Genome-Wide Analysis of Members of the WRKY Gene Family and Their Cold Stress Response in Prunus mume

Integration of Metabolomic and Transcriptomic Analyses Reveals the Molecular Mechanisms of Flower Color Formation in Prunus mume

Flower color is an important trait that affects the economic value of Prunus mume, a famous ornamental plant in the Rosaceae family. P. mume with purple-red flowers is uniquely charming and highly favored in landscape applications. However, little is known about its flower coloring mechanism, which stands as a critical obstacle on the path to innovative breeding for P. mume flower color. In this study, transcriptomic and targeted metabolomic analyses of purple-red P. mume and white P. mume were performed to elucidate the mechanism of flower color formation. In addition, the expression patterns of key genes were analyzed using an RT-qPCR experiment. The results showed that the differential metabolites were significantly enriched in the flavonoid synthesis pathway. A total of 14 anthocyanins emerged as the pivotal metabolites responsible for the differences in flower color between the two P. mume cultivars, comprising seven cyanidin derivatives, five pelargonium derivatives, and two paeoniflorin derivatives. Moreover, the results clarified that the metabolic pathway determining flower color in purple-red P. mume encompasses two distinct branches: cyanidin and pelargonidin, excluding the delphinidin branch. Additionally, through the integrated analysis of transcriptomic and metabolomic data, we identified 18 key genes responsible for anthocyanin regulation, thereby constructing the gene regulatory network for P. mume anthocyanin synthesis. Among them, ten genes (PmCHI, PmGT2, PmGT5, PmGST3, PmMYB17, PmMYB22, PmMYB23, PmbHLH4, PmbHLH10, and PmbHLH20) related to anthocyanin synthesis were significantly positively correlated with anthocyanin contents, indicating that they may be the key contributors to anthocyanin accumulation. Our investigation contributes a novel perspective to understanding the mechanisms responsible for flower color formation in P. mume. The findings of this study introduce novel strategies for molecular design breeding aimed at manipulating flower color in P. mume.

Genome-Wide Analysis of the WRKY Transcription Factor Family in Roses and Their Putative Role in Defence Signalling in the Rose-Blackspot Interaction

WRKY transcription factors are important players in plant regulatory networks, where they control and integrate various physiological processes and responses to biotic and abiotic stresses. Here, we analysed six rose genomes of 5 different species (Rosa chinensis, R. multiflora, R. roxburghii, R. sterilis, and R. rugosa) and extracted a set of 68 putative WRKY genes, extending a previously published set of 58 WRKY sequences based on the R. chinensis genome. Analysis of the promoter regions revealed numerous motifs related to induction by abiotic and, in some cases, biotic stressors. Transcriptomic data from leaves of two rose genotypes inoculated with the hemibiotrophic rose black spot fungus Diplocarpon rosae revealed the upregulation of 18 and downregulation of 9 of these WRKY genes after contact with the fungus. Notably, the resistant genotype exhibited the regulation of 25 of these genes (16 upregulated and 9 downregulated), while the susceptible genotype exhibited the regulation of 20 genes (15 upregulated and 5 downregulated). A detailed RT-qPCR analysis of RcWRKY37, an orthologue of AtWRKY75 and FaWRKY1, revealed induction patterns similar to those of the pathogenesis-related (PR) genes induced in salicylic acid (SA)-dependent defence pathways in black spot inoculation experiments. However, the overexpression of RcWRKY37 in rose petals did not induce the expression of any of the PR genes upon contact with black spot. However, wounding significantly induced the expression of RcWRKY37, while heat, cold, or drought did not have a significant effect. This study provides the first evidence for the role of RcWRKY37 in rose signalling cascades and highlights the differences between RcWRKY37 and AtWRKY75. These results improve our understanding of the regulatory function of WRKY transcription factors in plant responses to stress factors. Additionally, they provide foundational data for further studies.

Identification of WRKY Family Members and Characterization of the Low-Temperature-Stress-Responsive WRKY Genes in Luffa (Luffa cylindrica L.)

