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United States Department of Agriculture

Agricultural Research Service

Title: Frequency Distribution of Rust Resistance in Breeding Populations of Canal Point Sugarcane Cultivar Development Program

Authors
item Tai, Peter
item Miller, Jimmy
item COMSTOCK, JACK
item GLAZ, BARRY

Submitted to: Sugar Journal
Publication Type: Popular Publication
Publication Acceptance Date: July 14, 1997
Publication Date: N/A

Interpretive Summary: Rust (Puccinia melanocephala) is one of the major diseases that attack the leaves of sugarcane plants. This disease reduces the number of elite clones advanced to replicated tests from the early stages of cooperative Canal Point (CP) sugarcane breeding program. Several series of clones in early selection stages and six commercial cultivars were used to determine their reaction to rust infection under natural epidemics in the field during the 17-year period. Results indicate that change in the rust races occurred because some check cultivars had very similar patterns of rust infection during this period while the others appear to react differently. About 75 per cent of early stage selections were rated as highly or very resistant, but about 10 per cent were rated as moderately or very susceptible to rust infection. Even though there were new races of rust, populations of early stage selections had a wide range of diverse genotypes so, as a population, it responded with the same distribution regardless of the races present. Continued breeding effort is needed to meet the constant change in a rust pathogen by using diverse germplasm to widen the genetic base for rust resistance in the CP breeding program.

Technical Abstract: Sugarcane rust (Puccinia melanocephala H. & P. Syd.) reduces the number of elite clones advanced to replicated tests from the early stages of the cooperative Canal Point (CP) sugarcane breeding program. Five selection series (CP 78, CP 79, CP 81, CP 93, and CP 95) and six commercial cultivars were used to determine their reaction to rust infection under natural epidemics in the field during 1979, 1980, 1982, 1994, and 1996, respectively. Results indicate that some check cultivars had very similar rust infection patterns during this 17-year period while the others appeared to react differently, indicating changes in the rust races present. Rust ratings for Stage II clones were consistently skewed toward susceptible rust ratings. Even though there were new races of rust, Stage II populations had a wide range of diverse genotypes so, as a population, it responded with a similar distribution pattern regardless of the races present. A new breeding strategy is needed to reduce the frequency of rust susceptibility (ratings 3 and 4) by using diverse germplasm to broaden the genetic base for rust resistance in the CP breeding program.

Last Modified: 9/10/2014
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