Expression of the Galanthus nivalis agglutinin (GNA) gene in transgenic potato plants confers resistance to aphids

StMAPK10 gene functional identification and analysis in drought resistance of potato crop (Solanum tuberosum L.)

All over the world, potato (Solanum tuberosum L.) production is constrained by several biotic and abiotic factors. Many techniques and mechanisms have been used to overcome these hurdles and increase food for the rising population. In crop plants, the mitogen-activated protein kinase (MAPK) cascade, a significant regulator of the MAPK pathway under various biotic and abiotic stress conditions, is one of the targets to increase productivity. MAPK plays a significant role under drought stress in potato. However, the function of MAPK in drought resistance in potato is poorly understood. In this study, we wanted to identify the function of StMAPK10 in the drought resistance in potato. StMAPK10 was up-regulated under drought conditions and dynamically modulated by abiotic stresses. Over-expression and down-regulation of StMAPK10 revealed that StMAPK10 stimulated potato growth under drought conditions, as demonstrated by changes in SOD, CAT, and POD activity, as well as H2O2, proline, and MDA content. StMAPK10 up-regulation exaggerated the drought resistance of the potato plant by uplifting antioxidant activities and photosynthetic indices. Overexpressed-StMAPK10 potato lines showed highly significant results for physiological and photosynthetic indices in response to drought stress, while knockdown expression showed opposite outcomes. Additionally, subcellular localization and phenotypic analysis of transgenic and non-transgenic plants substantiated the role of the increased expression of StMAPK10 against drought stress. The results could provide novel insights into the functionality of StMAPK10 in drought responses and conceivable mechanisms.

Expression of Modified Snowdrop Lectin (Galanthus nivalis Agglutinin) Protein Confers Aphids and Plutella xylostella Resistance in Arabidopsis and Cotton

Cotton is a major fiber crop in the world that can be severely infested by pests in agricultural fields. Identifying new insect-resistance genes and increasing the expression of known insect-resistance genes are imperative in cultivated cotton. Galanthus nivalis agglutinin (GNA), a lectin that is toxic to both chewing and sucking pests, is mainly expressed in monocotyledons. It is necessary to improve the expression of the GNA protein and to test whether the lectin confers insect resistance to dicotyledons plants. We report a modified GNA gene (ASGNA) via codon optimization, its insertion into Arabidopsis thaliana, and transient expression in cotton to test its efficacy as an insect-resistance gene against cotton aphids and Plutella xylostella. The amount of ASGNA in transgenic plants reached approximately 6.5 μg/g of fresh weight. A feeding bioassay showed that the survival rate of aphids feeding on the leaves of ASGNA transgenic plants was lower than those of aphids feeding on the leaves of non-optimized GNA (NOGNA) transgenic plants and wild-type plants. Meanwhile, the fertility rate was 36% when fed on the ASGNA transgenic plants, while the fertility was 70% and 95% in NOGNA transgenic plants and wild-type plants. Correspondingly, the highest mortality of 55% was found in ASGNA transgenic lines, while only 35% and 20% mortality was observed in NOGNA transgenic plants and wild-type plants, respectively. Similar results were recorded for aphids feeding on cotton cotyledons with transient expression of ASGNA. Taken together, the results show that ASGNA exhibited high insecticidal activity towards sap-sucking insects and thus is a promising candidate gene for improving insect resistance in cotton and other dicotyledonous plants.

Biotechnological Approaches for Host Plant Resistance to Insect Pests

Annually, the cost of insect pest control in agriculture crosses billions of dollars around the world. Until recently, broad-spectrum synthetic pesticides were considered as the most effective means of pest control in agriculture. However, over the years, the overreliance on pesticides has caused adverse effects on beneficial insects, human health and the environment, and has led to the development of pesticide resistant insects. There is a critical need for the development of alternative pest management strategies aiming for minimum use of pesticides and conservation of natural enemies for maintaining the ecological balance of the environment. Host plant resistance plays a vital role in integrated pest management but the development of insect-resistant varieties through conventional ways of host plant resistance takes time, and is challenging as it involves many quantitative traits positioned at various loci. Biotechnological approaches such as gene editing, gene transformation, marker-assisted selection etc. in this direction have recently opened up a new era of insect control options. These could contribute towards about exploring a much wider array of novel insecticidal genes that would otherwise be beyond the scope of conventional breeding. Biotechnological interventions can alter the gene expression level and pattern as well as the development of transgenic varieties with insecticidal genes and can improve pest management by providing access to novel molecules. This review will discuss the emerging biotechnological tools available to develop insect-resistant engineered crop genotypes with a better ability to resist the attack of insect pests.

