Genome-Wide Identification and Transcriptional Expression Profiles of Transcription Factor WRKY in Common Walnut (Juglans regia L.)

Abstract

The transcription factor WRKY is widely distributed in the plant kingdom, playing a significant role in plant growth, development and response to stresses. Walnut is an economically important temperate tree species valued for both its edible nuts and high-quality wood, and its response to various stresses is an important factor that determines the quality of its fruit. However, in walnut trees themselves, information about the WRKY gene family remains scarce. In this paper, we perform a comprehensive study of the WRKY gene family in walnut. In total, we identified 103 WRKY genes in the common walnut that are clustered into 4 groups and distributed on 14 chromosomes. The conserved domains all contained a WRKY domain, and motif 2 was observed in most WRKYs, suggesting a high degree of conservation and similar functions within each subfamily. However, gene structure was significantly differentiated between different subfamilies. Synteny analysis indicates that there were 56 gene pairs in J. regia and A. thaliana, 76 in J. regia and J. mandshurica, 75 in J. regia and J. microcarpa, 76 in J. regia and P. trichocarpa, and 33 in J. regia and Q. robur, indicating that the WRKY gene family may come from a common ancestor. GO and KEGG enrichment analysis showed that the WRKY gene family was involved in resistance traits and the plant-pathogen interaction pathway. In anthracnose-resistant F26 fruits (AR) and anthracnose-susceptible F423 fruits (AS), transcriptome and qPCR analysis results showed that JrWRKY83, JrWRKY73 and JrWRKY74 were expressed significantly more highly in resistant cultivars, indicating that these three genes may be important contributors to stress resistance in walnut trees. Furthermore, we investigate how these three genes potentially target miRNAs and interact with proteins. JrWRKY73 was target by the miR156 family, including 12 miRNAs; this miRNA family targets WRKY genes to enhance plant defense. JrWRKY73 also interacted with the resistance gene AtMPK6, showing that it may play a crucial role in walnut defense.

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

“…In-depth analysis of the structural characteristics of introns and exons is a key step in the process of gene family evolution [ 60 , 61 ]. A varied number of introns was possessed by AtruWRKY genes, group Ⅰ had more introns in this study, implying that the molecular structure in the group Ⅰ of WRKY genes may be quite conserved in the process of evolution, which conductive to the protein diversity caused evolution [ 62 , 63 ]. It seems that the crucial function of the WRKY gene family in A. truncatum is very much related to group Ⅰ, and similar results were found in eggplant ( Solanum torvum L.) [ 60 ].…”

Genome-wide identification and characterization of PdbHLH transcription factors related to anthocyanin biosynthesis in colored-leaf poplar (Populus deltoids)

“…Gene duplication events, including five types of gene duplication events, namely WGD (whole-genome duplication), dispersed, tandem, proximal and singleton duplications, contribute to the expansion of protein-coding gene families in plants [ 47 – 49 ]. Some large transcription factor gene families, such as APETALA2/ethylene-responsive factor (AP2/ERF) and WRKY, most likely expanded through WGD/segmental duplication and tandem duplication [ 40 – 52 ]. Conversely, the expansion of some other transcription factor gene families, such as MADS (Minichromosome Maintenance1 Agamous Deficiens Serum response factor) box gene family and NBS-LRR (nucleotide-binding site–leucine-rich repeat) gene family, are derived from the transposed duplication [ 44 ].…”

JrWRKY21 interacts with JrPTI5L to activate the expression of JrPR5L for resistance to Colletotrichum gloeosporioides in walnut

“…lycopersicum ), which regulates the expression of abscisic acid (ABA) biosynthesis genes to improve resistance to Phytophthora infestans (Li et al., 2015). In walnut fruits, the expression of JrWRKY73 , JrWRKY74 and JrWRKY83 was significantly higher in resistant varieties, which may play an important role in resistance (Hao et al., 2021). However, in our study, these transcription factors were not significantly expressed in walnut leaves, indicating that the role in resistance to C. gloeosporioides may differ between walnut fruits and leaves.…”