Figure 6.

Translational activity and machinery in rice seed tissues. (A–C) Translational activities in isolated embryos and embryoless endosperms during germination sensu stricto. (A) Germination of isolated rice embryos (top panel) or complete seeds (lower panel) as evidenced by coleoptile emergence (arrows). Scale bars represent 2 mm. (B,C) Radiolabeled [³⁵S]-Methionine incorporation during 24 h of imbibition in 20 isolated embryos (E0) or five embryoless endosperm (A0). (B) [³⁵S]-Methionine incorporation per seed in isolated embryo (E0) and embryoless endosperm (A0). (C) [³⁵S]-Methionine incorporation per microgram of total protein in E0 and A0. Results are the mean (± SD) of three biological replicates and are expressed on a seed equivalent basis for comparison. Signal integration was performed during 10 min. Student's t-tests were applied to identify statistically significant differences (^* means statistically significant as P < 0.05 and ^** means statistically highly significant as P < 0.01). (D) Embryo and endosperm proteins involved in translation initiation identified in the dry mature rice seed. For each protein family, the number of proteins found in the rice seed proteome is indicated. Embryo-specific proteins (E0) are indicated along with their locus number. eIF, eukaryotic translation initiation factor; Met, methionine; PABP, polyadenylate-binding protein.