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United States Department of Agriculture

Agricultural Research Service

Research Project: ECONOMIC AND ENVIRONMENTAL BENEFITS FROM MULTIUSE AGRICULTURAL LANDSCAPES TO FAMILY FARMS

Location: Dale Bumpers Small Farms Research Center

Title: High temperature limits in vivo pollen tube growth rates by altering diurnal carbohydrate balance in field-grown Gossypium hirsutum pistils

Authors
item Snider, John
item Oosterhuis, Derrick -
item Loka, Dimitra -
item Kawakami, Eduardo -

Submitted to: Journal of Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 31, 2010
Publication Date: July 15, 2011
Citation: Snider, J.L., Oosterhuis, D.M., Loka, D.A., Kawakami, E.M. 2011. High temperature limits in vivo pollen tube growth rates by altering diurnal carbohydrate balance in field-grown Gossypium hirsutum pistils. Journal of Plant Physiology. 168(11):1168-75.

Interpretive Summary: Successful pollen tube growth on the day of flowering is a prerequisite for seed development in cotton. It has recently been reported that high temperature slows pollen tube growth rates in cotton pistils under field conditions. Although numerous physical and biochemical pollen-pistil interactions are necessary for pollen tube growth to occur, studies investigating the influence of heat-induced changes in pistil biochemistry on pollen tube growth rates are lacking. We hypothesized that high temperature would alter patterns of pistil biochemistry on the day of flowering and that pollen tube growth rates would be dependent upon the soluble carbohydrate content of the pistil during pollen tube growth. Cotton seeds were sown on different dates to obtain flowers exposed to contrasting ambient temperatures but at the same developmental stage. Pistil measurements included carbohydrate and energy balance, water-soluble calcium content, and antioxidant enzyme activity. Additionally, the relationship between pistil carbohydrate concentration and pollen tube growth rate was determined. High temperature increased antioxidant enzyme activity (glutathione reductase) in the pistil only during periods not associated with pollen tube growth, and pistil ATP and water soluble calcium were unaffected by the warmer temperatures. In contrast, soluble carbohydrate levels in cotton pistils were as much as 67.5% lower under high temperature conditions (34.6°C maximum air temperature; August 4, 2009) than under cooler conditions (29.9°C maximum air temperature; August 14, 2009), and pollen tube growth rates were highly correlated with the soluble carbohydrate content of the pistil during pollen tube growth. These findings suggest that the carbohydrate status of the pistil under high temperature may be a sensitive indicator of heat tolerance in cotton.

Technical Abstract: It has recently been reported that high temperature slows in vivo pollen tube growth rates in Gossypium hirsutum pistils under field conditions. Although numerous physical and biochemical pollen-pistil interactions are necessary for in vivo pollen tube growth to occur, studies investigating the influence of heat-induced changes in pistil biochemistry on in vivo pollen tube growth rates are lacking. We hypothesized that high temperature would alter diurnal pistil biochemistry and that pollen tube growth rates would be dependent upon the soluble carbohydrate content of the pistil during pollen tube growth. G. hirsutum seeds were sown on different dates to obtain flowers exposed to contrasting ambient temperatures but at the same developmental stage. Diurnal pistil measurements included carbohydrate balance, adenosine triphosphate (ATP), water-soluble calcium, superoxide dismutase, glutathione reductase and NADPH oxidase. Regression analysis was used to quantify the relationship between pistil carbohydrate concentration and pollen tube growth rates. High temperature increased GR activity in the pistil only during periods not associated with in vivo pollen tube growth, and pistil ATP and water soluble calcium were unaffected by the warmer temperatures. Soluble carbohydrate levels in cotton pistils were as much as 67.5% lower under high temperature conditions (34.6°C maximum air temperature; August 4, 2009) than under cooler conditions (29.9°C maximum air temperature; August 14, 2009), and pollen tube growth rates were highly correlated with the soluble carbohydrate content of the pistil during pollen tube growth (r2 = 0.932). We conclude that moderate heat stress significantly alters diurnal carbohydrate balance in the pistil and that decreased pollen tube growth rate through the style is limited by soluble carbohydrate supply in the pistil.

Last Modified: 9/23/2014
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