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Phosphatidylinositol (PtdIns) synthase is a key enzyme in the phospholipid pathway and catalyses the formation of PtdIns. PtdIns is not only a structural component of cell membranes, but also the precursor of the phospholipid signal molecules that regulate plant response to environment stresses. Here, we obtained transgenic maize constitutively overexpressing or underexpressing PIS from maize ( ZmPIS) under the control of a maize ubiquitin promoter. Transgenic plants were confirmed by PCR, Southern blotting analysis and real-time RT-PCR assay. The electrospray ionization tandem mass spectrometry (ESI-MS/MS)-based lipid profiling analysis showed that, under drought stress conditions, the overexpression of ZmPIS in maize resulted in significantly elevated levels of most phospholipids and galactolipids in leaves compared with those in wild type ( WT). At the same time, the expression of some genes involved in the phospholipid metabolism pathway and the abscisic acid ( ABA) biosynthesis pathway including ZmPLC, ZmPLD, ZmDGK1, ZmDGK3, ZmPIP5K9, ZmABA1, ZmNCED, ZmAAO1, ZmAAO2 and ZmSCA1 was markedly up-regulated in the overexpression lines after drought stress. Consistent with these results, the drought stress tolerance of the ZmPIS sense transgenic plants was enhanced significantly at the pre-flowering stages compared with WT maize plants. These results imply that ZmPIS regulates the plant response to drought stress through altering membrane lipid composition and increasing ABA synthesis in maize. [ABSTRACT FROM AUTHOR]

Stress resistance has repeatedly been enhanced in plants by the transfer of a single gene using genetic engineering. However, further enhancement of resistance to abiotic stress is still necessary. In our research, maize plants that were transgenic for both betA (encoding choline dehydrogenase from Escherichia coli) and TsVP (encoding V-H-PPase from Thellungiella halophila) were produced by cross-pollination. The existence of the transgenes in the pyramided plants was demonstrated by PCR and Southern blotting. The stable expression of transgenes was confirmed by real-time RT-PCR (reverse transcription polymerase chain reaction) analysis. An examination of the drought resistance characteristics demonstrated that the pyramided transgenic plants had higher glycinebetaine contents and H-PPase activity compared with the parental lines, which had either betA or TsVP, and contained higher relative water content (RWC), greater solute accumulation and lower cell damage under drought stress treatment. The pyramided plants grew more vigorously with less growth retardation, shorter anthesis-silking interval and higher yields than their parental lines and the wild-type. We concluded that co-expression of the two genes involved in different metabolism pathways in pyramided transgenic maize helped to improve the drought resistance over their parental lines that contained either single transgene. Our study suggests that the co-expression of multiple, effective genes in transgenic plants could effectively enhance the resistance to abiotic stress and provide a feasible approach for obtaining maize plants with improved drought resistance. [ABSTRACT FROM AUTHOR]

In this study, it was shown that the TsVP gene [vacuolar H+-pyrophosphatase (V-H+-PPase) gene from a dicotyledonous halophyte Thellungiella halophila] could be transferred into the monocotyledonous crop maize ( Zea mays L.), and that the heterologous expression of the transgene improved the drought resistance of transgenic plants. Polymerase chain reaction amplification and Southern blotting confirmed the existence of the foreign gene in transformed plants and their progeny. Expression differences of the TsVP gene in different transgenic lines were monitored by reverse transcriptase-polymerase chain reaction. The measurement of isolated vacuolar membrane vesicles from the TsVP transgenic and wild-type (WT) plants demonstrated that the transgenic plants had higher V-H+-PPase activity, and the performance of maize-expressed TsVP in response to osmotic/drought stress was better in lines with higher V-H+-PPase activity. Transgenic plants showed a higher percentage of seed germination, better developed root systems and greater biomass, greater solute accumulation and less cell membrane damage relative to WT plants under osmotic stress. After drought stress treatment, transgenic plants showed less growth retardation and shorter anthesis–silking interval, and produced much larger grain yields, than WT plants. It was concluded that the high V-H+-PPase activity of transgenic maize improved the drought resistance of plants. This report provides a feasible approach to increase monocotyledonous crop yields under conditions of soil water deficit by the heterologous expression of TsVP. [ABSTRACT FROM AUTHOR]