Gene Profile Analysis and Molecular-physiological Evaluation of Tomato Genotypes under Drought Stress

Introduction: It is believed that the identification of the differentially-expressed genes is extremely important for the clarification of the complex molecular mechanisms under drought conditions. This study aims to identify candidate genes in tomato genotypes under drought stress through transcriptomics analysis, investigate the expression of these genes, and also some physiological parameters.Materials and Methods: To the analysis of transcriptome profiles of sensitive and tolerant tomato genotypes under drought stress, three up-regulated genes were selected, including Chlorophyll a-b binding protein۳ (CAB۳), S-adenosylmethionine decarboxylase proenzyme (SAMDC), and ۱-aminocyclopropane-۱-carboxylate synthase ۹ (ACS۹). After bioinformatics analysis, the tomato genotypes were subjected to drought stress and gene expression was determined using Real-Time PCR. Physiological parameters of genotypes were also measured by spectrophotometer-based methods.Results: According to the results, these three genes play a key role in stress tolerance. Expression of the CAB۳ gene in both sensitive and tolerant genotypes was not significantly different compared to the control. This is while the SAMDC gene decreased in both genotypes, the ACS۹ gene decreased in the sensitive genotype and also increased in the tolerant genotype. The physiological analysis also showed that under stress conditions, the photosynthetic system of the plant was disrupted and the chlorophyll content was reduced. However, proline content and antioxidant enzymes activity increased, in which their quantity in the tolerant genotype was significantly higher than sensitive.Conclusions: In accordance with the obtained findings, it can be stated that under drought stress, due to damage to the lipid membrane, malondialdehyde content also increased, in which the sensitive genotype was more affected. 

Keywords:

Bioinformatics analysis , Drought stress , Gene expression , physiological parameters , Tomato , Transcriptome