The plant-specific WRKY transcription factor family members have diverse regulatory effects on the genes associated with many plant processes. Although the WRKY proteins in Arabidopsis thaliana and other species have been thoroughly investigated, there has been relatively little research on the WRKY family in Luffa cylindrica, which is one of the most widely grown vegetables in China. In this study, we performed a genome-wide analysis to identify L. cylindrica WRKY genes, which were subsequently classified and examined in terms of their gene structures, chromosomal locations, promoter cis-acting elements, and responses to abiotic stress. A total of 62 LcWRKY genes (471-2238 bp) were identified and divided into three phylogenetic groups (I, II, and III), with group II further divided into five subgroups (IIa, IIb, IIc, IId, and IIe) in accordance with the classification in other plants. The LcWRKY genes were unevenly distributed across 13 chromosomes. The gene structure analysis indicated that the LcWRKY genes contained 0-11 introns (average of 4.4). Moreover, 20 motifs were detected in the LcWRKY proteins with conserved motifs among the different phylogenetic groups. Two subgroup IIc members (LcWRKY16 and LcWRKY31) contained the WRKY sequence variant WRKYGKK. Additionally, nine cis-acting elements related to diverse responses to environmental stimuli were identified in the LcWRKY promoters. The subcellular localization analysis indicated that three LcWRKY proteins (LcWRKY43, LcWRKY7, and LcWRKY23) are localized in the nucleus. The tissue-specific LcWRKY expression profiles reflected the diversity in LcWRKY expression. The RNA-seq data revealed the effects of low-temperature stress on LcWRKY expression. The cold-induced changes in expression were verified via a qRT-PCR analysis of 24 differentially expressed WRKY genes. Both LcWRKY7 and LcWRKY12 were highly responsive to the low-temperature treatment (approximately 110-fold increase in expression). Furthermore, the LcWRKY8, LcWRKY12, and LcWRKY59 expression levels increased by more than 25-fold under cold conditions. Our findings will help clarify the evolution of the luffa WRKY family while also providing valuable insights for future studies on WRKY functions.

Genome-wide identification and comprehensive analysis of WRKY transcription factor family in safflower during drought stress

The WRKY family is an important family of transcription factors in plant development and stress response. Currently, there are few reports on the WRKY gene family in safflower (Carthamus tinctorius L.). In this study, a total of 82 CtWRKY genes were identified from the safflower genome and could be classified into 3 major groups and 5 subgroups based on their structural and phylogenetic characteristics. The results of gene structure, conserved domain and motif analyses indicated that CtWRKYs within the same subfamily maintained a consistent exon/intron organization and composition. Chromosomal localization and gene duplication analysis results showed that CtWRKYs were randomly localized on 12 chromosomes and that fragment duplication and purification selection may have played an important role in the evolution of the WRKY gene family in safflower. Promoter cis-acting element analysis revealed that the CtWRKYs contain many abiotic stress response elements and hormone response elements. Transcriptome data and qRT-PCR analyses revealed that the expression of CtWRKYs showed tissue specificity and a strong response to drought stress. Notably, the expression level of the CtWRKY55 gene rapidly increased more than eightfold under drought treatment and rehydration, indicating that it may be a key gene in response to drought stress. These results provide useful insights for investigating the regulatory function of the CtWRKY gene in safflower growth and development, as well as identifying key genes for future molecular breeding programmes.

Genome-Wide Identification of Bilberry WRKY Transcription Factors: Go Wild and Duplicate

WRKY transcription factor genes compose an important family of transcriptional regulators that are present in several plant species. According to previous studies, these genes can also perform important roles in bilberry (Vaccinium myrtillus L.) metabolism, making it essential to deepen our understanding of fruit ripening regulation and anthocyanin biosynthesis. In this context, the detailed characterization of these proteins will provide a comprehensive view of the functional features of VmWRKY genes in different plant organs and in response to different intensities of light. In this study, the investigation of the complete genome of the bilberry identified 76 VmWRKY genes that were evaluated and distributed in all twelve chromosomes. The proteins encoded by these genes were classified into four groups (I, II, III, and IV) based on their conserved domains and zinc finger domain types. Fifteen pairs of VmWRKY genes in segmental duplication and four pairs in tandem duplication were detected. A cis element analysis showed that all promoters of the VmWRKY genes contain at least one potential cis stress-response element. Differential expression analysis of RNA-seq data revealed that VmWRKY genes from bilberry show preferential or specific expression in samples. These findings provide an overview of the functional characterization of these proteins in bilberry.

