ARS | Publication request: Morphological comparison of aeciospores from rust fungi infecting Berberis spp.

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 12, 2011
Publication Date: N/A

Technical Abstract: Currently there are about 30 different species of rust fungi described that infect Berberis and/or Mahonia, and include both autoecious and heteroecious. Our current work is on the molecular phylogenetic and morphological characterization of macrocyclic, heteroecious rust fungi with cereal and grass telial hosts and Berberis/Mahonia aecial host. This group includes Puccinia brachypodii complex, P. graminis, P. magelhaencia, P. montanesis, P. pygmaea, and P. striiformis. This presentation will focus on the morphological characterization P. striiformis aeciospores and comparison with aeciospores from closely related rust fungi. Dried infected leaf material was rehydrated for 12 h, stained in aniline blue, lactophenol (95 C for 5 minutes) and mounted in clear lactophenol. P. striiformis aeciospores are more or less oblong and measured 17.6+1.2 – 20.9+1.6 um x 11.4+0.7 – 12.8+0.9 um with a cross sectional area of 201+/¬22 um**2 to 255+23 um**2. The spore wall is irregular in thickness ranging from 0.7 um to 1.7 um. Overall, the aeciospores from P. striiformis are slightly larger and more oblong than aeciospores from P. graminis (15.6+1.1 – 19.1+1.0 um x 9.7+ - 12.7+0.6 um; 151+19 – 242+15 um**2), however, the most distinct difference is that P. graminis has a thick apical spore wall (5-9 um). Aeciospores of P. montanensis (470+51 um**2) P. magelhaencia (317+38 um**2) are both significantly larger. These results suggest that morphological characters of aeciospores of these rust fungi may be a useful means for identification, but additional members of this group need to be examined.