A combination of plant-based compounds and extracts acts nematicidal and induces resistance against Meloidogyne incognita in tomato.

Considering the stricter European regulations for chemical pesticides (e.g. abolishment of the use of chemical soil fumigation products, such as methyl bromide), the need for more sustainable plant protection products is strongly increasing. In this research, Product X, an innovative mixture of bio-nematicidal compounds was developed and evaluated for efficacy. Product X showed a direct nematicidal effect against the root-knot nematode Meloidogyne incognita. In pot trials with tomato plants infected with M. incognita, Product X treatment lead to a significant reduction in nematode-induced gall formation. mRNA-sequencing indicated alterations in phytohormone levels and ROS-metabolism in tomato roots upon treatment with Product X, which was subsequently biochemically validated. Increased levels of abscisic acid and peroxidase activity seem to be the main factors in the response of tomato plants to Product X. Long-term administration of Product X did not yield negative effects on tomato growth or yield. In conclusion, Product X provides a new interesting mix of bio-active compounds in the combat against root-knot nematodes.

The nematode effector Mj-NEROSs interacts with Rieske's iron-sulfur protein influencing plastid ROS production to suppress plant immunity.

Root-knot nematodes (RKN; Meloidogyne species) are plant pathogens that introduce several effectors in their hosts to facilitate infection. The actual targets and functioning mechanism of these effectors largely remain unexplored. This study illuminates the role and interplay of the Meloidogyne javanica nematode effector ROS suppressor (Mj-NEROSs) within the host plant environment. Mj-NEROSs suppresses INF1-induced cell death as well as flg22-induced callose deposition and reactive oxygen species (ROS) production. A transcriptome analysis highlighted the downregulation of ROS-related genes upon Mj-NEROSs expression. NEROSs interacts with the plant Rieske's iron-sulfur protein (ISP) as shown by yeast-two-hybrid and bimolecular fluorescence complementation. Secreted from the subventral pharyngeal glands into giant cells, Mj-NEROSs localizes in the plastids where it interacts with ISP, subsequently altering electron transport rates and ROS production. Moreover, our results demonstrate that isp Arabidopsis thaliana mutants exhibit increased susceptibility to M. javanica, indicating ISP importance for plant immunity. The interaction of a nematode effector with a plastid protein highlights the possible role of root plastids in plant defense, prompting many questions on the details of this process.

Plant cell size: Links to cell cycle, differentiation and ploidy.

Cell size affects many processes, including exchange of nutrients and external signals, cell division and tissue mechanics. Across eukaryotes, cells have evolved mechanisms that assess their own size to inform processes such as cell cycle progression or gene expression. Here, we review recent progress in understanding plant cell size regulation and its implications, relating these findings to work in other eukaryotes. Highlights include use of DNA contents as reference point to control the cell cycle in shoot meristems, a size-dependent cell fate decision during stomatal development and insights into the interconnection between ploidy, cell size and cell wall mechanics.

Pathogens pulling the strings: Effectors manipulating salicylic acid and phenylpropanoid biosynthesis in plants.

During evolution, plants have developed sophisticated ways to cope with different biotic and abiotic stresses. Phytohormones and secondary metabolites are known to play pivotal roles in defence responses against invading pathogens. One of the key hormones involved in plant immunity is salicylic acid (SA), of which the role in plant defence is well established and documented. Plants produce an array of secondary metabolites categorized in different classes, with the phenylpropanoids as major players in plant immunity. Both SA and phenylpropanoids are needed for an effective immune response by the plant. To successfully infect the host, pathogens secrete proteins, called effectors, into the plant tissue to lower defence. Secreted effectors can interfere with several metabolic or signalling pathways in the host to facilitate infection. In this review, we will focus on the different strategies pathogens have developed to affect the levels of SA and phenylpropanoids to increase plant susceptibility.

Recent applications of biotechnological approaches to elucidate the biology of plant-nematode interactions.

Plant-parasitic nematodes are a major threat to food security. The most economically important species have remarkable abilities to manipulate host physiology and immunity. This review highlights recent applications of biotechnological approaches to elucidate the underlying biology on both sides of the interaction. Their obligate biotrophic nature has hindered the development of simple nematode transformation protocols. Instead, transient or stable expression of the effector (native or tagged) in planta has been instrumental in elucidating the biology of plant-nematode interactions. Recent progress in the development of functional genetics tools 'in nematoda' promises further advances. Finally, we discuss how effector research has uncovered novel protein translocation routes in plant cells and may reveal additional unknown biological processes in the future.