Integration of C₄-specific PPDK gene of maize to C₃ rice and its characteristics in relation to photosynthesis

Abstract

Pyruvate orthophosphate dikinase (PPDK) is a key enzyme in photosynthesis in some plants that exploit the C₄ photosynthetic pathway for the fixation of CO₂. The C₄-specific PPDK encoding pyruvate orthophosphate dikinase was introduced into C₃ plant, a rice (Oryza sativa L. cv. indica IR64) mediated by biolistic and Agrobacterium transformation. The C4-PPDK gene of maize was integrated to indica IR64 with polymerase chain reaction (PCR)-Southern blotting. The total nitrogen of flag leaves of transgenic IR64 was analyzed with Kjeldahl method for quantitative determination of nitrogen, indicating that the total nitrogen of flag leaves of most transgenic IR64 was higher than that of non-transgenic control IR64 formants in the greenhouse. The maximum value of total nitrogen of flag leaves was 3.61% among transgenic IR64 plants, 1.07% higher than that of non-transgenic control IR64 formants. The total nitrogen of flag leaves of transgenic IR64 was increased by 42.1%. The factors for yield of transgenic IR64 plants were analyzed, indicating there was a greater difference in yield-forming factors among transgenic IR64 plants in the greenhouse, i.e. dried plant weight, harvested index and so on. Thus, it could help rice breeders select different materials for breeding.