Abstract
Rice is the main food source in many countries in the world. One of the major limiting factors for rice growth and productivity is drought stress. In Bali there are several local rice cultivars, two of them are ‘Mansur' and ‘Putih Cempaka'. The cultivar ‘IR 64' is one rice cultivar released by IRRI. The responses of those rice cultivars to drought stress were tested. This study aimed to analyze growth responses and expression of DREB and SOD genes under drought stress induced by PEG. Rice seedlings were grown in a hydroponic system. Two weeks old seedlings were treated with PEG 20% (-0.49 MPa) and 30% (-1.03 MPa) for three days. Root to shoot ratio was calculated and chlorophyll content was measured. RNA was extracted from the shoot. Semi-quantitative real-time PCR was conducted and the products were visualized using 1% agarose gel electrophoresis. The result showed that root to shoot ratio increased as PEG concentration increased in all rice cultivars tested. The chlorophyll content decrease under PEG treatments in all rice cultivars. The expression of Superoxide Dismutase (Cu/Zn-SOD) gene increased under drought treatmentsin ‘Mansur’ and ‘Putih Cempaka’, while in ‘IR64’ using SOD primer tested, the gene was not expressed. The expression of Dehydration-Responsive Element Binding (DREB1) gene increased under PEG treatments both in ‘Mansur’ and ‘Putih Cempaka’.
Highlights
Rice (Oryza sativa L.) is a primary source of food for people in many countries including Indonesia
This study aimed to evaluate respond of Bali local rice ‘Mansur’ and ‘Putih Cempaka’ to drought stress at seedling stage and compare it to ‘IR64’ including root length, fresh weight root to shoot ratio, chlorophyll content and Dehydration-Responsive Element Binding (DREB) and Superoxide Dismutase (SOD) gene expression
The seedlings were grown for another week and Polyethylene Glycol (PEG) 6000 were added at the concentration of 20% (-0.49 MPa) and 30% (-1.03 MPa) as severe drought stress for three days, following Lima et al
Summary
Rice (Oryza sativa L.) is a primary source of food for people in many countries including Indonesia. Rice productivity is affected by several factors such as high temperature, salinity and drought stress. The main yield producing factor is drought stress (Karim and Rahman, 2015). Drought stress in plant is a condition of inadequate water availability in plant environment. This can be due to lack of water supply in the root areas and the need for excessive water by leaves because of high transpiration rate that exceeding the rate of water absorption (Farooq et al, 2012). Drought stress conditions change the structure of roots such as increased root branch and density (Eghball and Maranville, 1993)
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