Genome-wide analysis of ZAT gene family revealed GhZAT6 regulates salt stress tolerance in G. hirsutum

Recent advances in the multifaceted functions of Cys2/His2-type zinc finger proteins in plant growth, development, and stress responses

Recent research has highlighted the importance of Cys2/His2-type zinc finger proteins (C2H2-ZFPs) in plant growth and in responses to various stressors, and the complex structures of C2H2-ZFP networks and the molecular mechanisms underlying their responses to stress have received considerable attention. Here, we review the structural characteristics and classification of C2H2-ZFPs, and consider recent research advances in their functions. We systematically introduce the roles of these proteins across diverse aspects of plant biology, encompassing growth and development, and responses to biotic and abiotic stresses, and in doing so hope to lay the foundations for further functional studies of C2H2-ZFPs in the future.

Genome-wide identification of the Q-type C2H2 zinc finger protein gene family and expression analysis under abiotic stress in lotus (Nelumbo nucifera G.)

BACKGROUND

Lotus (Nelumbo nucifera G.) is an important aquatic plant with high ornamental, economic, cultural and ecological values, but abiotic stresses seriously affect its growth and distribution. Q-type C2H2 zinc finger proteins (ZFPs) play an important role in plant growth development and environmental stress responses. Although the Q-type C2H2 gene family has been identified in some plants, limited reports has been carried out it in lotus.

RESULTS

In this study, we identified 45 Q-type NnZFP members in lotus. Based on the phylogenetic tree, these Q-type NnZFP gene family members were divided into 4 groups, including C1-1i, C1-2i, C1-3i and C1-4i. Promoter cis-acting elements analysis indicated that most Q-type NnZFP gene family members in lotus were associated with response to abiotic stresses. Through collinearity analyses, no tandem duplication gene pairs and 14 segmental duplication gene pairs were identified, which showed that duplication events might play a key role in the expansion of the Q-type NnZFP gene family. The synteny results suggested that 54 and 28 Q-type NnZFP genes were orthologous to Arabidopsis and rice, respectively. The expression patterns of these Q-type NnZFP genes revealed that 30 Q-type NnZFP genes were expressed in at least one lotus tissue. Nn5g30550 showed relatively higher expression levels in all tested tissues. 12 genes were randomly selected with at least one gene from each phylogenetic clade, and the expression of these selected genes were confirmed by qRT-PCR (quantitative real-time polymerase chain reaction). The results indicated that Q-type NnZFP genes were extensively involved in cadmium, drought, salt and cold stresses responses. Among them, 11 genes responded to at least three different stress treatments, especially Nn2g12894, which induced by all four treatments.

CONCLUSIONS

These results could increase our understanding of the characterization of the Q-type NnZFP gene family and provide relevant information for further functional analysis of Q-type NnZFP genes in plant development, and abiotic stress tolerance in lotus.

Genome-Wide Analysis of ZAT Gene Family in Osmanthus fragrans and the Function Exploration of OfZAT35 in Cold Stress

Osmanthus fragrans is a popular ornamental and odorant plant with high commercial value, but its cultivation and exploitation are limited by low temperature. The ZAT (zinc finger of Arabidopsis thaliana) genes as a subclass of the C2H2-type zinc finger proteins (C2H2-ZFP) family play essential roles in various abiotic stresses. However, their roles in cold stress response in O. fragrans remain unclear. This study identified 38 OfZATs, which could be divided into 5 subgroups based on the phylogenetic tree, with OfZATs in the same subgroup harboring similar gene structures and motif patterns. In addition, 49 segmental and 5 tandem duplication events were detected among OfZAT genes, while some OfZAT genes exhibited specific expression patterns in different tissues. Furthermore, two OfZATs were induced in salt stress and eight OfZATs responded to cold stress. Interestingly, OfZAT35 showed a continuously increasing expression trend under cold stress, while its protein showed nucleus localization with no transcriptional activation activity. Transiently transformed tobacco overexpressing OfZAT35 exhibited a significantly higher relative electrolyte leakage (REL) level and increased activities of superoxide dismutase (SOD), peroxidase (POD), and Ascorbate peroxidase (APX), while there was significantly decreased activity of catalase (CAT). Moreover, CAT, DREB3, and LEA5, which are associated with cold stress, were dramatically decreased after cold treatment in transiently transformed tobacco, suggesting that overexpression of OfZAT35 negatively regulated cold stress. This study provides a basis for exploring the roles of ZAT genes and contributes to uncovering the mechanism of ZAT-mediated cold stress response in O. fragrans.

