Roles of Canavalia rosea metallothioneins in metal tolerance and extreme environmental adaptation to tropical coral reefs.

Canavalia rosea (Sw.) DC is a perennial twining herb distributed in the semi-arid and saline-alkali areas of coastal regions and has evolved halotolerance. In this study, we present the first comprehensive survey of the metallothionein (MT) gene family in C. rosea. MT proteins belong to a family of low-molecular-weight polypeptides with a high content of cysteine residues, which have an affinity to bind with heavy metal ions. MTs also play important roles in stress responses as reactive oxygen species (ROS) scavengers. A total of six CrMTs were identified in the C. rosea genome and classified into four subgroups by phylogenetic analysis. An analysis of the cis-acting elements revealed that a series of hormone-, stress-, and development-related cis-acting elements were present in the promoter regions of CrMTs. The expression of CrMTs also showed habitat- and environmental stress-regulated patterns in C. rosea. CrMT overexpression in yeast enhanced tolerance to heavy metals and ROS, as well as high osmotic and alkalinity stress, which is consistent with their predicted roles as metal-chelating proteins and ROS scavengers. Our results indicate that the CrMT genes might contribute to the detoxification of plants to metals and provide marked tolerance against abiotic stress. The expression patterns of CrMTs in C. rosea also indicate that CrMTs play important roles in this species' response to extreme environments on tropical islands and reefs, probably by improving the thermotolerance of C. rosea plants.

Zou T ，Pu L ，Lin R ，Mo H ，Wang Z ，Jian S ，Zhang M ... -  《-》

Genome-Wide Identification, Primary Functional Characterization of the NHX Gene Family in Canavalia rosea, and Their Possible Roles for Adaptation to Tropical Coral Reefs.

Pu L ，Lin R ，Zou T ，Wang Z ，Zhang M ，Jian S ... -  《Genes》

Genome-wide functional characterization of Canavalia rosea cysteine-rich trans-membrane module (CrCYSTM) genes to reveal their potential protective roles under extreme abiotic stress.

Cysteine-rich transmembrane module (CYSTM) proteins constitute small molecular protein families and have been identified across eukaryotes, including yeast, humans, and several plant species. Plant CYSTMs play vital roles in growth regulation, development, phytohormone signal transduction, pathogen defense, environmental stress response, and even heavy metal binding and detoxification. Canavalia rosea (Sw.) DC is a perennial halophyte with great semi-arid and saline-alkali tolerance. In this study, the CrCYSTM family including 10 members were identified in the C. rosea genome, with the purpose of clarifying the possible roles of CrCYSTMs in C. rosea plants development and stress resistance. The phylogenetic relationships, exon-intron structure, domain structure, chromosomal localization, and putative cis-acting elements in promoter regions were predicted and analyzed. Transcriptome analysis combined with quantitative reverse transcription PCR showed that different CrCYSTM members exhibited varied expression patterns in different tissues and under different abiotic stress challenges. In addition, several CrCYSTMs were cloned and functionally characterized for their roles in abiotic stress tolerance with yeast expression system. Overall, these findings provide a foundation for functionally characterizing plant CYSTMs to unravel their possible roles in the adaptation of C. rosea to tropical coral reefs. Our results also lay the foundation for further research on the roles of plant CYSTM genes in abiotic stress signaling, especially for heavy metal detoxification.

Ding Q ，Liu H ，Lin R ，Wang Z ，Jian S ，Zhang M ... -  《-》

Genome-wide identification and expression analysis of aquaporin family in Canavalia rosea and their roles in the adaptation to saline-alkaline soils and drought stress.

Canavalia rosea (Sw.) DC. (bay bean) is an extremophile halophyte that is widely distributed in coastal areas of the tropics and subtropics. Seawater and drought tolerance in this species may be facilitated by aquaporins (AQPs), channel proteins that transport water and small molecules across cell membranes and thereby maintain cellular water homeostasis in the face of abiotic stress. In C. rosea, AQP diversity, protein features, and their biological functions are still largely unknown. We describe the action of AQPs in C. rosea using evolutionary analyses coupled with promoter and expression analyses. A total of 37 AQPs were identified in the C. rosea genome and classified into five subgroups: 11 plasma membrane intrinsic proteins, 10 tonoplast intrinsic proteins, 11 Nod26-like intrinsic proteins, 4 small and basic intrinsic proteins, and 1 X-intrinsic protein. Analysis of RNA-Seq data and targeted qPCR revealed organ-specific expression of aquaporin genes and the involvement of some AQP members in adaptation of C. rosea to extreme coral reef environments. We also analyzed C. rosea sequences for phylogeny reconstruction, protein modeling, cellular localizations, and promoter analysis. Furthermore, one of PIP1 gene, CrPIP1;5, was identified as functional using a yeast expression system and transgenic overexpression in Arabidopsis. Our results indicate that AQPs play an important role in C. rosea responses to saline-alkaline soils and drought stress. These findings not only increase our understanding of the role AQPs play in mediating C. rosea adaptation to extreme environments, but also improve our knowledge of plant aquaporin evolution more generally.

Lin R ，Zheng J ，Pu L ，Wang Z ，Mei Q ，Zhang M ，Jian S ... -  《BMC PLANT BIOLOGY》

Functional Characterization of Heat Shock Factor (CrHsf) Families Provide Comprehensive Insight into the Adaptive Mechanisms of Canavalia rosea (Sw.) DC. to Tropical Coral Islands.

Zhang M ，Wang Z ，Jian S 《INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES》