“…In Picea abies, somatic embryos incubated with the auxin transport inhibitor NPA, showed defects in their ontogenetic process (Hakman et al, 2009;Petrášek and Friml, 2009). In a previous study conducted by our group in C. chinense (Regla-Márquez et al, 2019), PIN1 expression was highest at earlier stages of zygotic or somatic embryogenesis. These studies altogether support the hypothesis that the suspensor is another main source of IAA-hormone.…”