Visualizing and quantifying Fusarium oxysporum in the plant host.
Host-specific forms of Fusarium oxysporum infect the roots of numerous plant species. I present a novel application of familiar methodology to visualize and quantify F. oxysporum in roots. Infection in the roots of Arabidopsis thaliana, tomato, and cotton was detected with colorimetric reagents that are substrates for Fusarium spp.-derived arabinofuranosidase and N-acetyl-glucosaminidase activities and without the need for genetic modification of either plant host or fungal pathogen. Similar patterns of blue precipitation were produced by treatment with 5-bromo-4-chloro-3-indoxyl-α-l-arabinofuranoside and 5-bromo-4-chloro-3-indoxyl-2-acetamido-2-deoxy-β-d-glucopyranoside, and these patterns were consistent with prior histological descriptions of F. oxysporum in roots. Infection was quantified in roots of wild-type and mutant Arabidopsis using 4-nitrophenyl-α-l-arabinofuranoside. In keeping with an expectation that disease severity above ground is correlated with F. oxysporum infection below ground, elevated levels of arabinofuranosidase activity were measured in the roots of susceptible agb1 and rfo1 while a reduced level was detected in the resistant eir1. In contrast, disease severity and F. oxysporum infection were uncoupled in tir3. The distribution of staining patterns in roots suggests that AGB1 and RFO1 restrict colonization of the vascular cylinder by F. oxysporum whereas EIR1 promotes colonization of root apices.
University of California, Los Angeles, USA. diener@lifesci.ucla.edu
Andrew
A
Diener
D017360:Arabidopsis / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001089:Arabinose / Q000031:analogs & derivatives* / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D005670:Fusarium / Q000201:enzymology / Q000302:isolation & purification* / Q000472:pathogenicity; D044387:GTP-Binding Protein beta Subunits / Q000235:genetics / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism; D003368:Gossypium / Q000382:microbiology; D007210:Indoleacetic Acids / Q000378:metabolism; D018551:Solanum lycopersicum / Q000382:microbiology; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010935:Plant Diseases / Q000382:microbiology*; D018517:Plant Roots / Q000382:microbiology*; D018520:Plant Shoots / Q000382:microbiology; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000382:microbiology; D013045:Species Specificity; D013172:Spores, Fungal; D013194:Staining and Labeling / Q000379:methods*
D029681:Arabidopsis Proteins; D001089:Arabinose; D005656:Fungal Proteins; D044387:GTP-Binding Protein beta Subunits; D006026:Glycoside Hydrolases; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; D011494:Protein Kinases; C089590:AGB1 protein, Arabidopsis; C117013:AT5G57090 protein, Arabidopsis; C017567:4-nitrophenyl-alpha-L-arabinofuranoside; C514341:RFO1 protein, Arabidopsis; C019713:alpha-N-arabinofuranosidase