- NSF-PAR ID:
- 10450652
- Date Published:
- Journal Name:
- Plant Biotechnology Journal
- Volume:
- 21
- Issue:
- 4
- ISSN:
- 1467-7644
- Page Range / eLocation ID:
- 854 to 865
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ABSTRACT One of the most promising tools for the control of fungal plant diseases is spray‐induced gene silencing (SIGS). In SIGS, small interfering RNA (siRNA) or double‐stranded RNA (dsRNA) targeting essential or virulence‐related pathogen genes are exogenously applied to plants and postharvest products to trigger RNA interference (RNAi) of the targeted genes, inhibiting fungal growth and disease. However, SIGS is limited by the unstable nature of RNA under environmental conditions. The use of layered double hydroxide or clay particles as carriers to deliver biologically active dsRNA, a formulation termed BioClay™, can enhance RNA durability on plants, prolonging its activity against pathogens. Here, we demonstrate that dsRNA delivered as BioClay can prolong protection against Botrytis cinerea , a major plant fungal pathogen, on tomato leaves and fruit and on mature chickpea plants. BioClay increased the protection window from 1 to 3 weeks on tomato leaves and from 5 to 10 days on tomato fruits, when compared with naked dsRNA. In flowering chickpea plants, BioClay provided prolonged protection for up to 4 weeks, covering the critical period of poding, whereas naked dsRNA provided limited protection. This research represents a major step forward for the adoption of SIGS as an eco‐friendly alternative to traditional fungicides.more » « less
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Summary Recent discoveries show that fungi can take up environmental RNA, which can then silence fungal genes through environmental RNA interference. This discovery prompted the development of Spray‐Induced Gene Silencing (SIGS) for plant disease management. In this study, we aimed to determine the efficacy of SIGS across a variety of eukaryotic microbes. We first examined the efficiency of RNA uptake in multiple pathogenic and non‐pathogenic fungi, and an oomycete pathogen. We observed efficient double‐stranded RNA (dsRNA) uptake in the fungal plant pathogens
Botrytis cinerea ,Sclerotinia sclerotiorum ,Rhizoctonia solani ,Aspergillus niger andVerticillium dahliae , but no uptake inColletotrichum gloeosporioides , and weak uptake in a beneficial fungus,Trichoderma virens . For the oomycete plant pathogen,Phytophthora infestans , RNA uptake was limited and varied across different cell types and developmental stages. Topical application of dsRNA targeting virulence‐related genes in pathogens with high RNA uptake efficiency significantly inhibited plant disease symptoms, whereas the application of dsRNA in pathogens with low RNA uptake efficiency did not suppress infection. Our results have revealed that dsRNA uptake efficiencies vary across eukaryotic microbe species and cell types. The success of SIGS for plant disease management can largely be determined by the pathogen’s RNA uptake efficiency. -
Abstract Over 20 years ago double‐stranded RNA (dsRNA) was described as the trigger of RNAi interference (RNAi)‐based gene silencing. This paradigm has held since, especially for insect biopesticide technologies where dsRNAs, similar to those described in 1998, are used to inhibit gene expression. In the intervening years, investigation of RNAi pathways has revealed the small RNA effectors of RNAi are diverse and rapidly evolving. The rich biology of insect small RNAs suggests potential to use multiple RNAi modes for manipulating gene expression. By exploiting different RNAi pathways, the menu of options for pest control can be expanded and could lead to better tailored solutions. Fortunately, basic delivery strategies used for dsRNA such as direct application or transgenic expression will translate well between RNAs transiting different RNAi pathways. Importantly, further engineering of RNAi‐based biopesticides may provide an opportunity to address dsRNA insensitivity seen in some pests. Characterization of RNAi pathways unique to target species will be indispensable to this end and may require thinking beyond long dsRNA. © 2020 Society of Chemical Industry
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Abstract BACKGROUND Calmodulin (CaM) is an essential protein in cellular activity and plays important roles in many processes in insect development. RNA interference (RNAi) has been hypothesized to be a promising method for pest control. CaM is a good candidate for RNAi target. However, the sequence and function of CaM in
Nilaparvata lugens are unknown. Furthermore, the double‐stranded RNA (dsRNA) target to CaM gene in pest control is still unavailable.RESULTS In the present study, two alternatively spliced variants of
CaM transcripts, designatedNlCaM1 andNlCaM2 , were cloned from . The two cDNA sequences exhibited 100% identity to each other in the open reading frame (ORF), and only differed in the 3′ untranslated region (UTR).N. lugens NlCaM includingNlCaM1 andNlCaM2 mRNA was detectable in all developmental stages and tissues of , with significantly increased expression in the salivary glands. Knockdown ofN. lugens NlCaM expression by RNAi with different dsRNAs led to an inability to molt properly, increased mortality, which ranged from 49.7 to 92.5%, impacted development of the ovaries and led to female infertility. There were no significant reductions in the transcript levels of vitellogenin and its receptor or in the total vitellogenin protein level relative to the control group. However, a significant reduction in vitellogenin protein was detected in ovaries injected with dsNlCaM. In addition, a specific dsRNA ofNlCaM for control of was designed and tested.N. lugens CONCLUSION NlCaM plays important roles mainly in nymph development and uptake of vitellogenin by ovaries in vitellogenesis inN. lugens . dsRNA derived from the less conserved 3′‐UTR ofNlCaM shows great potential for RNAi‐based management. © 2018 Society of Chemical IndustryN. lugens -
null (Ed.)RNAi promises to reshape pest control by being nontoxic, biodegradable, and species specific. However, due to the plastic nature of RNAi, there is a significant variability in responses. In this study, we investigate small RNA pathways and processing of ingested RNAi trigger molecules in a hemipteran plant pest, the whitefly Bemisia tabaci . Unlike Drosophila , where the paradigm for insect RNAi technology was established, whitefly has abundant somatic piwi-associated RNAs (piRNAs). Long regarded as germline restricted, piRNAs are common in the soma of many invertebrates. We sought to exploit this for a novel gene silencing approach. The main principle of piRNA biogenesis is the recruitment of target RNA fragments into the pathway. As such, we designed synthetic RNAs to possess complementarity to the loci we annotated. Following feeding of these exogenous piRNA triggers knockdown as effective as conventional siRNA-only approaches was observed. These results demonstrate a new approach for RNAi technology that could be applicable to dsRNA-recalcitrant pest species and could be fundamental to realizing insecticidal RNAi against pests.more » « less