Responses of Arabidopsis thaliana in acclimation to decreases in growth irradiance

Due to the changing weather patterns, plants experience difficulties in surviving, so much so it could lead to stress conditions. Stress can be defined as an external factor that has detrimental influence on plants. Stress conditions can cause damage to plants and eventually can lead to death. To minimise the effects of stress, most plants are able to undergo a process named acclimation. A response mechanism to light irradiance is termed photoacclimation which is a phenotypic change in response to environmental adjustments in terms of light regime. Work by Athanasiou et al. (2010) showed that Arabidopsis grown at a low light intensity (100 ?mol m-2 s-1) had the ability to photosynthetically acclimate when being transferred to a higher light intensity (400 ?mol m-2 s-1). It was also found that the gene At1g61800, which encodes a Glucose-6-P/phosphate translocator (GPT2) is essential for this type of acclimation. GPT2 has a primary function of translocating sugar and phosphates across the chloroplast (Knappe et al., 2003). To confirm the impairment in acclimation of photosynthesis of gpt2 mutants, mutants were complemented with a copy of the gpt2 gene and it was shown that plants were able to acclimate. Therefore, it was concluded that GPT2 is important in dynamic acclimation to increased light in Arabidopsis. Previous studies also have shown that the gpt2 gene is also induced during sugar-feeding and sugar-induced senescence (Gonzali et al., 2006Li et al., 2006Pourtau et al., 2006). In order to study the plant mechanism under fluctuating light, the direction of light changing was studied separately as from low to high light and high to low light. This is to give better insights to how plants respond to each of set of light condition. In contrast to the work of Athanasiou et al., (2010), this work was designed to understand the acclimation of Arabidopsis WS and WS-gpt2 when plants were grown to maturity under high light condition and then transferred to a lower light condition. Plants were monitored by following the photosynthetic rate of low light plants upon transfer up to 9 days of acclimation. By doing the reverse acclimation, one question would be posed: Is this a simply the reverse of low to high light acclimation? The amount of light used in high light and low light was determined by previous work so that it would not put the plants in a stress condition. Besides, the high light condition (400 ?mol m-2 s-1) and low light condition (100 ?mol m-2 s-1) are set where the acclimation is clearly seen and maximum photosynthesis (Pmax) rate is achieved at this growth light intensity. (Copied from article)