Figure 4.

Relationship between HEMA1 expression, ALA synthesis, and greening ability in FRc-grown seedlings. A, ALA synthesis rates in seedlings of WT and the phyA mutant grown in the dark (black columns) or under 1 d of FRc (hatched columns), with or without 3% (w/v) Suc (as indicated). The inset graph shows the corresponding levels of Pchlide accumulated in the FR-irradiated WT and phyA seedlings. Data shown are the mean ± se (n = 3). B, Relationship between relative HEMA1 mRNA levels (as measured by densitometry scans of RNA gel blots) and corresponding rates of ALA synthesis in WT and phyA (inset) seedlings. Seedlings were allowed to germinate in the presence of 3% (w/v) Suc for 2 d in the dark and were transferred to FRc or maintained in the dark for an additional period of 1 or 3 d. Each datum point shows the individual value under either irradiation condition for these two incubation times for the Landsberg erecta (Ler) and Colombia (Col) backgrounds. C, Relationship between greening capacity measured after transfer to WL and ALA synthesis rates prior to transfer in dark- and FRc-grown WT (○) and phyA (●) seedlings. Seedlings were grown as for B. Data shown are the mean ± se (n = 3).