Effects of floral organ conversions caused by silencing of petunia SEPALLATA
Date Issued
2011
Date
2011
Author(s)
Lu, Yu-Hang
Abstract
ABCE model has been widely interpreted in flower organ formation of different species. In recent years, According to the model, flower organ formation is determined by interaction of four groups of genes, A-class (AP1 and AP2), B-class (AP3 and PI), C-class (AG) and E- class (SEP) genes. In Arabidopsis, there is a conservative function in E-class proteins. No phenotypic change was observed in single SEP gene mutants while when tree or four Arabidopsis SEP genes were mutated, all flowers organs were converted into sepals and leaves respectively. In Petunia, six E-class proteins, FBP2, FBP4, FBP5, FBP9, FBP23 and MADS12 have been found, and it was reported that down-regulation of two genes, FBP2 and FBP5, petals, stamens, and carpels were converted into sepaloid organs. The phylogenetic tree indicated that one subgroup of E-class genes (FBP9 and FBP23) only existed in Solanaceae. It was suspected that there are specialization and different functions in the E-class genes of petunia. To find out the functional differences among Petunia E-class proteins, we compared transcript abundance of E-class genes of experiment strain M1, which has leafloid sepals, and W115, which has normal sepals. Moreover, we used Tobacco Rattle Virus (TRV) that contains a FBP23 cDNA fragment to inoculate petunia plants to induce gene silencing, and then analyzed the correlation between morphological changes of flower organs and transcript abundance of E-class genes. The results showed that most of the E-class genes were repressed expect MADS12 in sepals of M1 flowers. Flowers from plants inoculated with TRV containing specific FBP23 sequence fragment showed no obvious morphological changes. However, we observed that an increase of FBP9 expression and an reduction of FBP23 expression in a flower showed leafloid sepals, which was from a plant inoculated with TRV containing FBP9 and FBP23 specific sequence fragments. In transformed flower, the expression pattern of FBP2, FBP9 and MADS12 in petaloid stamen is similar to normal petals. Compare with the petals and stamen of M1, that FBP4, FBP5 and FBP23 may be the co-regulators of petals and stamen identity.
Subjects
petunia
leafoid sepal
Type
thesis
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