Pest protection conferred by a Beta vulgaris serine proteinase inhibitor gene

Serine proteinase inhibitors from Nicotiana benthamiana, a nonpreferred host plant, inhibit the growth of Myzus persicae (green peach aphid)

BACKGROUND

The green peach aphid (Myzus persicae) is a severe agricultural crop pest that has developed resistance to most current control methods, requiring the urgent development of novel strategies. Plant proteinase inhibitors (PINs) are small proteins that protect plants against pathogens and/or herbivores, likely by preventing efficient protein digestion.

RESULTS

We identified 67 protease genes in the transcriptomes of three M. persicae lineages (USDA-Red, G002 and G006). Comparison of gene expression levels in aphid guts and whole aphids showed that several proteases, including a highly expressed serine protease, are significantly overexpressed in the guts. Furthermore, we identified three genes encoding serine protease inhibitors (SerPIN-II1, 2 and 3) in Nicotiana benthamiana, which is a nonpreferred host for M. persicae. Using virus-induced gene silencing (VIGS) with a tobacco rattle virus (TRV) vector and overexpression with a turnip mosaic virus (TuMV) vector, we demonstrated that N. benthamiana SerPIN-II1 and SerPIN-II2 cause reduced survival and growth, but do not affect aphid protein content. Likewise, SerPIN-II3 overexpression reduced survival and growth, and serpin-II3 knockout mutations, which we generated using CRISPR/Cas9, increased survival and growth. Protein content was significantly increased in aphids fed on SerPIN-II3 overexpressing plants, yet it was decreased in aphids fed on serpin-II3 mutants.

CONCLUSION

Our results show that three PIN-IIs from N. benthamiana, a nonpreferred host plant, effectively inhibit M. persicae survival and growth, thereby representing a new resource for the development of aphid-resistant crop plants. © 2024 Society of Chemical Industry.

Genetic Engineering Approaches for Enhanced Insect Pest Resistance in Sugarcane

Sugarcane (Saccharum officinarum), a sugar crop commonly grown for sugar production all over the world, is susceptible to several insect pests attack in addition to bacterial, fungal and viral infections leading to substantial reductions in its yield. The complex genetic makeup and lack of resistant genes in genome of sugarcane have made the conventional breeding a difficult and challenging task for breeders. Using pesticides for control of the attacking insects can harm beneficial insects, human and other animals and the environment as well. As alternative and effective strategy for control of insect pests, genetic engineering has been applied for overexpression of cry proteins, vegetative insecticidal proteins (vip), lectins and proteinase inhibitors (PI). In addition, the latest biotechnological tools such as host-induced gene silencing (HIGS) and CRISPR/Cas9 can be employed for sustainable control of insect pests in sugarcane. In this review overexpression of the cry, vip, lectins and PI genes in transgenic sugarcane and their disease resistance potential is described.

Beneficial implications of sugar beet proteinase inhibitor BvSTI on plant architecture and salt stress tolerance in Lotus corniculatus L

Food demands of increasing human population dictate intensification of livestock production, however, environmental stresses could jeopardize producers' efforts. Forage legumes suffer from yield losses and poor nutritional status due to salinity increase of agricultural soils. As tools aimed to reduce negative impacts of biotic or abiotic stresses, proteinase inhibitors (PIs) have been promoted for biotechnological improvements. In order to increase tolerance of Lotus corniculatus L. to salt stress, serine PI, BvSTI, was introduced into this legume using Agrobacterium rhizogenes, with final transformation efficiency of 4.57%. PCR, DNA gel-blot, RT-PCR and in-gel protein activity assays confirmed the presence and activity of BvSTI products in transformed lines. Plants from three selected transgenic lines (21, 73 and 109) showed significant alterations in overall phenotypic appearance, corresponding to differences in BvSTI accumulation. Lines 73 and 109 showed up to 7.3-fold higher number of tillers and massive, up to 5.8-fold heavier roots than in nontransformed controls (NTC). Line 21 was phenotypically similar to NTC, accumulated less BvSTI transcripts and did not exhibit an additional band of recombinant trypsin inhibitor as seen in lines 73 and 109. Exposure of the transgenic lines to NaCl revealed different levels of salt stress susceptibility. The NaCl sensitivity index, based on morphological appearance and chlorophyll concentrations showed that lines 73 and 109 were significantly less affected by salinity than NTC or line 21. High level of BvSTI altered morphology and delayed salt stress related senescence, implicating BvSTI gene as a promising tool for salinity tolerance improvement trials in L. corniculatus.

