HEAT STRESS EFFECTS ON GROWTH AND DEVELOPMENT IN THREE ECOTYPES OF VARYING LATITUDE OF ARABIDOPSIS

Abstract. Global temperatures have increased 0.6 °C over the past century; however regional temperatures have shown greater fluctuations. Since local environmental conditions vary along latitudinal clines, latitude has become an essential component in projecting plant response to warming. Three ecotypes of Arabidopsis were selected from varying latitudes in order to investigate heat stress within an ecotype and project potential effects across a gradient. Control and heat stressed groups received 12 hour photoperiods. Control plants were grown at 2.7/22.7 °C day/night mean temperatures and heat stressed plants were grown at 22.7/29 °C day/night mean temperatures. Plants were quantified and harvested 35 days after sowing. The number of rosette leaves, flower buds, and fruits resulted in significant differences both between control and heat stressed plants of the same ecotype and also across ecotypes. Heat overwhelmingly resulted in a quantitative decrease across all parameters, including overall plant size, with the exception of flowers in ecotype 902. And even though the heat stressed 902 plants flowered while the control group plants did not, neither produced fruit. Thus, heat adversely affects growth and development as well as reproductive success in Arabidopsis