Abstract
BackgroundThe members of the patatin-related phospholipase subfamily III (pPLAIIIs) have been implicated in the auxin response. However, it is not clear whether and how these genes affect plant and cell morphogenesis. Here, we studied the roles of the patatin-related phospholipase pPLAIIIδ in auxin-responsive cell morphology and organ size in Arabidopsis and Brassica napus.ResultsWe show that overexpression of pPLAIIIδ inhibited longitudinal growth but promoted transverse growth in most organs of Arabidopsis and Brassica napus. Compared to wild-type plants, pPLAIIIδ-KO plants exhibited enhanced cell elongation in hypocotyls, and pPLAIIIδ-OE plants displayed broadened radial cell growth of hypocotyl and reduced leaf pavement cell polarity. For the hypocotyl phenotype in pPLAIIIδ mutants, which resembles the “triple response” to ethylene, we examined the expression of the ACS and ACO genes involved in ethylene biosynthesis and found that ACS4 and ACS5 were up-regulated by 2.5-fold on average in two OE lines compared with WT plants. The endogenous auxin distribution was disturbed in plants with altered pPLAIIIδ expression. pPLAIIIδ-OE and KO plants exhibited different sensitivities to indole-3-acetic acid-promoted hypocotyl elongation in both light and dark conditions. Gene expression analysis of auxin-induced genes in the dark showed that OE plants maintained a higher auxin response compared with WT and KO plants after treatment with 1 μM IAA for 12 h. Following treatment with 10 μM IAA for 30 min in the light, early auxin-induced genes were significantly up-regulated in two OE plant lines.ConclusionsThese data suggest that the PLAIIIδ gene plays an important role in cell morphology and organ size through its involvement in the regulation of auxin distribution in plants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0332-1) contains supplementary material, which is available to authorized users.
Highlights
The members of the patatin-related phospholipase subfamily III have been implicated in the auxin response
During the development of the silique, pPLAIIIδ was mainly expressed in vascular bundles, as well as the septum, endocarp, mesocarp, and exocarp (Figure 1K), and there was no visible staining in mature siliques except for the coat and the junction point of the silique and pedicel (Figure 1L, arrow)
These findings showed that pPLAIIIδ was expressed in various tissues during the development and growth of plant organs, with preferential expression of this gene being observed in young tissues early in development
Summary
The members of the patatin-related phospholipase subfamily III (pPLAIIIs) have been implicated in the auxin response It is not clear whether and how these genes affect plant and cell morphogenesis. The patatin-related phospholipase A proteins consist of three subfamilies, pPLAI, pPLAII (α, β, γ, δ, ε), and pPLAIII (α, β, γ, δ), based on their sequence similarity [1]. This group of enzymes hydrolyses phospholipids and galactolipids [2]. Plant pPLAIII proteins participate in signal transduction, membrane remodelling, and lipid metabolism through the production of various fatty acids and lysophospholipids. Lysophosphatidic acid (LPA) stimulated the activation of phospholipase D (PLD) to generate PA, which has been identified as a vital signalling molecule during pathogen infection, drought, salinity, wounding, and cold stress [7]
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