Transcriptome analysis of yellow passion fruit in response to cucumber mosaic virus infection

Genetic Dissection of ToLCNDV Resistance in Resistant Sources of Cucumis melo

Tomato leaf curl New Delhi virus (ToLCNDV) is a begomovirus causing significant melon (Cucumis melo) crop losses globally. This study aims to map the ToLCNDV resistance in the PI 414723 melon accession, previously identified and characterized through phenotypic studies, thereby exploring shared genomic regions with the established resistant source WM-7. In the present study, WM-7 and PI 414723 were crossed with the susceptible accessions 'Rochet' and 'Blanco' respectively, to generate F1 hybrids. These hybrids were self-pollinated to generate the populations for mapping the ToLCNDV resistance region and designing markers for marker-assisted selection. Disease evaluation included visual symptom scoring, viral-load quantification and tissue printing. Genotyping-by-sequencing and SNP markers were used for quantitative trait loci (QTL) mapping. For genetic analysis, qPCR and bulked segregant RNA-seq (BSR-seq) were performed. Gene expression was assessed using RNA-seq, and qRT-PCR was used for confirmation. The research narrows the candidate region for resistance in WM-7 and identifies overlapping QTLs on chromosome 11 in PI 414723, found in the region of the DNA primase large subunit. BSR-seq and expression analyses highlight potential regulatory roles of chromosome 2 in conferring resistance. Differential expression was confirmed for six genes in the candidate region on chromosome 2. This study confirms the existence of common resistance genes in PI 414723 and WM-7.

Novel 4-Chromanone-Derived Compounds as Plant Immunity Inducers against CMV Disease in Passiflora spp. (Passion Fruit)

This study involved the design and synthesis of a series of novel 4-chromanone-derived compounds. Their in vivo anti-cucumber mosaic virus (CMV) activity in field trials against CMV disease in Passiflora spp. was then assessed. Bioassay results demonstrated that compounds 7c and 7g exhibited remarkable curative effects and protection against CMV, with inhibition rates of 57.69% and 51.73% and 56.13% and 52.39%, respectively, surpassing those of dufulin and comparable to ningnanmycin. Field trials results indicated that compound 7c displayed significant efficacy against CMV disease in Passiflora spp. (passion fruit) after the third spraying at a concentration of 200 mg/L, with a relative control efficiency of 47.49%, surpassing that of dufulin and comparable to ningnanmycin. Meanwhile, nutritional quality test results revealed that compound 7c effectively enhanced the disease resistance of Passiflora spp., as evidenced by significant increases in soluble protein, soluble sugar, total phenol, and chlorophyll contents in Passiflora spp. leaves as well as improved the flavor and taste of Passiflora spp. fruits, as demonstrated by notable increases in soluble protein, soluble sugar, soluble solid, and vitamin C contents in Passiflora spp. fruits. Additionally, a transcriptome analysis revealed that compound 7c primarily targeted the abscisic acid (ABA) signaling pathway, a crucial plant hormone signal transduction pathway, thereby augmenting resistance against CMV disease in Passiflora spp. Therefore, this study demonstrates the potential application of these novel 4-chromanone-derived compounds as effective inducers of plant immunity for controlling CMV disease in Passiflora spp. in the coming decades.

Occurrence and Distribution of Major Viruses Infecting Passion Fruit in Guizhou Province, China, and Molecular Characterization of Two Potyviruses

The planting of passion fruit (Passiflora edulis) in Guizhou Province has gradually increased, and the area under cultivation ranks third in China. However, the cultivation and production of passion fruit is severely affected by viral diseases. In 2021 and 2022, we investigated the occurrence of multiple viral diseases in major cultivation areas, identified the main viruses and conducted field surveys in different growing areas of passion fruit in Guizhou Province, China. In total, 308 samples were randomly collected from 10 different passion fruit cultivation areas, and seven viral diseases were identified using electron microscopy, small RNA sequencing, and reverse-transcription polymerase chain reaction. Among them, the infection rate of Telosma mosaic virus (TeMV) was the highest (50%), followed by East Asian Passiflora virus (EAPV) (19%), and cucumber mosaic virus (CMV) (15%). The detection rates of the other four viruses were lower: Passiflora latent virus (PLV) (1%), turnip mosaic virus (TuMV) (0.6%), Passiflora virus Y (PaVY) (0.3%), and Euphorbia leaf curl virus (ELCV) (6%). In addition, high rates of mixed TeMV + CMV + EAPV infections were found in the province. Notably, 79% of EAPV-infected plants were also infected with TeMV. Finally, the molecular characteristics of the two highly detected potyviruses, TeMV and EAPV, were analyzed. To our knowledge, this study is the first systematic survey of viral diseases of passion fruit in Guizhou Province, China.

The Role of Plant Transcription Factors in the Fight against Plant Viruses

Plants are vulnerable to the challenges of unstable environments and pathogen infections due to their immobility. Among various stress conditions, viral infection is a major threat that causes significant crop loss. In response to viral infection, plants undergo complex molecular and physiological changes, which trigger defense and morphogenic pathways. Transcription factors (TFs), and their interactions with cofactors and cis-regulatory genomic elements, are essential for plant defense mechanisms. The transcriptional regulation by TFs is crucial in establishing plant defense and associated activities during viral infections. Therefore, identifying and characterizing the critical genes involved in the responses of plants against virus stress is essential for the development of transgenic plants that exhibit enhanced tolerance or resistance. This article reviews the current understanding of the transcriptional control of plant defenses, with a special focus on NAC, MYB, WRKY, bZIP, and AP2/ERF TFs. The review provides an update on the latest advances in understanding how plant TFs regulate defense genes expression during viral infection.

