Roles And Potential Applications Of Phospholipase Ds In Brassica Napus Response To Drought And Nitrogen

Brassica napus plays an important role in edible oil production and consumption in China and the world. The yield and quality of rapeseed oil have been improved greatly in recent years. However, environment stresses, such as drought, salinity, and nutrient deprivation have adverse impacts on rapeseed growth and production. To explore new avenues to improve rapseed performance under stress conditions, this study was undertaken to determine the role of phospholipase D (PLD)-mediated membrane lipid-based signaling processes in rapeseed response to drought and nitrogen availability.The activation of PLDal produces lipid messenger phosphatidic acid and promotes stomatal closure. The Arabidopsis PLDal was ectopically expressed in guard cells under the control of the guard cell-specific promoter KatI in two cultivars of canola via agrobacterium-mediated transformation. The production of PLDal transgenic canola was demonstrated by in situ immunoblotting and western blotting. Multiple AtKatlprc,::PLDal lines in each cultivar displayed decreased water loss and improved biomass accumulation under hyperosmotic stress conditions, including drought and high salinity. The level of expression for drought-induced gene, such as ABI1, ABI2, and RD29B, was lower in AtKatIpro:.PLDal plants than that in WT. Moreover, AtKatlpn,::PLDal plants produced more seeds than did WT plants in fields under drought. The results indicate that the guard cell-specific expression of PLDal has the potential to improve crop yield by enhancing drought tolerance.In addition, PLDe was transferred to canola under the control of the35S cauliflower mosaic virus promoter to test its role in canola response to N availability. Compared to WT plants, multiple35S::PLDs transgenic lines displayed enhanced lateral root growth and biomass accumulation under low (0and0.3mM) and high (3and7.5mM) N conditions.35S::PLDe plants had a higher level of expression of the nitrate transporter genes NTR1.1and NTR2.1and an enhanced rate of nitrate uptake. In addition,35S::PLDe plants also showed higher activities of nitrate assimilation enzymes, nitrate reducatse and nitrite reductase. When plants were under a prolonged period of N deprivation, older, bottom leaves of35S::PLDε plants senesced faster than those of WT plants, whereas the chlorophyll content of newer, top leaves was higher in the transgenic plants than that of WT plants. In the field,35S::PLDε plants displayed later flowering and increased vegetative growth and seed production compared to WT plants. These data suggest that increased expression of PLDε promote nitrate uptake, assimilation, and remobilization.