The Peanut (Arachis hypogaea L.) Gene AhLPAT2 Increases the Lipid Content of Transgenic Arabidopsis Seeds

Abstract

Lysophosphatidic acid acyltransferase (LPAT), which converts lysophosphatidic acid (LPA) to phosphatidic acid (PA), catalyzes the addition of fatty acyl moieties to the sn-2 position of the LPA glycerol backbone in triacylglycerol (TAG) biosynthesis. We recently reported the cloning and temporal-spatial expression of a peanut (Arachis hypogaea) AhLPAT2gene, showing that an increase in AhLPAT2 transcript levels was closely correlated with an increase in seed oil levels. However, the function of the enzyme encoded by the AhLPAT2 gene remains unclear. Here, we report that AhLPAT2 transcript levels were consistently higher in the seeds of a high-oil cultivar than in those of a low-oil cultivar across different seed developmental stages. Seed-specific overexpression of AhLPAT2 in Arabidopsis results in a higher percentage of oil in the seeds and greater-than-average seed weight in the transgenic plants compared with the wild-type plants, leading to a significant increase in total oil yield per plant. The total fatty acid (FA) content and the proportion of unsaturated FAs also increased. In the developing siliques of AhLPAT2-overexpressing plants, the expression levels of genes encoding crucial enzymes involved in de novo FA synthesis, acetyl-CoA subunit (AtBCCP2) and acyl carrier protein 1 (AtACP1) were elevated. AhLPAT2 overexpression also promoted the expression of several key genes related to TAG assembly, sucrose metabolism, and glycolysis. These results demonstrate that the expression of AhLPAT2 plays an important role in glycerolipid production in peanuts.

Variant Amino Acid Residues Alter the Enzyme Activity of Peanut Type 2 Diacylglycerol Acyltransferases

“…Increased gene expression was especially pronounced for acetyl-CoA carboxylase (NtACC) and enoyl-ACP reductase (NtER) ( Figure 11 ), which encode the rate-limiting step and another important early step in FA biosynthesis, respectively ( Slabas and Fawcett, 1992 ; O’Hara et al, 2007 ). Overall, our results were similar to those recently described by Chen et al (2015) , who overexpressed peanut LPAT2, another important Kennedy pathway enzyme, in transgenic Arabidopsis.…”

Characterization of glycerol-3-phosphate acyltransferase 9 (AhGPAT9) genes, their allelic polymorphism and association with oil content in peanut (Arachis hypogaea L.)

“…However, lipid synthesis in plants is a complicated biological process involving multiple genes, and exploring the key functional genes involved in peanut oil accumulation is important for both theoretical and practical applications. There have been some reports of the functional genes involved in TAG biosynthesis in peanut, including GPAT9, LPAAT and DGAT [39][40][41][42] . For example, the gene expression level of AhLPAAT in high-oil cultivar was found to be much higher than that in low-oil cultivar during seed development, and overexpression of AhLPAT2 in Arabidopsis increased the seed oil content of the transgenic plants and the transcript levels of several key genes related to TAG assembly 40 .…”

“…There have been some reports of the functional genes involved in TAG biosynthesis in peanut, including GPAT9, LPAAT and DGAT [39][40][41][42] . For example, the gene expression level of AhLPAAT in high-oil cultivar was found to be much higher than that in low-oil cultivar during seed development, and overexpression of AhLPAT2 in Arabidopsis increased the seed oil content of the transgenic plants and the transcript levels of several key genes related to TAG assembly 40 . In a previous study, a GPAT9 gene was isolated from peanut and shown to be highly expressed in stems, flowers and seeds; the maximum transcript accumulation of the AhGPAT9 gene was observed at 50 DAP in the peanut cultivar Huayu19, and no GPAT genes involved in seed oil accumulation have been identified so far 39 .…”

PrLPAAT4, a Putative Lysophosphatidic Acid Acyltransferase from Paeonia rockii, Plays an Important Role in Seed Fatty Acid Biosynthesis

“…In addition, the result that PrLPAAT4 overexpression in Arabidopsis resulted in the improvement in the total FAs content ( Figure 6 e) is consistent with the findings from many previous reports. Overexpression of peanut AhLPAAT2 in Arabidopsis, the total FA content of the seeds significant increased [ 46 ]. The total FAs content is increased in the PrLPAAT1 -overexpressing Arabidopsis plants [ 29 ].…”

“…The same result was found in transgenic Arabidopsis overexpressing AhLPAT2 from A . hypogaea [ 46 ]. Nevertheless, the molecular mechanism of the result remains unknown and need further studies.…”