Starch turnover is stimulated by nitric oxide in embryogenic cultures of Araucaria angustifolia

Abstract

Embryogenesis is a complex developmental process dependent on the intercommunication of coordinated signals. Among these signals, carbohydrate metabolism seems to be central, modulating responses according to the spatio-temporal environmental variations. Nitric oxide (NO) is a molecule that is extensively involved in various growth processes; however, the regulatory mechanism effect of NO signaling on carbohydrate metabolism is still largely unknown. Thus, in this study, we investigated the interaction between carbohydrate metabolism and NO homeostasis. First, the expression values of sucrose, raffinose, and starch metabolisms target genes were evaluated during Araucaria angustifolia zygotic and early somatic embryo development. This result demonstrated that starch metabolism targets highlighted the differences between zygotic embryo development and progression in early somatic embryo establishment. Therefore, non-structural carbohydrate content, NO emission, and starch metabolism-related genes were evaluated under treatments with donor, scavenger, or inhibitor of NO biosynthesis. These analyses were conducted at the somatic embryogenesis proliferation phase. In this work, the results showed that NO acted on the starch content, and in a different way between cell lines with contrasting responsiveness for the development of early somatic embryos. This indicates that the modification of starch accumulation by NO might be an effective strategy to optimize the in vitro conditions for A. angustifolia somatic embryo development.