Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1 Tsukuba, Ibaraki, 305-8572, Japan.
Tsukuba Plant Innovation Research Center, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572, Japan.
Sci Rep. 2019 Dec 11;9(1):18871. doi: 10.1038/s41598-019-55400-7.
Parthenocarpy is the development of an ovary into a seedless fruit without pollination. The ubiquitous downregulation of SlIAA9 induces not only parthenocarpic fruit formation but also an abnormal vegetative phenotype. To make parthenocarpic transgenic tomato plants without unwanted phenotypes, we found two genes, namely, Solyc03g007780 and Solyc02g067760, expressed in ovary tissue but not in vegetative tissues. Solyc03g007780 was expressed in developing ovaries and anthers. Solyc02g067760 mRNA was detected in whole-flower tissues. The promoters of Solyc03g007780 (Psol80) and Solyc02g067760 (Psol60) predominantly induced the expression of genes in the ovule, placenta, endocarp and pollen and in whole-flower tissues, respectively. Psol80/60-SlIAA9i lines, created for SlIAA9-RNA interference controlled by two promoters, successfully formed parthenocarpic fruits without pleiotropic effects in vegetative tissues. Downregulation of SlIAA9, responsible for parthenocarpic fruit formation, was observed in ovules rather than ovaries in the Psol80/60-SlIAA9i lines. Although the weight of parthenocarpic fruits of the Psol80/60-SlIAA9i lines was lower than the weight of pollinated fruits of the wild type (WT), the parthenocarpic fruits presented redder and more saturated colors and higher levels of total soluble solids and titratable acidity than the WT fruits.
单性结实是指未经授粉而子房发育成果实的现象。SlIAA9 的广泛下调不仅诱导了单性结实果实的形成，还导致了异常的营养生长表型。为了获得没有不良表型的单性结实转基因番茄植株，我们发现了两个基因，即 Solyc03g007780 和 Solyc02g067760，它们在卵巢组织中表达，但在营养组织中不表达。Solyc03g007780 在发育中的卵巢和花药中表达。Solyc02g067760 mRNA 存在于整个花组织中。Solyc03g007780（Psol80）和 Solyc02g067760（Psol60）启动子分别主要诱导胚珠、胎座、内果皮和花粉以及整个花组织中基因的表达。创建的 SlIAA9-RNAi 由两个启动子控制的 Psol80/60-SlIAA9i 系成功地形成了单性结实果实，而营养组织没有多效性效应。在 Psol80/60-SlIAA9i 系中，负责单性结实果实形成的 SlIAA9 下调发生在胚珠中，而不是在卵巢中。尽管 Psol80/60-SlIAA9i 系的单性结实果实的重量低于野生型（WT）授粉果实的重量，但单性结实果实的颜色更红、更饱和，总可溶性固体和可滴定酸度水平更高。
