Analysis of Parthenocarpy in Fruits

1)已知几种苹果突变体只产生无花瓣的花，这些花很容易继续发育成单性结实的果实。这些苹果突变体的花表型与拟南芥突变体pistillata（pi）的花表型惊人地相似，后者产生的花中花瓣转化为萼片，雄蕊转化为心皮。该PI基因属于花器官发生调控的B类基因。苹果PI同源基因MdPI在突变体中的表达被抑制。在正常苹果中，MdPI仅在雄蕊和花瓣中表达。很难与单性结实联系起来。苹果MdPI具有与其它植物PI同源物相同的特性。说明PI基因家族在花的进化中高度保守。2）MdPI属于转录调控基因MADS家族。已知几个MADS基因在花器官发生中起作用。成功克隆了MADS基因家族和B类基因MdTM 6和MdMADS 13。 ...更多信息 原位杂交结果表明，MdMADS 13基因在单性结实品种中的表达量显著降低，且定位于与结实相关的子房和胚珠中。3）为研究MdPI或MdMADS 13基因在单性结实中的作用，将构建的MdPI或MdMADS 13基因抑制或促进表达的载体转入正常苹果品种中。目前苹果转化子的获得非常困难，但我们对转化方法和培养条件进行了改进。结果表明，该方法可提高苹果的转化率。并成功获得了MdPI基因反义表达或沉默转化的正常苹果品种。4）待转基因苹果开花坐果后，进一步阐明MdMADS 13和MdTM 6基因的功能。但是苹果是一种多年生植物，需要几年的时间才能开花。然后需要一个早期开花的苹果进行分析。我们成功地使转早花基因的苹果在转化后2 ~ 3年内开花。少

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