Aphids (Aphididae) are major agricultural pests that cause significant yield losses of crop plants each year by inflicting damage both through the direct effects of feeding and by vectoring harmful plant viruses. Expression of double-stranded RNA (dsRNA) directed against suitable insect target genes in transgenic plants has been shown to give protection against pests through plant-mediated RNA interference (RNAi). Thus, as a potential alternative and effective strategy for insect pest management in agricultural practice, plant-mediated RNAi for aphid control has received close attention in recent years. In this review, the mechanism of RNAi in insects and the so far explored effective RNAi target genes in aphids, their potential applications in the development of transgenic plants for aphid control and the major challenges in this regard are reviewed, and the future prospects of using plant-mediated RNAi for aphid control are discussed. This review is intended to be a helpful insight into the generation of aphid-resistant plants through plant-mediated RNAi strategy. © 2016 Society of Chemical Industry.

The current status of development of transgenic plants for improved aphid resistance, and the pros and cons of different strategies are reviewed and future perspectives are proposed. Aphids are major agricultural pests that cause significant yield losses of crop plants each year. Excessive dependence on insecticides for aphid control is undesirable because of the development of insecticide resistance, the potential negative effects on non-target organisms and environmental pollution. Transgenic plants engineered for resistance to aphids via a non-toxic mode of action could be an efficient alternative strategy. In this review, the distribution of major aphid species and their damages on crop plants, the so far isolated aphid-resistance genes and their applications in developments of transgenic plants for improved aphid resistance, and the pros and cons of these strategies are reviewed and future perspectives are proposed. Although the transgenic plants developed through expressing aphid-resistant genes, manipulating plant secondary metabolism and plant-mediated RNAi strategy have been demonstrated to confer improved aphid resistance to some degree. So far, no aphid-resistant transgenic crop plants have ever been commercialized. This commentary is intended to be a helpful insight into the generation and future commercialization of aphid-resistant transgenic crops in a global context.

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A modified introduction device and a preconcentration method were developed to enhance the sensitivity of the Hg isotopic analysis method.

Peritrophins are associated with structural and functional integrity of peritrophic membranes (PM), structures composed of chitin and proteins. PM lines the insect midgut and has roles in digestion and protection from toxins. We report the full-length cDNA cloning, molecular characterization and functional analysis of SfPER, a novel PM peritrophin A protein, in Spodoptera frugiperda . The predicted amino acid sequence indicated SfPER’s domain structure as a CMCMC-type, consisting of a signal peptide and three chitin-binding (C) domains with two intervening mucin-like (M) domains. Phylogenetic analysis determined a close relationship between SfPER and another S. frugiperda PM peritrophin partial sequence. SfPER transcripts were found in larvae and adults but were absent from eggs and pupae. Chitin affinity studies with a recombinant SfPER-C1 peritrophin A-type domain fused to SUMO/His-tag confirmed that SfPER binds to chitin. Western blots of S. frugiperda larval proteins detected different sized variants of SfPER along the PM, with larger variants found towards the posterior PM. In vivo suppression of SfPER expression did not affect susceptibility of larvae to Bacillus thuringiensis toxin, but significantly decreased pupal weight and adult emergence, possibly due to PM structural alterations impairing digestion. Our results suggest SfPER could be a novel target for insect control.

Pathogenicity tests and inter simple sequence repeat (ISSR) molecular fingerprinting markers were utilized to analyze 24 Corynespora cassiicola isolates obtained from a lot of Hevea clones grown in most rubber nurseries and a few plantations in China. The C. cassiicola isolates were collected from Hainan and Yunnan provinces, China, from 2006 to 2008. The assay of 24 C. cassiicola isolates on detached leaves of four different Hevea rubber clones (genotypes PR 107, Dafeng 95, RRIM 600, and Reyan 7-33-97) indicated that 23 of the isolates were susceptible to RRIM 600, and were therefore considered race 1 except for CC-023. ISSR analysis grouped 24 C. cassiicola isolates into four clusters (A, B, C, and D). Unweighted pair-group method with arithmetic averaging (UPGMA) analysis based on Nei and Li's coefficient (calculated from the binary matrix data of 103 DNA fragments generated from 16 ISSR primers) indicated that cluster A included 19 isolates from Hainan and Yunnan (this cluster was further divided into two sub clusters (I, II), sub cluster II contained isolate CC-023); clusters B and C comprised of 1 isolates from Hainan, respectively; while cluster D encompassed 3 isolates from Hainan and Yunnan. Pathogenicity tests and ISSR analysis showed that there was no correlation between race structure, the geographical origin of the pathogen and their ISSR clusters because 23 of the isolates belonging to four distinct clusters were considered race 1 except for isolate CC-023. However, most of the isolates with different pathogenicity levels shared the same clades, and furthermore, the ISSR clusters and cology color had an exact correlation. These results should facilitate the development of rubber clones with enhanced resistance against all genetic clusters of C. cassiicola.

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