Near-infrared light and PIF4 promote plant antiviral defense by enhancing RNA interference.

The molecular mechanism underlying phototherapy and light treatment, which utilize various wavelength spectra of light, including near-infrared (NIR), to cure human and plant diseases, is obscure. Here we revealed that NIR light confers antiviral immunity by positively regulating PHYTOCHROME-INTERACTING FACTOR 4 (PIF4)-activated RNA interference (RNAi) in plants. PIF4, a central transcription factor involved in light signaling, accumulates to high levels under NIR light in plants.

Structure-function analyses of coiled-coil immune receptors define a hydrophobic module for improving plant virus resistance.

Plant immunity relies on nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) that detect microbial patterns released by pathogens, and activate localized cell death to prevent the spread of pathogens. Tsw is the only identified resistance (R) gene encoding an NLR, conferring resistance to tomato spotted wilt orthotospovirus (TSWV) in pepper species (Capsicum, Solanaceae). However, molecular and cellular mechanisms of Tsw-mediated resistance are still elusive.

Red-light is an environmental effector for mutualism between begomovirus and its vector whitefly.

Environments such as light condition influence the spread of infectious diseases by affecting insect vector behavior. However, whether and how light affects the host defense which further affects insect preference and performance, remains unclear, nor has been demonstrated how pathogens co-adapt light condition to facilitate vector transmission. We previously showed that begomoviral βC1 inhibits MYC2-mediated jasmonate signaling to establish plant-dependent mutualism with its insect vector.

Laodelphax striatellus Atg8 facilitates Rice stripe virus infection in an autophagy-independent manner.

Rice stripe virus (RSV) is the causative agent of rice stripe disease and is completely dependent on insect vectors for its plant-to-plant transmission. Laodelphax striatellus is the major insect vector for RSV. In this study, we explored the interactions between RSV infection and L.

Viruses mobilize plant immunity to deter nonvector insect herbivores.

A parasite-infected host may promote performance of associated insect vectors; but possible parasite effects on nonvector insects have been largely unexplored. Here, we show that , the largest genus of plant viruses and transmitted exclusively by whitefly, reprogram plant immunity to promote the fitness of the vector and suppress performance of nonvector insects (i.e.

CMV2b-Dependent Regulation of Host Defense Pathways in the Context of Viral Infection.

RNA silencing (or RNA interference, RNAi) plays direct roles in plant host defenses against viruses. Viruses encode suppressors of RNAi (VSRs) to counteract host antiviral defenses. The generation of transgenic plants expressing VSRs facilitates the understanding of the mechanisms of VSR-mediated interference with the endogenous silencing pathway.

Genome-wide identification of endogenous RNA-directed DNA methylation loci associated with abundant 21-nucleotide siRNAs in Arabidopsis.

In Arabidopsis, the 24-nucleotide (nt) small interfering RNAs (siRNAs) mediates RNA-directed DNA methylation (RdDM) and transcriptional gene silencing (TGS) of transposable elements (TEs). In the present study, we examined genome-wide changes in DNA methylation and siRNA accumulation in Arabidopsis induced by expression of the Cucumber mosaic virus silencing suppressor protein 2b known to directly bind to both the 21/24-nt siRNAs as well as their associated Argonaute proteins. We demonstrated a genome-wide reduction of CHH and CHG methylation in the 2b-transgenic plants.

Dynamic and Coordinated Expression Changes of Rice Small RNAs in Response to Xanthomonas oryzae pv. oryzae.

Endogenous small RNAs are newly identified players in plant immune responses, yet their roles in rice (Oryza sativa) responding to pathogens are still less understood, especially for pathogens that can cause severe yield losses. We examined the small RNA expression profiles of rice leaves at 2, 6, 12, and 24 hours post infection of Xanthomonas oryzae pv. oryzae (Xoo) virulent strain PXO99, the causal agent of rice bacterial blight disease.

The periplasmic PDZ domain-containing protein Prc modulates full virulence, envelops stress responses, and directly interacts with dipeptidyl peptidase of Xanthomonas oryzae pv. oryzae.

