Stem cell activity in the Arabidopsis shoot apex controlled by a triad of CLE signaling peptides

Authors: DAO, THAI - University Of California; WEKSLER, NAAMA - University Of California; LIU, HANNAH - University Of California; Fletcher, Jennifer

Submitted to: American Society of Plant Biologists
Publication Type: Proceedings
Publication Acceptance Date: 7/23/2020
Publication Date: 7/27/2020
Citation: Dao, T.Q., Weksler, N., Liu, H., Fletcher, J.C. 2020. Stem cell activity in the Arabidopsis shoot apex controlled by a triad of CLE signaling peptides. American Society of Plant Biologists. https://doi.org/10.46678/PB.20.399335.
DOI: https://doi.org/10.46678/PB.20.399335

Interpretive Summary: The pressures of population growth combined with reductions in farmable land mean that sustaining agricultural productivity has become an important national food security issue. Many agricultural yield traits can be improved by understanding how stem cell reservoirs are sustained within the growing tips of plants, called meristems, as they produce the leaves, ears, fruits, pods, seeds and other structures that humans cultivate and eat. Our previous research showed that a gene called CLAVATA3 (CLV3) plays a key role in controlling plant stem cell activity. Here we show that the closely related CLE16 and CLE17 genes act together with CLV3 to regulate the number of stem cells produced by the meristems. We demonstrate that removing the function of all three genes causes the stem cell pools to dramatically enlarge, increasing the number of flowers, fruits and seeds made by the plants. Our study expands the set of genes that can be targeted to increase yield traits such as fruit number, fruit size and seed number in crop species.

Technical Abstract: Stem cell populations in plants are established and maintained by networks of transcription factors and signaling pathways. One notable example of such molecular signals is the CLE family of small secreted peptides, whose representative member CLAVATA3 in Arabidopsis thaliana controls shoot meristematic activity by modulating the transcription factor WUSCHEL in a negative feedback loop. Here, we describe two other CLE peptides, CLE16 and CLE17, that function in the Arabidopsis shoot apical meristem (SAM) to restrict stem cell proliferation in the absence of CLV3. Whereas null single and double mutants for cle16 and cle17 lack phenotypes, both contribute to SAM enlargement and organ production in the clv3 mutant background at all stages of development. Ongoing efforts to characterize receptors for CLE16 and 17, as well as their downstream transcription factors will also be discussed. Overall, this study reveals a complex functional relationship among members of the CLE family that allows for various degrees of redundancy and buffers stem cell homeostasis.