Role of GRP1a in tomato fruits: susceptibility to fungi pathogens and response to different post-harvest conditions

DENHOFF L.; ATTALA N.; BUSTAMANTE C.; DRINCOVICH M.F.; MULLER G.

Mendoza

Congreso; LVIII Reunión de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2022

SAIB

Tomato is one of the main food crops worldwide. Its climacteric fruit has a short period of time during which its organoleptic properties are optimal for marketing and consumption. Currently, the commercialization period of these fruits is from the mature green stage at temperatures between 12- 15ºC. Although lower temperatures delay ripening, allowing marketing, they induce cold damage leading to a deterioration in the fruit quality when they are purchased by the consumer. Glycine-rich RNA-binding proteins (GRPs) are involved in the regulation of gene expression at the post-transcriptional level. In previous research by the working group, transgenic tomato plants cv Microtom that express the GRP1a protein from the mature green stage (PG-preGRP1a plants) have been obtained. The fruits of these plants have been characterized as having a higher protein content, compared to fruits of wild type (WT) plants, when these were stored for 7 days at 4ºC. In this work, progress was made in the knowledge of the response of WT and transgenic tomato fruits (PG-preGRP1a plants) under prolonged cold postharvest storage and their susceptibility to pathogen-induced attack at different temperatures. A postharvest treatment that evidenced cold damage in tomato fruits was set up. The fruits were harvested at the yellowish mature green stage (D0) and stored at 4ºC (damage-inducing temperature) and 15ºC (control temperature) for 21 days (21D4 and 21D15, respectively). Storage of tomato fruits at 4°C for 21 days, although it delays ripening, induces cold damage, which was greater in WT fruits compared to transgenic fruits. This damage is exacerbated by storing the fruits at room temperature 1 day after treatment (21D4+1 and 21D15+1). Fruit samples were collected under the different treatments and prior to them (D0) for evaluation. Proteome analysis of the different genotype fruits and conditions help to explain the phenotypes observed in WT and PG-preGRP1a fruits. For example, different levels of proteins involved in the cell wall remodeling and proteins found to interact with GRP1, as it is the case of ribosomal proteins L10, were found in the different samples. The response to infection of tomato fruits with Botrytis cinerea (BC) and Fusarium oxysporum (FO) at different postharvest temperatures (4ºC and 15ºC) was also studied. The results obtained indicated a greater susceptibility to these pathogens in fruits WT with respect to PG-preGRP1a fruits. This observed characteristic is consistent with proteins differentially expressed in genotypes and treatments (proteomic data), among which, cell wall restructuring proteins and pathogen attack response proteins stand out. The differential response to pathogen attack adds to the observed differential response to cold stress, and it represents an aspect to consider in cold injury index evaluations.