Chitosan oligosaccharide as a plant immune inducer on the Passiflora spp. (passion fruit) CMV disease

Cucumber mosaic virus (CMV), one of the main viruses, is responsible for Passiflora spp. (passion fruit) virus diseases, which negatively affect its planting, cultivation, and commercial quality. In this study, a laboratory anti-CMV activity screening model for Passiflora spp. CMV disease was first established. Then, the effects of different antiviral agents of chitosan oligosaccharide (COS), dufulin (DFL), and ningnanmycin (Ning) on CMV virulence rate in Passiflora spp. were determined. The virulence rate and anti-CMV activity in Passiflora spp. treated with COS were 50% and 45.48%, respectively, which were even better than those of DFL (66.67% and 27.30%, respectively) and Ning (83.30% and 9.17%, respectively). Field trials test results showed COS revealed better average control efficiency (47.35%) against Passiflora spp. CMV disease than those of DFL (40.93%) and Ning (33.82%), indicating that COS is effective in the control of the Passiflora spp. CMV disease. Meanwhile, the nutritional quality test results showed that COS could increase the contents of soluble solids, titratable acids, vitamin C, and soluble proteins in Passiflora spp. fruits as well as enhance the polyphenol oxidase (PPO), superoxide dismutase (SOD), and peroxidase (POD) activity in the leaves of Passiflora spp. seedlings. In addition, the combined transcriptome and proteome analysis results showed that COS mainly acted on the Brassinosteroids (BRs) cell signaling pathway, one of plant hormone signal transduction pathway, in Passiflora spp., thus activating the up-regulated expression of TCH4 and CYCD3 genes to improve the resistance to CMV disease. Therefore, our study results demonstrated that COS could be used as a potential plant immune inducer to control the Passiflora spp. CMV disease in the future.

NMR-Based Metabolomic Profiling of Mungbean Infected with Mungbean Yellow Mosaic India Virus

Mungbean is an important legume mainly cultivated in Southeast Asia known for cheap source of food protein. Yellow mosaic disease (YMD) of mungbean is one of the most damaging diseases caused by mungbean yellow mosaic virus (MYMV) and mungbean yellow mosaic India virus (MYMIV) in India. The genetic basis of YMD resistance of mungbean is not well studied yet. Our present studies aimed to explore the genetic basis of YMD resistance through molecular, biochemical and metabolomics approach. Molecular analysis of YMV-infected mungbean plant materials revealed the presence of MYMIV. Chlorophyll contents were estimated as mosaic symptoms that cause chlorosis and necrosis in infected leaves. Chlorophyll a, b and total chlorophyll content were significantly reduced by 27-55% in infected samples compared non-infected control samples. ¹H NMR-based metabolomic profiling of virus-infected mungbean were carried out, and we found that vital changes occurred during the development of MYMIV infection in mungbean. A total of fifty metabolites were identified in mungbean leaf samples. Principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) separated the severely infected sample from the non-infected samples. Orthogonal partial least discrimination analysis (OPLS-DA) revealed significant differences in MYMIV-infected and non-infected control samples. The featured metabolites in MYMIV infected and control samples were amino acids, carbohydrates, and organic acids. Relative abundance of sucrose, γ-amino butyric acid (GABA), proline, alanine, phenylalanine, tryptophan, pyruvate, ascorbate, and citrates were found as differential metabolites. Our results suggest that metabolic changes in infected mungbean samples is related to the viral acquisition. The present study may help in better understanding the metabolic alterations during biotic stress in mungbean.

Transcriptome analysis reveals the molecular mechanisms of response to an emergent yellow-flower disease in green Chinese prickly ash (Zanthoxylum schinifolium)

Chinese prickly ash (Zanthoxylum) is extensively used as spice and traditional medicine in eastern Asian countries. Recently, an emergent yellow-flower disease (YFD) break out in green Chinese prickly ash (Zanthoxylum schinifolium, Qinghuajiao in Chinese) at Chongqing municipality, and then leads to a sharp reduction in the yield of Qinghuajiao, and thus results in great economic losses for farmers. To address the molecular response for the emergent YFD of Qinghuajiao, we analyzed the transcriptome of 12 samples including the leaves and inflorescences of asymptomatic and symptomatic plants from three different towns at Chongqing by high-throughput RNA-Seq technique. A total of 126,550 genes and 229,643 transcripts were obtained, and 21,054 unigenes were expressed in all 12 samples. There were 56 and 164 different expressed genes (DEGs) for the AL_vs_SL (asymptomatic leaf vs symptomatic leaf) and AF_vs_SF (asymptomatic flower vs symptomatic flower) groups, respectively. The results of KEGG analysis showed that the “phenylpropanoid biosynthesis” pathway that related to plant–pathogen interaction were found in AL_vs_SL and AF_vs_SF groups, and the “Plant–pathogen interaction” found in AF_vs_SF group, implying that this Qinghuajiao YFD might cause by plant pathogen. Interestingly, we detected 33 common unigenes for the 2 groups, and almost these unigenes were up-regulated in the symptomatic plants. Moreover, most of which were homologs to virus RNA, the components of viruses, implying that this YFD was related to virus. Our results provided a primary molecular basis for the prevention and treatment of YFD of Qinghuajiao trees.