Analysis of protein patterns during shoot initiation in cultured Pinus radiata cotyledons

Patterns of protein synthesis were analysed during the early stages of culture of excised cotyledons of Pinus radiata grown under shoot-inductive and non-inductive conditions. The use of-high resolution two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) enabled the analysis of the changes in polypeptide content of, and synthesis in, the cotyledons. A total of 54 polypeptides were identified, whose synthesis and accumulation were affected by the culture conditions. These were divided into seven classes based on their pattern of appearance in the different cultures. One class consisted of-three polypeptides whose synthesis and/or accumulation was specifically enhanced in, but not unique to, shoot-forming (SF) cotyledons. The largest class consisted of 29 polypeptides whose synthesis appeared to be specifically repressed in the SF cotyledons, suggesting that part-of-the role of cytokinin in inducing shoot formation is to repress maturation-related changes in the SF tissues. The remaining five classes did not display a pattern of expression that could be related directly to the organogenic process.