Morpho-anatomical characterization of mature embryo-derived callus of rice (Oryza sativa L.) suitable for transformation

Abstract

The objective of this study was to morpho-anatomically characterize embryogenic rice calli during early induction of somatic embryogenesis of three Brazilian rice cultivars. Herein, we explored embryogenic units (EUs) from 2-week-old cut proliferated calli to verify whether they were suitable for Agrobacterium tumefasciens-mediated transformation. Histological analysis and scanning electron microscopy (SEM) were used to analyze these types of calli during early rice callogenesis in the cultivars BRS Primavera, BRS Bonança, and BRS Caiapó. The characteristics of the embryogenic cells were preserved in the EUs, which showed a globular, compact structure that contained tightly packed cells and thus rendered the cells suitable for transformation. The EUs of BRS Caiapó also maintained the characteristics of the non-embryogenic callus, such as an elongated morphology and a lack of cellular organization. In general, the observations of the histological sections corresponded with those of the SEM images. The histological analysis suggested that all cultivars used in these experiments have morphogenic potential. The EUs from proliferated 2-week-old cut calli maintained their embryogenic features. The EUs were subjected to Agrobacterium-mediated transformation, which exhibited a regeneration frequency of 58 % for transformed hygromycin-resistant cell lines. These results show that EUs from proliferated 2-week-old cut calli are suitable for plant transformation.

Somatic Embryogenesis: Fundamental Aspects and Applications

“…Bevitori et al (2014) characterized the induction of embryogenic calli from three Brazilian rice cultivars (BRS Primavera, BRS Bonança, and BRS Caiapó) by histological analysis and scanning electron microscopy (SEM) as an approach to establish a suitable transformation system. Genetic transformation is a key tool for gene function in rice and also for crop improvement programs.…”

Histological and ultrastructural analysis of the Banana cv. Prata-Anã embryogenic calluses and cell suspension

“…Callus induction is considered to be of great importance for obtaining well-formed somatic embryos and for the subsequent stages of development, maturation and conversion into plants (Bevitori et at., 2014). Histological studies of callus and cell suspensions can validate successful induction and progression of somatic embryogenesis (Dai et al, 2011).…”

Establecimiento de un sistema de selección in vitro de variedades venezolanas de arroz (Oryza sativa L.) resistentes al hongo Pyricularia grisea.

“…Asimismo, las elevadas y diferenciales respuestas regenerativas en función del cultivar, ratifican los hallazgos encontrados por diferentes investigadores, que evidencian altas frecuencias de regeneración en cultivares de arroz indica, al emplear medios suplementados con BA entre 2 mg.L-1 (Jan et al, 2001) y 2,5 mg.L-1 (Tariq et al, 2008) en callos embriogénicos, caracterizados por presentar una gran cantidad de masas proembriogénicas (Ge et al, 2006), las cuales exhiben centros meristemáticos, como nódulos o sacos de células pequeñas con mayor contenido citoplasmático, que son capaces de originar embriones somáticos (Bevitori et al, 2014).…”