Proline-14C metabolism in barley seedlings during vernalization

The metabolism of proline-¹⁴C was examined in vernalized (LT)and unvernalized (HT) barley shoots. The content of prolinein cytoplasmic and cell wall protein fractions was a littlehigher in HT, against the accumulation of free proline in LT.Proline-¹⁴C was more heavily incorporated into HT and the cytoplasmicprotein had a higher radioactivity than the cell wall protein.In LT, the activity in the cytoplasmic protein was lower thanthat in the cell wall. The time course of incorporated proline-¹⁴Cshowed no distinct changes in HT. but decreased remarkably inthe LT cell wall. The distribution of proline-¹⁴C in hydroxyproline and otheramino acids in the two proteins was examined. In the cytoplasmicproteins, the conversion pattern of proline-¹⁴C was very similarin both treatments. The highest hydroxyproline activity wasfound at the beginning of incubation and was maintained at acomparatively high level in the HT cell wall. The LT cell wallshowed a gradual increase in radioactivity due to hydroxyprolineand reached maximum conversion at the last incubation period.Distribution of radioactivity due to incorporated proline-¹⁴Cwas examined by separating barley shoot tissues into three sections. (Received December 5, 1972; )