Drought and Salt Stressors Alter NAC and WRKY Gene Expression Profiles in Grafted Citrullus lanatus

Abstract Increasing drought and soil salinity pose significant threats to crop production around the world. One potential strategy to mitigate the impacts of these environmental changes is grafting, a horticultural technique that joins tissues from different plants. This study aimed to investigate and model changes in the expression of NAC and WRKY genes in grafted watermelon under varying salt and drought stress conditions (mild to extrem). The control groups were not restricted by any limitations. Citrullus lanatus (Thunb.) Matsum. & Nakai (watermelon) was used as the scion, and Lagenaria siceraria (Molina) Standl (bottle gourd) served as the rootstock in our experiments. During the 14-day treatment period, individuals from the grafted watermelon and bottle gourd plants were more successful to maintained water balance and growth rates, while ungrafted plants exhibited growth retardation and tissue damage, especially under salt stress. The analysis of gene expression revealed that grafted plants showed significantly increased expression of salt- and drought-sensitive genes, including ClNAC2b , ClNAC69 , ClNAC72 , ClWRKY13 , ClWRKY14 , and ClWRKY23 , compared to ungrafted plants under low-stress conditions. These adaptations, such as stomatal closure and regulation of evaporation, enabled the improved grafted plants to respond more effectively to abiotic stress, supporting their survival and normal development. Our findings underscore that grafting is an environmentally friendly, rapid, and effective technique to enhance plant resilience against abiotic stresses, offering promising avenues to improve stable food crop production amidst increasing environmental challenges.