Heterologous expression, and biochemical and cellular characterization of CaPLA1 encoding a hot pepper phospholipase A1 homolog

• Published in: The Plant journal : for cell and molecular biology Vol. 53; no. 6; pp. 895 - 908
• Main Authors: Seo, Young Sam, Kim, Eun Yu, Mang, Hyung Gon, Kim, Woo Taek
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.03.2008; Blackwell Publishing Ltd; Blackwell Science
• Subjects: Amino acids; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Biochemistry; Biological and medical sciences; Botany; Capsicum - enzymology; Capsicum - genetics; Cell biochemistry; Cell Cycle - physiology; cell division; Cell physiology; Cellular biology; Deoxyribonucleic acid; DNA; early bolting; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Plant - physiology; leaf and root growth; phospholipase A1; Phospholipases A1 - genetics; Phospholipases A1 - metabolism; phospholipid metabolism; phospholipid signaling; Plant Leaves - growth & development; Plant physiology and development; Plant Roots - growth & development; Plants, Genetically Modified; Reverse Transcriptase Polymerase Chain Reaction; Signal transduction; Up-Regulation; phospholipase A1; Phospholipid; Triacylglycerol lipase; Esterases; Gene; Cruciferae; Dicotyledones; leaf and root growth; Angiospermae; Cell cycle; Development; Aminoacid sequence; Root; Enzyme; Arabidopsis; Germination; Inflorescence; cell division; phospholipid signaling; phospholipid metabolism; Plant leaf; Fatty acids; Phospholipase A; Carboxylic ester hydrolases; Complementary DNA; early bolting; Hydrolases; Spermatophyta; Petiole
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2007.03380.x

Phospholipid signaling has been recently implicated in diverse cellular processes in higher plants. We identified a cDNA encoding the phospholipase A1 homolog (CaPLA1) from 5-day-old early roots of hot pepper. The deduced amino acid sequence showed that the lipase-specific catalytic triad is well conserved in CaPLA1. In vitro lipase assays and site-directed mutagenesis revealed that CaPLA1 possesses PLA1 activity, which catalyzes the hydrolysis of phospholipids at the sn-1 position. CaPLA1 was selectively expressed in young roots, at days 4-5 after germination, and rapidly declined thereafter, suggesting that the expression of CaPLA1 is subject to control by a development-specific mechanism in roots. Because transgenic work was extremely difficult in hot peppers, in this study we overexpressed CaPLA1 in Arabidopsis so as to provide cellular information on the function of this gene. CaPLA1 overexpressors had significantly longer roots, leaves and petioles, and grew more rapidly than the wild-type plants, leading to an early bolting phenotype with prolonged inflorescence. Microscopic analysis showed that the vegetative tissues of 35S:CaPLA1 plants contained an increased number of small-sized cells, which resulted in highly populated cell layers. In addition, mRNAs for cell cycle-controlled proteins and fatty acid catabolizing enzymes were coordinately upregulated in CaPLA1-overexpressing plants. These results suggest that CaPLA1 is functionally relevant in heterologous Arabidopsis cells, and hence might participate in a subset of positive control mechanisms of cell and tissue growth in transgenic lines. We discuss possible biochemical and cellular functions of CaPLA1 in relation to the phospholipid signaling pathway in hot pepper and transgenic Arabidopsis plants.