Engineered hybrid insecticidal protein improves resistance to lepidopteran insects in rice (Oryza sativa L.) and maize (Zea mays L.)

Though cry gene transformed crops have successfully revolutionized modern agriculture, it is still necessary to discover new Cry proteins to overcome potential threatens from the development of resistant insect populations. We swapped domain-IIIs with various Cry proteins and engineered seven chimeric proteins, aiming to produce new engineered hybrid insecticidal proteins. Seven recombinant proteins were expressed in Escherichia coli. Three proteins exhibited high toxicity against Asian corn borer in dietary exposure assays. Three hybrid proteins were further transformed to rice (cv. Jijing88) to determine their insecticidal activity. Cry1Ab/Gc hybrid proteins, Cry1Ab being replaced by the domain-III of Cry1Gc, showed significantly more toxic against rice stem borer than others. Furthermore, Cry1Ab/Gc gene was transformed into maize (cv. HiII), then backcrossed into commercial maize inbred lines (cv. Ji853 and Y822), and formulated into Xiangyu 998 hybrid to evaluate their commercial value. Transgenic maize performed significant resistance improvement to the Asian corn borer without affecting the yield, and this new protein did not have adverse effects on the environment. Our result proved domain-swapped could be used as an efficient method for exploring new cry genes and engineered hybrid insecticidal protein. Cry1Ab/Gc provides a new tool for Lepidopteran insects resistant management in rice and maize.

A discussion on cotton transformation during the last decade (2010–2021); an update on present trends and future prospects

The introduction of genetically modified (GM) cotton in 1996 in the US and its worldwide spread later rejuvenated cotton production in many parts of the world. The evolution is continued since then and currently, the 3rd and fourth generation of same GM cotton is grown in many parts of the world. The GM cotton introduced in 1996 was simple Bt cotton that expressed a single Cry1Ac gene, the later generation carried multiple Cry genes along with the genes controlling herbicide tolerance. Current day GM cotton does not only give stable resistance against lepidopteran insects but also facilitates the farmers to spray broad-spectrum herbicides without harming the crop. The evolution of GM cotton is continued both on the basic and applied side and interventions have been introduced during the last decade. Earlier the cotton transformation was limited to Cocker strains which are getting possible in many other varieties, too. It is successful with both gene gun, and Agrobacterium and inplanta transformation has made it a routine activity. Apart from overexpression studies for various purposes including biotic, abiotic, and quality traits, RNAi and genome editing are explored vigorously. Through this review, we have tried to explore and discuss various interventions for improving transformation protocols, the applications of cotton transformation, and future strategies being developed to get maximum benefits from this technology during the last decade.

Convergence of Bar and Cry1Ac Mutant Genes in Soybean Confers Synergistic Resistance to Herbicide and Lepidopteran Insects

Soybean is a globally important crop species, which is subject to pressure by insects and weeds causing severe substantially reduce yield and quality. Despite the success of transgenic soybean in terms of Bacillus thuringiensis (Bt) and herbicide tolerance, unforeseen mitigated performances have still been inspected due to climate changes that favor the emergence of insect resistance. Therefore, there is a need to develop a biotech soybean with elaborated gene stacking to improve insect and herbicide tolerance in the field. In this study, new gene stacking soybean events, such as bialaphos resistance (bar) and pesticidal crystal protein (cry)1Ac mutant 2 (M#2), are being developed in Vietnamese soybean under field condition. Five transgenic plants were extensively studied in the herbicide effects, gene expression patterns, and insect mortality across generations. The increase in the expression of the bar gene by 100% in the leaves of putative transgenic plants was a determinant of herbicide tolerance. In an insect bioassay, the cry1Ac-M#2 protein tested yielded higher than expected larval mortality (86%), reflecting larval weight gain and weight of leaf consumed were less in the T1 generation. Similarly, in the field tests, the expression of cry1Ac-M#2 in the transgenic soybean lines was relatively stable from T0 to T3 generations that corresponded to a large reduction in the rate of leaves and pods damage caused by Lamprosema indicata and Helicoverpa armigera. The transgenic lines converged two genes, producing a soybean phenotype that was resistant to herbicide and lepidopteran insects. Furthermore, the expression of cry1Ac-M#2 was dominant in the T1 generation leading to the exhibit of better phenotypic traits. These results underscored the great potential of combining bar and cry1Ac mutation genes in transgenic soybean as pursuant of ensuring resistance to herbicide and lepidopteran insects.

