Screening and analysis of ZjSGR transgenic creeping bentgrass (Agrostis stolonifera)

SGR (stay green regulation) are key regulatory genes of chlorophyll metabolism, which play criticial roles in senescence process in plants. In this work, the ZjSGR gene isolated from Zoysia japonica was used to complete the transgenic creeping bentgrass (Agrostis stolonifera) by Agrobacterium-mediated method. A total of 19 regenerated creeping bentgrass plants were obtained after inducing callus, differentiation, rooting, seedling adaptation and planting in soil. By PCR technology, 15 seedlings were confirmed as transgenic plants, with ZjSGR gene inserted into genome successfully. After analyzing with RT-PCR, the ZjSGR gene were proved to be transcribed into mRNA in those plants. The Real-Time Fluorescence Quantitative RT-PCR (qRT-PCR) was used to select transgenic plant with a high expression level of ZjSGR gene, and the result showed that line 10, 13 and 15 had the top three expression levels of ZjSGR, which were selected for further experiments. The analyses of bio-physiology and chemistry in transgenic and WT plants showed that the chlorophyll contents and net photosynthetic rate were drastically decreased in three transgenic plants, while the contents of MDA and soluble sugar were obviously increased. Those results demonstrated that overexpression of ZjSGR gene in creeping bentgrass accelerated plant senescence by degradation of chlorophyll.