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

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.

Metabolomics analysis reveals Embden Meyerhof Parnas pathway activation and flavonoids accumulation during dormancy transition in tree peony.

BACKGROUND: Bud dormancy is a sophisticated strategy which plants evolve to survive in tough environments. Endodormancy is a key obstacle for anti-season culture of tree peony, and sufficient chilling exposure is an effective method to promote dormancy release in perennial plants including tree peony. However, the mechanism of dormancy release is still poorly understood, and there are few systematic studies on the metabolomics during chilling induced dormancy transition. RESULTS: The tree peony buds were treated with artificial chilling, and the metabolmics analysis was employed at five time points after 0-4 °C treatment for 0, 7, 14, 21 and 28 d, respectively. A total of 535 metabolites were obtained and devided into 11 groups including flavonoids, amino acid and its derivatives, lipids, organic acids and its derivates, nucleotide and its derivates, alkaloids, hydroxycinnamoyl derivatives, carbohydrates and alcohols, phytohormones, coumarins and vitamins. Totally, 118 differential metabolites (VIP ≥ 1, P < 0.05) during chilling treatment process were detected, and their KEGG pathways involved in several metabolic pathways related to dormancy. Sucrose was the most abundant carbohydrate in peony bud. Starch was degradation and Embden Meyerhof Parnas (EMP) activity were increased during the dormancy release process, according to the variations of sugar contents, related enzyme activities and key genes expression. Flavonoids synthesis and accumulation were also promoted by prolonged chilling. Moreover, the variations of phytohormones (salicylic acid, jasmonic acid, abscisic acid, and indole-3-acetic acid) indicated they played different roles in dormancy transition. CONCLUSION: Our study suggested that starch degradation, EMP activation, and flavonoids accumulation were crucial and associated with bud dormancy transition in tree peony.