In vitro regeneration of the important North American oak species Quercus alba, Quercus bicolor and Quercus rubra

Abstract

North American oak species, with their characteristic strong episodic seasonal shoot growth, are highly problematic for clonal micropropagation, resulting in the inability to achieve a stabilized shoot multiplication stage. The potential for initiating and proliferating shoot cultures derived from Quercus alba, Q. bicolor and Q. rubra explants was investigated, and a micropropagation method for these species was developed. Branch segments from 6 to 7-year-old trees were forced-flushed and the forced shoots were used as source of explants for culture initiation. A consistent shoot multiplication stage was achieved, in 13 of the 15 genotypes established in vitro, although marked differences occurred in explants from different genotypes/species. The control of efficient shoot multiplication involved the culture of decapitated shoots in a stressful horizontal position on cytokinin-containing medium with a sequence of transfers within a 6-week subculture cycle, which was beneficial to overcoming the episodic character of shoot growth. During each subculture cycle, the horizontally placed explants were cultured on media containing 0.2 mg l -1 benzyladenine (BA) for 2 weeks with two successive transfers (2 weeks each) to fresh medium with 0.1 mg l -1 BA, giving a 6-week subculture cycle. The general appearance and vigor of Q. alba and Q. bicolor shoot cultures were improved by the inclusion of both 0.1 mg l -1 BA and 0.5 mg l -1 zeatin in the medium used for the second transfer within the 6-week subculture cycle. Addition of AgNO 3 (3 mg l -1 ) to the shoot proliferation medium of Q. rubra had a significant positive effect on shoot development pattern by reducing deleterious symptoms, including shoot tip necrosis and early senescence of leaves. The three species showed acceptable in vitro rooting rates by culturing microcuttings in medium containing 25 mg l -1 indolebutyric acid for 48 h with subsequent transfer to auxin-free medium supplemented with 0.4% activated charcoal. Although an initial 5-day dark period generally improved the rooting response, it was detrimental to the quality of regenerated plantlets. However, activated charcoal stimulated not only the rooting frequencies, but it also enhanced plant quality, as evidenced by root, shoot and leaf growth.

Direct adventitious shoot organogenesis and plant regeneration from cotyledon explants in Neolamarckia cadamba

“…Nodal sub-culturing in micro-shoot proliferation, which has been successful for some hardwoods and herbaceous plants, many species of oak (Vieitez et al 2009), Bixa orellana (Parimalan et al 2011), Senecio cruentus (Sivanesan and Jeong 2012), and Piper longum (Rani and Dantu 2012), was also effective with N. cadamba in the present study (data not shown).…”

Enraizamento de inhame em meios MS e carvão ativado

“…VIEITEZ et al (2009), contudo, para Bauhinia cheilantha, nas concentrações de 0; 1,0 e 2,0 g L -1 de carvão ativado testadas, não se observaram efeito favorável para a variável em análise, independentemente da concentração de regulador utilizada (GUTIÉRREZ et al, 2011 O desenvolvimento do sistema radicular a partir da formação de raízes adventícias, em plantas propagadas vegetativamente sob condições in vitro ou in vivo, é um processo de grande complexidade e envolve diversos fatores que ainda não estão completamente elucidados (SOUZA & PEREIRA, 2007). Com isso, é necessário fazer outros estudos adicionando outros reguladores de crescimento associados ao carvão ativado para comprovar qual a melhor inte-ração para promover o enraizamento in vitro.…”

RESPUESTAS MORFOGÉNICAS EN LA PROPAGACIÓN in vitro DE NOGAL PECANERO (Carya illinoinensis [Wangenh] K. Koch)

“…Los resultados aquí encontrados coinciden con los reportados por Poornima y Ravishankar (2007), quienes encontraron que el CA fue más eficaz que el PVP en la disminución de la exudación fenólica en Psidium guajava L. Estos autores también observaron que 60 % de los explantes sembrados en el medio de cultivo MS, suplementado con PVP, mostró oxidación después de 30 días de incubación. En encino, la aplicación de 3 mg·L -1 de AgNO 3 disminuyó el necrosamiento y la senescencia temprana de explantes de hojas durante la etapa de iniciación (Vieitez et al, 2009). Los efectos deletéreos en P. pinaster, debido a los fenoles, también fueron reducidos por la adición de CA en el medio de cultivo como lo señala Lelu-Walter et al (2006) y Álvarez et al (2009), quienes sugieren que este resultado puede atribuirse a la propiedad higroscópica del compuesto en el medio de iniciación.…”

“…There are studies that describe micropropagation protocols of P. pinaster based on organogenesis and somatic embryogenesis, using culture methods that contain both growth regulators and antioxidants (Álvarez et al, 2009). Various antioxidants have been applied in the culture medium to reduce tissue necrosis during the initiation stage of the explants extracted from woody species (Aliyu, 2005;Nomura, Matsumoto, Masuda & Inoue, 1998;Poornima & Ravishankar, 2007;Vieitez et al, 2009. In pecan micropropagation different types of tissue of the plant have been used (Rodríguez & Wetzstein, 1994), as well as somatic embryos (Long, Preece & Sambeeck, 1995).…”

“…Existen estudios que describen protocolos de micropropagación de P. pinaster basados en organogénesis y embriogénesis somática, utilizando medios de cultivo que contienen tanto reguladores de crecimiento como antioxidantes (Álvarez et al, 2009). Varios antioxidantes se han aplicado en el medio de cultivo para disminuir el necrosamiento del tejido durante la etapa de iniciación de los explantes extraídos de especies leñosas (Aliyu, 2005;Nomura, Matsumoto, Masuda & Inoue, 1998;Poornima & Ravishankar, 2007;Vieitez, Vieitez et al, 2009. En la micropropagación de nogal se han utilizado diferentes tipos de tejido de la planta (Rodríguez & Wetzstein, 1994), así como embriones somáticos (Long, Preece, & Sambeeck, 1995).…”