Genome-wide identification and analysis of the WRKY gene family and low-temperature stress response in Prunus sibirica

BACKGROUND

WRKY transcription factors are a prominent gene family in plants, playing a crucial role in various biological processes including development, metabolism, defense, differentiation, and stress response. Although the WRKY gene family has been extensively studied and analysed in numerous plant species, research on Prunus sibirica's WRKY genes (PsWRKY) remains lacking.

RESULTS

This study analysed the basic physicochemical properties, phylogeny, gene structure, cis-acting elements, and Gene ontology (GO) annotation of PsWRKY gene family members using bioinformatics methods based on the whole-genome data of P. sibirica. In total, 55 WRKYs were identified in P. sibirica and were heterogeneously distributed on eight chromosomes. Based on the phylogenetic analysis, these WRKYs were classified into three major groups: Group I, Group II (II-a, II-b, II-c, II-d, II-e), and Group III. Members of different subfamilies have different cis-acting elements, conserved motifs, and intron-exon structures, indicating functional heterogeneity of the WRKY family. Prediction of subcellular localisation indicated that PsWRKYs were mainly located in the nucleus. Twenty pairs of duplicated genes were identified, and segmental duplication events may play an important role in PsWRKY gene family expansion. Analysis of the Ka/Ks ratio showed that the PsWRKY family's homologous genes were primarily purified by selection. Additionally, GO annotation analysis showed that the WRKY gene family was mainly involved in responses to stimuli, immune system processes, and reproductive processes. Furthermore, quantitative real-time PCR (qRT-PCR) analysis showed that 23 PsWRKYs were highly expressed in one or more tissues (pistils and roots) and PsWRKYs showed specific expression patterns under different low-temperature stress conditions.

CONCLUSIONS

Our results provide a scientific basis for the further exploration and functional validation of WRKYs in P. sibirica.

Genome-Wide Identification and Gene Expression Analysis of Sweet Cherry Aquaporins (Prunus avium L.) under Abiotic Stresses

Aquaporins (AQPs) are integral transmembrane proteins well known as channels involved in the mobilization of water, small uncharged molecules and gases. In this work, the main objective was to carry out a comprehensive study of AQP encoding genes in Prunus avium (cv. Mazzard F12/1) on a genome-wide scale and describe their transcriptional behaviors in organs and in response to different abiotic stresses. A total of 28 non-redundant AQP genes were identified in Prunus spp. Genomes, which were phylogenetically grouped into five subfamilies (seven PIPs, eight NIPs, eight TIPs, three SIPs and two XIPs). Bioinformatic analyses revealed a high synteny and remarkable conservation of structural features among orthologs of different Prunus genomes. Several cis-acting regulatory elements (CREs) related to stress regulation were detected (ARE, WRE3, WUN, STRE, LTR, MBS, DRE, AT-rich and TC-rich). The above could be accounting for the expression variations associated with plant organs and, especially, each abiotic stress analyzed. Gene expressions of different PruavAQPs were shown to be preferentially associated with different stresses. PruavXIP2;1 and PruavXIP1;1 were up-regulated in roots at 6 h and 72 h of hypoxia, and in PruavXIP2;1 a slight induction of expression was also detected in leaves. Drought treatment strongly down-regulated PruavTIP4;1 but only in roots. Salt stress exhibited little or no variation in roots, except for PruavNIP4;1 and PruavNIP7;1, which showed remarkable gene repression and induction, respectively. Interestingly, PruavNIP4;1, the AQP most expressed in cherry roots subjected to cold temperatures, also showed this pattern in roots under high salinity. Similarly, PruavNIP4;2 consistently was up-regulated at 72 h of heat and drought treatments. From our evidence is possible to propose candidate genes for the development of molecular markers for selection processes in breeding programs for rootstocks and/or varieties of cherry.

