|SHIELDS, E. MARGARET|
Submitted to: World Cotton Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/12/2007
Publication Date: N/A
Technical Abstract: Previous research indicated that cool night temperatures may cause lower cotton lint yields and immature fiber. Biochemical analyses of leaf (source) and fiber (sink) metabolism indicated that increasing sucrose phosphate synthase (SPS) activity might increase lint yields and improve fiber quality at temperatures below 20 degrees C. To test this hypothesis, cotton (Gossypium hirsutum L., cv Coker 312) was transformed with the spinach SPS gene under the control of the CaMV 35S promoter. Transgenic plants were produced that expressed the gene and showed elevated levels of SPS activity, even though the CaMV 35S promoter proved to be weakly expressed in fiber. Growth chamber experiments under different temperature regimes, indicated that the transgenic plants expressing the SPS genes had altered fiber properties. To test whether the SPS gene might also improve fiber yield or quality, under more moderate Mississippi Delta conditions, field tests were conducted over two years at Stoneville, MS. The field trial included transgenic plants expressing the gene and not expressing the gene, with Coker 312, and 6 commercial cultivars as checks. The T3 and T4 progeny rows of the original transformants were tested over two years in replicated single row 4.5 m plots. The plots were evaluated for percent germination, flowering time, plant height, nodes to first boll, nodes above last boll, lint percent, cottonseed weight, 100 seed weight and average boll weight. Fiber samples were analyzed by HVI, AFIS, Fibrograph and Arealometer. The one transgenic line with the highest leaf and fiber SPS activity showed an increase in fiber strength over its transformation progenitor Coker 312 and was not significantly different than the commercial cultivars used as checks.