Phenotypical and biochemical characterization of tomato plants treated with triacontanol.

Biostimulants are heterogeneous products designed to support plant development and to improve the yield and quality of crops. Here, we focused on the effects of triacontanol, a promising biostimulant found in cuticle waxes, on tomato growth and productivity. We examined various phenological traits related to vegetative growth, flowering and fruit yield, the metabolic profile of fruits, and the response of triacontanol-treated plants to salt stress. Additionally, a proteomic analysis was conducted to clarify the molecular mechanisms underlying triacontanol action. Triacontanol application induced advanced and increased blooming without affecting plant growth. Biochemical analyses of fruits showed minimal changes in nutritional properties. The treatment also increased the germination rate of seeds by altering hormone homeostasis and reduced salt stress-induced damage. Proteomics analysis of leaves revealed that triacontanol increased the abundance of proteins related to development and abiotic stress, while down-regulating proteins involved in biotic stress resistance. The proteome of the fruits was not significantly affected by triacontanol, confirming that biostimulation did not alter the nutritional properties of fruits. Overall, our findings provide evidence of the effects of triacontanol on growth, development, and stress tolerance, shedding light on its mechanism of action and providing new insights into its potential in agricultural practices.

The Salt Tolerance-Related Protein (STRP) Is a Positive Regulator of the Response to Salt Stress in Arabidopsis thaliana.

Salt stress is a major abiotic stress limiting plant survival and crop productivity. Plant adaptation to salt stress involves complex responses, including changes in gene expression, regulation of hormone signaling, and production of stress-responsive proteins. The Salt Tolerance-Related Protein (STRP) has been recently characterized as a Late Embryogenesis Abundant (LEA)-like, intrinsically disordered protein involved in plant responses to cold stress. In addition, STRP has been proposed as a mediator of salt stress response in Arabidopsis thaliana, but its role has still to be fully clarified. Here, we investigated the role of STRP in salt stress responses in A. thaliana. The protein rapidly accumulates under salt stress due to a reduction of proteasome-mediated degradation. Physiological and biochemical responses of the strp mutant and STRP-overexpressing (STRP OE) plants demonstrate that salt stress impairs seed germination and seedling development more markedly in the strp mutant than in A. thaliana wild type (wt). At the same time, the inhibitory effect is significantly reduced in STRP OE plants. Moreover, the strp mutant has a lower ability to counteract oxidative stress, cannot accumulate the osmocompatible solute proline, and does not increase abscisic acid (ABA) levels in response to salinity stress. Accordingly, the opposite effect was observed in STRP OE plants. Overall, obtained results suggest that STRP performs its protective functions by reducing the oxidative burst induced by salt stress, and plays a role in the osmotic adjustment mechanisms required to preserve cellular homeostasis. These findings propose STRP as a critical component of the response mechanisms to saline stress in A. thaliana.