The blue-light receptor CRY1 serves as a switch to balance photosynthesis and plant defense.

Plant stomata open in response to blue light, allowing gas exchange and water transpiration. However, open stomata are potential entry points for pathogens. Whether plants can sense pathogens and mount defense responses upon stomatal opening and how blue-light cues are integrated to balance growth-defense trade-offs are poorly characterized.

A Pathogen Secreted Protein as a Detection Marker for Citrus Huanglongbing.

The citrus industry is facing an unprecedented crisis due to Huanglongbing (HLB, aka citrus greening disease), a bacterial disease associated with the pathogen Liberibacter asiaticus (Las) that affects all commercial varieties. Transmitted by the Asian citrus psyllid (ACP), Las colonizes citrus phloem, leading to reduced yield and fruit quality, and eventually tree decline and death. Since adequate curative measures are not available, a key step in HLB management is to restrict the spread of the disease by identifying infected trees and removing them in a timely manner.

Structure of a pathogen effector reveals the enzymatic mechanism of a novel acetyltransferase family.

Effectors secreted by the type III secretion system are essential for bacterial pathogenesis. Members of the Yersinia outer-protein J (YopJ) family of effectors found in diverse plant and animal pathogens depend on a protease-like catalytic triad to acetylate host proteins and produce virulence. However, the structural basis for this noncanonical acetyltransferase activity remains unknown.

Two serine residues in Pseudomonas syringae effector HopZ1a are required for acetyltransferase activity and association with the host co-factor.

Gram-negative bacteria inject type III secreted effectors (T3SEs) into host cells to manipulate the immune response. The YopJ family effector HopZ1a produced by the plant pathogen Pseudomonas syringae possesses acetyltransferase activity and acetylates plant proteins to facilitate infection. Using mass spectrometry, we identified a threonine residue, T346, as the main autoacetylation site of HopZ1a.