Genome-wide investigation of the WRKY transcription factor gene family in weeping forsythia: expression profile and cold and drought stress responses

Weeping forsythia is a wide-spread shrub in China with important ornamental, medicinal and ecological values. It is widely distributed in China's warm temperate zone. In plants, WRKY transcription factors play important regulatory roles in seed germination, flower development, fruit ripening and coloring, and biotic and abiotic stress response. To date, WRKY transcription factors have not been systematically studied in weeping forsythia. In this study, we identified 79 WRKY genes in weeping forsythia and classified them according to their naming rules in Arabidopsis thaliana. Phylogenetic tree analysis showed that, except for IIe subfamily, whose clustering was inconsistent with A. thaliana clustering, other subfamily clustering groups were consistent. Cis-element analysis showed that WRKY genes related to pathogen resistance in weeping forsythia might be related to methyl jasmonate and salicylic acid-mediated signaling pathways. Combining cis-element and expression pattern analyses of WRKY genes showed that more than half of WRKY genes were involved in light-dependent development and morphogenesis in different tissues. The gene expression results showed that 13 WRKY genes were involved in drought response, most of which might be related to the abscisic acid signaling pathway, and a few of which might be regulated by MYB transcription factors. The gene expression results under cold stress showed that 17 WRKY genes were involved in low temperature response, and 9 of them had low temperature responsiveness cis-elements. Our study of WRKY family in weeping forsythia provided useful resources for molecular breeding and important clues for their functional verification.

WRKY transcription factors: evolution, regulation, and functional diversity in plants

The recent advancements in sequencing technologies and informatic tools promoted a paradigm shift to decipher the hidden biological mysteries and transformed the biological issues into digital data to express both qualitative and quantitative forms. The transcriptomic approach, in particular, has added new dimensions to the versatile essence of plant genomics through the large and deep transcripts generated in the process. This has enabled the mining of super families from the sequenced plants, both model and non-model, understanding their ancestry, diversity, and evolution. The elucidation of the crystal structure of the WRKY proteins and recent advancement in computational prediction through homology modeling and molecular dynamic simulation has provided an insight into the DNA-protein complex formation, stability, and interaction, thereby giving a new dimension in understanding the WRKY regulation. The present review summarizes the functional aspects of the high volume of sequence data of WRKY transcription factors studied from different species, till date. The review focuses on the dynamics of structural classification and lineage in light of the recent information. Additionally, a comparative analysis approach was incorporated to understand the functions of the identified WRKY transcription factors subjected to abiotic (heat, cold, salinity, senescence, dark, wounding, UV, and carbon starvation) stresses as revealed through various sets of studies on different plant species. The review will be instrumental in understanding the events of evolution and the importance of WRKY TFs under the threat of climate change, considering the new scientific evidences to propose a fresh perspective.

A WRKY Transcription Factor PmWRKY57 from Prunus mume Improves Cold Tolerance in Arabidopsis thaliana

Prunus mume, a woody perennial tree, is valued for its ornamental traits and has been cultivated for a long history. Low temperature is the main environmental factor restricting the distribution and affecting the growth of P. mume. In plants, some WRKY transcription factors have been reported to participate in regulating cold tolerance. However, there were few researches about functional characterization of WRKYs involving in P. mume cold response. Here, a cold-induced WRKY gene named as PmWRKY57 was cloned from a P. mume cultivar 'Guhong Zhusha.' PmWRKY57 protein harboring a WRKY domain and a C2H2 zinc finger motif belongs to Group IIc of WRKY family. The PmWRKY57 protein was located to the nucleus and has transcriptional activation activity. PmWRKY57-overexpresing Arabidopsis thaliana lines showed improved cold tolerance, compared to wild-type plants. Under cold treatment, the leaves of transgenic lines contained significantly lower malondialdehyde content, and higher levels of superoxide dismutase activity, peroxidase activity, and proline content than wild-type plants. Furthermore, the expression levels of cold-response genes such as AtCOR6.6, AtCOR47, AtKIN1, and AtRCI2A were up-regulated in leaves of transgenic A. thaliana compared to those in wild-type plants. This study characterized the function of PmWRKY57 in improving cold tolerance of plants.

Integrated Transcriptome and Metabolome Analysis of Color Change and Low-Temperature Response during Flowering of Prunus mume

In China, Prunus mume is a famous flowering tree that has been cultivated for 3000 years. P. mume grows in tropical and subtropical regions, and most varieties lack cold resistance; thus, it is necessary to study the low-temperature response mechanism of P. mume to expand the scope of its cultivation. We used the integrated transcriptomic and metabolomic analysis of a cold-resistant variety of P. mume 'Meiren', to identify key genes and metabolites associated with low temperatures during flowering. The 'Meiren' cultivar responded in a timely manner to temperature by way of a low-temperature signal transduction pathway. After experiencing low temperatures, the petals fade and wilt, resulting in low ornamental value. At the same time, in the cold response pathway, the activities of related transcription factors up- or downregulate genes and metabolites related to low temperature-induced proteins, osmotic regulators, protective enzyme systems, and biosynthesis and metabolism of sugars and acids. Our findings promote research on the adaptation of P. mume to low temperatures during wintering and early flowering for domestication and breeding.

