Figure 6.

PG Proteome Composition in Wild-Type Plants during Natural Leaf Senescence and mRNA Levels for PG Genes.

(A) PGM48 relative protein accumulation levels determined by label-free spectral counting quantitative proteomics of isolated PG at bolting stage and advanced senescence stage in the wild type. Results from two replicates of independent PG preparations were analyzed; relative abundance was normalized to the total amount of PG core protein. Plants were grown under short-day conditions (10 h light/14 h dark). For the complete abundance data of all PG core proteins, see Supplemental Data Set 1. CCD4 and PGM48 showed >4- to 5-fold difference between the bolting and advanced senescence stage.

(B) and (C) mRNA expression data from publicly available microarray data for leaves from the wild type (Col-0); data were downloaded from http://bar.utoronto.ca/. (B) shows the relative abundance ratio between mRNA from mature leaf 2 and senescent leaves for all genes encoding for the PG core proteome, except for FBN1B, HBP3, and ESTERASE1 for which no data are available. (C) shows mRNA abundance levels of individual leaves from 17-d-old rosettes (continuous light), with leaf 2 being the oldest and leaf 12 the youngest. This genes selected are PGM48 and CCD4, showing ABC1K7 and PES1 as senescence-induced genes for comparison and AKR as a gene not induced by senescence. CCD4 mRNA very prominently increases with leaf age but is clearly declining in senescent leaves; this contrasts with PGM48, which also increases with increasing leaf age but continues to increase in senescing leaves.