Pylatuik Jeffrey D, Lindsay Donna L, Davis Arthur R, Bonham-Smith Peta C
Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5E2, Canada.
J Exp Bot. 2003 Oct;54(391):2385-7. doi: 10.1093/jxb/erg254. Epub 2003 Aug 8.
B-class floral homeotic genes are required for the proper formation and identity of petals and stamens in dicot flowers. A partial cDNA clone encoding a B-class gene, BnAP3 (Brassica napus APETALA3), was isolated from a B. napus cDNA library derived from young inflorescence meristems. The 5' region of the cDNA was retrieved by RACE. The deduced amino acid sequence of the full-length clone exhibited high similarity to APETALA3 of Arabidopsis thaliana and functionally homologous proteins from other species. 5' RACE and Southern analysis suggests that BnAP3 has multiple alleles in B. napus. Expression analysis assayed by RT-PCR shows that BnAP3 is expressed in floral tissues, as well as non-floral tissues such as root and bract. Transformation of wild-type A. thaliana and B. napus plants with BnAP3 under the control of a promoter specific to reproductive organs converts carpels to stamens, while the expression of this construct in A. thaliana plants mutant for AP3 restores the development of third-whorl stamens in addition to directing a carpel to stamen conversion in the fourth whorl.
B类花同源异型基因对于双子叶植物花中花瓣和雄蕊的正常形成及特性是必需的。从一个源自幼嫩花序分生组织的甘蓝型油菜cDNA文库中分离出了一个编码B类基因BnAP3（甘蓝型油菜APETALA3）的部分cDNA克隆。通过RACE获得了该cDNA的5'区域。全长克隆推导的氨基酸序列与拟南芥的APETALA3以及来自其他物种的功能同源蛋白具有高度相似性。5' RACE和Southern分析表明，BnAP3在甘蓝型油菜中有多个等位基因。通过RT-PCR进行的表达分析显示，BnAP3在花组织以及根和苞片等非花组织中均有表达。用生殖器官特异性启动子控制下的BnAP3转化野生型拟南芥和甘蓝型油菜植株，可使心皮转变为雄蕊，而该构建体在AP3突变的拟南芥植株中的表达除了能引导第四轮的心皮转变为雄蕊外，还能恢复第三轮雄蕊的发育。
