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Jasmonates, which include jasmonic acid (JA) and methyl jasmonate (MeJA), are compounds derived from linolenic acid. In recent years, the quality and phytochemical content of various fruits have been improved using plant growth regulators both before and after harvest. They play a significant role in improving the quality and biochemical composition of different fruit crops, including fruit peel colour, accumulation of anthocyanins, phenolic compounds, and antioxidant activities in the fruit. Further, the fruit ripening process is also accelerated by the application of jasmonate as it influences different physiological and molecular mechanisms of the plant system including regulation of the activities of different hormones during the entire period of fruit growth and development starting from fruit set to till ripening, activation of genes related to ripening, etc. In the case of apples, pre-harvest application of MeJA leads to enhanced fruit coloration by stimulating the anthocyanin biosynthesis gene MdUFGluT . The concentration of JA increases significantly during the early fruit development stage but then decreases sharply, reaching its lowest level when the fruits are fully ripe which signifies its role in initiating the fruit ripening process. Jasmonates can also induce the expression of genes related to ethylene synthesis and promote the production of ethylene gas. Application of jasmonates at the pre-climacteric stage increased the expression of 1-Aminocyclopropane-1-carboxylate synthase 1 (ACS 1) and 1-Aminocyclopropane-1-Carboxylic Acid Oxidase1 (ACO 1) genes. However, the accumulation of ACS1 mRNA decreased when Propyl Dihydro Jasmonate was applied at the climacteric stage, indicating that jasmonates influence system 2 ethylene synthesis pathway. In addition, these two compounds (MeJA and JA) are safe for human consumption; hence, can be applied at the commercial level to improve the fruit quality and ripening process in different fruit crops. This review provides an overview of the recent advancements in our understanding of the regulation of jasmonate biosynthesis, and the physiological and molecular mechanisms involved in the jasmonate-mediated fruit ripening process.

Abiotic stressorslike drought, salinity, and extreme temperatures significantly hamper global agricultural productivity by adversely affecting plant growth and crop production. As sessile organisms, plants have developed a sophisticated network of signaling pathways to recognize and address environmental challenges. At the heart of these responses are phytohormones, which play animportant role in conferring abiotic stress tolerance. The signaling pathways governed by these phytohormones are crucial for activating the physiological and molecular responses that enable plants to survive under stress conditions. Hormonal crosstalk, an integral component of the phytohormonal network, involves synergistic and antagonistic interactions that finely balance the growth-defense trade-off, allowing plants to optimize their responses to environmental stimuli. Current developments in genetics and molecular biology have shed light on the mechanisms by which phytohormonal signaling pathways are modulated during abiotic stress. This understanding opens new avenues for developing crop cultivars that are more resilient to stressthrough genetic engineering and biotechnological approaches. By manipulating hormonal pathways, it is possible to fortify plants against abiotic stresses, thus ensuring food production in the face of climate change. The present review emphasizes recent advances in understanding how phytohormones (PHs), the central regulators of plant physiological and biochemical responses, mediate plant resilience to such stresses and a strategic method to improve resistance toabiotic stressin horticultural plants, thereby helping agricultural systems remain resilient and sustainable in the face of escalating climatic challenges.

Advancements in tissue culture techniques have enabled the regeneration of a wide array of fruit varieties under in vitro condition. Use of micro-propagation technique is now available for numerous crops at a commercial scale. While this has facilitated clonal propagation and preservation of elite genotypes with superior traits, maintaining high genetic uniformity among regenerated plants remains a challenge due to the chance of induction of somaclonal variation, which results from gene mutations or changes in epigenetic marks. Such genetic variability can undermine the reliability of in vitro cloning and germplasm preservation, making it crucial to ensure the genetic fidelity of in vitro raised plants early in the process. Various strategies have been employed to assess genetic uniformity, including morphological, physiological, biochemical, cellular, and DNA-driven molecular marker methods. Despite its drawbacks, somatic variation also presents an opportunity for breeders to access new genetic diversity relatively quickly and without the need for sophisticated technology, which is especially beneficial for crops that are challenging to breed or possess limited genetic diversity. This paper examines the origins of variation triggered during the tissue culture process and investigates approaches for confirming different genetic fidelity in in vitro raised plantlets and discusses the potential applications of somaclonal variants in fruit crop improvement. Key message Identification of in vitro raised somaclonal variation through advance techniques has significant contribution in speed breeding of fruit crops.

Melatonin (MT), discovered as N‑acetyl-5-methoxytryptamine in 1958, exhibits significant potential as a regulator of plant growth, development and responses to environmental stressors. Its diverse levels across organs and species make it an intriguing subject for functional studies. This review explores the potential of MT, whether administered endogenously or exogenously, in mitigating various environmental stressors such as cold, metal toxicity, drought, salinity, chilling injuries, temperature fluctuations etc. A pivotal aspect of MT action involves its direct inhibition of reactive oxygen species (ROS) and reactive nitrogen species (RNS), pivotal players in oxidative stress. Mechanisms like enhanced antioxidant enzyme activity, bolstered non-enzymatic antioxidant systems, and activation of enzymes repairing oxidized proteins contribute to MT’s ability to confer resistance against abiotic stresses. Furthermore, by inducing the expression of genes related to antioxidant enzymes during stress, MT acts as a key regulator in orchestrating plant defense responses against environmental challenges. These collective actions underscore the role of MT in enhancing plant resilience to such challenges. The interaction of MT with various phytohormones in drought stress regulation prompts exploration of similar mechanisms to address diverse stressors in horticultural crops. MT’s collaborative synergy with fungicides presents a promising strategy for reducing reliance on harmful chemicals in fruit crop cultivation, thereby minimizing the environmental impact and enhancing crop management practices. However, this review also underscores the need for further research to explore how MT protects fruit crops from environmental challenges, potentially leading to environmentally friendly agricultural practices and safer food production.