Proline content and related gene expression in response to seasonal temperature variation in three Rosaceae fruit trees

Abstract

Seasonal patterns of proline (Pro) biosynthesis in peach (Prunus persica), plum (Prunus salicina), and apple (Malus x domestica) trees were compared by examining their Pro variation and relative gene expression. Pro levels in the shoots of peach and plum trees increased during spring and Pro level variations were similar during seasonal temperature changes. In apple, Pro content variation differed from that in Prunus species and were accumulated during the cold acclimation period and spring. Furthermore, the Pro contents in peach and plum shoots were positively correlated with the ornithine-d-aminotransferase (OAT) and pyrroline-5-carboxylate reductase (P5CR) expression. Although the Pro level in apple was not correlated with OAT, it was correlated with P5CR. Our study suggests that, under seasonal temperature variation, the ornithine pathway regulates Pro accumulation in the two Prunus species but not in M. x domestica.