Citrus FRIGIDA cooperates with its interaction partner dehydrin to regulate drought tolerance

Abstract

Drought is a major environmental stress that severely affects plant growth and crop productivity. FRIGIDA (FRI) is a key regulator of flowering time and drought tolerance in model plants. However, little is known regarding its functions in woody plants, including citrus. Thus, we explored the functional role of the citrus FRI ortholog (CiFRI) under drought. Drought treatment induced CiFRI expression. CiFRI overexpression enhanced drought tolerance in transgenic Arabidopsis and citrus, while CiFRI suppression increased drought susceptibility in citrus. Moreover, transcriptomic profiling under drought conditions suggested that CiFRI overexpression altered the expression of numerous genes involved in the stress response, hormone biosynthesis, and signal transduction. Mechanistic studies revealed that citrus dehydrin likely protects CiFRI from stress-induced degradation, thereby enhancing plant drought tolerance. In addition, a citrus brassinazole-resistant (BZR) transcription factor family member (CiBZR1) directly binds to the CiFRI promoter to activate its expression under drought conditions. CiBZR1 also enhanced drought tolerance in transgenic Arabidopsis and citrus. These findings further our understanding of the molecular mechanisms underlying the CiFRI-mediated drought stress response in citrus.

Mechanism of action of microRNA166 on nitric oxide in alfalfa (Medicago sativa L.) under drought stress

“…The combination of weak and non-functional alleles of the FRIGIDA (FRI) and FLOWERING LOCUS C (FLC) genes can significantly reduce a plant’s lifetime water consumption by controlling its flowering time [ 58 ]. Overexpression of FRI in Arabidopsis and Citrus can enhance plant drought tolerance [ 64 ]. FRI upregulates the expression of FLOWERING LOCUS C (FLC) , which is the main determinant of natural changes in flowering time in Arabidopsis [ 58 ].…”

The MsDHN1‐MsPIP2;1‐MsmMYB module orchestrates the trade‐off between growth and survival of alfalfa in response to drought stress

“…Dehydrins are highly hydrophilic proteins and are well known as molecular chaperone to interact and protect other proteins under abiotic stress conditions (Li et al ., 2019 ; Rorat, 2006 ). By this way, dehydrins involve in multiple physiological processes to protect plant cells against drought damage, such as enhancing water retention capacity, maintaining photosynthetic machinery, reducing ROS generation, and promoting osmotic substance accumulation (Maszkowska et al ., 2018 ; Szabala et al ., 2014 ; Xu et al ., 2022 ). Our previous study has proven that the MsDHN1 is a high hydrophilic protein (Lv et al ., 2021 ).…”

“…As a molecular chaperone, dehydrins can bind to nucleic acids (DNA and RNA) in plant cells (Graether and Boddington, 2014 ) and protect the target biomolecules from degradation under abiotic stress (Hara et al ., 2009 ; Kovacs et al ., 2008 ). The citrus dehydrin CiDHN protects a nuclear localization protein CiFRI from degradation through protein–protein interactions under drought conditions (Xu et al ., 2022 ). The C terminus of MsDHN1 protein was demonstrated to localize in cell nucleus in our previous study (Lv et al ., 2021 ), and it was also demonstrated to interact with mMYB in the nucleus (Figure 4 ).…”

“…As functional genes of protein protectors, dehydrins are known to interact with their partners under environmental stress conditions. The interactions of Rab16D with OsFKBP and CiDHN with CiFIR in cell nucleus act as a positive transcriptional co‐regulator and impart drought tolerance in rice ( Oryza sativa ) and citrus, respectively (Tiwari et al ., 2019 ; Xu et al ., 2022 ). The dehydrin MtCAS31 interacts specifically with aquaporin MtPIP2;7 and ATG8a to prevent plants from drought damage (Li et al ., 2019 ).…”

Flowering time: From physiology, through genetics to mechanism

“…FLC is known to bind to many genes and is associated with broader developmental contexts such as seed dormancy, cold tolerance, juvenile-to-adult phase transition, and inflorescence patterning ( Chiang et al 2009 ; Deng et al 2011 ; Huang et al 2013 ; Mateos et al 2017 ; Auge et al 2019 ). Moreover, FRI and FLC increase the stress tolerance of plants during drought and pathogen infection ( Wilson et al 2013 ; Chen et al 2018 ; Chen et al 2022 ; Shukla et al 2022 ; Xu et al 2022 ). The naming of genes based on original forward screens implies a specificity to their function, which in reality is not the case.…”