Over-Expressed Alternative Oxidase Gene Efficacy On Fiber Growth and Maturation in Cotton

In West Texas, the annual cotton crop rarely produces lint fibers that meet the cultivars full genetic potential. Late season cool temperature during boll and fiber maturation greatly slows the deposition of cellulose in the secondary cell wall. This produces immature fibers that greatly affect the agronomic performance of cotton by lowering yield and quality.  The negative impact of low micronaire values is lower prices and a reduced demand for West Texas cotton on the World market.

We have developed transgenic cotton plants that increase express of the alternative oxidase enzyme (AOX) which has been shown to increase cellular temperatures in some thermogenic plants. Our hypothesis is that by elevating AOX production in cotton, specifically in the boll, it will mitigate adverse effect of cool temperature on lint quality measures. In theory AOX overexpression would serve to create an optimum and stable temperature environment for fiber development under adverse temperatures. To test this hypothesis, a gene efficacy experiment was conducted on two AOX lines (66-6 and 94-20), their non-transgenic “null” lines (66-2, and 94-3), and Coker 312-17.  Agrobacterium mediated transformation was used to create transgenic Coker 312-17 lines to constitutively express the tobacco Aox1 gene. All five lines were evaluated in field trials at the Texas Tech Research Farm in Lubbock, Texas during the 2010, 2011, and 2012 seasons.  A time-course assessment of fiber development was conducted each season by tagging flowers daily then harvesting open boll according to the week it flowered.  Lint samples that represented each week were independently analysis using HVI and AFIS testing.  A statically analysis of each trait, using a glimmix model in SAS, is being used to assess gene efficacy of AOX.