Hairy root culture as a valuable tool for allelopathic studies in apple

Allelopathic plants exploit their chemical 'weapons' to prevail over the competition, suppress neighboring plants and consequently use the available resources more efficiently. However, the investigation of plant allelopathic interactions in rhizosphere is difficult to perform because of its high complexity due to interactions of biotic and abiotic factors. Thus, autonomous, aseptic root cultures of apple (Malus × domestica Borkh.) could facilitate allelopathic studies. We report on the successful genetic transformation of apple cultivars Melrose, Golden Delicious, Čadel and Gloster using Agrobacterium rhizogenes (Riker et al. 1930) Conn 1942 strain 15834 and for the first time the establishment of apple autonomous and permanent in vitro hairy root cultures that could be used as a new tool for apple allelopathic assays. Molecular characterization of transgenic hairy root lines was conducted to elucidate the possible relationship between expression of T-DNA genes and root growth characteristics that include branching. Similar content of phenolic acids (chlorogenic, caffeic, syringic, p-coumaric and ferulic), glycosilated flavonoids (rutin, quercitrin, isoquercitrin, kaempferol-3-glucoside) and flavonoid aglycones (quercetin and naringenin), and dihydrochalcone phloridzin, was detected in untransformed and transgenic apple root tissue by ultra high-performance liquid chromatography with mass spectrometry (UHPLC/(+/-)HESI-MS/MS) analyses, confirming that genetic transformation did not disturb secondary metabolite production in apple. Chlorogenic and caffeic acids and dihydrochalcones phloridzin and phloretin were detected as putative allelochemicals exuded into the growth medium in which transgenic roots were maintained for 4 weeks. Apple hairy root exudates significantly affected shoot and root development and growth of test plant Arabidopsis thaliana (L.) Heynh. seedlings after 5 or 10 days of treatment. Additionally, core cell-cycle genes CDKA1;1, CDKB2;1, CYCA3;1 and CYCB2;4 were down regulated in Arabidopsis shoots suggesting, in part, their role in inhibition of shoot growth. The present work highlighted an autonomous and permanent in vitro hairy root culture system as a valuable tool for studying allelopathic potential of apple, offering new perspective for allelopathy background elucidation in this important fruit species.

Plant Serine Protease Inhibitors: Biotechnology Application in Agriculture and Molecular Farming

The serine protease inhibitors (SPIs) are widely distributed in living organisms like bacteria, fungi, plants, and humans. The main function of SPIs as protease enzymes is to regulate the proteolytic activity. In plants, most of the studies of SPIs have been focused on their physiological role. The initial studies carried out in plants showed that SPIs participate in the regulation of endogenous proteolytic processes, as the regulation of proteases in seeds. Besides, it was observed that SPIs also participate in the regulation of cell death during plant development and senescence. On the other hand, plant SPIs have an important role in plant defense against pests and phytopathogenic microorganisms. In the last 20 years, several transgenic plants over-expressing SPIs have been produced and tested in order to achieve the increase of the resistance against pathogenic insects. Finally, in molecular farming, SPIs have been employed to minimize the proteolysis of recombinant proteins expressed in plants. The present review discusses the potential biotechnological applications of plant SPIs in the agriculture field.

Nicotiana benthamiana is a suitable transient system for high-level expression of an active inhibitor of cotton boll weevil α-amylase

BACKGROUND

Insect resistance in crops represents a main challenge for agriculture. Transgenic approaches based on proteins displaying insect resistance properties are widely used as efficient breeding strategies. To extend the spectrum of targeted pathogens and overtake the development of resistance, molecular evolution strategies have been used on genes encoding these proteins to generate thousands of variants with new or improved functions. The cotton boll weevil (Anthonomus grandis) is one of the major pests of cotton in the Americas. An α-amylase inhibitor (α-AIC3) variant previously developed via molecular evolution strategy showed inhibitory activity against A. grandis α-amylase (AGA).

RESULTS

We produced in a few days considerable amounts of α-AIC3 using an optimised transient heterologous expression system in Nicotiana benthamiana. This high α-AIC3 accumulation allowed its structural and functional characterizations. We demonstrated via MALDI-TOF MS/MS technique that the protein was processed as expected. It could inhibit up to 100% of AGA biological activity whereas it did not act on α-amylase of two non-pathogenic insects. These data confirmed that N. benthamiana is a suitable and simple system for high-level production of biologically active α-AIC3. Based on other benefits such as economic, health and environmental that need to be considerate, our data suggested that α-AIC3 could be a very promising candidate for the production of transgenic crops resistant to cotton boll weevil without lethal effect on at least two non-pathogenic insects.