Characterization of the WRKY gene family reveals its contribution to the adaptability of almond (Prunus dulcis)

Background

WRKY (WRKY DNA-binding domain) transcription factors an important gene family that widely regulates plant resistance to biological and abiotic stresses, such as drought, salt and ion stresses. However, research on the WRKY family in almond has not yet been reported. Almond is an economically important fruit tree in Xinjiang that have strong resistance to various stresses.

Results

A total of 62 PdWRKY genes were identified (including six pairs of homologous genes), and the phylogenetic tree was divided into three groups according to the WRKY domain and zinc finger motifs. The members of each group had a significant number of conserved motifs and exons/introns distributed unevenly across eight chromosomes, as well as 24 pairs of fragment duplicates and nine pairs of tandem duplicates. Moreover, the synteny and Ka/Ks analyses of the WRKY genes among almond and distinct species provided more detailed evidence for PdWRKY genes evolution. The examination of different tissue expression patterns showed that PdWRKY genes have tissue-specific expression characteristics. The qRT-PCR results showed that PdWRKY genes participate in the resistance of almond to the effects of low-temperature, drought and salt stress and that the expression levels of these genes change over time, exhibiting spatiotemporal expression characteristics. It is worth noting that many genes play a significant role in low-temperature stress resistance. In addition, based on the conserved WRKY motif, 321 candidate target genes were identified as having functions in multiple pathways.

Conclusions

We conducted systematic bioinformatics analysis and abiotic stress research on the WRKY gene family in almond, laying the foundation for future PdWRKY genes research and improvements to almond production and breeding.

Genome-Wide Identification of WRKY Genes and Their Responses to Chilling Stress in Kandelia obovata

Background:Kandelia obovata, a dominant mangrove species, is widely distributed in tropical and subtropical areas. Low temperature is the major abiotic stress that seriously limits the survival and growth of mangroves. WRKY transcription factors (TFs) play vital roles in responses to biotic and abiotic stresses. However, genome-wide analysis of WRKY genes in K. obovata and their responses to chilling stress have not been reported.

Methods: Bioinformatic analysis was used to identify and characterize the K. obovata WRKY (KoWRKY) gene family, RNA-seq and qRT–PCR analyses were employed to screen KoWRKYs that respond to chilling stress.

Results: Sixty-four KoWRKYs were identified and they were unevenly distributed across all 18 K. obovata chromosomes. Many orthologous WRKY gene pairs were identified between Arabidopsis thaliana and K. obovata, showing high synteny between the two genomes. Segmental duplication events were found to be the major force driving the expansion for the KoWRKY gene family. Most of the KoWRKY genes contained several kinds of hormone- and stress-responsive cis-elements in their promoter. KoWRKY proteins belonged to three groups (I, II, III) according to their conserved WRKY domains and zinc-finger structure. Expression patterns derived from the RNA-seq and qRT–PCR analyses revealed that 9 KoWRKYs were significantly upregulated during chilling acclimation in the leaves. KEGG pathway enrichment analysis showed that the target genes of KoWRKYs were significantly involved in 11 pathways, and coexpression network analysis showed that 315 coexpressed pairs (KoWRKYs and mRNAs) were positively correlated.

Conclusion: Sixty-four KoWRKYs from the K. obovata genome were identified, 9 of which exhibited chilling stress-induced expression patterns. These genes represent candidates for future functional analysis of KoWRKYs involved in chilling stress related signaling pathways in K. obovata. Our results provide a basis for further analysis of KoWRKY genes to determine their functions and molecular mechanisms in K. obovata in response to chilling stress.

