Study On The Hormone Regulation Mechanism And Physiological & Ecological Responses To Simulated Nitrogen Deposition In Wedelia Trilobata

The change of global environment, especially nitrogen deposition, could change morphological attributes and invasiveness of invasive plants. This paper choose invasive plant Wedelia trilobata(L.) Hitchc. as the research object to study its physiological and ecological response to different levels of nitrogen deposition to illustrate the effects of simulated nitrogen deposition on invasive plants. At the same time, when W.trilobata invade new habitats, its hormone content is bound to be changed, taking it into account, so when the nitrogen content of the invaded soil is not stable, or the nitrogen deposition levels of outside change, how does it adapt to this changing environment by ajusting its endogenous hormone? In this paper, we use gibberellin synthesis inhibitors paclobutrazol and nitrogen deposition to study how does W.trilobata adapt the changing environment, thus promoting its invasiveness.Combined with the new-generation sequencing transcriptome technology, this paper reveal its adaptation mechanism on the background of simulated nitrogen deposition from the prospective of endogenous hormone, which provides a new theoretical basis for biological control of W.trilobata. The main results of this paper are as follows:1. Through different levels of nitrogen deposition, the phenotypic traits of W.trilobata change significantly. The results show that the nitrogen concentration have positive correlation to the physiology indicators of W.trilobata. With the increase of the nitrogen concentration, the fresh weight of aboveground/underground parts, stem length, leaf number and chlorophyll content are showing an increasing trend, and these indicators between low nitrogen concentration(N5(0 g N·m-2·year-1))and high concentration(N15(15 g N·m-2·year-1), N30(30 g N·m-2·year-1)) difference significantly. W.trilobata at high concentrations of nitrogen treatments have a greater leaf number than the medium nitrogen concentration, chlorophyll content also significantly increase, and leaves are dark green, which indicate that the effects of the increase of nitrogen concentration on W.trilobata first reflected in photosynthesis.When no nitrogen(N0(0 g N·m-2·year-1)) is added, W.trilobata grows weaker, leavesturn yellow, which just show the effectiveness of the nitrogen treatment. Meanwhile,W.trilobata endogenous hormones-Gibberellin(GA), Abscisic acid(ABA),Auxin(IAA) content in different levels of nitrogen deposition also show different patterns, with the rise of nitrogen concentration, the content of IAA and GA decline significantly under long-term treatment(two months), and the increment of endogenous hormone in control treatment(N0) has significant difference with low,medium, high nitrogen concentration(N5, N15, N30).2. W.trilobata had the combined effects under the combined effects of PAC and nitrogen deposition: stem length of the plant is suppressed; leaves were like stressed,resulting in tumorous roots. Most importantly, there are significant differences in chlorophyll content in two months among different treatments. This shows that PAC and nitrogen deposition may generate the combined effects through the photosynthesis of plants. Comparing and analysing the changing patterns of endogenous hormone content variation in PAC and nitrogen deposition, we found that GA is the most sensitive hormone to environmental conditions among the three hormones. The endogenous hormone ratio ABA/GA and IAA/GA change significantly,however, the combined effects of PAC and nitrogen deposition have no any impacts on ABA/IAA.3. By the new-generation transcriptome sequencing of W.trilobata in the three treatment groups(nitrogen individual treatment and the combination of PAC and nitrogen deposition), we obtained 450 418 high quality sequences and then assemble them by denovo to obtain W.trilobata transcriptome Unigenes. KEGG metabolic pathway analysis make me find that there are 2084 genes annotated to the path “plant hormone signal transduction”, and there are 225 differentially expressed genes among the three treatment groups. All of the results provides an important basis for us to clone and identify hormone-related genes of W.Trilobata and analyse its expression difference.