Transgenic Rice Expressing Cyanobacterial Bicarbonate Transporter Exhibited Enhanced Photosynthesis, Growth and Grain Yield
Under Low Co2 Or Alkaline Water Conditions, Cyanobacteria Use Bicarbonate Transporters To Pump In Bicarbonate As A Major Carbon Source. This Adaptive Co2 Concentrating Mechanism Allows Cyanobacteria To Survive Unfavorable Growth Conditions. In This Study, We Have Constitutively Expressed The High Affinity Bicarbonate Transporter Gene, IctB, From Cyanobacterium In Rice. All Four Transgenic Rice Lines Expressing The Transporter Exhibited Enhanced Photosynthetic Capacity, Growth And Grain Yield. Relative To Untransformed Wild Type Plants, The Transgenic Plants Had 10–30% Higher Photosynthesis Rates, 15–20% Higher Carboxylation Efficiencies, And Lower Photosynthetic Co2 Compensation Points. Activities Of Ribulose 1,5-Bisphosphate Carboxylase And Pep Carboxylase Were Also Higher In These Transgenic Lines. Consistently, The Transgenic Plants Produced 10–120% More Tillers Or Panicles Per Plant And 10–70% More Grains, Relative To The Wild Type. The Enhancements In Growth And Grain Yield Are Closely Related With The Increased Photosynthetic Capacity Among The Transgenic Lines. Yield Increases Were Also Confirmed In A Preliminary Field Trial. This Study Demonstrates That The Simple Co2 Concentrating Mechanism From Cyanobacterium Can Largely Improve The Photosynthetic Efficiency, Growth And Productivity Of C3 Crops.
KeywordsCyanobacterium bicarbonate transporter transgenic rice photosynthesis growth
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