BackgroundRoot-knot nematodes (RKN– Meloidogyne genus) present extensive challenges to soybean crop. The soybean line (PI 595099) is known to be resistant against specific strains and races of nematode species, thus its differential gene expression analysis can lead to a comprehensive gene expression profiling in the incompatible soybean-RKN interaction. Even though many disease resistance genes have been studied, little has been reported about phytohormone crosstalk on modulation of ROS signaling during soybean-RKN interaction.ResultsUsing 454 technology to explore the common aspects of resistance reaction during both parasitism and resistance phases it was verified that hormone, carbohydrate metabolism and stress related genes were consistently expressed at high levels in infected roots as compared to mock control. Most noteworthy genes include those encoding glycosyltransferases, peroxidases, auxin-responsive proteins and gibberellin-regulated genes. Our data analysis suggests the key role of glycosyltransferases, auxins and components of gibberellin signal transduction, biosynthesis and deactivation pathways in the resistance reaction and their participation in jasmonate signaling and redox homeostasis in mediating aspects of plant growth and responses to biotic stress.ConclusionsBased on this study we suggest a reasonable model regarding to the complex mechanisms of crosstalk between plant hormones, mainly gibberellins and auxins, which can be crucial to modulate the levels of ROS in the resistance reaction to nematode invasion. The model also includes recent findings concerning to the participation of DELLA-like proteins and ROS signaling controlling plant immune or stress responses. Furthermore, this study provides a dataset of potential candidate genes involved in both nematode parasitism and resistance, which can be tested further for their role in this biological process using functional genomics approaches.

This review emphasizes the biotechnological potential of molecules implicated in the different layers of plant immunity, including, pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI), effector-triggered susceptibility (ETS), and effector-triggered immunity (ETI) that can be applied in the development of disease-resistant genetically modified (GM) plants. These biomolecules are produced by pathogens (viruses, bacteria, fungi, oomycetes) or plants during their mutual interactions. Biomolecules involved in the first layers of plant immunity, PTI and ETS, include inhibitors of pathogen cell-wall-degrading enzymes (CWDEs), plant pattern recognition receptors (PRRs) and susceptibility (S) proteins, while the ETI-related biomolecules include plant resistance (R) proteins. The biomolecules involved in plant defense PTI/ETI responses described herein also include antimicrobial peptides (AMPs), pathogenesis-related (PR) proteins and ribosome-inhibiting proteins (RIPs), as well as enzymes involved in plant defensive secondary metabolite biosynthesis (phytoanticipins and phytoalexins). Moreover, the regulation of immunity by RNA interference (RNAi) in GM disease-resistant plants is also considered. Therefore, the present review does not cover all the classes of biomolecules involved in plant innate immunity that may be applied in the development of disease-resistant GM crops but instead highlights the most common strategies in the literature, as well as their advantages and disadvantages.

BackgroundDrought is by far the most important environmental factor contributing to yield losses in crops, including soybeans [Glycine max (L.) Merr.]. To address this problem, a gene that encodes an osmotin-like protein isolated from Solanum nigrum var. americanum (SnOLP) driven by the UBQ3 promoter from Arabidopsis thaliana was transferred into the soybean genome by particle bombardment.ResultsTwo independently transformed soybean lines expressing SnOLP were produced. Segregation analyses indicated single-locus insertions for both lines. qPCR analysis suggested a single insertion of SnOLP in the genomes of both transgenic lines, but one copy of the hpt gene was inserted in the first line and two in the second line. Transgenic plants exhibited no remarkable phenotypic alterations in the seven analyzed generations. When subjected to water deficit, transgenic plants performed better than the control ones. Leaf physiological measurements revealed that transgenic soybean plants maintained higher leaf water potential at predawn, higher net CO2 assimilation rate, higher stomatal conductance and higher transpiration rate than non-transgenic plants. Grain production and 100-grain weight were affected by water supply. Decrease in grain productivity and 100-grain weight were observed for both transgenic and non-transgenic plants under water deficit; however, it was more pronounced for non-transgenic plants. Moreover, transgenic lines showed significantly higher 100-grain weight than non-transgenic plants under water shortage.ConclusionsThis is the first report showing that expression of SnOLP in transgenic soybeans improved physiological responses and yield components of plants when subjected to water deficit, highlighting the potential of this gene for biotechnological applications.

Coevolution has shaped the molecular basis of an extensive number of defense mechanisms in plant-pathogen interactions. Phytophthora parasitica, a hemibiothrophic oomycete pathogen and the causal agent of citrus root rot and gummosis, interacts differently with Citrus sunki and Poncirus trifoliata, two commonly favored citrus rootstocks that are recognized as susceptible and resistant, respectively, to P. parasitica. The molecular core of these interactions remains elusive. Here, we provide evidence on the defense strategies employed by both susceptible and resistant citrus rootstocks, in parallel with P. parasitica deployment of effectors. Time course expression analysis (quantitative real-time polymerase chain reaction) of several defense-related genes were evaluated during i) plant disease development, ii) necrosis, and iii) pathogen effector gene expression. In C. sunki, P. parasitica deploys effectors, including elicitins, NPP1 (necrosis-inducing Phytophthora protein 1), CBEL (cellulose-binding elicitor and lectin activity), RxLR, and CRN (crinkler), and, consequently, this susceptible plant activates its main defense signaling pathways that result in the hypersensitive response and necrosis. Despite the strong plant-defense response, it fails to withstand P. parasitica invasion, confirming its hemibiothrophic lifestyle. In Poncirus trifoliata, the effectors were strongly expressed, nevertheless failing to induce any immunity manipulation and disease development, suggesting a nonhost resistance type, in which the plant relies on preformed biochemical and anatomical barriers.

Background: Heterologous protein expression in microorganisms may contribute to identify and demonstrate antifungal activity of novel proteins. The Solanum nigrum osmotin-like protein (SnOLP) gene encodes a member of pathogenesis-related (PR) proteins, from the PR-5 sub-group, the last comprising several proteins with different functions, including antifungal activity. Based on deduced amino acid sequence of SnOLP, computer modeling produced a tertiary structure which is indicative of antifungal activity.