The uptake of phenylalanine during imbibition by seeds of the garden pea,Pisum sativum

摘要

The uptake of phenylalanine during imbibition by seeds of the garden pea (Pisum sativum, var. Alaska) was studied using 1-14C-L-phenylalanine. The distribution of the radioactivity within the seed was observed using a radioautographic procedure. The results indicate that phenylalanine, while presumably diffusing passively with water, nevertheless exhibited some independence of movement. This conclusion is based on (a) the decline in counts per milliliter of the imbibition medium, and (b) the low activity observed in the axis tissue, an area which becomes hydrated early in the imbibition process. Entry of phenylalanine into the seeds appears to be entirely through the micropyle, with rapid diffusion across the cavity occupied by the shootndash;root axis and between the seed coat and cotyledon, followed by diffusion inwards through the cotyledon tissue.