Morales Quintana, Luis

Expansins are proteins involved in cell wall metabolism that play an important role in plant growth, development, fruit ripening and abiotic stress tolerance. In the present study, we analyzed putative expansins that respond to drought stress. Five expansin genes were identified in cDNA libraries isolated from Colobanthus quitensis gown either with or without endophytic fungi under hydric stress. A differential transcript abundance was observed by qPCR analysis upon drought stress. To compare these expansin genes, and to suggest a possible mechanism of action at the molecular level, the structural model of the deduced proteins was obtained by comparative modeling methodology. The structures showed two domains and an open groove on the surface of the proteins was observed in the five structural models. The proteins were evaluated in terms of their protein-ligand interactions using four different ligands. The results suggested differences in their mode of protein-ligand interaction, in particular concerning the residues involved in the protein-ligand interaction. The presented evidence supports the participation of some members of the expansin multiprotein family in the response to drought stress in C. quitensis and suggest that the response is modulated by endophytic fungi.

Strawberry is one of the most widely consumed fruit, but this crop is highly susceptible to drought, a condition strongly associated with climate change, causing economic losses due to the lower product quality. In this context, plant root-associated fungi emerge as a new and novel strategy to improve crop performance under water-deficiency stress. This study aimed to investigate the supplementation of two Antarctic vascular plant-associated fungal endophytes, Penicillium brevicompactum and Penicillium chrysogenum, in strawberry plants to develop an efficient, effective, and ecologically sustainable approach for the improvement of plant performance under drought stress. The symbiotic association of fungal endophytes with strawberry roots resulted in a greater shoot and root biomass production, higher fruit number, and an enhanced plant survival rate under water-limiting conditions. Inoculation with fungal endophytes provokes higher photosynthetic efficiency, lower lipid peroxidation, a modulation in antioxidant enzymatic activity, and increased proline content in strawberry plants under drought stress. In conclusion, promoting beneficial symbiosis between plants and endophytes can be an eco-friendly strategy to cope with drought and help to mitigate the impact of diverse negative effects of climate change on crop production.

Strawberries (Fragaria x ananassa) are valued worldwide for their aroma among other quality traits. Pyruvate decarboxylase (PDC) is a key enzyme in aroma, initiating the conversion of pyruvate into acetaldehyde. This process produces precursors for esters and aromatic compounds that enhance strawberry aroma. Additionally, alcohol acyltransferases (AATs) are essential for catalyzing acyl group transfers, further enriching fruit aroma diversity. However, strawberries are highly vulnerable to drought, which affects product quality. Plant root-associated fungi offer a novel approach to mitigate water deficiency stress. This study investigates the effect of Antarctic fungal inoculation on the gene expression of FaPDC, and the FaAAT gene family, related to the accumulation of volatile organic compounds (VOCs) in strawberries. Fruits of fungi-inoculated plants under drought stress showed significant changes in gene expression, leading to increased total volatile ester production, primarily in acetate esters, which are important for strawberry aroma. These findings underscore the role of Antarctic fungi in modulating the metabolic pathway of volatile esters by inducing the expression of FaPDC and FaAAT genes. Beyond elucidating the molecular mechanisms underlying aromatic compound biosynthesis in fruits, this study highlights the potential of Antarctic microorganisms as valuable tools to restore and maintain the sensory attributes of agricultural products under water deficiency stress.