No abstract

Due to the economic importance of wood production, species including Cedrela fissilis Vell. and Cariniana legalis (Mart.) Kuntze have been heavily exploited and are currently threatened with extinction. In addition, these species produce seeds with low viability when stored for long periods. In this work, the effect of storage time on seedling emergence and alterations in the levels of biomolecules such as carbohydrates, polyamines (PAs), and amino acids were analyzed in C. fissilis and C. legalis seeds. Seedling emergence and the emergence speed index were significantly reduced during seed storage in both species, with a greater reduction for C. legalis seeds. Sucrose was detected in both species, with the highest levels in C. fissilis seeds, whereas the monosaccharides glucose and fructose were detected only in C. legalis seeds. Higher levels of putrescine (Put) were observed in C. legalis seeds than in C. fissilis seeds. In contrast, C. fissilis seeds showed a significant increase in most of the amino acids analyzed. These results suggest that the presence of glucose and fructose, the higher level of Put, and the lower levels of amino acids observed in C. legalis seeds may be associated with greater reductions in vigor and seedling emergence compared with C. fissilis seeds. This is the first report showing these relationships among carbohydrates, PAs, and amino acids in these species and may be useful for further studies on seed conservation of timber species.

No abstract

No abstract

No abstract

Long-term subculture plays an essential role in the large-scale multiplication and production of somatic plantlets. We investigated the effects of long-term subculture on in vitro shoot development and ex vitro rooting associated with changes in the hormones and protein profiles in C. fissilis. The number of subcultures of shoots induced a decrease in the ex vitro rooting response. The reduction in adventitious root (AR) formation was associated with decreases in the contents of indole-3-acetic acid (IAA), abscisic acid (ABA), 12-oxo phytodienoic acid (OPDA), putrescine (Put), and spermine and increases in jasmonic acid (JA), jasmonoyl-isoleucine, trans-cinnamic acid, and salicylic acid contents in shoots at the fourth subculture compared to the first. The ornithine decarboxylase enzyme preferentially functions in the Put biosynthesis pathway and was related to the highest AR formation in shoots at the first subculture. Down-accumulation of the auxin-binding protein ABP19a in shoots from the fourth subculture compared to the first subculture was related to a decrease in both IAA contents and AR formation. In addition, down-accumulation of glucose-6-phosphate isomerase, glutamine synthetase leaf isozyme chloroplastic, 5-methyltetrahydropteroyltriglutamate-homocysteine methyltransferase, L-ascorbate peroxidase, cytosolic, monodehydroascorbate reductase, and 2-Cys peroxiredoxin BAS1-like, chloroplastic and up-accumulation of caffeoyl-CoA O-methyltransferase 1 and isoforms of peroxidase 4 proteins in shoots from the fourth relative to the first subculture were associated with a reduction in AR formation. These results showed that the understanding of hormonal and molecular mechanisms related to the potential of AR formation in shoots under successive subcultures is relevant to improving large-scale plantlet production in C. fissilis.

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 alteration of PAs and variations in protein abundance, were investigated. Furthermore, the effect of Put and TIBA on ex vitro root development and the endogenous content of PAs was 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.

No abstract