Genome-Wide Identification and Analysis of the WRKY Gene Family and Cold Stress Response in Acer truncatum

WRKY transcription factors constitute one of the largest gene families in plants and are involved in many biological processes, including growth and development, physiological metabolism, and the stress response. In earlier studies, the WRKY gene family of proteins has been extensively studied and analyzed in many plant species. However, information on WRKY transcription factors in Acer truncatum has not been reported. In this study, we conducted genome-wide identification and analysis of the WRKY gene family in A. truncatum, 54 WRKY genes were unevenly located on all 13 chromosomes of A. truncatum, the highest number was found in chromosomes 5. Phylogenetic relationships, gene structure, and conserved motif identification were constructed, and the results affirmed 54 AtruWRKY genes were divided into nine subgroup groups. Tissue species analysis of AtruWRKY genes revealed which were differently exhibited upregulation in flower, leaf, root, seed and stem, and the upregulation number were 23, 14, 34, 18, and 8, respectively. In addition, the WRKY genes expression in leaf under cold stress showed that more genes were significantly expressed under 0, 6 and 12 h cold stress. The results of this study provide a new insight the regulatory function of WRKY genes under abiotic and biotic stresses.

Genome-Wide Identification and Low-Temperature Expression Analysis of bHLH Genes in Prunus mume

Prunus mume is an illustrious ornamental woody plant with colorful flowers, delicate fragrances, and graceful tree forms. Low temperature limits its geographical distribution. The basic helix-loop-helix (bHLH) proteins exist in most eukaryotes as a transcription factor superfamily, which play a crucial role in metabolism, physiology, development, and response to various stresses of higher organisms. However, the characteristics of the bHLH gene family and low-temperature response remain unknown in P. mume. In the present study, we distinguished 95 PmbHLH genes in the P. mume whole-genome and analyzed their features. PmbHLHs were divided into 23 subfamilies and one orphan by phylogenetic analysis. Similar gene structures and conserved motifs appeared in the same subfamily. These genes were situated in eight chromosomes and scaffolds. Gene duplication events performed a close relationship to P. mume, P. persica, and P. avium. Tandem duplications probably promoted the expansion of PmbHLHs. According to predicted binding activities, the PmbHLHs were defined as the Non-DNA-binding proteins and DNA-binding proteins. Furthermore, PmbHLHs exhibited tissue-specific and low-temperature induced expression patterns. By analyzing transcriptome data, 10 PmbHLHs which are responsive to low-temperature stress were selected. The qRT-PCR results showed that the ten PmbHLH genes could respond to low-temperature stress at different degrees. There were differences in multiple variations among different varieties. This study provides a basis to research the evolution and low-temperature tolerance of PmbHLHs, and might enhance breeding programs of P. mume by improving low-temperature tolerance.

VvXYLP02 confers gray mold resistance by amplifying jasmonate signaling pathway in Vitis vinifera

Xylogen-like proteins (XYLPs) are essential for plant growth, development, and stress responses. However, little is known about the XYLP gene family in grape and its protective effects against gray mold a destructive disease caused by Botrytis cinerea. We identified and characterized six common XYLPs in the Vitis vinifera genome (VvXYLPs). VvXYLP expression pattern analyses with B. cinerea infection showed that VvXYLP02 was significantly up-regulated in the resistant genotype but down-regulated or only slightly up-regulated in the susceptible genotype. VvXYLP02 overexpression in Arabidopsis thaliana significantly increased resistance to B. cinerea, indicating that the candidate gene has functional importance. Furthermore, JA treatment significantly up-regulated VvXYLP02 expression in V. vinifera. JA-responsive genes were also up-regulated in VvXYLP02 overexpression lines in A. thaliana under B. cinerea inoculation. These findings suggest that VvXYLP02, which is induced by JA upon the pathogen infection, enhances JA dependent response to enforce plant resistance against gray mold disease.

