Pseudomonas syringae pv. tomato DC3000 Type III Secretion Effector Polymutants Reveal an Interplay between HopAD1 and AvrPtoB.

The bacterial pathogen Pseudomonas syringae pv. tomato DC3000 suppresses the two-tiered plant innate immune system by injecting a complex repertoire of type III secretion effector (T3E) proteins. Beyond redundancy and interplay, individual T3Es may interact with multiple immunity-associated proteins, rendering their analysis challenging.

Pto kinase binds two domains of AvrPtoB and its proximity to the effector E3 ligase determines if it evades degradation and activates plant immunity.

The tomato--Pseudomonas syringae pv. tomato (Pst)--pathosystem is one of the best understood models for plant-pathogen interactions. Certain wild relatives of tomato express two closely related members of the same kinase family, Pto and Fen, which recognize the Pst virulence protein AvrPtoB and activate effector-triggered immunity (ETI).

Temperature-dependent regulation of flowering by antagonistic FLM variants.

The appropriate timing of flowering is crucial for plant reproductive success. It is therefore not surprising that intricate genetic networks have evolved to perceive and integrate both endogenous and environmental signals, such as carbohydrate and hormonal status, photoperiod and temperature. In contrast to our detailed understanding of the vernalization pathway, little is known about how flowering time is controlled in response to changes in the ambient growth temperature.

Nonhost resistance of tomato to the bean pathogen Pseudomonas syringae pv. syringae B728a is due to a defective E3 ubiquitin ligase domain in avrptobb728a.

The bean pathogen Pseudomonas syringae pv. syringae B728a expresses homologs of the type III effectors AvrPto and AvrPtoB, either of which can trigger resistance in tomato cultivars expressing Pto and Prf genes. We found that strain B728a also elicits nonhost resistance in tomato cultivars VFNT Cherry and Moneymaker that lack Pto but express other members of the Pto family (e.

Synteny-based mapping-by-sequencing enabled by targeted enrichment.

Mapping-by-sequencing, as implemented in SHOREmap ('SHOREmapping'), is greatly accelerating the identification of causal mutations. The original SHOREmap approach based on resequencing of bulked segregants required a highly accurate and complete reference sequence. However, current whole-genome or transcriptome assemblies from next-generation sequencing data of non-model organisms do not produce chromosome-length scaffolds.

Structural analysis of Pseudomonas syringae AvrPtoB bound to host BAK1 reveals two similar kinase-interacting domains in a type III Effector.

To infect plants, Pseudomonas syringae pv. tomato delivers ~30 type III effector proteins into host cells, many of which interfere with PAMP-triggered immunity (PTI). One effector, AvrPtoB, suppresses PTI using a central domain to bind host BAK1, a kinase that acts with several pattern recognition receptors to activate defense signaling.

The genome of Tetranychus urticae reveals herbivorous pest adaptations.

The spider mite Tetranychus urticae is a cosmopolitan agricultural pest with an extensive host plant range and an extreme record of pesticide resistance. Here we present the completely sequenced and annotated spider mite genome, representing the first complete chelicerate genome. At 90 megabases T.

Orchestration of the floral transition and floral development in Arabidopsis by the bifunctional transcription factor APETALA2.

The Arabidopsis thaliana transcription factor APETALA2 (AP2) has numerous functions, including roles in seed development, stem cell maintenance, and specification of floral organ identity. To understand the relationship between these different roles, we mapped direct targets of AP2 on a genome-wide scale in two tissue types. We find that AP2 binds to thousands of loci in the developing flower, many of which exhibit AP2-dependent transcription.

Just say no: floral repressors help Arabidopsis bide the time.

Floral repressors ensure correct reproductive timing by safeguarding against premature flowering. In the past decade, several mechanisms of floral repression have come to light. Discrimination between direct and indirect repressors has been facilitated by increasing the use of chromatin immunoprecipitation assays.

Repression of flowering by the miR172 target SMZ.

A small mobile protein, encoded by the FLOWERING LOCUS T (FT) locus, plays a central role in the control of flowering. FT is regulated positively by CONSTANS (CO), the output of the photoperiod pathway, and negatively by FLC, which integrates the effects of prolonged cold exposure. Here, we reveal the mechanisms of regulation by the microRNA miR172 target SCHLAFMUTZE (SMZ), a potent repressor of flowering.

Export of FT protein from phloem companion cells is sufficient for floral induction in Arabidopsis.

Several endogenous and environmental factors need to be integrated to time the onset of flowering. Genetic and molecular analyses, primarily in Arabidopsis thaliana and rice, have shown that CONSTANS (CO) and FLOWERING LOCUS T (FT) play central roles in photoperiod-dependent flowering. The overall picture is that CO acts in the phloem companion cells of leaves and that its main effect is to induce FT mRNA in these cells.

The enteropathogenic Escherichia coli (EPEC) Map effector is imported into the mitochondrial matrix by the TOM/Hsp70 system and alters organelle morphology.

Enteropathogenic Escherichia coli (EPEC) is a human intestinal pathogen and a major cause of diarrhoea, particularly among infants in developing countries. EPEC target the Map and EspF multifunctional effector proteins to host mitochondria - organelles that play crucial roles in regulating cellular processes such as programmed cell death (apoptosis). While both molecules interfere with the organelles ability to maintain a membrane potential, EspF plays the predominant role and is responsible for triggering cell death.