Flowers don't just catch our eyes, they catch those of pollinators（传粉者） like bees as well. They have to, in order to reproduce. Because plants need to maximize the opportunity for pollinators to gain access to their seeds, variations in the timing¹ of flowering can have profound effects on flower, fruit, and seed production, and consequently agricultural yields. We know that the major driving forces of flowering are external factors such as light and temperature. However, new research from CSHL Assistant Professor Zach Lippman, Ph.D. and his collaborators, published online November 11 in Nature Genetics, shows there is a second, previously³ unknown mechanism⁴ controlling flowering.

 

Using the tomato plant as their model, Lippman and CSHL co-authors, Cora MacAlister, Soon Ju Park and Ke Jiang, show that loss of control of the timing of flowering, such that the flowering program turns on too fast, results in production of only a single flower on each branch, rather than the usual 7 to 10. Conversely, slowing down the flowering program enables more flowering branches to grow, which means more fruit.

 

Such dissection⁵ of the timing mechanism of flowering in plants like tomato is leading to new strategies for increasing agricultural yield in important crops.

 

During the flowering process, plants form reproductive shoot structures called inflorescences（花序）. These structures derive⁶ from small stem cell populations buried inside the tiny growing tips of plants called meristems. As plants sense and respond to signals from light and/or temperature, it is at the meristems（分生组织） where plant organs -- leaves or flowers -- are formed.

 

Domesticated⁷ tomato plants, which we know and love for their shiny, tasty red fruit, typically grow several multi-flowered inflorescences on each shoot. Each inflorescence is arranged in a zigzag⁸ pattern of 7 to 10 flowers on a single branch. Curiously⁹, many wild species of tomato produce multiple branches on each inflorescence, with each branch having many flowers, thereby¹⁰ increasing the reproductive potential of the plant. In rare cases, genetic² mutants of domesticated tomatoes form broom-like inflorescences with dozens of branches like the wild species. Interestingly, there is another class of mutants that produce just a solitary¹¹, sometimes abnormal looking, flower.

 

In previous research Lippman and others reasoned that the timing of flowering would be important in determining whether an inflorescence was highly branched or not. By characterizing the activity of thousands of genes¹² involved in the flowering process of tomato, Lippman and members of his laboratory revealed a "molecular¹³ clock" coordinating¹⁴ whether meristems give rise to branched or unbranched inflorescences.

 

In their newly published research, they reveal that one of those genes plays a critical role in keeping the clock from ticking too fast.

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