Separate sites of action for cry1 and phot1 blue-light receptors in the Arabidopsis hypocotyl.

Rapid cell expansion pushes the Arabidopsis hypocotyl (juvenile stem) through the soil until blue light, acting first through phototropin 1 (phot1) and then through cryptochrome 1 (cry1), suppresses elongation to produce a length characteristic of established, photosynthetically capable seedlings. To determine where these two different blue-light receptors act to suppress hypocotyl elongation, we measured relative elemental growth rate, specifically along the hypocotyl midline at 5-min intervals before and during blue light, using a machine-learning-based image analysis pipeline designed specifically for this kinematic analysis of growth. In darkness, hypocotyl material expanded most rapidly (approximately 4% h) in a broad zone approximately 1 mm below the apical terminus of the hypocotyl (cotyledonary node).

A protease and a lipoprotein jointly modulate the conserved ExoR-ExoS-ChvI signaling pathway critical in Sinorhizobium meliloti for symbiosis with legume hosts.

Sinorhizobium meliloti is a model alpha-proteobacterium for investigating microbe-host interactions, in particular nitrogen-fixing rhizobium-legume symbioses. Successful infection requires complex coordination between compatible host and endosymbiont, including bacterial production of succinoglycan, also known as exopolysaccharide-I (EPS-I). In S.

A Digital Image-Based Phenotyping Platform for Analyzing Root Shape Attributes in Carrot.

Root shape in carrot ( subsp. ), which ranges from long and tapered to short and blunt, has been used for at least several centuries to classify carrot cultivars. The subjectivity involved in determining market class hinders the establishment of metric-based standards and is ill-suited to dissecting the genetic basis of such quantitative phenotypes.

Crosstalk between the tricarboxylic acid cycle and peptidoglycan synthesis in Caulobacter crescentus through the homeostatic control of α-ketoglutarate.

To achieve robust replication, bacteria must integrate cellular metabolism and cell wall growth. While these two processes have been well characterized, the nature and extent of cross-regulation between them is not well understood. Here, using classical genetics, CRISPRi, metabolomics, transcriptomics and chemical complementation approaches, we show that a loss of the master regulator Hfq in Caulobacter crescentus alters central metabolism and results in cell shape defects in a nutrient-dependent manner.

Analysis of a taurine-dependent promoter in Sinorhizobium meliloti that offers tight modulation of gene expression.

Background: Genetic models have been developed in divergent branches of the class Alphaproteobacteria to help answer a wide spectrum of questions regarding bacterial physiology. For example, Sinorhizobium meliloti serves as a useful representative for investigating rhizobia-plant symbiosis and nitrogen fixation, Caulobacter crescentus for studying cell cycle regulation and organelle biogenesis, and Zymomonas mobilis for assessing the potentials of metabolic engineering and biofuel production. A tightly regulated promoter that enables titratable expression of a cloned gene in these different models is highly desirable, as it can facilitate observation of phenotypes that would otherwise be obfuscated by leaky expression.