UNASSIGNED: Plant productivity is determined in large part by the partitioning of assimilates between the sites of production and the sites of utilization. Proton-pumping pyrophosphatases (H+-PPases) are shown to participate in many energetic plant processes including general growth and biomass accumulation, @entity3158 fixation, nutrient acquisition, and stress responses. H+-PPases have a well-documented role in hydrolyzing @entity9955 ( @entity7371 ) and capturing the released energy to pump protons (H+) across the tonoplast and endomembranes to create proton motive force (pmf). Recently, an additional role for H+-PPases in phloem loading and biomass partitioning was proposed. In companion cells of the phloem, H+-PPases localize to the plasma membrane rather than endomembranes, and rather than hydrolyzing @entity7371 to create pmf, pmf is utilized to synthesize @entity7371 . Additional @entity7371 in the companion cells promotes Suc oxidation and @entity855 synthesis, which the plasma membrane P-type ATPase in turn uses to create more pmf for phloem loading of @entity969 via @entity969 -H+ symporters (SUTs). To test this model, transgenic @entity958 plants were generated with constitutive and companion cell-specific overexpression of @entity68782 , encoding Type-1 @entity958 Vacuolar Pyrophosphatase-1. Plants with both constitutive and companion cell specific-overexpression accumulated more biomass in shoot and root systems. 14C-labelling experiments showed enhanced photosynthesis, phloem loading, phloem transport, and delivery to sink organs. These results support the model for an alternative @entity8108 -PPases function in the phloem by arguing that the increases in biomass observed with @entity68782 overexpression stem from improved phloem loading and transport.

Constitutive and companion cell-specific overexpression of XXXX , encoding a proton-pumping pyrophosphatase, enhances biomass accumulation, phloem loading and long-distance transport.

@entity7371 :: ('CHEBI:60614', 'Chemical') :: ['PPi'] @entity958 :: ('3702', 'Species') :: ['Arabidopsis', 'Arabidopsis thaliana'] @entity68782 :: ('838138(Tax:3702)', 'Gene') :: ['AVP1'] @entity3158 :: ('D002245', 'Chemical') :: ['CO2'] @entity969 :: ('MESH:D013395', 'Chemical') :: ['sucrose'] @entity8108 :: ('D006859', 'Chemical') :: ['H+'] @entity9955 :: ('MESH:C107241', 'Chemical') :: ['pyrophosphate'] @entity855 :: ('MESH:D000255', 'Chemical') :: ['ATP']
@entity68782 :: (838138(Tax:3702),Gene) :: ['AVP1']
