Cloning And Studies Of The MADS-box Gene TAGL104 In Tomato(Solanum Lycopersicum )

MADS-box gene family is an important family of transcription factor in plants.They are involved in various aspects of plant growth and development.And they also have wide and complex functions.One of the most important functions is to regulate the development and morphogenesis of floral organs.According to the different functions of the floral developmental genes in the four floral organs of the dicotyledonous plants,we divide them into A,B,C,D and E five classes,and thus,ABCDE model of flower development was proposed.These genes affect the morphological development of the four round floral organs alone or jointly,so that the flowers can grow normally.Among them,A class genes control the development of sepal,A class and B class genes control the development of petal,B class and C class genes control the development of stamen,C class genes control the development of carpel,D class genes control the development of ovule,E class genes are expressed in the four floral organs,which regulate the transformation from vegetative organs to floral organs.At the same time,the research on the interaction between the five class genes showed that these genes are generally combined with each other through the formation of tetramers,thus the four factor model is proposed.And this model further clarified the molecular mechanism of flower development.With the deepening of the research,it was found that the flower development genes not only affect the development of floral organs,but also play an important role in the growth of plant roots,stems,leaves,fruit maturity,and stress resistance and so on.So the complex functions of flower development genes have been paid more and more attention by researchers.But current researchs are still focus on Arabidopsis,Antirrhinum and other model plants,and these plants are not the typical fruit and vegetable plants,so these results can not be used in practice,and cannot have guiding significances for the actual production.This study used the model plant---tomato(Solanum lycopersicum)as the research object,and silenced the tomato flower development B class gene TAGL104 by RNAi technology.And we have got the transgenic plants,and studied the function of TAGL104 in tomato.The main research contents and results are as follows:(1)Identifing the TAGL104 gene as the research object by screening the flower development related genes of MADS-box gene family and obtaining the gene amino acid sequence from NCBI.Through the analysis of protein,we confirmed that this gene encoding a protein with a length of 333 aa,and its molecular weight is 38.043 kDa and isoelectric point is 5.68.At the same time,the BLAST results of NCBI showed that this protein contain a MEF2-like domain,it means this gene belong to the MIKC type MADS-box gene.Protein sequence alignment and homology analysis showed that TAGL104 is homologous with S class proteins of MIKC* type MADS-box genes in Arabidopsis.It is speculated that the protein encoded by this gene may also belong to the S class protein of MADS-box gene family.(2)Analysis of the expression pattern of TAGL104 gene in wild type tomato showed that this gene is mainly expressed in the stamen,and secondly expressed in the fruit of B+4 and B+7 times.These results indicate that this gene may be involved in the regulation of stamen morphology and fruit ripening.Promoter analysis showed that this gene might also be involved in the response of the hormone and play a role in plant stress resistance.(3)According to the principle of RNA interference technology,we constructed the TAGL104 silencing vector and obtained 4 transgenic lines.Because of the silence of TAGL104,the transgenic plants showed the abnormal development of inflorescence and the fruit ripening time has been moved up,but there was no obvious abnormality of stamen development has been observed.(4)The sensitivity test of MeJA and NaCl showed that the growth of transgenic seedlings was not obviously inhibited when compared to wild type seedlings.The length changes of root and hypocotyl are not so obvious in transgenic seedlings,and these results indicate that the silencing of TAGL104 gene reduced the sensitivity of MeJA and NaCl in tomato seedlings.In summary,TAGL104 gene,as a B class gene of tomato flower development,belongs to the MADS-box family,and which is mainly expressed in tomato stamen,and is involved in the response of multiple hormones and drought and heat stress.Silencing of TAGL104 gene in tomato produced an abnormal inflorescence and made the fruit ripening ahead of time.These results indicated that this gene involved in the regulation of inflorescence development and fruit ripening.Moreover,it also makes the transgenic seedlings' sensitivity of MeJA and NaCl decreased and enhanced the resistance.And these results indicated that this gene may be involved in the response of MeJA and abiotic stress.