Identification and characterization of a gene encoding a putative lysophosphatidyl acyltransferase from Arachis hypogaea.

Lysophosphatidyl acyltransferase (LPAT) is the important enzyme responsible for the acylation of lysophosphatidic acid (LPA), leading to the generation of phosphatidic acid (PA) in plant. Its encoding gene is an essential candidate for oil crops to improve oil composition and increase seed oil content through genetic engineering. In this study, a full length AhLPAT4 gene was isolated via cDNA library screening and rapid amplification of cDNA ends (RACE); our data demonstrated that AhLPAT4 had 1631 nucleotides, encoding a putative 43.8 kDa protein with 383 amino acid residues. The deduced protein included a conserved acyltransferase domain and four motifs (I­IV) with putative LPA and acyl-CoA catalytic and binding sites. Bioinformatic analysis indicated that AhLPAT4 contained four transmembrane domains (TMDs), localized to the endoplasmic reticulum (ER) membrane; detailed analysis indicated that motif I and motifs II­III in AhLPAT4 were separated by the third TMD, which located on cytosolic and ER luminal side respectively, and hydrophobic residues on the surface of AhLPAT4 protein fold to form a hydrophobic tunnel to accommodate the acyl chain. Subcellular localization analysis confirmed that AhLPAT4 was a cytoplasm protein.Phylogenetic analysis revealed that AhLPAT4 had a high homology (63.7­78.3%) with putative LPAT4 proteins from Glycine max, Arabidopsis thaliana and Ricinus communis. AhLPAT4 was ubiquitously expressed in diverse tissues except in flower, which is almost undetectable. The expression analysis in different developmental stages in peanut seeds indicated that AhLPAT4 did not coincide with oil accumulation.

[A SCAR marker for resistance to Aspergillus flavus in peanut (Arachis hypogaea L.)].

Aflatoxin contamination is an important constraint to peanut (Archis hypogaea L. ) industry worldwide. Genetic improvement for host resistance in peanut to fungal infection and aflatoxin (Aspergillus flavus) production is among the approaches for integrated management of the problem. However, the progress in peanut breeding for resistance to aflatoxin is slow due to various reasons, among which, lack of cost-effective method for resistance identification in breeding materials or segregating progenies has been encountered in most breeding programs. Hence there is a need to develop a rapid and reliable screening method for selecting A. flavus infection resistance in peanut. Here we report a SCAR (Sequence characterized Amplified Region) marker "AFs-412" converted from AFLP (amplified fragment length polymorphism) marker "E45/M53-440" which closely linked with resistance to A. flavus infection. Twenty peanut genotypes with resistance to infection of A. flavus were used to verify the reliability of the resistance markers, and high correlation between the molecular markers and the resistance result. The result shows that the potential of the markers which can be used in other resistant peanut genotypes to seed infection by Aspergillus flavus.