Provided are plants that express, or overexpress, a pPLAIIIδ protein. Constitutive or seed-specific expression of pPLAIIIδ protein in Arabidopsis increases seed oil content, the amount of C20 and C22 fatty acids, and the amount of C56, C58, and C60 triacylglycerols, effectively resulting in significantly higher oil yield per plant. Use of pPLAIIIδ is therefore an effective biotechnological tool to significantly increase plant yield, including oil, and the amount of high value long chain fatty acids in agricultural and horticultural crops, especially oilseed crops.