its yield is significantly impacted. Plants, confronting combined biotic and abiotic stresses, exhibit diverse responses through the evolution of cellular defense mechanisms. Sensitivity to extreme temperatures and pathogenic threats, such as the white fly-transmitted tomato leaf curl New Delhi virus (ToLCNDV), a Begomovirus, underscores the global susceptibility of tomato crops. This study aimed to assess tomato plant responses to the compounding stress of heat and agroinfiltrated ToLCNDV, analyzing four key physiological parameters viz., photosynthesis rate, stomatal conductance, transpiration rates, and Water use efficiency. Results indicated reduced photosynthesis rate of 5.1 ± 0.54 % mol CO₂ m^-2s^-1, diminished stomatal conductance of 89.84±1.27% mmol.m^-2s^-1, and transpiration rates of 0.978 ± 0.148 %mmol.m^-2s^-1 as compared to control group as 8.56 ± 0.55 % mol CO₂ m^-2s^-1, 189.08±19.13%mmol.m^-2s^-1and 2.586 ± 0.415 % mmol.m^-2s^-1respectively. Water use efficiency increased in double-stressed plants at 9.1 ± 0.96 % mmol CO₂mol^-1 H₂O with respect to control 5.84 ± 0.48 % mmol CO₂mol^-1 H₂O. The combined stressors manifested a net adverse impact, with neither ToLCNDV mitigating heat stress effects nor vice versa. Contrarily, their combined consequences were significantly amplified compared to individual stressors, emphasizing the intricate interplay of heat stress and ToLCNDV on tomato plants. This research marks a pioneering effort to uncover the physiological responses of a vulnerable tomato cultivar to the combined pressures of ToLCNDV and heat stress. Furthermore, it signifies a novel pathway towards the development of transgenic cultivars capable of effectively managing these stresses.