Expression Analyses Of Flowering Locus T (FT) Gene In Developmental Transitions In Mulberry (Morus Alba L.)

Floral induction of high plants is a complex process, regulated by multiple signalingpathways which interlace into a net. Flowering Locus T gene locates in the junction of this netand plays a key regulatory role in floral induction of plants. Flowering means the plants goinginto the reproductive growth stage, the correlation between FT gene expression and plantdevelopmental status is not clear. In this experiment, FT gene expression was detected indevelopmental transitions from juvenile vegetative phase to adult vegetative phase inmulberry. And FT gene expression was compared between mulberry plants cultivated bysexual reproduction and asexual reproduction to reveal the expression pattern of MaFT genein developmental transitions. This experiment provides theoretical basis for researching thefunction of MaFT gene, exploring the flowering mechanism of mulberry, shortening juvenilevegetative phase and breeding process of mulberry. The results are as follows:1. Optimization of immunohistochemical method in silkworm midgut sectionTo research the expression of ATG8protein in midgut of silkworm by immunohisto-chemical method, choice of second antibody was optimized. The result showed that the effectof biotin-conjugated second antibody was superior to normal second antibody, providing areference for subsequent experiments.2. Analysis of ESTs in mulberry under drought stressRehydration was implemented after drought treatment nine days in mulberry. Genefragments which expressed differently during this treatment were screened by cDNA-AFLPand blasted in NCBI database after cloning and sequencing.41ESTs were sequenced and23ESTs were similar to nucleotide or protein sequences in database. These ESTs includedoligopeptide transporter family, G Protein-Coupled Receptors lung₇-TM_R family,glutathione reductase, glutathione transporter and DNA binding protein. And the other18sequences had no homologous sequences. These ESTs provides the basic data for mulberryresistance research.3. Expression analyses of FT gene in developmental transitions in mulberry MaFT gene coding sequence was blasted in mulberry genome（NCBI taxid:981085）, theresult showed that it consisted of four exons, the length of every exon was highlyconservative.qPCR experiment showed that in juvenile vegetative phase of mulberry cultivated bysexual reproduction, the expression quantity of MaFT gene increased as age of the plant. Afterthe mulberry came into adult reproductive phase, the expression of this gene maintained arelatively level. Mulberry seedlings were bred by seed gemination, belonged to sexualreproduction. Annual mulberry plants cultivated by asexual reproduction we used in thisexperiment divided into two kinds. One was tissue cultured seedlings and cutting seedlingswhich were induced adventitious root, the other was grafted seedlings that scions or budswere grafted on annual mulberry plants. The result indicated that the expression of MaFTgene in seedling cultivated by asexual reproduction was significantly higher than that ofseedling bred by seed germination, and was quite to scion. The high expression of MaFT genereflected the adulthood development state of asexual reproduction individual, so it wassupposed that physiological age nature of asexual reproduction plants may be associated withFT expression. This issue deserves further exploration.