Identification of MicroRNAs in Taxillus chinensis (DC.) Danser Seeds under Cold Stress

Taxillus chinensis (DC.) Danser, a parasitic plant that belongs to the Loranthaceae family, has a long history of being used in the Chinese medicine. We observed that the loranthus seeds were sensitive to temperature and could lose viability below 0°C quickly. Thus, we performed small RNA sequencing to study the microRNA (miRNA) regulation in the loranthus seeds under cold stress. In total, we identified 600 miRNAs, for the first time, in the loranthus seeds under cold stress. Then, we detected 224, 229, and 223 miRNAs (TPM > 1) in A0 (control), A1 (cold treatment for 12 h at 0°C), and A2 (cold treatment for 36 h at 0°C), respectively. We next identified 103 differentially expressed miRNAs (DEmiRs) in the loranthus seeds in response to cold. Notably, miR408 was upregulated during the cold treatment, which can regulate genes encoding phytocyanin family proteins and phytophenol oxidases. Some DEmiRs were specific to A1 and may function in early response to cold, such as gma-miR393b-3p, miR946, ath-miR779.2-3p, miR398, and miR9662. It is interesting that ICE3, IAA13, and multiple transcription factors (e.g., WRKY and CRF4 and TCP4) regulated by the DEmiRs have been reported to respond cold in other plants. We further identified 4, 3, and 4 DEmiRs involved in the pathways “responding to cold,” “responding to abiotic stimulus,” and “seed development/germination,” respectively. qRT-PCR was used to confirm the expression changes of DEmiRs and their targets in the loranthus seeds during the cold treatment. This is the first time to study cold-responsive miRNAs in loranthus, and our findings provide a valuable resource for future studies.

Cotton CC-NBS-LRR Gene GbCNL130 Confers Resistance to Verticillium Wilt Across Different Species

Verticillium wilt (VW) is a destructive disease in cotton caused by Verticillium dahliae and has a significant impact on yield and quality. In the absence of safe and effective chemical control, VW is difficult to manage. Thus, at present, developing resistant varieties is the most economical and effective method of controlling Verticillium wilt of cotton. The CC-NBS-LRR (CNL) gene family is an important class of plant genes involved in disease resistance. This study identified 141 GbCNLs in Gossypium barbadense genome, with 37.5% (53 genes) GbCNLs enriched in 12 gene clusters (GC01-GC12) based on gene distribution in the chromosomes. Especially, seven GbCNLs from two largest clusters (GC11 and GC12) were significantly upregulated in the resistant cultivar (Hai No. 7124) and the susceptible (Giza No. 57). Virus-induced gene silencing of GbCNL130 in G. barbadense, one typical gene in the gene cluster 12 (GC12), significantly altered the response to VW, compromising plant resistance to V. dahliae. In contrast, GbCNL130 overexpression significantly increased the resistance to VW in the wild-type Arabidopsis thaliana. Based on our research findings presented here, we conclude that GbCNL130 promotes resistance to VW by activating the salicylic acid (SA)-dependent defense response pathway resulting in strong accumulation of reactive oxygen species and upregulation of pathogenesis-related (PR) genes. In conclusion, our study resulted in the discovery of a new CNL resistance gene in cotton, GbCNL130, that confers resistance to VW across different hosts.

Characterization of the AP2/ERF Transcription Factor Family and Expression Profiling of DREB Subfamily under Cold and Osmotic Stresses in Ammopiptanthus nanus

APETALA2/ethylene-responsive factor (AP2/ERF) is one of the largest transcription factor (TF) families in plants, which play important roles in regulating plant growth, development, and response to environmental stresses. Ammopiptanthus nanus, an unusual evergreen broad-leaved shrub in the arid region in the northern temperate zone, demonstrates a strong tolerance to low temperature and drought stresses, and AP2/ERF transcription factors may contribute to the stress tolerance of A. nanus. In the current study, 174 AP2/ERF family members were identified from the A. nanus genome, and they were divided into five subfamilies, including 92 ERF members, 55 dehydration-responsive element binding (DREB) members, 24 AP2 members, 2 RAV members, and 1 Soloist member. Compared with the other leguminous plants, A. nanus has more members of the DREB subfamily and the B1 group of the ERF subfamily, and gene expansion in the AP2/ERF family is primarily driven by tandem and segmental duplications. Promoter analysis showed that many stress-related cis-acting elements existed in promoter regions of the DREB genes, implying that MYB, ICE1, and WRKY transcription factors regulate the expression of DREB genes in A. nanus. Expression profiling revealed that the majority of DREB members were responsive to osmotic and cold stresses, and several DREB genes such as EVM0023336.1 and EVM0013392.1 were highly induced by cold stress, which may play important roles in cold response in A. nanus. This study provided important data for understanding the evolution and functions of AP2/ERF and DREB transcription factors in A. nanus.