Tomatoes have lots of functional ingredients and are produced globally all the year round. The tomato fruits, which we eat daily, are made from enlarged ovary of pistil from flowers. Usually, tomatoes do not form fruit without pollination. Most of the fruit forming are promoted because of the plant hormone including auxin and gibberellin after the pollination. On the other hand, ethylene is a plant hormone with its type of gas. So, no details have been found in regards to the direct relationship of ethylene to forming fruits even though scientists thought that ethylene is surely connected to the ripping of various fruits.

　The research group led by Professor Tohru Ariizumi and Professor Hiroshi Ezura at the University of Tsukuba proved that ethylene suppresses the ripening of tomato fruits from pistil pollination without by ethylene low-sensitivity mutant Sletr1, found from tomato group called "micro-tom mutant mass group" at Gene Research Center of the University of Tsukuba. Ethylene, produced enormously in pistil before pollination, has been thought for a long time as a suppressor of synthesizing gibberellin to enhance ripening fruits. Regulation of the mechanism would invent a technology for a higher productivity of fruits.

A model of the role of ethylene in tomato fruit set.
The effects of multiple phytohormones on the regulation of fruit set. Pollination triggers the activation of auxin, which down-regulates ethylene iosynthesis. This in turn reduces the suppressive effects of ethylene on GA biosynthesis, thereby promoting cell expansion. Pollination also activates cytokinin (CK) metabolism and suppresses abscisic acid (ABA) action, both of which likely influence fruit set and/or growth.

Original Paper

Yoshihito Shinozaki, Shuhei Hao, Mikiko Kojima, Hitoshi Sakakibara, Yuko Ozeki-Iida, Yi Zheng, Zhangjun Fei, Silin Zhong, James J. Giovannoni, Jocelyn K.C. Rose, Yoshihiro Okabe, Yumi Heta, Hiroshi Ezura, and Tohru Ariizumi, Plant Journal, Ethylene suppresses tomato fruit set through modification of gibberellin metabolism. DOI: 10.1111/tpj.12882