Sex- and stage-dependent expression patterns of odorant-binding and chemosensory protein genes in Spodoptera exempta

As potential molecular targets for developing novel pest management strategies, odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) have been considered to initiate odor recognition in insects. Herein, we investigated the OBPs and CSPs in a major global crop pest (Spodoptera exempta). Using transcriptome analysis, we identified 40 OBPs and 33 CSPs in S. exempta, among which 35 OBPs and 29 CSPs had intact open reading frames. Sequence alignment indicated that 30 OBPs and 23 CSPs completely contained the conserved cysteines. OBPs of lepidopteran insects usually belonged to classical, minus-C, and plus-C groups. However, phylogenetic analyses indicated that we only identified 28 classical and seven minus-C OBPs in S. exempta, suggesting that we might have missed some typical OBPs in lepidopteran insects, probably due to their low expression levels. All of the CSPs from S. exempta clustered with the orthologs of other moths. The identification and expression of the OBPs and CSPs were well studied in insect adults by transcriptional analyses, and herein we used samples at different stages to determine the expression of OBPs and CSPs in S. exempta. Interestingly, our data indicated that several OBPs and CSPs were especially or more highly expressed in larvae or pupae than other stages, including three exclusively (SexeOBP13, SexeOBP16 and SexeCSP23) and six more highly (SexeOBP15, SexeOBP37, SexeCSP4, SexeCSP8, SexeCSP19, and SexeCSP33) expressed in larvae, two exclusively (SexeCSP6 and SexeCSP20) and three more highly (SexeOBP18, SexeCSP17, and SexeCSP26) expressed in pupae. Usually, OBPs and CSPs had both male- and female-biased expression patterns in adult antennae. However, our whole-body data indicated that all highly expressed OBPs and CSPs in adults were male-biased or did not differ, suggesting diverse OBP and CSP functions in insect adults. Besides identifying OBPs and CSPs as well as their expression patterns, these results provide a molecular basis to facilitate functional studies of OBPs and CSPs for exploring novel management strategies to control S. exempta.

Isolation and Comparative Analysis of Culturable Cellulose degrading Gut Bacteria from a Coleopteran and Lepidopteran Insects

Insect gut microbiota has been reported to influence multiple biological functions of the host such as nutrition, digestion and immunity. In this study, nine and eight culturable bacteria were isolated from the gut of eri silkworm, Samia ricini and root grub, Anamola dimidiata. The gut bacteria were assayed for their ability to degrade filter paper.. The results indicated that filter paper digestion was faster in A. dimidiata compared to S. ricini reaching 50% within five incubation days. Cellulolytic activity indicated significant endoglucanase, exoglucanase and β-glucosidase activity in A. dimidiata compared to S. ricini, an indication that A. dimidiata harbours more robust cellulose degrading bacteria than S. ricini. The culturable gut bacterial isolates with cellulolytic activity may be good sources for preparing probiotic formulations to boost eri-nutrition as well as profiling cellulolytic enzymes or genes for biotechnological application..

Two new species of Hirsutella (Ophiocordycipitaceae, Sordariomycetes) that are parasitic on lepidopteran insects from China

Hirsutella are globally distributed entomopathogenic fungi that offer important economic applications in biological control and biomedicine. Hirsutella was suppressed in favour of Ophiocordyceps affected by the ending of dual nomenclature for pleomorphic fungi in 2011. Currently, Hirsutella has been resurrected as a genus under Ophiocordycipitaceae. In this study, we introduce two new species of Hirsutella, based on morphological and phylogenetic analyses. Hirsutella flava and H. kuankuoshuiensis are pathogenic on different species of larval Lepidoptera in China. Hirsutella flava primarily differs from related species by its awl-shaped base; long and narrow neck, 24–40.8 × 2.2–2.5 μm; long and narrow cymbiform or fusoid conidia, 6.5–10 × 2.1–4.3 μm. Hirsutella kuankuoshuiensis has two types of phialides and distinctive 9.9–12.6 × 2.7–4.5 μm, clavate or botuliform conidia. The distinctions amongst the new species and phylogenetic relationships with other Hirsutella species are discussed.