Caught in the genetic network: a novel regulator of lipid metabolism

Phylogenomics and functional analysis of Glycerol-3-Phosphate Acyltransferase (GPAT) Genes: A critical role in lipid biosynthesis

The tung tree (Vernicia fordii Hemsl.), an economically important woody plant, is widely planted for the production of high-quality tung oil. Glycerol-3-phosphate acyltransferases (GPATs), the rate-limiting enzymes in triacylglycerol synthesis, play an important role in seed oil biosynthesis. In this study, we performed a genome-wide analysis of VfGPATs. A total of 9 VfGPATs were identified from the whole tung genome, and phylogenetic analysis divided the VfGPATs into three major clades: clade II (VfGPAT9), clade III (VfATS1) and clade IV (VfGPAT1 ~ 8). Subcellular localization analysis revealed that five VfGPATs (1, 5, 6, 8, and 9) are localized in the endoplasmic reticulum, and four VfGPATs (3-1, 3-2, 3-3, and ATS1) are localized in the chloroplast. Overexpression of VfGPATs in Arabidopsis thaliana revealed that the oil content in VfGPAT8- and VfGPAT9-transgenic plants were significantly increased by 26.60 and 55.94% compared to the wild-type. Transient expression of VfGPAT8 + VfFADX and VfGPAT9 + VfFADX could promote the synthesis of α-eleostearic acid and enhance the accumulation of lipid droplets in tobacco (Nicotiana benthamiana) leaves. We further tested the enzymatic activities of VfGPAT8 and VfGPAT9 with the yeast double mutant strain ZAFU1. The results showed that VfGPAT8 complemented the phosphatidate biosynthetic defect in the double mutant, while VfGPAT9 could not, suggesting that VfGPAT8 has a high acetyltransferase activity. However, altering serine (S) residue at position 113 of VfGPAT9 to threonine (T) could restore its enzymatic activity. This study provided important insights into the evolutionary history of VfGPATs and will promote the genetic improvement of tung trees and related species.

Effects of Maternal Nutrition on Female Offspring Weight Gain and Sexual Development

Maternal nutrition during pregnancy influences postnatal life of animals; nevertheless, few studies have investigated its effects on the productive performance and reproductive development of heifers. This study evaluated the performance, reproductive development, and correlation between reproduction × fat thickness and performance × ribeye area (REA) traits of heifers. We also performed an exploratory genomic association during the rearing period in heifers submitted to fetal programming. The study comprised 55 Nellore heifers born to dams exposed to one of the following nutritional planes: control, without protein-energy supplementation; PELT, protein-energy last trimester, protein-energy supplementation offered in the final third of pregnancy; and PEWG, protein-energy whole gestation, protein-energy supplementation upon pregnancy confirmation. Protein-energy supplementation occurred at the level of 0.3% live weight. After weaning, heifers were submitted to periodic evaluations of weight and body composition by ultrasonography. From 12 to 18 months, we evaluated the reproductive tract of heifers to monitor its development for sexual precocity and ovarian follicle population. The treatments had no effect (p > 0.05) on average daily gain; however, the weight of the animals showed a significant difference over time (p = 0.017). No differences were found between treatments for REA, backfat, and rump fat thickness, nor for puberty age, antral follicular count, and other traits related to reproductive tract development (p > 0.05). The correlation analysis between performance traits and REA showed high correlations (r > 0.37) between REA at weaning and year versus weight from weaning until yearling; however, no correlation was found for reproductive development traits versus fat thickness (p > 0.05). The exploratory genomic association study showed one single-nucleotide polymorphism (SNP) for each treatment on an intergenic region for control and PEWG, and the one for PELT on an intronic region of RAPGEF1 gene. Maternal nutrition affected only the weight of the animals throughout the rearing period.