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ARS Home » Midwest Area » St. Paul, Minnesota » Cereal Disease Lab » Research » Publications at this Location » Publication #174311


item EILAM, T
item KOSMAN, E

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2005
Publication Date: 3/1/2005
Citation: Anikster, Y., Eilam, T., Bushnell, W.R., Kosman, E. 2005. Spore dimensions of Puccinia species of cereals hosts as determined by image analysis. Mycologia. 97:474-484.

Interpretive Summary: Rusts are one of the most important diseases of cereals in the U.S. and worldwide. These diseases are spread by long distance movement of summer spores (urediniospores) in the wind. However, rust fungus pathogens produce four additional spore types that allow the fungus to go through its complete life cycle. The shapes and dimensions of these spores as viewed with a microscope are used to identify the species of each rust. To facilitate measurement of spore dimensions, we applied image analysis of digital microscope images to measure length and width of all five spore types. In addition, the area of individual spores was determined, which cannot be done readily by conventional microscope methods. For several species of cereal rust fungi, dimensions of all but one of the five spore types were shown to be useful for differentiating species. This is important when only certain spore types are available in a given rust fungus collection. The methods developed for using image analysis will be useful to plant pathologists investigating rusts and other diseases caused by fungi as well as by investigators who specialize in the identification, genetics, and physiology of fungi.

Technical Abstract: Digital image analysis was used to measure dimensions of spores produced by Puccinia coronata, P. graminis, P. hordei, P. recondita, P. striiformis, and P. triticina. Included were teliospores, basidiospores, urediniospores, and, except for P. striiformis, pycniospores and aeciospores. Length, width, and projection area of spores were measured using NIH Image or Scion software. This procedure gave values for length and width close to results obtained with an ocular micrometer. Projection area was determined as the number of pixels within spore boundaries multiplied by the area represented by each pixel, giving values which are not feasible to obtain accurately with an ocular micrometer. Of the species studied, spores of P. recondita had the largest dimensions; P. triticina had the smallest. The rank of the six species based on increasing width, length or projection area was virtually the same using each spore type except pycniospores. Differences between species were greater with basidiospores and aeciospores than with other spore types. Teliospores were unique in that length and width were negatively correlated, resulting in less variation in area than in length or width. The results indicate that image analysis is useful for measuring spore dimensions, that projection area of spores is a useful added parameter for characterizing rust species, and that dimensions of teliospores, basidiospores, aeciospores and urediniospores are each potentially useful for differentiating species.