# DSK2-mediated degradation of F-box protein LAO1 and class I TCPs modulates the nitrogen starvation response

## TL;DR

This study reveals how plants adapt to nitrogen starvation through a new regulatory network involving the proteins DSK2, LAO1, and class I TCPs.

## Contribution

The paper identifies a novel regulatory mechanism involving DSK2-mediated degradation of LAO1 and class I TCPs during nitrogen starvation.

## Key findings

- LAO1 negatively regulates plant fitness during nitrogen starvation and is degraded by DSK2.
- Class I TCPs are crucial for plant adaptation to nitrogen starvation and function downstream of LAO1.
- DSK2 balances plant responses by degrading both LAO1 and class I TCPs.

## Abstract

Plants have evolved intricate strategies to cope with various abiotic stresses. Ubiquitin-mediated protein degradation plays a key role in plant development as well as abiotic stress tolerance. In this study, we identify LAO1, an F-box protein with unknown function, as a negative regulator of plant fitness during nitrogen starvation. DOMINANT SUPPRESSOR OF KAR 2 (DSK2) interacts with and mediates the autophagic degradation of LAO1 protein during nitrogen starvation. The loss of LAO1 improves the fitness of an autophagy-deficient mutant, atg5-1, under nitrogen starvation. Intriguingly, mutations in DSK2 facilitate rather than reduce plant growth after nitrogen starvation. This unexpected effect of DSK2 knockout led us to discover that DSK2 also interacts with and degrades a group of class I TCP transcription factors. Phenotypic observations demonstrate that class I TCPs are crucial for plant adaptation to nitrogen starvation. Moreover, genetic analyses indicate that class I TCPs function downstream of LAO1 and counteract its negative effects. Collectively, our findings unveil a previously undescribed regulatory network governing plant fitness during nitrogen starvation.

The ubiquitin receptor protein DSK2 modulates the protein stability of F-box protein LAO1 and class I TCP transcription factors as part of a novel regulatory network for plant adaptation to nitrogen starvation.

The F-box protein LAO1 negatively regulates plant fitness during nitrogen starvation, and its protein levels are tightly controlled by nitrogen availability through transcriptional and autophagic degradation.DSK2 interacts with and mediates the degradation of both LAO1 and class I TCP transcription factors, thereby balancing plant responses to nitrogen starvation.Class I TCP transcription factors act genetically downstream of LAO1 and DSK2 to positively regulate plant tolerance to nitrogen starvation.

The F-box protein LAO1 negatively regulates plant fitness during nitrogen starvation, and its protein levels are tightly controlled by nitrogen availability through transcriptional and autophagic degradation.

DSK2 interacts with and mediates the degradation of both LAO1 and class I TCP transcription factors, thereby balancing plant responses to nitrogen starvation.

Class I TCP transcription factors act genetically downstream of LAO1 and DSK2 to positively regulate plant tolerance to nitrogen starvation.

The ubiquitin receptor protein DSK2 modulates the protein stability of F-box protein LAO1 and class I TCP transcription factors as part of a novel regulatory network for plant adaptation to nitrogen starvation.