Phospholipase Dε enhances Braasca napus growth and seed production in response to nitrogen availability

Phospholipase D (PLD), which hydrolyses phospholipids to produce phosphatidic acid, has been implicated in plant response to macronutrient availability in Arabidopsis. This study investigated the effect of increased PLD epsilon expression on nitrogen utilization in Brassica napus to explore the application of PLD epsilon manipulation to crop improvement. In addition, changes in membrane lipid species in response to nitrogen availability were determined in the oil seed crop. Multiple PLD epsilon over expression (PLD epsilon-OE) lines displayed enhanced biomass accumulation under nitrogen-deficient and nitrogen-replete conditions. PLD epsilon-OE plants in the field produced more seeds than wild-type plants but have no impact on seed oil content. Compared with wild-type plants, PLD epsilon-OE plants were enhanced in nitrate transporter expression, uptake and reduction, whereas the activity of nitrite reductase was higher under nitrogen-depleted, but not at nitrogen-replete conditions. The level of nitrogen altered membrane glycerolipid metabolism, with greater impacts on young than mature leaves. The data indicate increased expression of PLD epsilon has the potential to improve crop plant growth and production under nitrogen-depleted and nitrogen-replete conditions.