Explore the vast range of titles available.

Rice blast disease is caused by the hemibiotrophic fungus Magnaporthe oryzae, which invades living plant cells using intracellular invasive hyphae (IH) that grow from one cell to the next. The cellular and molecular processes by which this occurs are not understood. We applied live-cell imaging to characterize the spatial and temporal development of IH and plant responses inside successively invaded rice (Oryza sativa) cells. Loading experiments with the endocytotic tracker FM4-64 showed dynamic plant membranes around IH. IH were sealed in a plant membrane, termed the extra-invasive hyphal membrane (EIHM), which showed multiple connections to peripheral rice cell membranes. The IH switched between pseudohyphal and filamentous growth. Successive cell invasions were biotrophic, although each invaded cell appeared to have lost viability when the fungus moved into adjacent cells. EIHM formed distinct membrane caps at the tips of IH that initially grew in neighboring cells. Time-lapse imaging showed IH scanning plant cell walls before crossing, and transmission electron microscopy showed IH preferentially contacting or crossing cell walls at pit fields. This and additional evidence strongly suggest that IH co-opt plasmodesmata for cell-to-cell movement. Analysis of biotrophic blast invasion will significantly contribute to our understanding of normal plant processes and allow the characterization of secreted fungal effectors that affect these processes.

The constant interactions between plants and pathogens in the environment and the resulting outcomes are of significant importance for agriculture and agricultural scientists. Disease resistance genes in plant cultivars can break down in the field due to the evolution of pathogens under high selection pressure. Thus, the protection of crop plants against pathogens is a continuous arms race. Like any other type of crop plant, legumes are susceptible to many pathogens. The dawn of the genomic era, in which high-throughput and cost-effective genomic tools have become available, has revolutionized our understanding of the complex interactions between legumes and pathogens. Genomic tools have enabled a global view of transcriptome changes during these interactions, from which several key players in both the resistant and susceptible interactions have been identified. This review summarizes some of the large-scale genomic studies that have clarified the host transcriptional changes during interactions between legumes and their plant pathogens while highlighting some of the molecular breeding tools that are available to introgress the traits into breeding programs. These studies provide valuable insights into the molecular basis of different levels of host defenses in resistant and susceptible interactions.

Knowledge remains limited about how fungal pathogens that colonize living plant cells translocate effector proteins inside host cells to regulate cellular processes and neutralize defense responses. To cause the globally important rice blast disease, specialized invasive hyphae (IH) invade successive living rice (Oryza sativa) cells while enclosed in host-derived extrainvasive hyphal membrane. Using live-cell imaging, we identified a highly localized structure, the biotrophic interfacial complex (BIC), which accumulates fluorescently labeled effectors secreted by IH. In each newly entered rice cell, effectors were first secreted into BICs at the tips of the initially filamentous hyphae in the cell. These tip BICs were left behind beside the first-differentiated bulbous IH cells as the fungus continued to colonize the host cell. Fluorescence recovery after photobleaching experiments showed that the effector protein PWL2 (for prevents pathogenicity toward weeping lovegrass [Eragrostis curvula]) continued to accumulate in BICs after IH were growing elsewhere. PWL2 and BAS1 (for biotrophy-associated secreted protein 1), BIC-localized secreted proteins, were translocated into the rice cytoplasm. By contrast, BAS4, which uniformly outlines the IH, was not translocated into the host cytoplasm. Fluorescent PWL2 and BAS1 proteins that reached the rice cytoplasm moved into uninvaded neighbors, presumably preparing host cells before invasion. We report robust assays for elucidating the molecular mechanisms that underpin effector secretion into BICs, translocation to the rice cytoplasm, and cell-to-cell movement in rice.

Rice blast is a major fungal disease on rice, caused by the hemibiotrophic filamentous ascomycete fungus, Magnaporthe oryzae. This disease accounts for 157 million tons of grain loss annually. The fungus produces a specialized cell called appressorium to penetrate the host surface barrier and enter inside. It produces intracellular Invasive Hyphae (IH) that grow form cell to cell to colonize the host. The mechanisms of appressorium formation and host penetration have been studied in detail but the host colonization strategies remain largely unknown. We applied live-cell imaging to characterize spatial and temporal development of IH and plant responses inside successively-invaded rice cells. Early loading experiments with the endocytotic tracker, FM4-64, showed dynamic plant membranes around IH. These hyphae showed remarkable plasticity and recruited plant cell components. IH exhibited pseudohyphal growth and were sealed in plant membrane, termed the Extra-Invasive Hyphal Membrane (EIHM). The fungus spent up to 12 hours in the first cell, often tightly packing it with IH. IH that moved into neighboring cells were biotrophic, although they were initially thinner and grew more rapidly. IH in neighboring cells were wrapped in EIHM with distinct membrane caps at the hyphal tips. Time-lapse imaging showed IH scanning plant cell walls before crossing them, and transmission electron microscopy showed crossing occurring at pit fields. This and additional evidence strongly suggest that IH co-opt plasmodesmata for cell-to-cell movement. Our studies have revealed insights into a novel hemibiotrophic strategy employed by the blast fungus. Few genes have been previously characterized that impact the biotrophic IH. To understand the molecular basis of the biotrophic infection strategy we employed Laser Microdissection (LM) technology to isolate and purify the IH at this early growth stage. We compared the gene expression of these samples with axenically-grown mycelium using M. oryzae whole genome microarrays. We identified several hundreds of infection specific genes. We have shown that LM technology can be used to isolate homogenous cells from the infected rice tissues to study the underlying molecular mechanisms of signaling during disease formation. These studies will be very critical to understand the host-pathogen interactions to eventually develop durable management strategies.

Thiourea is an important building block found in several drug molecules such as thioacetazone, enzalutamide, thiocarlide etc. Thiourea derivatives have been used for activation of carbonyl and imine compounds to facilitate Michael addition reactions, and as an oxyanion stabilizer for [Ir] catalyzed amination of alcohols without using any base or acid. Chiral bifunctional thiourea catalysts have been successfully applied for asymmetric synthesis of several drug molecules.

Copper (II) bromide/ N-methylmorpholine N-oxide promoted α-amination of esters in solvent-free condition is reported. The α-amino esters are precursors for α-amino acids. This method provides α-amino esters in 58-83% yields. The polar solvent dimethyl sulfoxide was avoided and the reactions were performed in solvent-free condition. NMO successfully oxidizes Cu(I)Br to regenerate the Cu(II)Br catalyst. The isolated CuBr2 catalyst was recycled twice.

A new metal- and activator-free method for the synthesis of selenoesters from carboxylic acids, Michael acceptors, and selenourea is reported. This is the first reported method for the synthesis of selenoesters directly from carboxylic acids, using selenourea as a nucleophile, source of selenium, and an activator of carbonyl group. A new multifunctional selenourea (source of selenium, activator, base) has been synthesized, tried in a flow reactor to reduce impurity and reaction time.