Tropical Plant Biology

Li, Ruimin; Yang, Cheng; Wang, Xinyou; Yan, Yana; Huang, Guiyan

2024 Tropical Plant Biology

doi: 10.1007/s12042-024-09362-4

Ascorbate peroxidases (APXs) are essential for plants as they act as hydrogen peroxide-scavenging enzymes, providing protection against oxidative damage. Using bioinformatic methods, five APX genes were discovered in the genome of Citrus sinensis in this study. APX genes of C. sinensis (CsAPXs) encode polypeptides between 250 and 436 residues in length, with molecular weights that range from 27.56 to 47.34 kDa. Additionally, the isoelectric point of CsAPXs varies from 5.64 to 8.63. The predicted locations of CsAPXs are peroxisome, chloroplast, and mitochondrion, with an uneven distribution across four chromosomes and eight orthologous gene pairs with Arabidopsis thaliana. A phylogenetic analysis revealed that the CsAPXs were divided into three clades. The CsAPXs all contained a conserved APX domain and six common motifs. Upon promoter analysis, it was found that CsAPXs could respond to abscisic acid, auxin, ethylene, gibberellin, methyl jasmonate, salicylic acid, and wounding stress treatments. In addition, the analysis of expression patterns revealed that the presence of Candidatus Liberibacter asiaticus (CLas) has a dynamic impact on the expression of CsAPXs, with CsAPX2 showing significant inhibition in response to CLas infection. These findings will provide novel insights for the forthcoming functional investigations of CsAPXs within the process of citrus-CLas interactions.

Duan, Xiangbo; Xu, Yanang; Zhang, Ke; Liu, Zhouli; Yu, Yang

2024 Tropical Plant Biology

doi: 10.1007/s12042-024-09361-5

Dynamin and dynamin-related proteins (DRPs) are large GTPases that are vital for cytokinesis, endocytosis and multiple biological processes. However, knowledge of the DRP gene family in soybean (Glycine max L.), an important leguminous crop plant, is still limited. In this study, 31 GmDRPs were identified from soybean genome, and were classified into five groups based on phylogenetic analysis. We observed that each group displayed specific conserved domain distribution and exon–intron structures. Collinearity analysis indicated that gene duplication events contribute largely to the expansion of GmDRP family. According to functional annotation, soybean dynamins were found implicated in cell division, endocytosis, and mitochondrion/peroxisome fission in GTP-dependent manner. Promoter analysis implied the potential roles of GmDRPs in mediating developmental processes, plant hormone signaling, and stress responses. Based on RNA-seq data, some of the GmDRPs were found ubiquitously expressed in various tissues/organs, some were barely expressed, while some showed obvious tissue/organ-preference. The expression analysis also revealed the involvement of GmDRPs in cold and/or drought stress response. In sum, we performed a systematic analysis of soybean dynamin family and our results provide a foundation for further researches on their functional roles.

Jadhav, Pritam Ramesh; Ekatpure, Sachin Chandrakant; Soni, K. B.; Swapna, Alex; Lekshmi, R. S.; Wagh, Yogesh Sahebrao; Manju, R. V.

2024 Tropical Plant Biology

doi: 10.1007/s12042-024-09360-6

Banana bract mosaic virus (BBrMV), transmitted by aphids, is a major threat to banana cultivation, causing substantial economic losses. This study focuses on the development of BBrMV-resistant lines of banana cv. ‘Grand Naine’ by silencing viral coat protein (CP) gene using RNA interference (RNAi) strategy. To achieve this, an intron hairpin RNA (ihpRNA) construct containing a 326 bp fragment of the CP gene was designed using the pSTARLING vector. Identification of a Dicer substrate within the CP gene facilitated the prediction of small interfering RNAs (siRNAs) through Custom Dicer-Substrate siRNA analysis. The absence of viral silencing suppressors was validated using the VsupPred tool. Cloning of the sense and antisense fragments of the CP gene into the pSTARLING vector, flanking the cre intron, was confirmed through PCR analysis. Subsequently, the NotI fragment comprising the ubiquitin promoter, ubiquitin intron, sense fragment inserts, cre intron, antisense strand insert, and tumour morphology locus (tmL) terminator was transferred to the Agrobacterium tumefaciens binary vector pART27. Embryogenic calli were transformed with the ihpRNA-CP cassette, and regenerated plantlets were screened for complete cassette integration using PCR. Northern hybridization confirmed the production of siRNAs against coat protein mRNA. Upon exposure to virulent aphids carrying BBrMV, the transformed lines exhibited no disease symptoms. Additionally, reverse transcription quantitative PCR (RT-qPCR) demonstrated the absence of BBrMV, with transformed lines resembling healthy, non-inoculated controls both morphologically and in terms of coat protein gene expression. This RNAi-based approach showcases the successful creation of BBrMV-resistant banana lines, presenting a promising strategy for combating the virus's detrimental effects on banana cultivation.

