Genetic Transformation And Expression Analysis Of Three MADS-box Genes In Populous Tomentosa Carr

Populus plant spreads all over the world, with the capacity to adapt to various changeful climate. Populus plant is the model plant for woody plant study. It has many characters such as a relatively mature system of rapid asexual reproduction, a relatively mature system of genetic transformation, a small genome(four times as many as Arabidopsis thaliana genome, similar to rice’s genome, 40 to 50 times smaller than the pine tree genome,about 450 to 550 Mbp).The genome sequence of Populus trichocarpa of Populus plants has already been measured, which makes the Populus plant become the model tree of the transgenic research on woody plant.To study the function of MADS- box genes of Populus tomentosa, four MADS-box genes are extracted from the cambium of Populous tomentosa, and are named as PtMADS1, PtMADS2, PtMADS3 respectively.Antisense expression vector of PtMADS1 is constructed. We transformed the Populus by using the method of agrobacterium tumefaciens to abtain 35S:: PtMADS1 antisense expression plants. By expression and phenotype analyses on wild type and transgenetic plants, evidence for researching function of PtMADS1 was provided, which laid the groundwork for studying the molecular mechanism of genes. The results were as follows:First, protein homology analyses. PtMADS1 was most similar to SVP(AGL22) and AGL24 of Arabidopsis with similarity value of 97.3% and 83% respectively. PtMADS2 and AGL12 have the highest similarity value of 65%. PtMADS3 was most similar to AGL14 and AGL19 of Arabidopsis with similarity value of 60% respectively. The result showed that PtMADS1, PtMADS2, PtMADS3 belonged to the orphan type, MICK group. And PtMADS1 belonged to STMADS11 group. PtMADS3 belonged to AGL12 group. PtMADS3 and PtMADS5 belonged to SOC1/TM3 group.Second, PtMADS1 gene expresses at stem tip in wild type, and its expression can be detected at young leaves. It doesn’t express at root, stem, leaf, female inflorescence. In wild type plants, PtMADS1 expresses strongly in stem tip, weakly in young leaf.There were many phenotypes after the transition of antisense PtMADS1 into Populus. Antisense PtMADS1 makes the leaves’ apex longer than wild type, the basic part sharper, the leaves glabrous. Its tissue culture shoot’s characteristics are as follow. First, transgenetic type has more buds. Second, transgenetic type’s bud’s structure is abnormal, usually showing as rod, petal which usually can’t differenciate. Third, leaf is longer and more narrow than wild type, like a line. Fourth, leaf is like branch. The line-like leaf has many growing point structure, and leaf may regenerate leaf. PtMADS1 antisense transgenetic shoot put on the root medium(RM) can’t generate root, but generate callus. The callus put on the MS medium can generate buds. 35S∷PtMADS1 antisense transgenetic buds put on the MS medium can’t generate root, but generate great amount of buds.By expression and phenotype analyses of PtMADS1 antisense transgenetic Populus, we know that, PtMADS1 may act at the vegetative apical meristem.The results provided us reliable evidence for our study on PtMADS1. PtMADS1, a MADS-box gene family genes, acts on shoot apical meristem of plants by its essential characteristics to act on plant’s vegetative growth.