CONCLUSIONS

We propose this expression system can be complementary to molecular evolution strategies to identify the most promising variants before starting long-lasting stable transgenic programs.

Screening for Resistance Against the Sugarbeet Root Maggot, Tetanops myopaeformis (Diptera: Ulidiidae), Using a Greenhouse Bioassay

The sugarbeet root maggot, Tetanops myopaeformis (von Röder) (Diptera: Ulidiidae), is a major pest of sugar beet Beta vulgaris L. (Carophyllales: Amaranthaceae)in the United States and Canada. Larval feeding on roots can reduce both stand and yield. Current management practices are heavily reliant on chemical control. However, the carbamate and organophosphate insecticides that are commonly used against T. myopaeformis are being phased out of use. Host plant resistance against this pest shows promise, but difficulties with maintaining T. myopaeformis in culture have largely limited such studies to the field. A primary objective of this study was to develop protocols for rearing a laboratory colony of T. myopaeformis that would expedite assays aimed at screening for host plant resistance. Third (final) instar larvae were collected from the field and reared to the adult stage. These laboratory-reared adults laid eggs and ultimately produced a second generation of third-instar larvae in the lab. Adult flies reared from field-collected larvae were used to examine the modality of resistance of a known resistant variety by performing no-choice and paired-choice experiments alongside a susceptible variety in the greenhouse. Paired-choice tests showed no difference in oviposition rates between the two varieties, whereas no-choice tests showed significantly greater feeding damage and abundance of larvae on the susceptible variety. For the resistant variety examined here, we observed evidence of antibiosis, not antixenosis, as the putative modality of resistance. Our laboratory and greenhouse protocols can be used to expedite the process of developing varieties with resistance to this key pest of sugar beet.

Transcriptome analysis of sugar beet root maggot (Tetanops myopaeformis) genes modulated by the Beta vulgaris host

Sugar beet root maggot (SBRM, Tetanops myopaeformis von Röder) is a major but poorly understood insect pest of sugar beet (Beta vulgaris L.). The molecular mechanisms underlying plant defense responses are well documented, however, little information is available about complementary mechanisms for insect adaptive responses to overcome host resistance. To date, no studies have been published on SBRM gene expression profiling. Suppressive subtractive hybridization (SSH) generated more than 300 SBRM ESTs differentially expressed in the interaction of the pest with a moderately resistant (F1016) and a susceptible (F1010) sugar beet line. Blast2GO v. 3.2 search indicated that over 40% of the differentially expressed genes had known functions, primarily driven by fruit fly D. melanogaster genes. Expression patterns of 18 selected EST clones were confirmed by RT-PCR analysis. Gene Ontology (GO) analysis predicted a dominance of metabolic and catalytic genes involved in the interaction of SBRM with its host. SBRM genes functioning during development, regulation, cellular process, signaling and under stress conditions were annotated. SBRM genes that were common or unique in response to resistant or susceptible interactions with the host were identified and their possible roles in insect responses to the host are discussed.

Expression of two barley proteinase inhibitors in tomato promotes endogenous defensive response and enhances resistance to Tuta absoluta

BACKGROUND

Plants and insects have coexisted for million years and evolved a set of interactions which affect both organisms at different levels. Plants have developed various morphological and biochemical adaptations to cope with herbivores attacks. However, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) has become the major pest threatening tomato crops worldwide and without the appropriated management it can cause production losses between 80 to 100%.

RESULTS

The aim of this study was to investigate the in vivo effect of a serine proteinase inhibitor (BTI-CMe) and a cysteine proteinase inhibitor (Hv-CPI2) from barley on this insect and to examine the effect their expression has on tomato defensive responses. We found that larvae fed on tomato transgenic plants co-expressing both proteinase inhibitors showed a notable reduction in weight. Moreover, only 56% of these larvae reached the adult stage. The emerged adults showed wings deformities and reduced fertility. We also investigated the effect of proteinase inhibitors ingestion on the insect digestive enzymes. Our results showed a decrease in larval trypsin activity. Transgenes expression had no harmful effect on Nesidiocoris tenuis (Reuter) (Heteroptera: Miridae), a predator of Tuta absoluta, despite transgenic tomato plants attracted the mirid. We also found that barley cystatin expression promoted plant defense by inducing the expression of the tomato endogenous wound inducible Proteinase inhibitor 2 (Pin2) gene, increasing the production of glandular trichomes and altering the emission of volatile organic compounds.

CONCLUSION

Our results demonstrate the usefulness of the co-expression of different proteinase inhibitors for the enhancement of plant resistance to Tuta absoluta.

