Abstract
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.
Highlights
Agriculture aims to provide food and nutritional security for human life
The same proportion of recombinant inbred lines (RILs) conferred a larger degree of tolerance, measured as the proportional change in shoot dried weight (ShDW) between watering levels, than both controls
Correlation and principal component analyses (Figure 2) revealed that ShDW, ShFW, LFW, LDW, and FlN were associated under both irrigation regimes
Summary
Agriculture aims to provide food and nutritional security for human life It is highly dependent on water availability, since plants with limited water supply have a reduced capacity to transpire and draw water and nutrients to the root surface, which limits photosynthesis and final crop yield [1]. The closest wild relative to domestic tomato is Solanum piminellifolium [5,6], which originated in Ecuador and expanded to northern and Southern Peru, where its niche space became more associated with cold and drought [7]. Various transcription factors are involved in the regulation of the ABA-dependent signaling pathway and play a major role in the stress response by regulating the expression of many downstream droughtresponsive genes [3,14].
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