Introduction of herbicide resistant gene (bar) into maize (Zea mays L.) via pollen tube pathway

The pollen tube pathway method of transformation has been reported to be successful in most crops, but less successfu in maizc. DNA can be transferred by cutting the stigma following pollination and applying the DNA solution in a suitable period DNA presumably reaches the ovary by flowing down the pollen tube and then integrates into the just fertilized but undivided zygotic cells. To provide the molecular evidence for this procedure, the plasmids pGBIRC carrying a CaMV35S promoter-PPT acetyle transferase （bar） gene-nos terminator genc fusion construct were used. Total 3 276 seeds were produced from the ears trcated with DNA. It was found that 35 scedlings were GUS assay positive, but less intense than that of the positive controls, of which 17 were PCR amplification positive. But, only 13 of the seeds from the plants treated with DNA containing the bar gene were found to be resistant compared with the negative control. Less than 1.07% of progeny seedlings tested cxpressed a herbicide positive reaction and polymerase chain reaction （PCR） with seedling DNA did detect the bar genc. Morphological variation was observed in six plants. We succeed in obtain PPT-resistant maize inbred lines via pollen tube pathway

Construction of Maize Universal Expression Vector PGM-35Sbar and Maize Transformation

[Objective] The paper was to construct maize universal expression vector, in order to provide basis for using transgenic methods to improve abiotic stress tolerance of maize. [Method] Based on the transformation of existing pGreen0229 plant expression vector, phosphinothricin-resistant selectable marker-bar gene driving by CaMv35S promoter was constructed, which could be used to connect target gene of maize expression vector PGM-35Sbar, and transform Ji444 maize inbred lines by pollen tube pathway. [Result] The universal expression vector for PGM-35Sbar maize had been successfully constructed. When the maize plants were transformed, 14 resistant plants were obtained, and 12 plants were identified to be positive plants by PCR detection. [Conclusion] The study provided basis for rapid construction of maize expression vector containing specific target gene.

Actin organization and regulation during pollen tube growth

Pollen is the male gametophyte of seed plants and its tube growth is essential for successful fertilization.Mounting evidence has demonstrated that actin organization and regulation plays a central role in the process of its germination and polarized growth.The native structures and dynamics of actin are subtly modulated by many factors among which numerous actin binding proteins(ABPs)are the most direct and significant regulators.Upstream signals such as Ca^(2+),PIP_(2)(phosphatidylinositol-4,5-bis-phosphate)and GTPases can also indirectly act on actin organization through several ABPs.Under such elaborate regulation,actin structures show dynamically continuous modulation to adapt to the in vivo biologic functions to mediate secretory vesicle transportation and fusion,which lead to normal growth of the pollen tube.Many encouraging progress has been made in the connection between actin regulation and pollen tube growth in recent years.In this review,we summarize different factors that affect actin organization in pollen tube growth and highlight relative research progress.