My research team studies the genes that determine when and where, and thus how many, flowers are produced on plants. Flowers form on branches called inflorescences, which originate from stem cells. By studying the genes that control how stem cells become inflorescences, we are able to manipulate flower production to improve crop yields.
Zachary Lippman’s research focuses on the process of flowering and flower production, which is a major contributor to plant reproductive success and agricultural yield. By identifying genes that control how tomato plants produce their flowers in their characteristic repeated zigzag arrangement (e.g., tomatoes on a vine), Lippman’s lab is addressing when and how flowering branches known as inflorescences develop on plants, particularly fruit-bearing plants. Of particular interest is how these “reproductive phase transitions” have contributed to the evolution of diverse inflorescence branching patterns in tomato’s larger Solanaceae family, which includes plants that make just one flower, such as pepper and petunia, in each inflorescence, to plants whose inflorescences produce dozens of branches and hundreds of flowers, such as many wild species of tomato. Using a combination of genetic, genomic, and molecular approaches, Lippman is dissecting the gene networks that are responsible for the variation in inflorescence branching found in nature. He hopes to leverage these discoveries to improve crop yields. Already, his work on genes that are responsible for the production and activity of a universal flowering hormone known as florigen has resulted in novel approaches to fi ne-tune plant architecture and flower production, boosting yield beyond leading commercial varieties. To continue hunting for new genes, Lippman has adopted a systems-biology approach and next-generation sequencing technology to capture those genes that are active as stem cells mature from a vegetative to a reproductive state. Nearly 4000 genes were found to reflect the existence of a “maturation clock,” and one of the clock genes known as Terminating Flower acts as a key regulator to maintain a progressive pace to flowering—which in turn, dictates how many flowers are produced on each tomato inflorescence. Finally, the Lippman lab determined the genome sequence of the “currant tomato,” the wild ancestor of larger-fruited cultivated tomatoes, in order to better understand how flower and fruit production changed during the process of crop domestication.