Figure 2.

fbl17 Mutants Show Severe Growth and Developmental Alterations and Overaccumulate the KRP2 Protein.

(A) Relative expression levels of FBL17 transcripts were determined by quantitative RT-PCR in the two mutant lines fbl17-1 and fbl17-2 and compared with Col-0 and the respective fbl17± heterozygous mutant lines. The bar graph depicts expression level mean values of FBL17 transcripts of one independent replicate (±se of the technical triplicate). The experiment was repeated at least three times giving the same results. The locations of the quantitative PCR primers used to quantify FBL17 transcript levels are indicated in Supplemental Figure 1.

(B) and (C) Using leaves 1 and 2 of 20-d-old seedlings of the indicated genotypes grown under in vitro conditions (B), leaf areas were scored (C). The bar graph depicts mean leaf areas (±sd) of five independent replicates based on five leaf pairs per genotype, except for krp2-3 krp5-1, for which three replicates were performed, and for pFBL17:FBL17i lines, for which two pairs were analyzed in two independent replicates. According to Student’s t test, * and # indicate P ≥ 0.05 and ** and ## indicate P ≤ 0.05 when compared with Col-0 and fbl17-1 bulked data, respectively. Bars in (B) = 1 cm.

(D) to (F) fbl17-1 and fbl17-2 mutants compared with fbl17-1± heterozygous plants grown on soil for 7 weeks (D) and 11 weeks (E). FBL17 loss-of-function mutants eventually flower and produce short siliques but are fully sterile (F). Bars = 1 cm.

(G) Immunoblot analysis using an antibody against endogenous KRP2 (@KRP2) revealed strong accumulation of the protein in the fbl17-1 null mutant and pFBL17:FBL17i lines. Coomassie blue staining was used as a loading control (CB). Three independent replicates were performed, yielding similar results.