PDZ domain-containing proteases, also known as HtrA family proteases, play important roles in bacterial cells by modulating disease pathogenesis and cell-envelope stress responses. These proteases have diverse functions through proteolysis- and nonproteolysis-dependent modes. Here, we report that the genome of the causative agent of rice bacterial blight, Xanthomonas oryzae pv.

A three-component signalling system fine-tunes expression kinetics of HPPK responsible for folate synthesis by positive feedback loop during stress response of Xanthomonas campestris.

During adaptation to environments, bacteria employ two-component signal transduction systems, which contain histidine kinases and response regulators, to sense and respond to exogenous and cellular stimuli in an accurate spatio-temporal manner. Although the protein phosphorylation process between histidine kinase and response regulator has been well documented, the molecular mechanism fine-tuning phosphorylation levels of response regulators is comparatively less studied. Here we combined genetic and biochemical approaches to reveal that a hybrid histidine kinase, SreS, is involved in the SreK-SreR phosphotransfer process to control salt stress response in the bacterium Xanthomonas campestris.

Satellite RNA-derived small interfering RNA satsiR-12 targeting the 3' untranslated region of Cucumber mosaic virus triggers viral RNAs for degradation.

RNA silencing provides protection against RNA viruses by targeting both the helper virus and its satellite RNA (satRNA). Virus-derived small interfering RNAs (vsiRNAs) bound with Argonaute (AGO) proteins are presumed participants in the silencing process. Here, we show that a vsiRNA targeted to virus RNAs triggers the host RNA-dependent RNA polymerase 6 (RDR6)-mediated degradation of viral RNAs.

A novel rice gene, NRR responds to macronutrient deficiency and regulates root growth.

To better understand the response of rice to nutrient stress, we have taken a systematic approach to identify rice genes that respond to deficiency of macronutrients and affect rice growth. We report here the expression and biological functions of a previously uncharacterized rice gene that we have named NRR (nutrition response and root growth). NRR is alternatively spliced, producing two 5'-coterminal transcripts, NRRa and NRRb, encoding two proteins of 308 and 223 aa, respectively.

The expression level of Rosa Terminal Flower 1 (RTFL1) is related with recurrent flowering in roses.

We examined the relationship between the recurrent flowering character and the expression patterns of TERMINAL FLOWER 1 (TFL1) homologs in roses, using flower buds of Rosa multiflora, R. rugosa, R. chinensis, and six other rose species and nine rose cultivars.

Satellite RNA reduces expression of the 2b suppressor protein resulting in the attenuation of symptoms caused by Cucumber mosaic virus infection.

Satellite RNAs (satRNAs) depend on cognate helper viruses for replication, encapsidation, movement and transmission. Many satRNAs with different symptom modulation effects have been reported. The pathogenicity of satRNAs is thought to be the result of a direct interaction among the satRNA, helper viruses and host factors by unknown mechanisms.

Functional analysis of the HS185 regulatory element in the rice HSP70 promoter.

A series of HSP70 promoter deletion constructs was established. Analysis of beta-glucuronidase activities from the promoter deletion constructs in transient expression assays identified a cis-element, located from -493 to -308 bp upstream of the ATG start site. This element was designated as HS185 and has a crucial role in HSP70 promoter activity.

Identification and functional characterization of small non-coding RNAs in Xanthomonas oryzae pathovar oryzae.

Background: Small non-coding RNAs (sRNAs) are regarded as important regulators in prokaryotes and play essential roles in diverse cellular processes. Xanthomonas oryzae pathovar oryzae (Xoo) is an important plant pathogenic bacterium which causes serious bacterial blight of rice. However, little is known about the number, genomic distribution and biological functions of sRNAs in Xoo.

Immunogenicity and virus-like particle formation of rotavirus capsid proteins produced in transgenic plants.

The human pathogen, group A rotavirus, is the most prevalent cause of acute infantile and pediatric gastroenteritis worldwide, especially in developing countries. There is an urgent demand for safer, more effective and cheaper vaccines against rotavirus infection. Plant-derived antigens may provide an exclusive way to produce economical subunit vaccines.

Overexpression of an F-box protein gene reduces abiotic stress tolerance and promotes root growth in rice.

