Caracterização fisiológica e molecular do microtomateiro cv. Micro-Tom (Solanum lycopersicum) e seus mutantes dgt e Nr e transgênicos hormonais DR5-GUS e EBS-GUS em resposta a toxicidade por alumínio

Abstract

Aluminum (Al) is a toxic element found in the soil, promoting changes in growth, development and crop productivity. The objectives of this research were to verify the physiological and anatomical responses of Solanum lycopersicum L. (Solanaceae) cv. Micro-Tom cultivated with Al, and to characterize the potential of this plant as a genetic model for studying the toxicity to this metal; to verify the possibility of two Micro-Tom hormonal mutant strains, with low sensitivity for AIA (dgt) and for ETo (Nr) demonstrating physiological changes in growth, development and productivity, in the presence of Al; and to verify the expression of the hormones auxin and ethylene for fruit and seed development under Al action, through the expression of transcription promoters fused to the GUS reporter gene in two Micro-Tom transgenic lines, pDR5::GUS and pEBS: :GUS. Plants were cultivated in nutrient solution until fruiting. The following were evaluated: concentration of nutrients in plant organs, photosynthetic rates, content of chloroplastic pigments, growth, fruit productivity, histological location of Al in fruits and seeds, lignification of roots, expression and activity of the GUS enzyme fused to transcription promoting genes in fruits of 5 and 8 mm and mature. Micro-Tom plants showed a reduction in the absorption of nutrients Mg, K, Ca, Mn, Fe, Cu, Zn and Mo, as well as in growth, productivity and relative water content, mainly in the concentrations of 200 µM and 300 µM of Al . There was a higher concentration of soluble solids in the fruits of plants cultivated with 300 µM Al. Histolocalization with Morin showed Al present in the fruits and seeds, mainly in the xylem, evidencing the translocation of Al to the aerial part. In dgt in the presence of Al, there was a greater reduction in biomass and nutrient concentration in the root, less accumulation of Al in roots and fruits compared to the wild strain (WT), reduction in chloroplast pigment contents and in carbon and carbon assimilation rates. transpiration, presence of more unripe than ripe fruits, higher content of soluble solids in the intermediate stage of development, and more rigid texture. In Nr there was a reduction in the concentration of nutrients in the root and an increase in Mg in the fruits, but there was no increase in the concentration of Al as occurred for WT and dgt in the fruits. There was reduced root growth, increased chlorophyll b content, lower rate for chlorophyll a fluorescence efficiency, the same proportion of unripe and ripe fruit, higher soluble solids content in the fruit, and less rigid fruit texture as found in plants wt. Al altered shoot and root growth and development in pDR5::GUS and pEBS::GUS strains. In fruits, transcription of genes fused to auxin and ethylene promoters occurred in an antagonistic manner in the evaluated developmental stages. GUS enzyme activity was highest in 5mm and mature fruits in the pDR5-GUS strain and highest in 8mm fruits in pEBS-GUS, indicating hormone signaling in response to Al through induction of prolonged fruit ripening and development of the seed.