Virus-induced gene silencing (VIGS) is a potent way to study gene function in plants. In this study, a tobacco rattle virus (TRV)-mediated gene silencing system (TRV-VIGS) was established with the phytoene desaturase (HcPDS) as the marker gene in kenaf. Firstly, the seed soak agroinoculation method of the VIGS system was explored. HcPDS gene silencing led to photobleaching phenotype in kenaf leaves. According to qRT-PCR analysis, photobleached leaves had significantly lower gene expression levels compared with the control. Secondly, an optimizing approach with leaf infiltration was used to improve silencing efficiency. After the kenaf leaves were injected with Agrobacterium cultures with OD600 0.8, the plants were cultivated in chamber growth at 24 °C with approximately 60

Suitable flowering time can improve fiber yield and quality, which is of great significance for jute biological breeding. In this study, 242 jute accessions were planted in Fujian for 2 consecutive years, and 244,593 SNPs distributed in jute genome were used for genome-wide association analysis of flowering time. A total of 19 candidate intervals (P < 0.0001) were identified by using GLM and FaST-LMM and were significantly associated with flowering time, with phenotypic variation explained (PVE) ranging from 5.8 to 18.61

MYB transcription factors (TFs) are vital players in various plant biochemical and physiological processes. To date, MYB TFs have been comprehensively investigated in numerous plant species. Corchorus capsularis is one of the most important fiber crops worldwide. However, systematic investigation of the MYB TFs in C. capsularis remains elusive, which limits our insights into the contribution of MYB TFs regulating numerous biochemical processes such as anthocyanin accumulation and physiological processes (Color, growth, etc.) in this crop. Therefore, this study systematically investigated MYB genes comprising the gene structure, phylogeny, chromosomal locations, protein motifs, expression patterns, protein-protein interaction, and collinearity analysis. A total of 88 Corchorus capsularis R2R3-MYB (CcMYB) genes were characterized and distributed on seven chromosomes. The collinearity study revealed that the segmental duplication events were responsible for the enlargement of CcMYB genes. The highest syntenic relationship was observed between CcMYB genes (70/88) and Gossypium hirsutism genes. Further, phylogenetic tree analysis classified the 88 CcMYBs into 25 subgroups based on domain similarity and phylogenetic topology. Furthermore, the phylogenetic investigation of CcMYBs and Arabidopsis MYBs displayed the functional discrepancy of the CcMYB genes throughout evolution. Changes in anthocyanin content were observed among white jute's stem bark tissues, which may be due to their different colors. Expression study of 11 CcMYB genes in total by real-time quantitative PCR revealed the diverse expression profiles in various tissues organs and functional predictions found that some CcMYBs might be associated with stem bark color and anthocyanin content, cellulose, and lignin biosynthesis. Co-expression interaction analysis showed that CcMYB genes could be involved in physiological, biological, and molecular processes. Our study provides comprehensive details on MYB genes and contributes to a better understanding of their functions in Corchorus capsularis.

Jute (Corchorus L.) is one of the important fiber crops, and its fiber yield accounts for about 80% of the total bast fiber yield in the world. Compared with other crops, there is a lack of high-quality reference genome for researches, which has seriously hindered genetic studies and limited the application of jute fiber improvement. Here, the initiative jute genome sequencing in China was launched by Fujian Agriculture and Forestry University and other related institutes in 2012. Two high-yield, good-quality and disease-resistant jute varieties, ‘Huangma 179’ (Corchorus capsularis) and ‘Kuanyechangguo’ (C. olitorius), were selected for reference genome sequencing. They were sequenced for the whole genome sequences by PacBio RSII, and assembled by CANU package in 2017. As a result, 336 Mb of C. capsularis and 361 Mb of C. olitorius, including seven pseudo-chromosomes, were assembled. The two jute chromosome-scale genomes, that are publicly accessible at https://bigd.big.ac.cn , will provide new insights for analyses of the fiber biogenesis, and other biologically important traits in jute.

