The GA2ox Gene Family in Solanum pennellii: Genome-Wide Identification and Expression Analysis Under Salinity...

GA 2-oxidases (GA2oxs), a class of enzymes, inhibit the biosynthesis of bioactive gibberellins (GAs) in plants. The GA2 oxidase gene is crucial for regulating the passivation process of active GA and is widely involved in hormone signaling and abiotic stress processes.

To examine the potential effects of the GA2 oxidase gene on Solanum pennellii, one of the important stress-tolerance wild species of tomato, a systematic analysis was performed to study the structure, phylogenetic tree, genomic locus, and upstream cis-regulatory elements of SpGA2ox genes. The expression patterns of the SpGA2ox family in various tissues were analyzed on the basis of published RNA-seq data, and the changes in SpGA2ox expression in the leaves of seedlings were detected under salinity stress and GA treatment by real-time fluorescence quantitative PCR.

We identified nine SpGA2ox genes in S. pennellii. They were located on chromosomes 1, 2, 4, 7, 8, and 10. The SpGA2ox family was clearly divided into three groups through phylogenetic relationship analysis, namely, five in C19-GA2ox class I, one in C19-GA2ox class II, and three in C20-GA2ox class. And cis-element analysis provided the basis for understanding the function of growth, development, hormones, and abiotic stress of GA2ox genes in S. pennellii. The expression patterns of the SpGA2ox family were different in three classes, and SpGA2ox1 exhibited higher expression levels in the stem compared to other tissues. The expression levels of all SpGA2ox genes increased significantly under salt stress and decreased by treatment with GA₃. With the largest changes in relative expression levels, SpGA2ox3 and SpGA2ox8 might exert key effects on the regulation of GA synthesis and the response to salt stress.

The present study may be instrumental for further investigation into the impact of SpGA2oxs on responses to abiotic stress and provide potential targets for the genetic improvement of S. pennellii.