Project Summaries

12-223  Project Manager: D. C. Jones


C. Wayne Smith, Texas AgriLife Research

Early mapping studies of fiber quality QTLs were characterized by low levels of congruence among studies. Recent advances in molecular genetics have facilitated the discovery of DNA markers with tighter linkages to fiber quality QTLs as well as co-locating QTLs across different genetic backgrounds. Yet in the public sector, the utilization of marker assisted selection (MAS) for the improvement of fiber quality has yet to be reported. Studies indicate that fiber quality QTLs are non-randomly distributed across the genome and that the same QTL can be detected in different genetic backgrounds and environments. Many questions remain to be addressed before MAS can successfully be utilized in the improvement of fiber quality traits, including whether or not marker/QTL linkages will hold in different genetic backgrounds and generations and whether or not QTL will have the same effect in different genetic backgrounds. The objectives of this research are to (1) evaluate the portability of simple sequence repeat (SSR) markers associated with QTLs for fiber length and bundle strength across different genetic backgrounds and generations and (2) compare their effectiveness in MAS across different genetic backgrounds.

In 2012, F2 plants among five different families were selected based on fiber quality. The top and bottom 10% of F2 individuals for (HVI) upper half mean length and bundle strength among each of the five families were planted as F2:3 rows (180 rows) along with 44 rows of parents for a total of 224 plant rows. In summer 2012, tissue samples were collected from eight random plants per F2:3 row plus eight plants per parent. Tissue samples were collected from a total of 1,488 plants and stored in a -80 °C freezer. Boll samples from the 1,488 selected plants were ginned and sent to the Cotton Incorporated Product Evaluation Lab for HVI testing.

In February 2013, DNA will be extracted from the tissue samples. Approximately 300 SSR markers associated with fiber length and strength have been selected from previous QTL mapping studies. The allelic state of sampled F2:3 plants will be determined to address whether or not the selected markers are present in the top 10% of individuals for fiber length and strength and absent from the bottom 10%. Researchers at the University of Georgia recently conducted a diversity study using SSR markers that included the four parents used to derive the five families discussed above. The results suggest that the parents represent notably different genetic backgrounds. The range of genetic similarity between parents ranged from 46 to 55%.

This is the project of Cotton Incorporated Fellow Kari Hugie.


Project Year: 2012

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