Effects Of C2C2 Znic Finger Protein Gene OsLSD2 On Rice Growth And Nitrogen Utilization

In the process of plant growth and development, there are various biotic and abiotic stresses. The regulation of functional genes is essential for the response of plants to the stresses. Transcription factors play important roles in the regulation of inducible genes. Therefore, more and more researches on the function of transcription factors have been launched over the world. Over-expression and knockout of the genes are commonly used to characterized the functions of transcription factors.LSD 1-type proteins are the transcription factors belonging to a family that contains a specific class of C2C2 type zinc finger domain, encoding the plant-specific transcription factors. OsLSD2 is one of the members of LSD 1-type gene family. In Arabidopsis, two members AtLSDl, AtLOL1 have been identified and were involved in plant death and disease resistance. In rice, OsLSDl played a crucial role in modulating disease defense and cell death. OsLSD2 and OsLSDl have a homology of 52.15% in their coding sequences, besides the high homology in the zinc finger domain. In this study, By agrobacterium tumefaciens transformation, the function of rice OsLSD2 gene in rice growth and nitrogen utilization was tested by over-expression in the cultivars of Wuyujing 7 (Wyj7) and Nipponbare, using wild type of Wyj7 (WT-W) and Nipponbare(WT-N) as control. The main results were as follows:1. Generation of OsLSD2 over-expression in rice. OsLSD2 over-expression vector by ubiquitin promoter was constructed and transformed by agrobacterium tumefaciens transformation into Nipponbare and Wuyujing 7 callus. Using hygromycin, GUS staining, RT-PCR, real-time PCR and Southern blot technique, six low-copy transgenic lines were selected and identified that can be stably inherited.2. Analysis of OsLSD2 over-expression effects on agronomic traits of Nipponbare and Wuyujing 7 by field experiment. Similarities:in comparison to WT, the transgenic plants’ plant height was decreased, while the tiller number was not obviously changed; shortened the growth period, decreased the number of seeds per panicle, shortened the panicle length, decreased the seed setting rate and grain yield per plant. The differences:over expression of OsLSD2 showed more effect on Nipponbare. Growth period was more shortened; the decrease of seed setting rate and grain yield per panicle was more significant; while the Wuyujing 7’plant height was shortened more.3. Analysis of OsLSD2 over-expression effects on nitrogen utilization and translocation in Nipponbare and Wuyujing 7 by field experiment. Similarities:in comparison to WT, over expression of OsLSD2 leaded to both cultivars’ nitrogen absorption amoumt decreased significantly at full heading stage and mature stage, resulted in lower nitrogen uptake efficiency lower nitrogen fertilizer use efficiency and less translocation amount of nitrogen in plants. Differences:the effection on Nipponbare was more obvious in late growth period, after full heading stage the amount of nitrogen absorption reduced significantly; while the influence on Wuyujing 7 was mainly in the the early growth period, before full heading stage the total N uptake decreased more significantly, after full heading stage N uptake increased significantly. Effects of OsLSD2 over-expression on nitrogen distribution in the plants were also different. In Nipponbare, nitrogen distribution were not consistent with control at maximum tillering stage and mature stage, promoted the translocation of nitrogen from stem to leaf at maximum tillering stage, inhibited the translocation of nitrogen from stem to leaf at mature stage, ultimately resulted in grain nitrogen content reduced; and the effect on Wuyunjing 7 in full heading period, inhibited nitrogen transportion to the grain.Conclusion:the over-expression of OsLSD2 in rice resulted in the decrease of plant height, growth and developing period, totaol nitrogen uptake and nitrogen use efficiency, and change of the distribution of nitrogen in the plants. Presuming that participating of OsLSD2 in the regulation of plant death may lead to these changes, the molecular mechanism needs to be further studied.