Researches On Genes Regulating Locule Number In Tomato

The trait of locule number plays an important role in determining fruit size, fruit shape and the ratio of abnormal fruit. So it is of great significance to research on the locule number in tomato. Two QTLs, fascinated(fas) and locule number(lc), increased locule number, which are located on the Chrll and Chr2, respectively. The value leading to increase locule number of fas is 37% and the value of lc is 12%. MLK1 with about 15 locule numbers and FL1 with about 2 to 4 locule number were selected to research on the genetic background of fas and lc in tomato. YABBY2, which was highly homology with fas, was cloned in tomato. And phylogenetic tree of YABBY2 was constructed among various species. Meanwhile, the expression of YABBY2 was analyzed in various tissues of tomato. The overexpressed vector of YABBY2 was constructed and taken into tomato using highly genetic transformation to illustrate the function of YABBY2. This study played important roles in plant growth and development and the mechanism of formation of locule number. The results are:1. Based on molecular method, the lc locus and the expression of wuschel were identified in MLK1 and FL1. lc locus was mutant in MLK1, but lc locus was normal in FL1. Wuschel was totally same in MLK1 and FL1, but wuschel expression was highly in MLK1 than in FL1. And wuschel was expressed only in stem apex.2. The genome variation at fas locus was identified in MLK1 and FL1 tomato. The results showed that fas was normal in FL1, but fas was inversion mutation in MLK1. At transcriptional level, the complete ORF of fas was transcribed in FL1 and fas was completely same to NCBI. Two novel transcripts were cloned at fas locus in MLK1 using 5’RACE and 3’RACE. One transcript was 2085bp, constituted with the sequence at 5’of inversion locus, the second, third, fourth, fifth, sixth exon of fas gene. The other transcript was 1930bp, constituted with the sequence at 5’of inversion locus, the second, third, fourth exon of fas and the fourth intron of fas.3. YABBY2 was cloned in tomato, and YABBY2 was totally same in MLK1 and FL1. There were YABBY domain and Zinc-figner domain in YABBY2 gene. The phylogenetic tree showed that tomato YABBY2 was highly homology with tomato fas, Arabidopsis thaliana YAB2 and Artrirrhinum majus YAB2.4. Tomato YABBY2 was expressed in stem, leaf and stem apex, but not in root. YABBY2 was exactly expressed in petiole of cambium and the placenta of stem apex using hybridization in situ. In leaf and stem apex of MLK1 and FL1, the expression of YABBY2 was lower in weak light than CK at 1d,3d,5d and 7d, respectively. In leaf and stem apex of MLK1 and FL1, the expression of YABBY2 was lower in high temperature than CK at Id,3d and 5d, respectively.5. Based on Gateway method, the pMDC141-YABBY2 vector was successfully constructed. 3 positive transplants were got. Based on the traits of YABBY2 overexpressed transgenic plants, the locule number of each transplant was deduced and the leaves above the position of the 11th were twisted and abnormal. The results showed that YABBY2 function might be relative to forming locule number in tomato. But more researches shouled be taken to indentify the relationship between the YABBY2 and locule number due to that YABBY2 gene sequence was totally same in MLK1 and FL1.