Survey of aphid population in a yellow passion fruit crop and its relationship on the spread Cowpea aphid-borne mosaic virus in a subtropical region of Brazil

The role of rhamnolipids in the growth and defense responses of passion fruit plants

Rhamnolipids (RLs) are bioactive compounds that have gained a lot of attention for their potential applications in agriculture. However, the exploration of RLs in passion fruit plants remains limited. This study aimed to investigate the role of RLs in passion fruit plants growth and defense responses. Firstly, the results demonstrated that RLs act as plant growth regulators, significantly enhancing the survival rate and root system development of passion fruit seedlings propagated by cutting. Further analyses suggested that RLs may enhance photosynthetic capacity and modulate the accumulation of indoleacetic acid (IAA) and cytokinin (CTK) in passion fruit cuttings, thereby promoting plant growth and development. Additionally, this study revealed that RLs effectively reduced susceptibility to viral pathogen telosma mosaic virus (TeMV) in passion fruit plants compared to distilled water-pretreated controls, resulting in alleviated disease symptoms. Significant up-regulation of antioxidative enzyme activities and reducing substances were observed in RL's-pretreated plants upon TeMV-inoculation compared to distilled water-pretreated ones. Moreover, RLs were found to promote other defense-related signaling pathways upon TeMV-inoculation in passion fruit plants, including salicylic acid (SA) accumulation and expression levels of defense-related genes such as pathogenesis-related gene (PR3), phenylalanine ammonia-lyase (PAL), transcription factors (TFs) WRKY and NAC. Collectively, these findings underscored the positive roles played by RLs both in promoting growth and eliciting defense responses within passion fruit plants. These results provided valuable insights for designing environment-friendly management strategies for cutting propagation as well as prevention and control measures against viral diseases in passion fruits.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-024-01511-z.

Ethyl Formate Fumigation for Controlling Two Major Aphid Pests, Aphis spiraecola and Aphis gossypii, on Passion Fruit, from Cultivation to Post-Harvest Storage

Tropical and subtropical crops are being increasingly cultivated in South Korea, leading to an increase in damage by exotic insect pests. Consequently, ethyl formate (EF) is currently being considered for quarantine and pre-shipment fumigation. In this study, we evaluated the effectiveness of EF fumigation for controlling Aphis spiraecola Patch and Aphis gossypii Glover, two representative quarantine pests on passion fruit ("Pink Bourbon") during greenhouse cultivation and post-harvest storage. The efficacy of EF against both aphids in terms of the lethal concentration causing 50% mortality (LCt50%) and LCt99% was 1.36-2.61 g h/m3 and 3.73-7.55 g h/m3 under greenhouse conditions (23 °C), and 1.37-2.02 g h/m3 and 3.80-14.59 g h/m3 post-harvest (5 °C), respectively. EF at 4 g/m3 for 4 h resulted in 100% mortality of A. spiraecola, which was more resistant to EF, without causing phytotoxic damage to the trees in a 340 m3 greenhouse. Post-harvest fruit fumigation at 10 g/m3 for 4 h in a mid-size (0.8 m3) fumigation chamber resulted in complete disinfection. Moreover, the EF level decreased below the EF threshold within 10 min after natural ventilation in the greenhouse. Therefore, our results suggest EF fumigation as an effective method for controlling A. spiraecola and A. gossypii.

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

The cultivation and production of passion fruit (Passiflora edulis) are severely affected by viral disease. Yet there have been few studies of the molecular response of passion fruit to virus attack. In the present study, RNA-based transcriptional profiling (RNA-seq) was used to identify the gene expression profiles in yellow passion fruit (Passiflora edulis f. flavicarpa) leaves following inoculation with cucumber mosaic virus (CMV). Six RNA-seq libraries were constructed comprising a total of 42.23 Gb clean data. 1,545 differentially expressed genes (DEGs) were obtained (701 upregulated and 884 downregulated). Gene annotation analyses revealed that genes associated with plant hormone signal transduction, transcription factors, protein ubiquitination, detoxification, phenylpropanoid biosynthesis, photosynthesis and chlorophyll metabolism were significantly affected by CMV infection. The represented genes activated by CMV infection corresponded to transcription factors WRKY family, NAC family, protein ubiquitination and peroxidase. Several DEGs encoding protein TIFY, pathogenesis-related proteins, and RNA-dependent RNA polymerases also were upregualted by CMV infection. Overall, the information obtained in this study enriched the resources available for research into the molecular-genetic mechanisms of the passion fruit/CMV interaction, and might provide a theoretical basis for the prevention and management of passion fruit viral disease in the field.

A synthesis of virus-vector associations reveals important deficiencies in studies on host and vector manipulation by plant viruses

Plant viruses face many challenges in agricultural environments. Although crop fields appear to be abundant resources for these pathogens, it may be difficult for viruses to "escape" from crop environments prior to host senescence or harvesting. One way for viruses to increase the odds of persisting outside of agricultural fields across seasons is by evolving traits that increase transmission opportunities between crops and wild plant communities. There is accumulating evidence that some viruses can achieve this by manipulating crop plant phenotypes in ways that enhance transmission by vectors. Putative manipulations occur through alteration of plant cues (color, size, texture, foliar volatiles, in-leaf metabolites, defenses, and leaf cuticles) that mediate vector orientation, feeding, and dispersal behaviors. Virus effects on host phenotypes are not uniform but appear to exhibit convergence depending on virus traits underlying transmission, particularly the duration of probing and feeding required to acquire and inoculate distinct types of plant viruses. This shared congruence in manipulation strategies and mechanisms across divergent virus lineages suggests that such effects may be adaptive. To discern if this is the case, researchers must consider molecular and environmental constraints on virus evolution, including those imposed by insect vectors from organismal to landscape scales. In this review, we synthesize applied research on vector-borne virus transmission in laboratory and field settings to identify the main factors determining transmission opportunities for plant viruses, and thus, selection pressure to evolve manipulative traits. We then examine these outputs in the context of studies reporting putative instances of plant virus manipulation. Our synthesis reveals important disconnects between virus manipulation studies and actual selection pressures imposed by vectors in real-world contexts.

Characterization of Cowpea aphid-borne mosaic virus in Passiflora edulis ‘Catarina’ in the southern coast of Santa Catarina State, Brazil

ABSTRACT: CABMV is a limiting virus for passion fruit crop in Brazil, its main producing country. This virus has been reported in all producing states of the country, with the state of Santa Catarina (SC) in 2017 standing as the third largest passion fruit producer. In 2017, it reached 8.4% of the national production. The southern coast is the main responsible for the increase in production, which has been supplying the domestic market. However, in that same year, this region recorded the first symptom expressions in plants and fruits. The evaluation of the samples collected in the municipalities of Sombrio, Praia Grande and São João do Sul, southern coast of SC, was performed by using a mechanical transmission to indicator plants, PTA-ELISA and RT-PCR, and by sequencing. The evaluation results were positive for CABMV and negative for CMV in PTA-ELISA. In RT-PCR, there was the formation of a 700bp ca band, expected size for Potyvirus, whose sequence comparison with those deposited in GenBank reveled 98% identity with the isolates from São Paulo State. The occurrence of the virus in the southern coast of SC did not reach a serious decrease in passion fruit production due to the union of producers, who adopted preventive management measures to control the virus, whose effect led to a consolidation of the passion fruit production chain in the region.