Genome-Wide Identification of WRKY Family Genes and Analysis of Their Expression in Response to Abiotic Stress in Ginkgo biloba L.

Abstract

Ginkgo biloba is widely planted, and the extracts of leaves contain flavonoids, terpene esters and other medicinal active ingredients. WRKY proteins are a large transcription factor family in plants, which play an important role in the regulation of plant secondary metabolism and development, as well as the response to biotic and abiotic stress. In our study, we identified 40 genes with conserved WRKY motifs in the G. biloba genome and classified into groups I (groups I-N and -C), II (groups IIa, b, c, d, and e), and III, which include 12, 26, and 2 GbWRKY genes, respectively. Meanwhile, the expression patterns of 10 GbWRKY (GbWRKY2, GbWRKY3, GbWRKY5, GbWRKY7, GbWRKY11, GbWRKY15, GbWRKY23, GbWRKY29, GbWRKY31, GbWRKY32) under different tissue and abiotic stress conditions were analyzed. Under stress treatment, the expression patterns of 10 WRKY genes were changed. 10 ginkgo WRKY transcription factors were induced by ETH and SA, but there are two different induced response modes. The expression of 10 WRKY genes was inhibited under low temperature, high temperature and MeJA hormone induction. Most WRKY genes were up-regulated under the induction of high salt and ABA. GbWRKYs were differentially expressed in various tissues after abiotic stress and plant hormone treatments, thereby indicating their possible roles in biological processes and abiotic stress tolerance and adaptation. Our results provided insight into the genome-wide identification of GbWRKYs, as well as their differential responses to stresses and hormones. These data can also be utilized to identify potential molecular targets to confer tolerance to various stresses in G. biloba.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********