Xin Huang, China Agricultural University, Beijing, CHINA
In the experiment, the possible roles of three genes, miR164, nac60 and mimiR164 in regulating the responses of perennial ryegrass plants to different illumination intensity were investigated. Four types of perennial ryegrass plants, miR164 transgenic plants, SRDX-nac60 transgenic plants, mimic miR164 transgenic plants and WT plants, were exposed to 5000- lux, 20000- lux and 60000- lux light. These four perennial ryegrass plants were different in the phenotypic characters (plant height, leaf length, and leaf width) and physiological parameters measured (PSII yield, ETR, Fv/Fm, zeatin riboside content, ABA content, IAA content, GA3 content and SOD activity). For example, the zeatin riboside content sharply dropped both in miR164 transgenic plants and SRDX-nac60 transgenic plants compared to the mimic miR164 transgenic plants and WT plants, when being exposed to the light from 5000lux to 20000lux. In the meanwhile, four kinds of perennial ryegrass plants grew in the field with and without shade (building shade). These four perennial ryegrass plants also showed similar differences in the phenotypic characters (plant height, leaf width) and physyological parameters measured (SOD activity, POD activity, CAT activity, Chlorophyll a content, Chlorophyll b content, carotenoid content). Further scanning electron microscope and transmission electron microscope analysis found some differences in morphology and distribution of stomatal, of chloroplast, mitochondria, and peroxisome. For instance, the Chlorophyll a content in miR164 transgenic plants and SRDX-nac60 transgenic plants with shade are more than it without shade, however, it unchanged both in mimic miR164 transgenic plants and WT plants.
This research could provide information for us to explore the further research about the signaling pathway involved in miR164, nac60 and mimiR164 in regulating of the responses of perennial ryegrass plants to different light intensities.