Plant growth conditions
Oryza sativa L. ‘Notohikari’ wild-type, Rubisco-sense and antisense rice plants were used (Makino et al., 2000; Suzuki et al., 2007). Seeds were imbibed at 30 °C for three days and were subsequently grown on a plastic net floating on tap water for 3 weeks in an environmentally controlled phytotron (NK system, Japan). Subsequently, rice seedlings were grown in hydroponic culture (Makino et al., 1994). Here, we used six different Pi application conditions by changing NaH2PO4 concentration: 0.06 (low-Pi), 0.6 (control-Pi), 1.2,1.8, 2.4, and 3.0 mM. Na+concentration was normalized by applying NaCl. The pH of the hydroponic culture was adjusted to 5.2 with 6 M HCl, and it was replenished twice in a week. The chamber was maintained at 60 % relative humidity with a 14-h light (28 oC) and a 10-h dark (25oC) photoperiod. The light intensity was 500-600 µE m−2 s−1. All physiological and genetical analyses were performed for fully and newly expanded leaves after 70 days of their germination.