Abiotic Stress-Induced Actin-Depolymerizing Factor 3 From Deschampsia antarctica Enhanced Cold Tolerance When Constitutively Expressed in Rice.

Mi Young Byun,Yo-Han Yoo,Li Hua Cui,Jungeun Lee,Hyung Geun Oh,Andosung Lee,Woo Taek Kim,Hyoungseok Lee

doi:10.3389/fpls.2021.734500

Mi Young Byun, Yo-Han Yoo + Show 6 more

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https://doi.org/10.3389/fpls.2021.734500

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Abstract

The Antarctic flowering plant Deschampsia antarctica is highly sensitive to climate change and has shown rapid population increases during regional warming of the Antarctic Peninsula. Several studies have examined the physiological and biochemical changes related to environmental stress tolerance that allow D. antarctica to colonize harsh Antarctic environments; however, the molecular mechanisms of its responses to environmental changes remain poorly understood. To elucidate the survival strategies of D. antarctica in Antarctic environments, we investigated the functions of actin depolymerizing factor (ADF) in this species. We identified eight ADF genes in the transcriptome that were clustered into five subgroups by phylogenetic analysis. DaADF3, which belongs to a monocot-specific clade together with cold-responsive ADF in wheat, showed significant transcriptional induction in response to dehydration and cold, as well as under Antarctic field conditions. Multiple drought and low-temperature responsive elements were identified as possible binding sites of C-repeat-binding factors in the promoter region of DaADF3, indicating a close relationship between DaADF3 transcription control and abiotic stress responses. To investigate the functions of DaADF3 related to abiotic stresses in vivo, we generated transgenic rice plants overexpressing DaADF3. These transgenic plants showed greater tolerance to low-temperature stress than the wild-type in terms of survival rate, leaf chlorophyll content, and electrolyte leakage, accompanied by changes in actin filament organization in the root tips. Together, our results imply that DaADF3 played an important role in the enhancement of cold tolerance in transgenic rice plants and in the adaptation of D. antarctica to its extreme environment.

Highlights

The Antarctic monocot plant Deschampsia antarctica Desv. has a considerably wider habitat and larger numbers of populations than Colobanthus quitensis, the Antarctic dicot plant (Komárková et al, 1985)
To identify the actin depolymerizing factor (ADF) gene family members in D. antarctica, we searched a previously reported transcriptome database (Lee et al, 2013) using the BLASTX program with rice ADF proteins as queries and used the SMART web tool to determine whether the ADF domain (SM000102) was present in the candidate ADF genes
Eight ADF domain-containing genes were identified; these eight genes were designated as D. antarctica ADF (DaADF) and the corresponding proteins were named DaADF

Summary

Introduction

The Antarctic monocot plant Deschampsia antarctica Desv. has a considerably wider habitat and larger numbers of populations than Colobanthus quitensis, the Antarctic dicot plant (Komárková et al, 1985). DaGolS2, which encodes a galactinol synthase that is the key enzyme mediating raffinose family oligosaccharide synthesis, improves the resistance of transgenic rice to both cold and drought (Cui et al, 2020). These findings imply that D. antarctica could be a model for studying the genetic and metabolic mechanisms of plant adaptations to various abiotic stresses; the molecular mechanisms of its adaptation to Antarctic environments remain poorly understood

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