Luo, Hai-Bin; Huang, Cheng-Mei; Cao, Hui-Qing; Wei, Yuan-Wen; Xu, Lin; Wu, Kai-Chao; Deng, Zhi-Nian; Wu, Xing-Jian; Ye, Li-Ping; Yi, Xiao-Ping

2024 Tropical Plant Biology

doi: 10.1007/s12042-024-09363-3

Transcriptional regulation of the high-affinity K+ (HAK) transporter gene is an important mechanism of plant response to low potassium stress. Cloning and analysis of the promoter of potassium transporter gene is not only helpful to its expression pattern and regulation mechanism but also important to improve the potassium absorption efficiency in sugarcane. The potassium transporter gene ScHAK10 is highly expressed and induced by low potassium stress in sugarcane, but the functions of its promoter is still unclear. In the present article, the 1918 bp promoter region of the ScHAK10 gene (pScHAK10) was cloned by genomic walking technique. Computational analysis affirmed the existence of abiotic stress-responsive cis and core cis-elements, such as TATA box, CAAT box, phytohormone responsive, stress response and light response motifs. GUS histochemical staining of transgenic Arabidopsis thaliana seedlings showed that the leaf, corolla, and root tip were deeply stained. The 5′-terminal deletion of the promoter was cloned, and the lengths of 1918 bp (full), 1623 bp (Q1), 1332 bp (Q2), 957 bp (Q3), 576 bp (Q4), and 357 bp (Q5) were cloned into the GUS reporter vector for A. thaliana transient transformation. The transgenic plants generated through a single event exhibited a promising expression of the GUS reporter protein, which was treated with salt, low potassium, IAA and cold stress conditions. The results showed that the promoter activity correlates with the promoter fragment’s length, and the long promoter fragment exhibits higher training. The Q5 was the least active and could not drive GUS expression. Under abiotic stress, the expression of GUS enzyme activity varies among different promoter fragments. Under low potassium and high salt stress, Q3 and Q4 showed the highest promoter activity. The Q1 and Q4 led the highest promoter activity during IAA and cold stress. These findings help to understand the molecular mechanism of ScHAK10 expression regulation and could be an excellent tool for future crop improvement.

Xu, Shugang; Zhu, Xingcheng; Zhang, Qian; Zeng, Shixian; Li, Yan; Wang, Yong

2024 Tropical Plant Biology

doi: 10.1007/s12042-024-09355-3

The WRKY gene family is an important class of transcription factors in higher plants that play key roles in secondary metabolism, phytohormone signaling, plant defense responses, and abiotic stress responses. The WRKY gene family has not been systematically studied in Passiflora edulis, a tropical fruit with edible and medicinal values. In this study, we performed a genome-wide analysis of passion fruit and identified 58 candidate PeWRKY genes distributed unevenly on nine chromosomes of passion fruit. Phylogenetic and gene structure analyses showed that members of the PeWRKY gene family could be categorized into three groups: class I (9), class II (40), and class III (9). Promoter and target gene prediction analyses indicated that the PeWRKY gene may be involved in various biological processes, including growth and development, metabolism, hormones, and stress responses, by regulating multiple target genes. The Ka/Ks ratios of PeWRKY indicated that PeWRKY may have undergone strong purification selection in the passion fruit genome. Tissue expression analysis showed that the PeWRKY gene was expressed in different tissues of Passiflora edulis, where the number and expression of the PeWRKY gene were more significant in the roots. Quantitative real-time polymerase chain reaction (qRT-PCR) showed that the relative expression of all 10 candidate PeWRKY genes was significantly up-regulated in leaf tissues after 48 h of drought stress compared with the control, and only PeWRKY55 and PeWRKY30 genes were down-regulated. In addition, at the time of biotic stress treatment up to 24 h, most PeWRKY genes were up-regulated after treatment, except the PeWRKY40 gene, which showed down-regulation. Three genes, PeWRKY02, PeWRKY30 and PeWRKY58, showed significant up-regulation of their expression after treatment up to 48 h. This study provides a valuable reference for the functional characterization of WRKY genes in passion fruit and other plants.