Water Loss and Gene Expression of Rice (Oryza sativa L.) Plants Under Dehydration
This study aims to determine physiological and molecular alterations as exposed to dehydration stress in rice plant. Rice seedlings were grown in a nutrient solution within a managed environment chamber prior to the imposition of the dehydration stress. Dehydration was imposed through uprooting and exposing to controlled environment condition (25°C, RH 50%, and 290 PAR). Water loss of intact plant was determined by continuous weightings with every minute interval till 300 minutes after starting the imposition of dehydration. The imposition of dehydration caused signifi cant loss of internal water, resulting in 44% out of initial water content at 300 minutes-long dehydration. The dehydration imposition also reduced the rate of water loss per minute per gram dry weight from 14.2 to 2.1 mg min−1 g dry weight−1. These results indicate that the dehydration imposition could causes osmotic stress due to water loss in tissue. The dehydration stress also reduced signifi cantly relative water content and osmotic potentials over the time. The dehydration stress induced the mRNA expression of drought-induced protein (Dip1), drought-induced hydrophobic protein (DRR2) and mitogen-activated protein kinase (MAPK). MAPKs were mostly expressed before 20% water loss out of the initial water content. However, Dip1 and DRR2 were strongly expressed after 20–40 water loss out of the initial water content. These results indicate that the physiological parameters such as water loss rate and water status can be used a physiological scale, especially to explore the genes related to simple response and/or tolerance against internal water deficit.
KeywordsDehydration gene expression osmotic stress rice water loss
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