Genome-wide analysis of the MdZR gene family revealed MdZR2.2-induced salt and drought stress tolerance in apple rootstock

The DNL-type zinc finger protein constitutes a zinc ribbon protein (ZR) family, which belongs to a branch of zinc finger protein and plays an essential role in response to abiotic stress. Here, we identified six apple (Malus domestica) MdZR genes. Based on their phylogenetic relationship and gene structure, the MdZR genes were divided into three categories, including MdZR1, MdZR2, and MdZR3. Subcellular results showed that the MdZRs are located on the nuclear and membrane. The transcriptome data showed that MdZR2.2 is expressed in various tissues. The expression analysis results showed that MdZR2.2 was significantly upregulated under salt and drought treatments. Thus, we selected MdZR2.2 for further research. Overexpression of MdZR2.2 in apple callus improved their tolerance to drought and salt stress and ability to scavenge reactive oxygen species (ROS). In contrast, transgenic apple roots with silenced MdZR2.2 grew more poorly than the wild type when subjected to salt and drought stress, which reduced their ability to scavenge ROS. To our knowledge, this is the first study to analyze the MdZR protein family. This study identified a gene that responds to drought and salt stress. Our findings lay a foundation for a comprehensive analysis of the MdZR family members.

Analysis of PAT1 subfamily members in the GRAS family of upland cotton and functional characterization of GhSCL13-2A in Verticillium dahliae resistance

GhSCL13-2A, a member of the PAT1 subfamily in the GRAS family, positively regulates cotton resistance to Verticillium dahliae by mediating the jasmonic acid and salicylic acid signaling pathways and accumulation of reactive oxygen species. Verticillium wilt (VW) is a devastating disease of upland cotton (Gossypium hirsutum) that is primarily caused by the soil-borne fungus Verticillium dahliae. Scarecrow-like (SCL) proteins are known to be involved in plant abiotic and biotic stress responses, but their roles in cotton defense responses are still unclear. In this study, a total of 25 GhPAT1 subfamily members in the GRAS family were identified in upland cotton. Gene organization and protein domain analysis showed that GhPAT1 members were highly conserved. GhPAT1 genes were widely expressed in various tissues and at multiple developmental stages, and they were responsive to jasmonic acid (JA), salicylic acid (SA), and ethylene (ET) signals. Furthermore, GhSCL13-2A was induced by V. dahliae infection. V. dahliae resistance was enhanced in Arabidopsis thaliana by ectopic overexpression of GhSCL13-2A, whereas cotton GhSCL13-2A knockdowns showed increased susceptibility. Levels of reactive oxygen species (ROS) and JA were also increased and SA content was decreased in GhSCL13-2A knockdowns. At the gene expression level, PR genes and SA signaling marker genes were down-regulated and JA signaling marker genes were upregulated in GhSCL13-2A knockdowns. GhSCL13-2A was shown to be localized to the cell membrane and the nucleus. Yeast two-hybrid and luciferase complementation assays indicated that GhSCL13-2A interacted with GhERF5. In Arabidopsis, V. dahliae resistance was enhanced by GhERF5 overexpression; in cotton, resistance was reduced in GhERF5 knockdowns. This study revealed a positive role of GhSCL13-2A in V. dahliae resistance, establishing it as a strong candidate gene for future breeding of V. dahliae-resistant cotton cultivars.