Analysis of Parthenocarpy in Fruits

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1) Several apple mutants are known to produce only apetalous flowers that readily go on to develop into parthenocarpic fruit. Flower phenotypes of these apple mutants are strikingly similar to those of the Arabidopsis mutant pistillata (pi), which produces flowers where petals are transformed sepals and stamens to carpels. This PI is categorized as class B gene on floral organogenesis. The PI homolog of apple gene, MdPI, was abolished the expression in the mutant cultivars. The expression of MdPI in normal apple was limited at stamens and petals. It was so difficult to be connected with the parthenocarpy. The apple MdPI has same characters as the PI homologs from other plants. It suggests that the PI gene family is highly conservative in flower evolution.2) The MdPI belongs to the transcription regulators, MADS gene family. Several MADS genes are known to function of floral organogenesis. The MdTM6 and MdMADS13 which belong to MADS gene family and class B gene were cloned successfully. … More The expression of the MdMADS13 showed that remarkable decrease was observed in the parthenocarpic cultivars, and in situ hybridization showed the expression localized at ovary and ovule related with fruiting.3) To access the function of MdPI or MdMADS13 about the parthenocarpy, the vector constructed with suppression or promotion of MdPI or MdMADS13 was transfected into normal apple cultivars. It had been very difficult to get apple transformants so far, but we improved the methods of the transformation and culture conditions. Then the improvement resulted on high ratio of transformation of apple. Then the normal apple cultivars transformed by the antisense expression or the silencing of MdPI gene were obtained successfully. And in addition, the apples transformed by the antisense expression of MdMADS13 or MdTM6 were obtained4) The function of the genes will be clarified after these transgenic apples bloomed and set fruits. But Apple is a sort of perennial plants and takes a several years to the bloom. Then an early flowering apple was required for analysis. We succeeded that the transgenic apple by early flowering gene bloomed within 2 or 3 years after the transformation. Less