Biology subjects

Silvestri, A.

Publications and source records attributed to Silvestri, A..

2 recordsLinked to original sources

bioRxiv2026

The miR319-targeted TCP transcription factors play crucial roles in the establishment of Arabidopsis thaliana shoot architecture in response to carbon and nitrogen availability.

Shoot branching is a highly plastic developmental process that allows plants to adjust their architecture to environmental conditions, such as carbon and nitrogen availability. Although the class II TCP transcription factor BRANCHED1 is a well-established repressor of shoot branching, the contribution of other TCP factors during this process remains less well understood. Here, we show that the miR319-targeted TCP module promotes shoot branching in Arabidopsis thaliana. Overexpression of miR319 reduced rosette branch production, whereas repression of TCP3 activity or triple knockout (KO) mutation in TCP3, TCP4 and TCP10 inhibited branching. Conversely, expression of a miR319-resistant TCP3 triggered a highly branched phenotype, indicating that TCP3 and related miR319 targets act as positive regulators of shoot branching. Genetic analysis with the strigolactone-deficient max4 mutant showed that strigolactones mediate, at least partly, the reduced branching observed in the miR319 overexpressing line and in the tcp3,4,10 triple mutant. Transcriptomic and DNA-binding analyses indicated indirect effect of TCP3 on strigolactone biosynthesis genes. Instead, miR319 overexpression increased the sensitivity of branching to nitrogen limitation and reduced nitrate uptake, thereby increasing the expression of strigolactone synthesis genes. We further show that carbon starvation reduced the transcription levels of miR319-targeted TCPs, independently of miR319 accumulation, and that TCP3 may connect carbon availability to sugar signalling via HEXOKINASE1. Together, our results identify the miR319-targeted TCP module as a positive regulator of shoot branching that links plant architecture to carbon and nitrogen availability.

plant biology↗

bioRxiv2025

Carbon availability acts via cytokinins to promote gemma cup formation in Marchantia polymorpha

Liverworts can clonally propagate by producing compact shoot structures called gemmae, which develop within basket-like structures known as gemma cups. It was previously reported in Marchantia nepalensis that carbon availability promotes gemma cup formation. However, the mechanisms by which carbon availability controls this process remains largely unexplored. To address this knowledge gap, we investigated how carbon promotes gemma cup formation using Marchantia polymorpha as a model species. Through a series of pharmacological and genetic experiments, we found that carbon availability promotes gemma cup formation by inducing the cytokinin pathway, thereby increasing the expression of MpGCAM1 and MpSTG, which encode two transcription factors involved in forming the basal floor of gemma cups. Indeed, our data show that cytokinins accumulate in marchantia thallus in response to sucrose and to high light treatments. In addition, constitutive induction of cytokinin signalling could overcome the repressive effect of low sucrose on gemma cup formation, whereas suppression of this hormonal pathway led to inhibition of sucrose-induced gemma cup formation. Furthermore, our results indicate that sucrose can induce gemma cup formation independently of KAI2A and MAX2, two molecular components of karrikin signalling known to control this developmental process by inducing cytokinin synthesis. Interestingly, in flowering plants, carbon availability also promotes cytokinin accumulation to induce axillary bud outgrowth, a process involving the transcription factors AtRAX and AtLOF1, the Arabidopsis thaliana orthologues of MpGCAM1 and MpSTG, respectively. Collectively, these observations indicate that the interactions between carbon and cytokinins are critical for the developmental plasticity of land plants in response to their environment.

plant biology↗