Genome-Wide Identification and Expression Analysis of the KCS Gene Family in Yellow Horn Reveal Their Putative Function on Abiotic Stress Responses and Wax Accumulation

Abstract

The β-ketoacyl CoA synthase encoded by the KCS genes is a rate-limiting enzyme for the synthesis of very-long-chain fatty acid (VLCFA), which catalyzes the VLCFA elongation. Yellow horn (Xanthoceras sorbifolium) is a horticultural tree species known for its kernel oil, which has strong resistance to drought, cold, high temperature, and saline-alkali. The conserved domain FAE1-CUT1-RPPA and ACP-syn-III_C of the KCS gene family were used to search the KCS sequences across the whole genomic sequence of yellow horn; a total of 20 XsKCS genes were identified and divided into four subfamilies. The conserved motif and transmembrane structure analysis revealed that most XsKCSs had a conserved transmembrane domain except XsKCS10 and XsKCS20. The prediction of cis-acting elements of XsKCS genes showed that XsKCS genes contained many stress and hormone response elements, such as ABRE, MBS, and LTR. Furthermore, XsKCS genes exhibited differential expression profiles under abiotic stress and stress-related hormone treatment conditions. Transcriptomic data showed that XsKCS1, XsKCS11, and XsKCS17 had higher expression in yellow horn with high leaf cuticular wax, indicating that they may function in the cuticular wax accumulation and drought response. This study laid a foundation for further functional verification of XsKCS genes in yellow horn stress response.

Genome-wide identification and expression analysis of the KCS gene family in soybean (Glycine max) reveal their potential roles in response to abiotic stress

“…In contrast, other gene family members don’t contain any of the motifs ( Figure 3C ). The different distribution of motifs within KCS proteins was also reported in previous studies ( Lian et al., 2020 ; Liu et al., 2022 ; Rizwan et al., 2022 ). Differences in GmKCS protein sequence characteristics imply that functional differentiation through evolution may have occurred, and further research on these sequence variations is needed for their functional elucidation and exploration.…”

“…To explore whether group β KCS genes have been lost only in soybean, rice and sorghum, we searched for articles on the KCS gene family in other plant species. Interestingly, the loss of the β group KCS gene was also reported in cotton ( Xiao et al., 2016 ), apple ( Lian et al., 2020 ), peanut ( Huai et al., 2020 ), barely ( Tong et al., 2021 ), yellow horn ( Liu et al., 2022 ), sorghum ( Zhang et al., 2022a ), passion fruit ( Rizwan et al., 2022 ), and rice ( Yang et al., 2023 ). Consistent with our results, KCS genes in group β have also been found in rapeseed and cabbage ( Xue et al., 2020 ), implying that group β KCS genes may be unique to cruciferous plants.…”

The Stilbene Synthase Family in Arachis: A Genome-Wide Study and Functional Characterization in Response to Stress

“…(Figures 5 and 6), consisting of the chalcone and stilbene synthases N-terminal (PF00195; Motifs 1, 3, and 4) and C-terminal (PF02797; Motifs 2 and 5) domains, both used here to identify CHS and STS proteins. In addition, these proteins also share three common domains, FAE1_CUT1_RppA (PF08392), ACP_synthase_III (PF08545), and ACP_synthase_III_C (PF08541) (Figure 6), which are characteristic features of type III PKSs in plants and are involved with lipid metabolism [35].…”