| Preparation |
Arabidopsis thaliana (Col-0) plants were used as the wild type in this study. MYB12OX and pap1-D were described previously (Borevitz et al., 2000; Mehrtens et al., 2005). Homozygous WOX1-1 and WOX1-2 were prepared by crossing MYB12OX and pap1-D, followed by self-fertilization of the F1 generation. Two progenies, exhibiting both Basta and kanamycin tolerance in the F2 and F3 generations, were obtained and named WOX1-1 and WOX1-2. The homozygous MYB12OX/tt4 and pap1-D/tt4 lines were prepared by crossing MYB12OX or pap1-D with tt4, respectively. Progenies that exhibited both Basta and kanamycin tolerance (F2 and F3 generations) were obtained. Sterilized seeds were kept for 2 days at 4°C in the dark and were sown on plates of growth medium (GM) agar containing 1% sucrose (Valvekens et al., 1988). Black paper was used for wrapping the plates used for the light-shielding condition. All plates were set in a growth chamber at 22°C and a relative humidity of approximately 60% under a 16-h light (approximately 40 μmol sec-1 m-2)/8-h dark cycle. The drought stress experiment was conducted at 21°C and 40 ± 5% relative humidity under 16 h/8 h light/dark conditions in a plant growth room. Harvested plant samples were immediately frozen in liquid nitrogen and stored at -80°C until use. |