As one of the largest gene families, F-box domain proteins have important roles in regulating various developmental processes and stress responses. In this study, we have investigated a rice F-box domain gene, MAIF1. The MAIF1 protein is mainly localized in the plasma membrane and nucleus.

RNA-dependent RNA polymerase 1 from Nicotiana tabacum suppresses RNA silencing and enhances viral infection in Nicotiana benthamiana.

Endogenous eukaryotic RNA-dependent RNA polymerases (RDRs) produce double-stranded RNA intermediates in diverse processes of small RNA synthesis in RNA silencing pathways. RDR6 is required in plants for posttranscriptional gene silencing induced by sense transgenes (S-PTGS) and has an important role in amplification of antiviral silencing. Whereas RDR1 is also involved in antiviral defense in plants, this does not necessarily proceed through triggering silencing.

A critical domain of the Cucumber mosaic virus 2b protein for RNA silencing suppressor activity.

Alignment of Cucumber mosaic virus (CMV) 2b protein sequences from two CMV subgroups revealed two highly variable regions. To examine contributions of variable sequence domains to the suppressor activity, we performed a comparative study between 2b proteins of a subgroup I strain (SD-CMV) and a subgroup II strain (Q-CMV). Here we show that the suppressor activity of SD2b is stronger than that of Q2b and that a domain existent in SD2b but absent in Q2b is a major determinant of the suppressor activity of SD2b.

Artificial MicroRNAs highly accessible to targets confer efficient virus resistance in plants.

Short-hairpin RNAs based on microRNA (miRNA) precursors to express the artificial miRNAs (amiRNAs) can specifically induce gene silencing and confer virus resistance in plants. The efficacy of RNA silencing depends not only on the nature of amiRNAs but also on the local structures of the target mRNAs. However, the lack of tools to accurately and reliably predict secondary structures within long RNAs makes it very hard to predict the secondary structures of a viral genome RNA in the natural infection conditions in vivo.

DCL4 targets Cucumber mosaic virus satellite RNA at novel secondary structures.

It has been reported that plant virus-derived small interfering RNAs (vsiRNAs) originated predominantly from structured single-stranded viral RNA of a positive single-stranded RNA virus replicating in the cytoplasm and from the nuclear stem-loop 35S leader RNA of a double-stranded DNA (dsDNA) virus. Increasing lines of evidence have also shown that hierarchical actions of plant Dicer-like (DCL) proteins are required in the biogenesis process of small RNAs, and DCL4 is the primary producer of vsiRNAs. However, the structures of such single-stranded viral RNA that can be recognized by DCLs remain unknown.

[Construction of selectable marker-removable plant expression vectors].

The commonly used plant constitutive expression vector pBI121 was modified by insertion of two directly orientated lox sites each at one end of the selectable marker gene NPTII and by replacing the GUS gene with a sequence composed of multiple cloning sites (MCS). The resulting plant expression vector pBI121-lox-MCS is widely usable to accommodate various target genes through the MCS, and more importantly to allow the NPTII gene removed from transformed plants upon the action of the Cre recombinase. In addition, the CaMV 35S promoter located upstream of the MCS can be substituted with any other promoters to form plant vectors with expression features specified by the introduced promoters.

[Using green fluorescent protein as a reporter to monitor elimination of selectable marker genes from transgenic plants].

In genetic modification of plants, once the transformants are obtained, selection markers are no longer required in mature plants. At present, the Cre/lox site-specific recombination system is most widely used to eliminate the selectable marker genes from the transgenic plants. In this study, attempt was made to favour the selection of marker-free plants in the re-transformation method.

[A simple and visible assay for cre recombinase activity in Escherichia coli by using two incompatible plasmids].

The Cre/loxP system derived from bacteriophage P1 is widely used to carry out complex manipulations of DNA molecules both in vitro and in vivo. In order to further characterize and modify the Cre/loxP system, a convenient method for assaying the recombination efficiency is needed. A simple and visible assay is described, in which two incompatible plasmids, separately carrying the cre gene and loxP-flanked gfp gene, were co-transferred into E.