Histological analysis of somatic embryogenesis of Melia azedarach and Prosopis alpataco.

BOERI P; ARAMBARRI A; ROMERO ALVES M; RANGEL CANO R; CABRERA PONCE; BARRIO DA; SHARRY, S

La Plata

Conferencia; 4th International Conference of the IUFRO Working Party 2.09.02; 2016

IUFRO

Histological methods contribute significantly to the understanding of in-vitro tissue culture systems, sincethey provide information since they provide information to be able to make the right decisions to optimizein vitro propagation protocols. Melia azedarach (chinaberry) and Prosopis alpataco (alpataco) are twomultipurpose woody species. They provide wood, food and varied use of active principles. Cotyledonsplaced in the induction medium were used to induce somatic embryogenesis (Sharry et al. 2006; Boeri etal. 2015). Both species are managed to differentiate between morphogenic and not morphogenic callus. Inchinaberry there were no differences between the embryogenic calli to the organogenic, since both processestook place in the same type of callus. This mixed callus originated both organs and embryos. They wereanalyzed microscopically showing the coexistence of processes of differentiation as meristemoids, shoots,somatic embryos and vascular tissue, as well as still dedifferentiated cells. Prosopis cotyledons producedonly somatic embryos. In both, pro-embryogenic (ce) and non-embryogenic (cne) cells were observed. Are-differentiation process took place in different types of cells with intense cell divisions that were locatedin regions distributed randomly. The cne were rounded or elongated, of thin walls, cytoplasm little dense.The ce were also rounded, small, with relatively thick-walled, dense cytoplasm and prominent nucleus,which is colored in deep red; typical characters of meristematic and pro embryogenic cells. Embryogenesiswas initiated in individual cells located in the periphery of the callus and from superficial cells from ce cellsexisting. Divisions observed in these surface cells adopt the affirmation of the unicellular origin of embryosobtained in alpataco and chinaberry. The different stages of embryogenic development observed in bothspecies were similar to a process of embryogenesis in vivo, suggesting the genetic potential of the plantbeing used. The formation of somatic embryos was a continuous process during the period of incubation ofthe explants. Given that not all cells differentiate into somatic embryos at the same time, it was possible toobserve all the stages of development of the embryo in a same callus. Finally, somatic embryos germinatednormally. Both processes of somatic embryogenesis were highly similar despite the no systematicrelationship of the species studied, but the explants and environmental conditions were similar. In vitrodevelopment of cells and tissues depends on different factors such as: genotype, type of plant, age anddevelopmental stage of an explant, physiological state of an explant-donor plant, and the externalenvironment which includes composition of media and physical culture conditions. The majority of themechanisms that regulate plant embryogenesis still remain to be clarified. The availability of model systemsof plant somatic embryogenesis in woody perennials has created effective tools for examining the details ofplant embryogenesis. However, studies that used no model plants for somatic embryogenesis systems alsorevealed the molecular mechanisms in charge of controlling the expression of some genes during somaticembryogenesis, and with practical applications. Nowadays SE can be achieved for any plant provided thatthe appropriate explant and adequate culture treatment.