ASSESSMENT OF HIGH TEMPERATURE TOLERANCE IN TOMATO THROUGH PHYSIOLOGICAL, METABOLITE AND GENE EXPRESSION ANALYSIS
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Date
2019-10-05
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UNIVERSITY OF AGRICULTURAL SCIENCES, GKVK BENGALURU
Abstract
Temperature is one of the important environmental factors which affect the plant
growth and development. In order to assess the high temperature tolerance mechanism in
tomato, three susceptible and three tolerant genotypes were grown under high temperature
conditions (40±2°C). Susceptible genotypes showed significant decrease in photosynthetic
rate and Fv/Fm ratio under high temperature stress. Fruit quality parameters like TSS,
acidity, Vitamin C content, total phenols and flavonoids, total carotenoids and lycopene
were also highly affected in the susceptible genotypes compared to tolerant genotypes
under stress. Pollen germination and viability were significantly reduced thereby fruit yield
was also markedly decreased in susceptible genotypes. The tolerant genotypes recorded
significantly better root growth compared to susceptible genotypes. With regard to
metabolomics, sugars, amino acids, phenols, flavonoids, polyamines and some of the stress
related hormones were highly accumulated in tolerant genotypes compared to susceptible
genotypes under stress. Some of the vitamins and organic acids were also up regulated
under stress in tolerant genotypes. GC-MS/MS data revealed that tolerant genotype
recorded higher content of aroma compounds compared to susceptible genotype under
stress. This study provides a compendium of metabolite levels from leaves and flowers of
tolerant and susceptible genotypes of tomato under control and high temperature stress.
The qRT-PCR study clearly showed genes like NCED, P5CS, spermidine synthase, TPS12
and TPS20 were highly up regulated at different stages of high temperature stress in
tolerant genotype compared to susceptible genotype. Further, there is an urgent need to
analyze all the metabolites of biosynthetic pathway (including intermediates) to understand
the rate limiting step of each pathway both under control and high temperature stress
conditions.