Transformation of Barnyardgrass ( Echinochloa crusgalli ) Root Type Phosphoenolpyruvate Carboxylase Gene into Rice ( Oryza sativa ) Plants and Their Effects on Photosynthesitic Gas Exchange

Abstract

Barnyardgrass(Echinochloa crusgalli) is a C4 weed commonly found in rice field. To fully utilize the photosynthestic potential of Barnyardgrass C4 gene, we transformed Barnyardgrass root Phosphoenolpyruvate Carboxylase gene into rice plant with vectors contained promoters of Ubiqitin gene and Rubisco small unit gene by Agrobactirium- mediated transformation. Both marker genes Hygr and ppc were detected by PCR in regenerated plants. RT-PCR and Western blot analysis confirmed that the ppc gene was incorporated into rice plant and expressed with stable transcripts and proteins. PEPC activity as measured in most of the transgenic rice plants was higher than that in control, being up to 5.85-fold of that in untransformed rice. At T0 generation, net photosynthetic rate(Pn) in most of transgenic rice plants was 20.00% higher than that in untransformed rice, with the highest increase of 47.16%. Water utilization efficiency(WUE) in transgenic rice was also improved. At T6 generation, PEPC activity and Pn of transgenic lines remained higher than those of the wild type. These indicate that over-expressing C3 Eppc gene also can improve rice photosynthesis.