Figure 6.

Effect of calcium on the germination and phenotype of pollen tubes. A and B, Germination percentage of wild-type (black bars) and pme48−/− (gray bars) pollen grains in the optimal solid medium (5 mm CaCl₂), in the optimal solid medium supplemented with 1 mm EDTA, and in the optimal medium supplemented with 2.5 mm calcium (i.e. final concentration of CaCl₂, 7.5 mm) after 6 h (A) and 24 h (B) of growth. Pollen grains were considered germinated when the length of the tube was equal to the diameter of the pollen grain. C, Estimation of the imbibition rate by measuring the ratio of length to width of wild-type (black bars) and pme48−/− (gray bars) pollen grains in the solid medium containing 7.5 mm CaCl₂. D, Estimation of the rate of burst pollen tubes in the wild type (wt; black bar) and pme48−/− (gray bar) in solid medium containing 7.5 mm CaCl₂. E, Estimation of the rate of pollen grains with two emerging tips in the wild type (black bar) and pme48−/− (gray bar) in solid medium containing 7.5 mm CaCl₂. Different letters indicate statistically significant differences between the wild-type and pme48−/− lines, as determined by Student’s t test (P < 0.0001); n > 1,000 in A and B; n > 500 in C; and n > 250 in D and E.