1. F9315 Is Required For Flowering-time Control And Trichome Development In Arabidopsis Thaliana 2. F9231, An Important Gene That Is Involved In The Sugar Signaling Transduction Pathway In Arabidopsis Thaliana

With Ac/Ds transposon system, we identified an Arabidopsis mutant from 800 F2 lines. This mutant, named f9315, displays pleiotropic phenotypic abnormalities. The most obvious phenotypes are late-flowering, and reduced trichome number and trichome branches. Genetic analysis shows that f9315 phenotypes are caused by a single gene recessive mutation, however, the Ds insertion does not link with the mutant locus. By SSLP method, we map the f9315 locus at about 1.8cM proximal to UFO on chromosome 1. The addition of auxin, gibberellin and 24-epibrassinolide to the growth medium can not rescue the f9315 phenotype. In long-day photoperiod, the flowering time in f9315 is about 10 days later than that in wild type, while in short-day photoperiod the flowering time in mutant is further delayed. Vernalization can accelerate f9315 flowering. We have constructed f9315 double mutants with some other known mutants and compared their flowering time in both long-day and short-day photoperiod. We found that the f9315 ap1double mutant with a flowering time similar to that in f9315 single mutant, indicating f9315 is epistatic to ap1. Double mutant f9315 gai with a flowering time similar to that in gai single mutant, suggesting gai is epistatic to f9315. f9315 clv1-1, f9315 clv3-1 and f9315 lfy double mutants show a later flowering time than that in each of the single mutant, indicating these genes interact synergistically to promote flowering. The flowering time in f9315 tfl1double mutant is earlier than that in f9315 single mutant, but later than that in tfl1 single mutant. These results suggest that F9315 promote flowering by repressing the TFL1 function directly or indirectly. TFL1 acts downstream to F9315. We have also studied F9315 function in trichome development. f9315 mutant shows reduced trichome number and tricome branches, which is about a half as those in the wild type. In addition, the trichomes in mutant are mainly two-branched, some even without branch. We have constructed f9315 ttg1 and f9315 gl1 double mutants, and the leaves of these double mutants are glabrous, suggesting that ttg1 and gl1 are epistatic to f9315.With Ac/Ds transposon system, we identified an Arabidopsis mutant from 600 F2 lines, designated f9321. When this mutant grows at normal conditions, it shows a variable phenotypic abnormalities, such as dwarf, reduced apical dorminance, increased auxillary meristems, late flowering, short silique and longer stamens, sterile, and smaller and dark green rosette leaves. The pattern formation in mutant flower is almost normal. By reciprocal crosses, we found that f9321 is female sterile. Genetic analysis indicates that f9231 is a single gene recessive mutant. By SSLP mapping , we have mapped F9231 between molecular markers CER448446 and CER450872 on chromosome1 . Treatments with auxin, gibberellin and 24-epibrassinosteroid cannot rescue f9321 phenotype indicating that the mutant phenotypes are not caused by the phytohormone synthesis defects. Treatments with root elongation inhibitors, 2,4-D and TIBA at a very low concentration resulted in a stimulation of root elongation in wild type, but not in f9321 mutant. At low level concentration of 24-epibrassinosteroid, the root elongation inhibition in WT and mutant is the same, but with the increase of 24-epibrassinosteroid, the mutant shows less inhibition that WT, this indicates that mutant is less sensitive to 24-epibrassinosteroid. ABA and mannose can inhibit seed germination at the same level in mutant and WT. By the I2-KI staining, we found a high concentration of starch was accumulated in mutant leaves, about 6 times higher than that in wild type, in addition, the amylopectin was increased in mutant leaves. We found that starch degradation rate in leaves under the dark is similar to that in the wild type, and the α-amylase and β-amylase activities in mutant leaves increased significantly. Fructose and soluble sugars in mutant leaves increased, while sucrose content in mutant is about the same as in the wild type. As a control, 6%(W/V) sorbitol don't affect wild type and f9231 germination,...