Comprehensive Analysis of SRO Gene Family in Sesamum indicum (L.) Reveals Its Association with Abiotic Stress Responses

Abstract

SIMILAR TO RCD-ONEs (SROs) comprise a small plant-specific gene family which play important roles in regulating numerous growth and developmental processes and responses to environmental stresses. However, knowledge of SROs in sesame (Sesamum indicum L.) is limited. In this study, four SRO genes were identified in the sesame genome. Phylogenetic analysis showed that 64 SROs from 10 plant species were divided into two groups (Group I and II). Transcriptome data revealed different expression patterns of SiSROs over various tissues. Expression analysis showed that Group II SROs, especially SiSRO2b, exhibited a stronger response to various abiotic stresses and phytohormones than those in Group I, implying their crucial roles in response to environmental stimulus and hormone signals. In addition, the co-expression network and protein-protein interaction network indicated that SiSROs are associated with a wide range of stress responses. Moreover, transgenic yeast harboring SiSRO2b showed improved tolerance to salt, osmotic and oxidative stress, indicating SiSRO2b could confer multiple tolerances to transgenic yeast. Taken together, this study not only lays a foundation for further functional dissection of the SiSRO gene family, but also provides valuable gene candidates for genetic improvement of abiotic stress tolerance in sesame.

Molecular Cloning, Characterization, and Expression Analysis of SIMILAR TO RCD-ONE (SRO) Family Genes Responding to Abiotic and Biotic Stress in Cucumber

“…It was reported that genes in SRO family play vital roles in the resistance to various abiotic stresses. In this work, many cis-elements responding to stresses (especially ARE and STRE) were distributed in the promoters of CsSRO genes (Figure 5), and similar results were reported in the promoter regions of SolySRO and SiSRO genes [46,50]. The qRT-PCR analysis also revealed that the expression of four CsSRO genes were significantly induced under salt and drought stress (Figure 7), suggesting their involvement in stress tolerance.…”

“…As shown in the phylogenetic tree, these SRO proteins were irregularly divided into two groups, namely group I and group II, and group I can be further divided into four subgroups (Ia to Id) (Figure 1). Consistent with previous reports [45,46], the SRO proteins of these species were clustered in dicot-or monocot-specific patterns. For example, group II had only dicotyledonous SRO proteins, while group I contained both monocotyledonous and dicotyledonous SRO proteins.…”

“…In this study, the cucumber SRO family genes were identified and cloned, and these genes were named as CsSRO1-CsSRO4, making it a small gene family. The number of SRO family genes was compared to those of previously identified plant species, such as sesame, rice, Arabidopsis, maize, Brachypodium distachyon, tomato, banana, and apple, which generally contained 4-6 SRO genes in their genomes [46,[48][49][50], but was much less than that in Chinese cabbage (12 genes) [51], and wheat (30 genes) [45]. These findings indicated that the expansion of the SRO gene family was relatively conservative, and the number of SRO family genes may not possess an absolute correlation with genome size during plant evolution.…”

“…For example, Arabidopsis AtSRO1 and AtRCD1 [16], rice OsSRO1d and OsSRO1e [21], tomato SolySRO5 and SolySRO6 [50] were found to have a broad expression in various tissues. In sesame, SiSRO1a and SiSRO1b were highly transcribed in various tissues, while SiSRO2a and SiSRO2b exhibited the highest transcript levels in root [46]. We thus investigated the spatio-temporal expression patterns of CsSRO genes during the development of various tissues based on the published RNA-Seq data.…”

“…Overexpression of MdRCD1 in Arabidopsis promotes plant adaptation to drought, salt, and H 2 O 2 stresses [52]. Overexpression of SiSRO2b also conferred the tolerance of transgenic yeast cells to osmotic, salt, and oxidative stress [46]. SRO family genes are also known as regulators function in plant defense response against pathogens, and the regulatory mechanisms depend on the hormone signaling pathways, such as JA, SA, and so on.…”