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Quantification of transcripts abundance of key RNAi pathway genes involved in dsRNA processing in fusion-dsRNA silenced J2s of Meloidogyne incognita. 18 s rRNA and actin of M. incognita was used as a reference gene and fold-change was calculated using the 2−ΔΔCT method. Each bar represents the log2-transformed mean of qRT-PCR runs in three biological and three technical replicates with standard errors. Asterisks indicate significant differential expression compared to that of J2s treated with gfp dsRNA and water control at P < 0.05 and P < 0.01
Source publication
Key message
This study demonstrates multi-gene silencing approach for simultaneous silencing of several functional genes through a fusion gene strategy for protecting plants against root-knot nematode,Meloidogyne incognita.
The ability of root-knot nematode (RKN), Meloidogyne incognita, to cause extensive yield decline in a wide range of cultivated...
Citations
... Recently, host delivered double stranded RNA for Chymotrypsin-like serine protease (CTLP), Alpha-amylase (α-amylase), and Tropomyosin (TPM) has shown tolerance against pod borer, Maruca vitrata, an important pest of legumes [5]. Similarly, another study has shown improved tolerance in Nicotiana tabacum against plant parasitic nematodes (PPNs) M. incognita with combinatorial gene silencing of four esophageal genes using host-delivered gene silencing (HD-RNAi) strategy [6]. In addition, in-vitro silencing of FLP genes demonstrate the broad-spectrum resistance against nematode in rice and wheat cultivars [7]. ...
... Soaking, in planta delivery Decreased attraction towards roots and reduced nematode penetration, reduced number of galls and egg masses Subventral oesophageal gland (Hada et al., 2023) Mi-msp-9 / Mi8D05 (GenBank AF531169) Putative oesophageal gland cell secretory protein 9 (interaction with plant aquaporin tonoplast intrinsic protein 2, regulation of solute and water transport within giant cells) ...
... Soaking, in planta delivery Reduction in the number of galls Subventral oesophageal gland (Hada et al., 2023;Niu et al., 2016) Hg-pel (GenBank AF520566) ...
... Soaking, in planta delivery Decreased attraction towards roots, reduced nematode penetration, reduced number of galls and egg masses Subventral oesophageal gland cell (Hada et al., 2023) Mi-pel2 (GenBank AY327873) Pectate lyase 2 (postulated role in penetration and intercellular migration during the early stages of plant parasitism) ...
The foundation of most food production systems underpinning global food security is the careful management of soil resources. Embedded in the concept of soil health is the impact of diverse soil‐borne pests and pathogens, and phytoparasitic nematodes represent a particular challenge. Root‐knot nematodes and cyst nematodes are severe threats to agriculture, accounting for annual yield losses of US$157 billion. The control of soil‐borne phytoparasitic nematodes conventionally relies on the use of chemical nematicides, which can have adverse effects on the environment and human health due to their persistence in soil, plants, and water. Nematode‐resistant plants offer a promising alternative, but genetic resistance is species‐dependent, limited to a few crops, and breeding and deploying resistant cultivars often takes years. Novel approaches for the control of phytoparasitic nematodes are therefore required, those that specifically target these parasites in the ground whilst minimizing the impact on the environment, agricultural ecosystems, and human health. In addition to the development of next‐generation, environmentally safer nematicides, promising biochemical strategies include the combination of RNA interference (RNAi) with nanomaterials that ensure the targeted delivery and controlled release of double‐stranded RNA. Genome sequencing has identified more than 75 genes in root knot and cyst nematodes that have been targeted with RNAi so far. But despite encouraging results, the delivery of dsRNA to nematodes in the soil remains inefficient. In this review article, we describe the state‐of‐the‐art RNAi approaches targeting phytoparasitic nematodes and consider the potential benefits of nanotechnology to improve dsRNA delivery.
Main conclusion
Integrated management strategies, including novel nematicides and resilient cultivars, offer sustainable solutions to combat root-knot nematodes, crucial for safeguarding global agriculture against persistent threats.
Abstract
Root-knot nematodes (RKN) pose a significant threat to a diverse range of host plants, with their obligatory endoparasitic nature leading to substantial agricultural losses. RKN spend much of their lives inside or in contact by secreting plant cell wall-modifying enzymes resulting in the giant cell development for establishing host-parasite relationships. Additionally, inflicting physical harm to host plants, RKN also contributes to disease complexes creation with fungi and bacteria. This review comprehensively explores the origin, history, distribution, and physiological races of RKN, emphasizing their economic impact on plants through gall formation. Management strategies, ranging from cultural and physical to biological and chemical controls, along with resistance mechanisms and marker-assisted selection, are explored. While recognizing the limitations of traditional nematicides, recent breakthroughs in non-fumigant alternatives like fluensulfone, spirotetramat, and fluopyram offer promising avenues for sustainable RKN management. Despite the success of resistance mechanisms like the Mi gene, challenges persist, prompting the need for integrative approaches to tackle Mi-virulent isolates. In conclusion, the review stresses the importance of innovative and resilient control measures for sustainable agriculture, emphasizing ongoing research to address evolving challenges posed by RKN. The integration of botanicals, resistant cultivars, and biological controls, alongside advancements in non-fumigant nematicides, contributes novel insights to the field, laying the ground work for future research directions to ensure the long-term sustainability of agriculture in the face of persistent RKN threats.
Key message
The study demonstrates the successful management of Meloidogyne incognita in eggplant using Mi-flp14 RNA interference, showing reduced nematode penetration and reproduction without off-target effects across multiple generations.
Abstract
Root-knot nematode, Meloidogyne incognita, causes huge yield losses worldwide. Neuromotor function in M. incognita governed by 19 neuropeptides is vital for parasitism and parasite biology. The present study establishes the utility of Mi-flp14 for managing M. incognita in eggplant in continuation of our earlier proof of concept in tobacco (US patent US2015/0361445A1). Mi-flp14 hairpin RNA construct was used for generating 19 independent transgenic eggplant events. PCR and Southern hybridization analysis confirmed transgene integration and its orientation, while RT-qPCR and Northern hybridization established the generation of dsRNA and siRNA of Mi-flp14. In vitro and in vivo bio-efficacy analysis of single-copy events against M. incognita showed reduced nematode penetration and development at various intervals that negatively impacted reproduction. Interestingly, M. incognita preferred wild-type plants over the transgenics even when unbiased equal opportunity was provided for the infection. A significant reduction in disease parameters was observed in transgenic plants viz., galls (40–48%), females (40–50%), egg masses (35–40%), eggs/egg mass (50–55%), and derived multiplication factor (60–65%) compared to wild type. A unique demonstration of perturbed expression of Mi-flp14 in partially penetrated juveniles and female nematodes established successful host-mediated RNAi both at the time of penetration even before the nematodes started withdrawing plant nutrients and later stage, respectively. The absence of off-target effects in transgenic plants was supported by the normal growth phenotype of the plants and T-DNA integration loci. Stability in the bio-efficacy against M. incognita across T1- to T4-generation transgenic plants established the utility of silencing Mi-flp14 for nematode management. This study demonstrates the significance of targeting Mi-flp14 in eggplant for nematode management, particularly to address global agricultural challenges posed by M. incognita.