Chitinase (EC 3.2.1.14) is a kind of chitin-degrading glycosidase, which plays important roles in the abiotic and biotic defense of plants. In this study, we conducted whole-genome annotation, molecular evolution, and gene expression analyses on the chitinase-like (CTL) gene family members of Petunia axillaris. Thirty-three Petunia axillarischitinase-like genes (PaCTLs) were identified from the latest Petunia genome database. According to the phylogenetic analyses, these genes were divided into GH18 and GH19 subgroups and further subdivided into five classes (Class I to Class V). Conserved motif arrangements indicated their functional relevance within each group. The expansion and homeology analyses showed that gene replication events played an important role in the evolution of PaCTLs and the increase of the GH18 subgroup members was the main reason for the expansion of the PaCTL gene family in the evolution progress. By qRT-PCR analysis, we found that most of the PaCTLs showed a very low expression level in the normal growing plants. But lots of PaCTLs showed upregulated expression profiles when the plants suffered different abiotic stress conditions. Among them, five PaCTLs responded to high temperature and exhibited significantly upregulate expression level. Correspondingly, many hormone responses, as well as biotic and abiotic stress elements were found in the promoters of PaCTLs by using cis-acting element analysis. These results provide a foundation for the exploration of PaCTLs' function and enrich the evolutionary process of the CTL gene family.

Kenaf (Hibiscus cannabinus L.) is one of the most important bast fiber crops. And the MYB transcription factor plays a vital role in plant development regulation. In this study, the transcriptome data of 9 tissues of kenaf was analyzed deeply. The differentially expressed genes (DEGs) between stem bark at 60 days after sowing (DAS) and other tissues were screened out and the number of overlapping DEGs between different groups varied greatly. Interestingly, plenty of MYB transcription factors were identified among these overlapping DEGs suggesting that these genes may be related to the growth of stem bark and need to be further characterized. Totally, 353 HcMYBs were identified from the whole genome and classified into four groups: 1R-MYB, 2R-MYB, 3R-MYB, and 4R-MYB, with 1R-MYB and 2R-MYB accounting for the majority. Phylogenetic analysis revealed that members of the 1R-MYB and 2R-MYB families were divided into 12 and 37 subgroups. Synteny analysis indicated that segmental and tandem duplication events played a key role in the expansion of the MYB gene family in kenaf. Analysis of the HcMYB expression patterns in various tissues or developmental stages led to the screening of numerous HcMYB, including HcMYB92, HcMYB162, HcMYB143, and HcMYB213, which may have the ability to influence stem bark development. The sole HcMYB identified by Weighted Gene Co-Expression Network Analysis (WGCNA) in the stem bark at 60 DAS module, HcMYB207, co-expressed with a large number of genes with various functions. These findings might provide valuable information for further research on the potential function of HcMYBs.

Taken together, our results establish a reciprocal relationship between vine elongation and flowering, and reveal that GA is a positive signal for stem elogation but a negative regulator of flowering in this species. Vines or climbing plants exhibit vigorous vegetative shoot extension. GA have long been recognized as an important signal for seasonal stem elongation and flowering in many woody perennials. However, less is explored as how GA pathway is involved in the regulation of shoot extension in woody vines. Here, we investigated the role of GA and its signaling components in shoot elongation in Jasminum sambac. We found high accumulation of GA4 in the elongating internode, in contrast to a depletion of GAs in the floral differentiating shoot, which in turn featured a higher zeatin content, and a lower IAA and JA concentrations. This GA accumulation was coincident with the strong expression of JsGA20ox1 and JsGAS1 in the leaves, as well as of the JsGA2ox3 in the internode. Treatment of GA biosynthesis inhibitor reduced elongation while stimulated the terminal flowering. Remarkably, three B-type GA-receptor genes were abundantly expressed in both internodes and leaves of the extending shoots, which could enhance GA responsiveness in heterologous transgenic Arabidopsis. Furthermore, these JsGID1s showed distinct GA-dependent interaction with the JsDELLA in a yeast-two-hybrid assay. Taken together, our results establish a reciprocal relationship between vine elongation and flowering, and reveal that GA is a positive signal for stem elogation but a negative regulator of flowering in this species.