Figure 5.

Evidence for GA as the Mobile Shoot-Derived Signal That Triggers Hypocotyl Xylem Expansion upon Flowering.

(A) Examples of scion and stock hypocotyl sections from micrograftings of indicated genotypes, sampled at 8 d after flowering.

(B) Xylem area quantification of scion and stock hypocotyls obtained from indicated micrograftings, sampled at 8 d after flowering. Error bars are se.

(C) Examples of scion and stock hypocotyl sections from micrograftings of indicated genotypes, sampled at 8 d after flowering.

(D) Xylem area quantification of scion and stock hypocotyls obtained from indicated micrograftings, sampled at 8 d after flowering. Error bars are se.

(E) Expression level quantifications of GA biosynthetic genes in SUC2:CO-GR transgenic plants (co-2 mutant background), comparing hypocotyls and shoots of 9-d-old mock-treated samples and samples treated with dexamethasone (dex) from 6 to 8 d after germination to induce flowering and thereby xylem expansion. Averaged relative expression levels normalized with respect to the EF1 housekeeping gene are indicated. Expression was quantified for all genes in each of three replicates; measurements represent the average of the relative expression with respect to EF1 from each sample. Error bars are se.

(F) Same experiment as (E), for GA catabolic genes. Error bars are se.

(G) Examples of scion and stock hypocotyl sections from micrograftings of indicated genotypes, sampled at 8 d after flowering.

(H) Xylem area quantification of scion and stock hypocotyls obtained from indicated micrograftings, sampled at 8 d after flowering. Error bars are se.

(I) Development of a ga1-3 shoot scion grafted onto a Ler root stock.

(J) Development of a ga1-3 shoot scion grafted onto a ga1-3 root stock. n.s., not significant; *P < 0.05; **P < 0.01; ***P < 0.001.