Minc00344 and Mj-NULG1a effectors interact with GmHub10 protein to promote the soybean parasitism by Meloidogyne incognita and M. javanica.

Several economically important crops are susceptible to root-knot nematode (RKNs). Meloidogyne incognita and M. javanica are the two most reported species from the RKN complex, causing damage to several crops worldwide. The successful outcome of the Meloidogyne-plant interaction is associated with molecular factors secreted by the nematode to suppress the plant's immune response and promote nematode parasitism. In contrast, several plant factors are associated with defense against nematode infection. In this study, we identified and characterized the specific interaction of Minc00344 and Mj-NULG1a effectors with soybean GmHub10 (Glyma.19G008200) protein in vitro and in vivo. An Arabidopsis thaliana T-DNA mutant of AtHub10 (AT3G27960, an orthologous gene of GmHub10) showed higher susceptibility to M. incognita. Thus, since soybean and A. thaliana Hub10 proteins are involved in pollen tube growth and indirect activation of the defense response, our data suggest that effector-Hub10 interactions could be associated with an increase in plant susceptibility. These findings indicate the potential of these effector proteins to develop new biotechnological tools based on RNA interference and the overexpression of engineered Hub10 proteins for the efficient management of RKN in crops.

Insights Into Genetic and Molecular Elements for Transgenic Crop Development.

Climate change and the exploration of new areas of cultivation have impacted the yields of several economically important crops worldwide. Both conventional plant breeding based on planned crosses between parents with specific traits and genetic engineering to develop new biotechnological tools (NBTs) have allowed the development of elite cultivars with new features of agronomic interest. The use of these NBTs in the search for agricultural solutions has gained prominence in recent years due to their rapid generation of elite cultivars that meet the needs of crop producers, and the efficiency of these NBTs is closely related to the optimization or best use of their elements. Currently, several genetic engineering techniques are used in synthetic biotechnology to successfully improve desirable traits or remove undesirable traits in crops. However, the features, drawbacks, and advantages of each technique are still not well understood, and thus, these methods have not been fully exploited. Here, we provide a brief overview of the plant genetic engineering platforms that have been used for proof of concept and agronomic trait improvement, review the major elements and processes of synthetic biotechnology, and, finally, present the major NBTs used to improve agronomic traits in socioeconomically important crops.

Rice susceptibility to root-knot nematodes is enhanced by the Meloidogyne incognita MSP18 effector gene.

MAIN CONCLUSION: This study revealed novel insights into the function of MSP18 effector during root-knot nematode parasitism in rice roots. MSP18 may modulate host immunity and enhance plant susceptibility to Meloidogyne spp. Rice (Oryza sativa) production is seriously impacted by root-knot nematodes (RKN), including Meloidogyne graminicola, Meloidogyne incognita, and Meloidogyne javanica, in upland and irrigated culture systems. Successful plant infection by RKN is likely achieved by releasing into the host cells some effector proteins to suppress the activation of immune responses. Here, we conducted a series of functional analyses to assess the role of the Meloidogyne-secreted protein (MSP) 18 from M. incognita (Mi-MSP18) during rice infection by RKN. Developmental expression profiles of M. javanica and M. graminicola showed that the MSP18 gene is up-regulated throughout nematode parasitic stages in rice. Reproduction of M. javanica and M. graminicola is enhanced in rice plants overexpressing Mi-MSP18, indicating that the Mi-MSP18 protein facilitates RKN parasitism. Transient expression assays in onion cells suggested that Mi-MSP18 is localized to the cytoplasm of the host cells. In tobacco, Mi-MSP18 suppressed the cell death induced by the INF1 elicitin, suggesting that Mi-MSP18 can interfere with the plant defense pathways. The data obtained in this study highlight Mi-MSP18 as a novel RKN effector able to enhance plant susceptibility and modulate host immunity.

Review: Potential biotechnological assets related to plant immunity modulation applicable in engineering disease-resistant crops.

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.

Ectopic expression of a Meloidogyne incognita dorsal gland protein in tobacco accelerates the formation of the nematode feeding site.

Meloidogyne spp., plant-parasitic nematodes present worldwide, are intensively studied because of the damage caused to a large variety of agronomically important crops. Several reports indicate that proteins from the Meloidogyne spp. dorsal gland might play an important role to allow proper establishment of a functional nematode feeding site. The precise role of these proteins in the process of feeding cell development is unknown. To gain insights into the function of these secreted M. incognita proteins, we constitutively (ectopically) expressed the nematodes dorsal gland protein 7E12 in tobacco plants. It was found that the number of galls at 8 and 16 days after nematode infection was significantly higher in transgenic plants compared to control plants. Eggs from nematodes in transgenic plants hatched faster than those in control plants. Histological analysis of nematode induced galls in transgenic plants clearly shows a different morphology. Giant feeding cells harbor more vacuoles and an increased amount of cell wall invaginations, while neighboring cells surrounding feeding cells are more numerous. These results suggest that the presence of the 7E12 protein in tobacco accelerates gall formation. This assumption is supported by our data illustrating faster gall formation and egg eclosion in transgenic plants.

Identification of a novel beta-N-acetylhexosaminidase (Pcb-NAHA1) from marine Zoanthid Palythoa caribaeorum (Cnidaria, Anthozoa, Zoanthidea).

beta-N-Acetylhexosaminidases (EC 3.2.1.52) belong to an enzyme family that hydrolyzes terminal beta-d-N-glucosamine and beta-d-N-galactosamine residues from oligosaccharides. In this report, we purified a novel beta-N-acetylhexosaminidase (Pcb-NAHA1) from the marine zoanthid Palythoa caribaeorum by applying ammonium sulfate fractionation, affinity chromatography on a chitin column, followed by two rounds of size exclusion chromatography. SDS-PAGE analysis indicated a single band protein of apparent homogeneity with a molecular mass of 25kDa. The purified enzyme preferentially hydrolyzed p-nitrophenyl-2-acetoamide-2-deoxyamide-2-deoxy-beta-d-N-acetylglucosamide (pNP-GlcNAc) and to a lesser extent p-nitrophenyl-2-acetoamide-2-deoxyamide-2-deoxy-beta-d-N-acetylgalactosamide (pNP-GalNAc). Detailed kinetic analysis using pNP-GlcNAc resulted in a specific activity of 57.9 U/mg, a K(m) value of 0.53 mM and a V(max) value of 88.1 micromol/h/mg and k(cat) value of 0.61s(-1). Furthermore, purified Pcb-NAHA1 enzyme activity was decreased by Hg Cl(2) or maltose and stimulated in the presence of Na(2)SeO(4,) BaCl(2), MgCl(2,) chondroitin 6-sulfate, and phenylmethylsulfonylfluoride. The optimum activity of Pcb-NAHA1 was observed at pH 5.0 and elevated temperatures (45-60 degrees C). Direct sequencing of proteolytic fragments generated from Pcb-NAHA1 revealed remarkable similarities to plant chitinases, which belong to family 18, although no chitinase activity was detected with Pcb-NAHA1. We conclude that beta-N-acetylhexosaminidases, representing a type of exochitinolytic activity, and endo-chitinases share common functional domains and/or may have evolved from a common ancestor.