Frequent extreme weather events exacerbate agricultural abiotic stress, with drought causing widespread yield loss. Tomato, a globally important vegetable sensitive to water deficit, has been predominantly studied under single-drought scenarios that poorly reflect recurrent field conditions. This study investigated physiological and molecular responses of two tomato genotypes to repeated drought stress. Results showed that the drought-sensitive genotype ‘TGTB’ exhibited faster ABA accumulation and more pronounced ABA-mediated stomatal closure. During the second drought cycle, stomatal pore length and width were significantly smaller than during the first drought, indicating a strong stress memory effect. In contrast, the drought-tolerant ‘LA1598’ showed minimal memory responses. Under extreme drought stress, primed and non-primed ‘TGTB’ plants showed significantly lower H₂O₂ content than controls, whereas primed ‘LA1598’ plants maintained a significantly lower O₂^·− production rate than non-primed plants during both extreme drought cycles. Antioxidant enzyme systems contributed to ROS homeostasis, supported by the regulation of key drought-responsive genes. This study demonstrates genotype-dependent memory capacity and reveals that drought priming enhances repeated drought tolerance through ABA-regulated stomatal adjustment. These findings provide a theoretical basis for improving tomato resilience to recurrent drought and supporting breeding of drought-tolerant varieties.

As the primary harvested organ, fruit size and weight hold significant economic importance during tomato production. Therefore, elucidating the genetic mechanisms underlying fruit size and weight is of considerable agronomic value. In this study, the Solanum pimpinellifolium introgression lines were constructed with “LA2093” as the donor and “Jina” as the recipient, and a genetic linkage map was constructed. Preliminary QTL mapping was conducted using four fruit-related traits: single fruit weight, fruit diameter, fruit length, and fruit shape index. A total of 10 QTLs were identified, including one for single fruit weight (qFw-3), five for fruit diameter (qFtd-3-1, qFtd-3-2, qFtd-4, qFtd-7, and qFtd-12), two for fruit length (qFl-3 and qFl-11), and two for fruit shape index (qFsi-2 and qFsi-3). To explore the key regulatory genes of the single fruit weight QTL qFw-3 locus, it was further finely mapped between SSR3-14 and C03M65101. The SSR3-14 and C03M65101 interval contained 57 genes on chromosome 3 (64.68–65.10 Mb) in the reference genome. Among these, eight genes, including Solyc03g114830, Solyc03g114870, Solyc03g114880, Solyc03g114890, Solyc03g114900, Solyc03g114910, Solyc03g115200, and Solyc03g115380, were identified as candidate genes involved in regulating fruit weight. These studies provide a basis for future functional validation of key regulatory genes and offer valuable genetic resources for the improvement of fruit size and weight during tomato breeding.