2,3,5-triiodobenzoic acid affects the in vitro propagation of Cedrela fissilis Vell. (Meliaceae) through alterations in endogenous polyamine and indol-3-acetic acid levels and the proteomic profile

Endogenous levels of some molecules, such as polyamines (PAs) and auxin, can be associated with the control of shoot and root development. The effects of 6-benzyladenine (BA), putrescine (Put) and the auxin transport inhibitor 2,3,5-triiodobenzoic acid (TIBA) on the development of Cedrela fissilis shoots, as well as the effects on endogenous alterations in PAs and variations in protein abundance, were investigated. Furthermore, the effects of Put and TIBA on ex vitro root development and the endogenous content of PAs were investigated. The BA + Put combined with TIBA treatment promoted an inhibition of shoot growth from cotyledonary nodal segments, decreasing endogenous total free PA levels and increasing IAA-free content compared to shoots treated with BA + Put without TIBA. A comparative proteomic analysis of BA + Put + TIBA-treated shoots showed reduced accumulation of proteins mainly related to cytoskeleton organization, carbon metabolism, and photosynthesis and increased accumulation of proteins related to the degradation of valine, leucine and isoleucine compared to those without TIBA. The percentage and number of rooted shoots were significantly reduced by Put + TIBA treatment, showing that auxin inhibitors and not Put are responsible for the decrease in rooting. These results show that the combination of BA + Put with the auxin transport inhibitor TIBA interferes with endogenous PA metabolism and alters protein abundance, thereby altering shoot development. Moreover, Put is not related to rooting induction in C. fissilis.