Ishida B K, Jenkins S M, Say B
Western Regional Research Center, United States Department of Agriculture, Albany, CA 94710, USA.
Plant Mol Biol. 1998 Mar;36(5):733-9. doi: 10.1023/a:1005941330004.
In vitro culture of VFNT Cherry tomato sepals (calyx) at 16-21 degrees C results in developmental changes that are similar to those that occur in fruit tissue [10]. Sepals become swollen, red, and succulent, produce ethylene, and have increased levels of polygalacturonase RNA. They also produce many flavor volatiles characteristic of ripe tomato fruit and undergo similar changes in sugar content [11]. We examined the expression of the tomato AGAMOUS gene, TAG1, in ripening, in vitro sepal cultures and other tissues from the plant and found that TAG1 RNA accumulates to higher levels than expected from data from other plants. Contrary to reports on the absence of AGAMOUS in sepals, TAG1 RNA levels in green sepals from greenhouse-grown plants is detectable, its concentration increasing with in vitro ripening to levels that were even higher than in red, ripe fruit. Sepals of fruit on transgenic tomato plants that expressed TAG1 ectopically were induced by low temperature to ripen in vivo, producing lycopene and undergoing cell wall softening as is characteristic of pericarpic tissue. We therefore propose that the induction of elevated TAG1 gene expression plays a key role in developmental changes that result in sepal ripening.
在16-21摄氏度下对VFNT樱桃番茄萼片（花萼）进行体外培养，会导致其发生与果实组织中相似的发育变化[10]。萼片会肿胀、变红且多汁，产生乙烯，多聚半乳糖醛酸酶RNA水平升高。它们还会产生许多成熟番茄果实特有的风味挥发物，并且糖分含量会发生类似变化[11]。我们检测了番茄AGAMOUS基因TAG1在成熟过程中的表达情况，以及在体外萼片培养物和植株的其他组织中的表达情况，发现TAG1 RNA积累的水平高于其他植物数据预期的水平。与关于萼片中不存在AGAMOUS的报道相反，温室种植植株绿色萼片中的TAG1 RNA水平是可检测到的，其浓度随着体外成熟而增加，甚至高于红色成熟果实中的水平。在体内异位表达TAG1的转基因番茄植株上，果实的萼片会被低温诱导成熟，产生番茄红素并经历细胞壁软化，这是果皮组织的特征。因此，我们认为TAG1基因表达升高的诱导在导致萼片成熟的发育变化中起关键作用。
