Genome-Wide Identification of Expansin Gene Family and Their Response under Hormone Exposure in Ginkgo biloba L.

Abstract

Expansins are pH-dependent enzymatic proteins that irreversibly and continuously facilitate cell-wall loosening and extension. The identification and comprehensive analysis of Ginkgo biloba expansins (GbEXPs) are still lacking. Here, we identified and investigated 46 GbEXPs in Ginkgo biloba. All GbEXPs were grouped into four subgroups based on phylogeny. GbEXPA31 was cloned and subjected to a subcellular localization assay to verify our identification. The conserved motifs, gene organization, cis-elements, and Gene Ontology (GO) annotation were predicted to better understand the functional characteristics of GbEXPs. The collinearity test indicated segmental duplication dominated the expansion of the GbEXPA subgroup, and seven paralogous pairs underwent strong positive selection during expansion. A majority of GbEXPAs were mainly expressed in developing Ginkgo kernels or fruits in transcriptome and real-time quantitative PCR (qRT-PCR). Furthermore, GbEXLA4, GbEXLA5, GbEXPA5, GbEXPA6, GbEXPA8, and GbEXPA24 were inhibited under the exposure of abiotic stresses (UV-B and drought) and plant hormones (ABA, SA, and BR). In general, this study expanded our understanding for expansins in Ginkgo tissues’ growth and development and provided a new basis for studying GbEXPs in response to exogenous phytohormones.

Transcriptome- and genome-wide systematic identification of expansin gene family and their expression in tuberous root development and stress responses in sweetpotato (Ipomoea batatas)

“…These 59 IbEXP genes were divided into four subfamilies: IbEXPA , IbEXPB , IbEXLA , and IbEXLB , which were similar to those in other plant species. The number of 59 IbEXP genes is more than 46, 38, 36, 46, 36, and 38 EXP genes in barley ( Liu et al., 2021a ), Brachypodium distachyon ( Chen et al., 2020b ), Arabidopsis ( Sampedro and Cosgrove, 2005 ), gingkgo ( Guo et al., 2023 ), potato ( Chen et al., 2019 ), and tomato ( Lu et al., 2016 ), and is similar to 52 and 58 EXP genes in tobacco ( Ding et al., 2016 ) and rice ( Sampedro and Cosgrove, 2005 ), while is obviously less than 75, 88, 92, 93, and 241 EXP genes in soybean ( Zhu et al., 2014 ), maize ( Zhang et al., 2014 ), sugarcane ( Santiago et al., 2018 ), cotton ( Lv et al., 2020 ), and common wheat ( Han et al., 2019 ). These differing numbers suggest that the size of the EXP gene family has changed significantly in different plants during evolution.…”

“…A large number of EXP genes have been identified in a diverse range of plants. For instance, in monocots, 92, 58, 241, 88, 46, and 38 genes have been identified in sugarcane ( Santiago et al., 2018 ), rice ( Sampedro and Cosgrove, 2005 ), common wheat ( Han et al., 2019 ), maize ( Zhang et al., 2014 ), barley ( Liu et al., 2021a ), and Brachypodium distachyon ( Chen et al., 2020b ), respectively; and in dicotyledons, 36, 75, 46, 93, 52 genes were found in Arabidopsis ( Sampedro and Cosgrove, 2005 ), soybean ( Zhu et al., 2014 ), gingkgo ( Guo et al., 2023 ), cotton ( Lv et al., 2020 ), and tobacco ( Ding et al., 2016 ), respectively. The genome sequencing of hexaploid sweetpotato (Taizhong6) has been completed ( Yang et al., 2017 ).…”