AUTHOR=Zhao Xuewei , Liu Ding-Kun , Wang Qian-Qian , Ke Shijie , Li Yuanyuan , Zhang Diyang , Zheng Qinyao , Zhang Cuili , Liu Zhong-Jian , Lan Siren 

TITLE=Genome-wide identification and expression analysis of the GRAS gene family in Dendrobium chrysotoxum

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1058287

DOI=10.3389/fpls.2022.1058287

ISSN=1664-462X

ABSTRACT=<p>The GRAS gene family encodes transcription factors that participate in plant growth and development phases. They are crucial in regulating light signal transduction, plant hormone (e.g. gibberellin) signaling, meristem growth, root radial development, response to abiotic stress, etc. However, little is known about the features and functions of GRAS genes in Orchidaceae, the largest and most diverse angiosperm lineage. In this study, genome-wide analysis of the GRAS gene family was conducted in <italic>Dendrobium chrysotoxum</italic> (Epidendroideae, Orchidaceae) to investigate its physicochemical properties, phylogenetic relationships, gene structure, and expression patterns under abiotic stress in orchids. Forty-six <italic>DchGRAS</italic> genes were identified from the <italic>D. chrysotoxum</italic> genome and divided into ten subfamilies according to their phylogenetic relationships. Sequence analysis showed that most <italic>DchGRAS</italic> proteins contained conserved VHIID and SAW domains. Gene structure analysis showed that intronless genes accounted for approximately 70% of the <italic>DchGRAS</italic> genes, the gene structures of the same subfamily were the same, and the conserved motifs were also similar. The <italic>K</italic>a/<italic>K</italic>s ratios of 12 pairs of <italic>DchGRAS</italic> genes were all less than 1, indicating that <italic>DchGRAS</italic> genes underwent negative selection. The results of <italic>cis</italic>-acting element analysis showed that the 46 <italic>DchGRAS</italic> genes contained a large number of hormone-regulated and light-responsive elements as well as environmental stress-related elements. In addition, the real-time reverse transcription quantitative PCR (RT−qPCR) experimental results showed significant differences in the expression levels of 12 genes under high temperature, drought and salt treatment, among which two members of the LISCL subfamily (<italic>DchGRAS13</italic> and <italic>DchGRAS15</italic>) were most sensitive to stress. Taken together, this paper provides insights into the regulatory roles of the GRAS gene family in orchids.</p>