The inhibition of putrescine synthesis affects the in vitro shoot development of Cedrela fissilis Vell. (Meliaceae) by altering endogenous polyamine metabolism and the proteomic profile

Abstract

Polyamines —(PAs) and proteins have been demonstrated to be fundamental for in vitro shoot development of Cedrela fissilis. We evaluated the influence of 6-benzyladenine (BA) and putrescine (Put) on the growth of shoots, PA metabolism and proteomic profiles of C. fissilis. The longest shoots were obtained under 2.5 µM BA + 2.5 mM Put treatment. The inhibition of Put synthesis by d-arginine (d-arg) reduced the activities of the Put biosynthesis enzymes arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) and the endogenous contents of free Put, resulting in reduced shoot growth. The ODC activity was higher than that of ADC, being ODC the main enzyme in the synthesis of Put in C. fissilis. Inhibition of Put synthesis affected the proteomic profile, reducing the accumulation of the ubiquitin receptor RAD23c, peroxidase 15, ADP-ribosylation factor 1, ADP-ribosylation factor-like protein 8a, profilin-4, profilin-2, glucan endo-1,3-beta-glucosidase, and expansin-like B1 and increasing the accumulation of V-type proton ATPase catalytic subunit A and methionine gamma-lyase, highlighting the relevance of these proteins in promoting the length of shoots. Moreover, the transport protein SEC13 homolog B and the basic isoform glucan endo-1,3-beta-glucosidase, unique proteins in shoots treated with BA + Put, were related to the promotion of shoot growth. Our results show that the modulation of endogenous PAs and proteomic profiles is necessary to regulate in vitro morphogenesis in C. fissilis. Moreover, the ODC enzyme is highly involved in the synthesis of Put during in vitro shoot development and is described for the first time in this species.