GPA3, GPA1/Rab5a, and GPA2/VPS9a Act Synergistically to Regulate Storage Protein Trafficking in Rice Endosperm.
(A) Immunoblot analysis of storage proteins in dry seeds using antiglutelin acidic subunit (top) and anti-α-globulin (middle) antibodies showing increased accumulation of 57-kD proglutelins (arrow), accompanied by reduced accumulation of acidic subunits (arrowhead) and α-globulins in various single and double mutants, compared with their respective wild-type variety. Antitubulin antibodies were used as a loading control (bottom).
(B) Quantitative comparison of the proglutelin intensity (proglutelins/acidic subunits) in the wild type, single mutants, and double mutants.
(C) Morphology comparison of PBIIs from subaleurone cells among the wild type, single mutants, and double mutants. Secondary antibodies conjugated with Alexa fluor 488 (green) were used to visualize the reaction between glutelins and antiglutelin acidic subunit antibodies. Bars = 10 μm.
(D) and (E) Quantitative comparison of PBII area (D) and number (E) in the wild type, single mutants, and double mutants. Values are means ± sd (n > 500, Student’s t test).