|Other Abstract||Syntrichia caninervis is an extremly drought-resistant moss which can survive in losing 98% body water. Once given water, it can recover rapidly in 30s. Based on the transcription data of S. caninervis, we found that the chorophyll a/b binding proteins are all up regulated. Among these proteins, Early light induced proteins expressed early than others. They belong to the chlorophyll a/b-binding protein superfamily. They are kind of transmembrane proteins which are located at chloroplast thylakoid membrane. They have been found in organisms such as cyanobacteria, bryophytes, higher plants, etc. It is initially found in the process of etiolated pea seedlings turning green. Due to being induced earlier than other light-induced proteins, they are named as ELIPs. They have the characteristics of transient accumulation and disappear once after the photosystem is completely developed. In this research, we analysized the ELIP gene family in Syntrichia caninervis based on the transcriptom data and screened out two ScELIP genes which have complete ORFs. We studied the bioinformatic characteritics, expression patterns and functions of these two ScELIP genes. The results were as follows:
1. Thirty nine annotated ScELIP unigenes were obtained in this research. Then we identified 27 Unigenes as ScELIP genes among which 6 genes have complete ORFs and chlorophyll-a/b binding domains.
2. Two ScELIP genes (ScELIP1 and ScELIP2) were screened out and their bioinformatic properties were analyzed. The results showed that ORFs of ScELIP1 and ScELIP2 contained 711bp and 624bp and they encoded 236 and 207 amino acids, respectively. Both of them contained a complete Chloroaophyll a/b-bind functional domain. Subcellular localization prediction revealed that the two ScELIPs were both located at the thylakoid membrane of chloroplast. Secondary structure prediction demonstrated that they both had three transmembrane helixes. Protein sequence alignment and phylogenetic analysis revealed that ScELIP1 had the closest relationship with moss and green alga, while ScELIP2 was closer to higher vascular plants, which showed the evolutionary trend clue from moss to vascular plants.
3. On the basis of bioinformatics analysis, we cloned these two ELIPs of S. caninervis and analyzed the expression patterns of ELIPs under various abiotic stresses and different light conditions. The results showed: ①ScELIP1 responded to all kinds of stresses such as slow dry, rapid dry, salt, cold, heat, while ScELIP2 didn’t respond to rapid dry. The reactions of both genes under NaCl, cold stress were fast and durable. ②They both had responses to UVA and UVB. However, ScELIP1 had a weak and transient response to UVA and ScELIP2 responded strongly and enduringly. Blue light could induce the expression of ScELIPs and enhance the induction of red light; On the contrary, red light inhibited the induction of blue light. The transcription levels of ScELIP1 and ScELIP2 increased with the increasing of light intensity.
4. We used genetically modified (GM) yeast to verify the functions of ScELIPs. By comparing the growth condition of GM yeast and control yeast under 20% PEG, 5mol/L NaCl, 53 ℃, -20 ℃ and UV stress, we finally found that GM yeast and the control showed the same growth condition. So the GM yeast system was not qualified to validate the functions of stress-resistance and photoprotection of ELIPs. Then we choosed model plant Arabidopsis to testify the function of ScELIPs. After exposed the transgenic and wild type Arabidopsis thaliana to high light, UV, red light, blue light, dry, salt, cold and heat stress, we observed the growth conditions and measured the related physiological indexes of them. Ultimately, we came to the conclusion that the two ScELIP2 gene was stress resistant and can help to avoid photooxidation.|