Contrasting photosynthetic and biochemical adjustments in two aubergine (Solanum melongena L.) flooding-tolerant rootstocks subjected to waterlogging

ADIS, MARÍA JOSÉ; MIGNOLLI, FRANCESCO; VIDOZ, MARÍA LAURA

Congreso; XXXIV Reunión Argentina de Fisiología Vegetal; 2023

In addition to being a crop of economic importance, aubergine (Solanum melongena L.) is used as rootstock for tomato plant in areas subject to frequent flooding. This research aimed to study the response of 2 aubergine accessions to waterlogging stress. Genotypes (EG203 and TS03) were obtained and selected as flooding tolerant genotypes by Taiwan´s WorldVeg genetic resource centre. Six-week-old plants were transplanted into pots containing a commercial substrate and subjected to control and waterlogging treatments. Chlorophyll fluorescence (OJIP-test) and stomatal conductance were assessed for nine days. Photosynthetic pigments, soluble sugar, starch, total flavonoids, total phenols, thiobarbituric acid reactive substances (TBARS) and total antioxidant activity (TAA) were also analysed. Stomatal conductance did not decrease in response to flooding. However, fluorescence analysis yielded a significant increase in ABS/RC and DI0/RC parameters in EG203, indicating a decrease in the number of active reaction centres and an increase in the dissipation of the energy absorbed by the antennas. In addition, the Fv/Fm index inEG203, which expresses the maximum efficiency of PSII, decreased steadily, while it remained similar to the control in TS03. Biochemical analysis showed that chlorophyll b decreased in EG203, probably due to a reduction of antenna pigments. While soluble sugars did not differ between genotypes, starch content in EG203 was significantly lower, possibly due to the reduced photosynthetic efficiency. Despite a lower content of flavonoids in flooded EG203, total phenols and antioxidant activity did not vary in response to flooding stress, and TBARS (a lipid peroxidation marker) concentration was similar in both genotypes. We suggest, therefore, that oxidative stress in leaves is not so intense as to cause membrane lipid peroxidation, but enough to cause photoinhibition of photosynthesis in EG203.