Mitogen-activated protein kinase 11 (MAPK11) maintains growth and photosynthesis of potato plant under drought condition

KEY MESSAGE

StMAPK11 overexpression promotes potato growth, physiological activities and photosynthesis under drought conditions. Mitogen-activated protein kinases (MAPKs) are import regulators of MAPK pathway in plants under drought condition. However, the critical role in potato (Solanum tuberosum L.) drought resistance is not fully understood. In this study, we aimed to explore the role of StMAPK11 under drought stress. The result of RT-qPCR for assay of StMAPKs expression demonstrated that 15 StMAPKs were differentially expressed in leaves, flowers, petioles, stamens, pistils, stems, stolons, roots, tubers and tuber peels of potato. StMAPKs was dynamically modulated by abiotic stresses and plant hormone treatments, and StMAPK11 was apparently up-regulated under drought conditions. Therefore, the vectors pCPB-StMAPK11 and pCPBI121-miRmapk11 for over-expression and down-regulation of StMAPK11 were constructed, respectively, and introduced into potato cultivar Atlantic. The result showed that StMAPK11 promoted potato growth under drought conditions, as well as the physiological activities evidenced by changes in SOD, CAT and POD activity and H2O2, proline and MDA content. StMAPK11 up-regulation intensified drought resistance of potato plant by elevating antioxidant activities and photosynthesis. Moreover, we consolidated the protective role of StMAPK11 in tobacco and Arabidopsis against drought stress. The result could provide new insights into the function of StMAPK11 in drought response and its possible mechanisms.

StMAPK3 controls oxidase activity, photosynthesis and stomatal aperture under salinity and osmosis stress in potato

Mitogen-activated protein kinase 3 (MAPK3) is involved in plant growth and development, as well as response to adverse stress. Here we aimed to explore the role of StMAPK3 in response to salt and osmosis stress. Polyethylene glycol (PEG) (5% and 10%) and mannitol (40 mM and 80 mM) were used to induce osmosis stress. To induce salinity stress, potato plant was cultured with NaCl (40 mM and 80 mM). StMAPK3 overexpression and RNA interference-mediated StMAPK3 knockdown were constructed to explore the role of StMAPK3 in potato growth, stomatal aperture size, activity of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), and contents of H₂O₂, proline and malonaldehyde (MDA). Meanwhile, we detected transpiration, net photosynthesis, stomatal conductance, and water use efficiency. Subcellular location of StMAPK3 protein was also detected. PEG, mannitol and NaCl treatments induced the accumulation of StMAPK3 mRNA in potato plants. StMAPK3 protein was located on the membrane and nucleus. Abnormal expression of StMAPK3 changed potato phenotypes, enzyme activity of SOD, CAT and POD, as well as H₂O₂, proline and MDA contents under osmosis and salinity stress. Photosynthesis and stomatal aperture were regulated by StMAPK3 in potato treated by PEG, mannitol and NaCl. Modulation of potato phenotypes and physiological activity indicates StMAPK3 as a regulator of osmosis and salinity tolerance.

Functional analysis of StDWF4 gene in response to salt stress in potato

The DWARF4 (DWF4) gene encodes a C-22 hydroxylase which is pivotal for brassinosteroids (BRs) biosynthesis. In this research, aimed to understand the molecular mechanism of DWF4 on regulation of potatoes tolerance to salt stress, DWF4 was cloned from potato, named as StDWF4. Its 1476 bp open reading frame encodes a protein of 491 amino acids. The StDWF4-overexpressing (OE) and interference-expressing (RNAi) transgenic potato plants were acquired using Agrobacterium-mediated transformation, respectively. Tissue specific analysis using Quantitative real-time polymerase chain reaction (qRT-PCR) demonstrated that the StDWF4 gene expressed in the leaves, stems and roots of the transgenic and un-transgenic (NT) plants, with specially increased (StDWF4-OE)/reduced (StDWF4-RNAi) expression in the roots. The content of malondialdehyde (MDA) in StDWF4-OE potato plants was lower than that of NT, and proline content was higher than that of NT. MDA and proline content in StDWF4-OE and NT under salt-stress was significantly higher than that of the control and was increased at different sampling times. The content of soluble protein, soluble sugar and the activities of superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX) was higher in the StDWF4-OE plantlets at varied salt treatment time than in the NT potatoes. Reduction of H₂O₂ content in the StDWF4-OE plants was observed. All above plant physiology indicators in the StDWF4-RNAi potatoes showed opposite variation trends. The results proved that the overexpressing of StDWF4 in potato plantlets can enhance the salt resistance by alleviating the negative effects of salt-stress. However, its interference expression in potato plants depresses the salt resistance. The results lay the groundwork for intensive study of BRs regulation in potato growth and development, and will help us to reveal the molecular mechanisms of how the BRs signaling regulate potato salt tolerance.