Location: Sugarcane Field StationTitle: Phenotypic Characterization of the Miami World Collection of Sugarcane and Related Grasses for Selecting a Representative Core) Author
Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2014
Publication Date: 7/14/2014
Citation: Todd, J.R., Wang, J., Glaz, B.S., Sood, S.G., Ayala Silva, T., Nayak, S.N., Glynn, N.C., Gutierrez, O.A., Kuhn, D.N., Tahir, M., Comstock, J.C. 2014. Phenotypic Characterization of the Miami World Collection of Sugarcane and Related Grasses for Selecting a Representative Core. Genetic Resources and Crop Evolution. 61:1581-1596. Interpretive Summary: There are two World Collections of Sugarcane and Related Grasses (World Collection). One is located in Miami, Florida, USA and the other is in Coimbatore, India. These collections contain materials that could potentially be used in sugarcane and bioenergy breeding programs as genetic sources of improved yields and resistance to biological and other stresses. However, these materials have not been widely used because little is known about their attributes. We studied the World Collection in Miami which contains 1167 accessions (genotypes) representing 26 species, most of which are closely related to sugarcane. This research was the first step of a two-step process, which was to identify a core collection of 300 accessions that represent about 90% of the diversity present in the World Collection. The second step is now ongoing and that involves studying these 300 accessions for growth and yield characters in a replicated study. In the identification of the core collection, we found 12 genotypes of the wild grass Saccharum spontaneum with a high Brix content. This was a major finding because sugarcane breeders often try to breed spontaneums with sugarcane in order to improve cold, flood, or disease tolerance of sugarcane. This transfer of stress tolerance is often successful, but because the spontaneums often have low sucrose content (measured by a low Brix value), the resulting resistant offspring are often not useful because they have very low sugar contents. Perhaps these spontaneums with higher Brix will help breeders overcome this problem. A second major finding was that 26.6 % of the accessions in the World Collection already similar genetically to sugarcane are resistant to Sugarcane Yellow Leaf Virus. This finding was important for breeders because they have not been able to find much genetic resistance to this disease in sugarcane. Future plans of this project are to study the core collection intensely and link with a genomics program that is working with the same core collection with the ultimate goals of identifying important yield traits and association mapping panels that will benefit sugarcane and bioenergy breeders.
Technical Abstract: The Saccharum genus includes important crops that are utilized for sugar and fuel production. The World Collection of Sugarcane and Related Grasses (World Collection) in Miami, FL contains diverse and potentially useful germplasm for this and related genera; however, this collection has been underutilized because little is known about the traits of its accessions. Our objectives were to phenotypically characterize the World Collection and to select a representative core collection that could then be studied intensely. In total, 11 morphological traits of the World Collection were evaluated three times in one year. A core of 300 accessions that included each species in the World Collection was selected using the Maximization Strategy (M Strategy) in MStrat software and had a higher diversity than a random selection of the same number. A Principal Component Analysis (PCA) was conducted and the data were clustered by the Euclidian and Unweighted Neighbor Joining (UNJ) methods. No species patterns were observed in the PCA analysis or UNJ tree other than between sponteneum (grown in pots) and officinarum (grown in field) accessions, which was probably due to differences in growing conditions. The Shannon scores demonstrated that 97.31% of the diversity of the World Collection was captured by the core collection. These data were analyzed using the non-parametric Wilcoxon method, and no median of any trait in the core differed from its respective median in the World Collection at P = 0.05. Thus, the phenotypic diversity of the World Collection was almost fully represented by the core collection and agronomic studies on the core should successfully characterize almost any useful trait in the World Collection and genes for these traits should be available in the core collection.