Key glycolytic branch influences mesocarp oil content in oil palm

Abstract

The fructose-1,6-bisphosphate aldolase catalyzed glycolysis branch that forms dihydroxyacetone phosphate and glyceraldehyde-3-phosphate was identified as a key driver of increased oil synthesis in oil palm and was validated in Saccharomyces cerevisiae. Reduction in triose phosphate isomerase (TPI) activity in a yeast knockdown mutant resulted in 19% increase in lipid content, while yeast strains overexpressing oil palm fructose-1,6-bisphosphate aldolase (EgFBA) and glycerol-3-phosphate dehydrogenase (EgG3PDH) showed increased lipid content by 16% and 21%, respectively. Genetic association analysis on oil palm SNPs of EgTPI SD_SNP_000035801 and EgGAPDH SD_SNP_000041011 showed that palms harboring homozygous GG in EgTPI and heterozygous AG in EgGAPDH exhibited higher mesocarp oil content based on dry weight. In addition, AG genotype of the SNP of EgG3PDH SD_SNP_000008411 was associated with higher mean mesocarp oil content, whereas GG genotype of the EgFBA SNP SD_SNP_000007765 was favourable. Additive effects were observed with a combination of favourable alleles in TPI and FBA in Nigerian x AVROS population (family F7) with highest allele frequency GG.GG being associated with a mean increase of 3.77% (p value = 2.3E−16) oil content over the Family 1. An analogous effect was observed in yeast, where overexpressed EgFBA in TPI- resulted in a 30% oil increment. These results provide insights into flux balances in glycolysis leading to higher yield in mesocarp oil-producing fruit.

Transcriptomic analysis of mesocarp tissue during fruit development of the oil palm revealed specific isozymes related to starch metabolism that control oil yield

“…Several previous studies in oil palm have shown that high glycolytic activity is associated with high mesocarp oil content ( Loei et al., 2013 ; Wong et al., 2014 ; Wong et al., 2017 ). Similar overexpression of oil palm fructose-1,6-bisphosphate aldolase (FBA) and glyceraldehyde-3-phosphate (G3PDH) resulted in increased lipid content in yeast ( Ruzlan et al., 2017 ).…”

Functional Genome Analyses Reveal the Molecular Basis of Oil Accumulation in Developing Seeds of Castor Beans

“…Glycolysis is a crucial metabolic pathway for supplying precursors for oil biosynthesis [ 45 ]. In various oilseed crops such as Arabidopsis, sunflower, and oil palm, several limiting-rate enzyme genes involved in carbon allocation into oil have been identified to play a critical role in generating precursors for oil biosynthesis and regulating oil accumulation in developing seeds [ 30 , 33 , 46 , 47 , 48 ]. In our analysis, we identified several candidate genes (such as RcGPDH , RcGAPC , RcPGK , and RcPGM ) in glycolysis that may act as limiting-rate enzyme genes for generating precursors of oil biosynthesis in castor-developing seeds.…”

“…While the duration of seed development and oil content (TAG content) varied among different cultivars, previous investigations have generally characterized the seed development process of castor beans into three typical stages: the early stage, the rapid oil accumulation stage, and the late stage [17,18]. To characterize the process of oil accumulation during seed development, we divided the seed development of variety ZB306 into three stages, the early (10-20 DAP, days after pollination), middle , and late stage (46)(47)(48)(49)(50)(51)(52)(53)(54)(55), as shown in Figure 1a. Physiologically, in the early stage, there is the down-loading of soluble sugar from capsules where basic carbohydrate metabolism occurs, although the accumulation of TAG does not begin.…”