Structural and functional characterization of proteinase inhibitors from seeds of Cajanus cajan (cv. ICP 7118)

Proteinase inhibitors (C11PI) from mature dry seeds of Cajanus cajan (cv. ICP 7118) were purified by chromatography which resulted in 87-fold purification and 7.9% yield. SDS-PAGE, matrix assisted laser desorption ionization time-of-flight (MALDI-TOF/TOF) mass spectrum and two-dimensional (2-D) gel electrophoresis together resolved that C11PI possessed molecular mass of 8385.682 Da and existed as isoinhibitors. However, several of these isoinhibitors exhibited self association tendency to form small oligomers. All the isoinhibitors resolved in Native-PAGE and 2-D gel electrophoresis showed inhibitory activity against bovine pancreatic trypsin and chymotrypsin as well as Achaea janata midgut trypsin-like proteases (AjPs), a devastating pest of castor plant. Partial sequences of isoinhibitor (pI 6.0) obtained from MALDI-TOF/TOF analysis and N-terminal sequencing showed 100% homology to Bowman-Birk Inhibitors (BBIs) of leguminous plants. C11PI showed non-competitive inhibition against trypsin and chymotrypsin. A marginal loss (<15%) in C11PI activity against trypsin at 80 (°)C and basic pH (12.0) was associated with concurrent changes in its far-UV CD spectra. Further, in vitro assays demonstrated that C11PI possessed significant inhibitory potential (IC50 of 78 ng) against AjPs. On the other hand, in vivo leaf coating assays demonstrated that C11PI caused significant mortality rate with concomitant reduction in body weight of both larvae and pupae, prolonged the duration of transition from larva to pupa along with formation of abnormal larval-pupal and pupal-adult intermediates. Being smaller peptides, it is possible to express C11PI in castor to protect them against its devastating pest A. janata.

Optimized scorpion polypeptide LMX: a pest control protein effective against rice leaf folder

Lepidopteran insect pests are the main class of pests causing significant damage to crop plant yields. Insecticidal scorpion peptides exhibit toxicity specific for insects. Here, we report that a peptide LMX, optimized from the insect-specific scorpion neurotoxin LqhIT2, showed high levels of activity against rice leaf folder in vitro and in planta. Oral ingestion of LMX protein led to a significant decrease in feeding on rice leaves, repression of larval growth and development, delay in molting, and increase in larval lethality. Compared with LqhIT2 protein, the stability and insecticidal efficacy of LMX was better. Meanwhile, biochemical analysis showed that LMX protein ingestion dramatically decreased ecdysone content in rice leaf folder larvae, and down-regulated enzymatic activities of the detoxification system (α-naphthyl acetate esterase and glutathione S-transferase), the digestive system (tryptase and chymotrypsin), and the antioxidant system (catalase). These changes were tightly correlated with the dosage of LMX protein. Transgene analysis showed that the rate of leaf damage, and the number of damaged tillers and leaves in the transgenic line were greatly reduced relative to wild type plants and empty vector plants. Based on these observations, we propose that the insect-specific scorpion neurotoxin peptide LMX is an attractive and effective alternative molecule for the protection of rice from rice leaf folder.

Comparative studies on species identification of Noctuoidea moths in two nature reserve conservation zones (Beijing, China) using DNA barcodes and thin-film biosensor chips

Rapid and accurate identification of species is required for the biological control of pest Noctuoidea moths. DNA barcodes and thin-film biosensor chips are two molecular approaches that have gained wide attention. Here, we compare these two methods for the identification of a limited number of Noctuoidea moth species. Based on the commonly used mitochondrial gene cytochrome c oxidase I (the standard DNA barcode for animal species), 14 probes were designed and synthesized for 14 species shared by two national nature reserves in Beijing and Hebei, China. Probes ranged in length from 18 to 27 bp and were designed as mismatch probes to guarantee that there were at least three base differences between the probe and nontarget sequences. The results on the chip could be detected by the naked eye without needing special equipment. No cross-hybridizations were detected although we tested all probes on the 14 target and 24 nontarget Noctuoidea species. The neighbour-joining tree of the 38 species based on COI sequences gave 38 highly supported independent groups. Both DNA barcoding and thin-film biosensor chips, based on the COI gene, are able to accurately identify and discriminate the 14 targeted moth species in this study. Because of its speed, high accuracy and low cost, the thin-film biosensor chip is a very practical means of species identification. Now, a more comprehensive chip will be developed for the identification of additional Noctuoidea moths for pest control and ecological protection.