C-5-6 - Citrus Thorn as a Model System to Study Vegetative Meristem Determinacy

Sunday, July 15
2:43 PM - 2:45 PM

Thorns represent a unique and previously unexplored opportunity to examine how stem cell proliferation is controlled in plants. Thorns arise from vegetative shoot apical meristems that, instead of maintaining a stem cell fate, switch from indeterminate to determinate growth, resulting in terminal differentiation. Here we report on the development of Citrus thorns as a model system. We demonstrate that these thorn primordia express the STM stem cell marker in a dynamic fashion, and that Citrus thorns differentiate in a tip-to-base fashion based on both analysis of cell cycle markers and lignification. We also show that the stem cell organizer WUS is expressed in thorn primordia and its expression is terminated in elongating thorns. WUS is important for thorn development as the disruption of WUS activity blocks thorn production. We further identify a gene encoding a TCP transcription factor, Thorn Identity (TI), which is expressed in elongating thorns and is required to terminate WUS expression for the determinate growth of thorns. Silencing or mutation of TI transforms thorns into branches as indicated by the presence of an indeterminate apex that produces leaves and secondary growth indicative of branch formation. Our results reveal new mechanisms underlying meristem stem cell arrest, using Citrus as a novel model system.



Vivian Irish – Yale University

Fei Zhang, PhD

postdoctoral associate
Yale University

Fei Zhang is a postdoctoral associate in the Department of Molecular, Cellular and Developmental Biology at Yale University. Fei obtained his B.S. and Ph.D. from Shanghai Jiao Tong University in plant biotechnology in Dr. Kexuan Tang’s lab. There he uncovered new regulators of cotton fiber cell differentiation. Fei has been trained in plant biology at University of California, Riverside with Dr. Jian-Kang Zhu and at Harvard University with Dr. Elena Kramer as a visiting scholar. Fei has carried out postdoctoral work with Dr. Million Tadege on leaf development at Oklahoma State University, with a focus on how STENOFOLIA, a WOX family transcription factor,regulates leaf meristem development. Fei is now pursuing investigations of thorn development in Citrus with Dr. Vivian Irish at Yale University. A central focus of Fei’s work has been applying various approaches to address fundamental questions in meristem establishment and termination in Citrus.


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C-5-6 - Citrus Thorn as a Model System to Study Vegetative Meristem Determinacy

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