Developing drought-tolerant crops is an important strategy to mitigate climate change impacts. Modulating root system function provides opportunities to improve crop yield under biotic and abiotic stresses. With this aim, a commercial hybrid tomato variety was grafted on a genotyped population of 123 recombinant inbred lines (RILs) derived from Solanum pimpinellifolium, and compared with self- and non-grafted controls, under contrasting watering treatments (100% vs. 70% of crop evapotranspiration). Drought tolerance was genetically analyzed for vegetative and flowering traits, and root xylem sap phytohormone and nutrient composition. Under water deficit, around 25% of RILs conferred larger total shoot dry weight than controls. Reproductive and vegetative traits under water deficit were highly and positively correlated to the shoot water content. This association was genetically supported by linkage of quantitative trait loci (QTL) controlling these traits within four genomic regions. From a total of 83 significant QTLs, most were irrigation-regime specific. The gene contents of 8 out of 12 genomic regions containing 46 QTLs were found significantly enriched at certain GO terms and some candidate genes from diverse gene families were identified. Thus, grafting commercial varieties onto selected rootstocks derived from S. pimpinellifolium provides a viable strategy to enhance drought tolerance in tomato.

Grafting techniques are being used to improve economically important horticultural crops including Cucumis melo L. This 2-year study was carried out at Cukurova University, Adana, Turkey. This study aimed to evaluate the effects of grafting using different rootstocks on plant, fruit and seed quality in cantaloupe melons. The double haploid (DH) female (H27) and male (H4) parental lines of Solmaz F₁ (Cucumis melo L. var. cantalupensis) variety developed by Cukurova University Faculty of Agriculture were used as scion and three commercial interspecific hybrid Cucurbita (Cucurbita maxima Duchesne × Cucurbita moschata Duchesne) varieties, Nun-9075 F₁ (Nunhems), Ares F₁ (ITU) and TZ-148 (Clause) were used as rootstocks. The parental lines were also self grafted and ungrafted parents were used as the control group. The grafted and ungrafted parents were crossed during pollination. Graft combinations and control were compared for performances in measured parameters such as the main stem length (cm), main stem diameter (mm), node number, harvest time (day), fruit weight (g), fruit length (cm), fruit diameter (cm), fruit cavity length (cm), fruit cavity diameter (cm), fruit flesh thickness (cm), fruit rind thickness (mm), total soluble solids (TSS, %), fruit flesh productivity (%), number of full and empty seeds (number/fruit), 1000 seeds weight (g), seed germination rate (%) and time (day), seed emergence rate (%), and time (day). Most of the plant, fruit and seed parameters have been positively affected by grafting. The use of commercial interspesific Cucurbita hybrid rootstocks resulted in high values compared to the control group however, harvest time, fruit cavity length and diameter, fruit rind thickness and fuit flesh productivity parameters were not statistically significant between rootstocks. Considering seed emergence and germination rate Cucurbita hybrid rootstocks performed lower values than self grafted and ungrafted control. The current study concludes that grafting plays a crucial role in plant growth, fruit and seed characters in cantaloupe melons. Statistically significant differences were mostly observed based on evaluated parameters.