B cells migrate to the lymphoid follicles. They are directed there by chemokine interactions between CXCL13, which is secreted by follicular dendritic cells (FDCs).

TLS Online TPP Program

#Id: 9280

#Section 2: General Biology

The interaction between NFR and SYMRK initiates calcium spiking in the nucleus, presumably via a second messenger molecule.

Core symbiotic genes are activated.

Cytokinin signaling is initiated.

TLS Online TPP Program

#Id: 9281

#Section 2: General Biology

Root hair cellular responses to bacterial Nod factor

TLS Online TPP Program

#Id: 9282

#Section 2: General Biology

Plant genes expressed early, or in the absence of bacterial infection, are termed “early nodulins” or ENOD

TLS Online TPP Program

#Id: 9283

#Section 2: General Biology

Three factors are important in maintaining low O2 concentrations in nodules. 

First, entry of O2 into the nodule is controlled by a variable‐permeability barrier in the nodule parenchyma

TLS Online TPP Program

#Id: 9284

#Section 2: General Biology

O2‐binding plant protein Lb plays an active role in regulating and delivering O2 in the infected cells

Bacterial respiration is the major O2 sink

TLS Online TPP Program

#Id: 9285

#Section 2: General Biology

O2‐sensitive hemoprotein kinase FixL controls a regulatory cascade that activates transcription of nitrogen fixation genes