CLAVATA3 signaling buffers Arabidopsis shoot apical meristem activity in response to photoperiod

Authors: Fletcher, Jennifer

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/2024
Publication Date: 8/29/2024
Citation: Fletcher, J.C. 2024. CLAVATA3 signaling buffers Arabidopsis shoot apical meristem activity in response to photoperiod. International Journal of Molecular Sciences. 25(17). Article 9357. https://doi.org/10.3390/ijms25179357.
DOI: https://doi.org/10.3390/ijms25179357

Interpretive Summary: Plants respond to a wide variety of environmental cues by changing their growth to increase their reproductive success. Arabidopsis plants grow faster when the days are long in the summer than when they are short in the winter, but the molecular basis for this behavior is unclear. Here I tested the hypothesis that the CLAVATA3 (CLV3) signaling peptide, which regulates the amount of stem cell activity during plant development, plays a role in controlling plant growth in response to long summer days versus short winter days. I found that CLV3 signaling restrains stem cell activity in both long day and short day environments but plays a greater role when the days are short. These results provide insight into how plant growth can be optimized in response to changing environmental conditions.

Technical Abstract: Land plants grow throughout their life cycle via the continuous activity of stem cell reservoirs contained within their apical meristems. The shoot apical meristem (SAM) of Arabidopsis and other land plants responds to a variety of environmental cues, yet little is known about the response of meristems to seasonal changes in day length, or photoperiod. Here I analyzed the vegetative and reproductive growth of Arabidopsis wild-type and clavata3 (clv3) plants in different photoperiod conditions. I found that SAM size in wild-type Arabidopsis plants grown in long day (LD) conditions gradually increased from embryonic to reproductive development. clv3 plants produced significantly more leaves as well as larger inflorescence meristems and more floral buds than wild-type plants in LD and short day (SD) conditions, demonstrating that CLV3 signaling limits vegetative and inflorescence meristem activity in both photoperiods. The clv3 phenotypes were more severe in SDs, indicating a greater requirement for CLV3 restriction of SAM function when the days are short. In contrast, clv3 floral meristem size and carpel number was unchanged between LD and SD conditions, which shows that photoperiod does not affect the regulation of floral meristem activity by the CLV3 pathway. This study reveals that CLV3 signaling specifically restricts vegetative and inflorescence meristem activity in both LD and SD photoperiods but plays a more prominent role during short days.