BREAKING OF DORMANCY DURING AFTER-RIPENING OF TRITICUM-DURUM DESF - RNA, POLY(A)(-METABOLISM IN IMBIBED EMBRYOS()RNA AND PROTEIN)

Triticum durum DESF. caryopses have a relative dormancy which is relea sed during a period of after- ripening. Their embryos were studied dur ing seed storage under laboratory conditions at intervals of two month s, from harvest to loss of dormancy (six months). The metabolism of to tal RNA, poly(A)(+)RNA and proteins was studied on dry, early (40 min) , and late imbibed embryos (5 h, 25 h) with or without cordycepin, a p olyadenylation inhibitor. Results showed that the macromolecules studi ed were synthesized in both non after-ripened (dormant) and after-ripe ned (non dormant) embryos. However, after 2-4 months of storage, no sy nthesis was evident. The results suggest the occurrence, 2-4 months af ter harvest, of a transition phase from a metabolism typical of seed m aturation to a metabolism typical of germination. During after-ripenin g and imbibition, the embryos showed a degradation of some stored mRNA .