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

Yale University

Fei Zhang has had a long-standing interest in plant developmental biology, obtaining his B.S. and Ph.D. from Shanghai Jiao Tong University in plant biotechnology. There, he worked on cotton fiber development with Dr. Kexuan Tang. During his graduate study, Fei had professional training on epigenetics at University of California, Riverside for one and a half years. After graduation, Fei joined Dr. Million Tadege's lab at Oklahoma State University as postdoc studying Medicago leaf development. Fei also had professional training on virus induced gene silencing and in situ hybridization in Dr.Elena Kramer's lab at Harvard University. He is now a postdoc in Dr. Vivian Irish's lab at Yale University, pursuing investigations of thorn development in Citrus.


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

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