Genome-wide identification and analysis of Oleosin gene family in four cotton species and its involvement in oil accumulation and germination

Abstract

Background Cotton is not only a major textile fiber crop but also a vital oilseed, industrial, and forage crop. Oleosins are the structural proteins of oil bodies, influencing their size and the oil content in seeds. In addition, the degradation of oleosins is involved in the mobilization of lipid and oil bodies during seed germination. However, comprehensive identification and the systematic analysis of the Oleosin gene (OLEOs) family have not been conducted in cotton. Results An in-depth analysis has enabled us to identify 25 and 24 OLEOs in tetraploid cotton species G. hirsutum and G. barbadense, respectively, while 12 and 13 OLEOs were identified in diploid species G. arboreum and G. raimondii, respectively. The 74 OLEOs were further clustered into three lineages according to the phylogenetic tree. Synteny analysis revealed that most of the OLEOs were conserved and that WGD or segmental duplications might drive their expansion. The transmembrane helices in GhOLEO proteins were predicted, and three transmembrane models were summarized, in which two were newly proposed. A total of 24 candidate miRNAs targeting GhOLEOs were predicted. Three highly expressed oil-related OLEOs, GH_A07G0501 (SL), GH_D10G0941 (SH), and GH_D01G1686 (U), were cloned, and their subcellular localization and function were analyzed. Their overexpression in Arabidopsis increased seed oil content and decreased seed germination rates. Conclusion We identified OLEO gene family in four cotton species and performed comparative analyses of their relationships, conserved structure, synteny, and gene duplication. The subcellular localization and function of three highly expressed oil-related OLEOs were detected. These results lay the foundation for further functional characterization of OLEOs and improving seed oil content.

A computational study on the structure–function relationships of plant caleosins

“…Besides, CNC-and NC-classes account for 90% of plant oleosins and are mainly expressed in seed and flower parts, respectively (data not shown). It is in agreement with other structural classifications of oleosins 8,11 . This data resolves the importance and role of each class of oleo-proteins.…”

“…However, our investigations show that CNC is not the only functional arrangement of caleosins. Though several bioinformatics analyses have been conducted on oleosins and caleosins [6][7][8][9][10][11] , to our knowledge, this is the first time that the presence of transmembrane (TM) domains has been included in the description and classification of caleosins.…”

Integrative Analysis of Oleosin Genes Provides Insights into Lineage-Specific Family Evolution in Brassicales

“…Among six oleosin genes identified in papaya, CpOLE6 in Clade N and CpOLE1 in Clade U have evolved to be constitutively expressed, whereas CpOLE3 in Clade SL and CpOLE4 in Clade SH have evolved into two dominant isoforms in seeds, calluses, and shoots, though CpOLE4 is more likely to be a WGD (γ) repeat of CpOLE5 , another SH member. The constitutive expression of U oleosin genes has been widely reported in other species, e.g., castor bean ( Ricinus communis ), physic nut ( Jatropha curcas ), cassava, rubber tree, safflower ( Carthamus tinctorius ), rapeseed ( Brassica napus ), and tigernut ( Cyperus esculentus ) [ 5 , 9 , 10 , 11 , 12 , 13 ]. Nevertheless, to our surprise, CpOLE1 was shown to be rarely expressed in both sap and pulp, which is different from CpOLE6 .…”

“…Oleosins are a class of highly abundant structural proteins of lipid droplets (LDs), which represent a major carbon reserve and are widely present in various plant organs such as seeds, pollen, flowers, fruits, and certain tubers [ 1 , 2 , 3 , 4 , 5 ]. Oleosins are typical for their small molecular weight (MW) of 14–30 kDa [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Nevertheless, all of them share a conserved central hydrophobic portion of approximately 72 residues, which could form a hairpin penetrating the surface phospholipid monolayer of an LD into the matrix.…”

Evolutionary and Integrative Analysis of the Gibberellin 20-oxidase, 3-oxidase, and 2-oxidase Gene Family in Paeonia ostii: Insight into Their Roles in Flower Senescence

“…The functional classification of genes is reflected in their subfamilies to some extent (Cheng et al, 2022;Yuan et al, 2021) [44,45]. On the basis of the phylogenetic tree, PoGA20oxs and PoGA3oxs were grouped into one subfamily, while PoGA2oxs were divided into two subgroups: GA2ox-A subfamily (GA2ox1~6) and GA2ox-B subfamily (GA2ox7~10) (Figure 1).…”