Embriogénesis somática y producción de callo embriogénico friable de dos cultivares de yuca (Manihot esculenta Crantz) / Somatic Embryogenesis and friable embryogenic callus production in two cassava cultivars (Manihot esculenta Crantz)

La yuca (Manihot esculenta Crantz) es un cultivo de alta importancia en países tropicales. La transformación genética de yuca ha sido posible desde hace 15 años mediante la producción que callo embriogénico friable (CEF) a partir de embriones somáticos. En el presente trabajo se evalúan la inducción de embriones somáticos usando tres diferentes auxinas sintéticas y la producción de CEF a partir de éstos en los cultivares de yuca SG107-35 y BRA685. Estos cultivares son resistentes a la bacteriosis vascular de yuca cuyo agente causal es Xanthomonas axonopodis pv. manihotis, una de las principales limitantes del cultivo. Los resultados obtenidos muestran que en ambos cultivares la hormona Picloram a una concentración de 12 mg/l fue más eficiente que 2,4-D y Dicamba para producir embriones somáticos. Adicionalmente se consiguió la producción de CEF y la regeneración de plantas mediante embriogénesis somática en el cultivar BRA685. Los resultados del presente trabajo son importantes para evaluar la transformabilidad de distintos cultivares de yuca. Actualmente este número es bastante reducido principalmente porque la producción de CEF es fuertemente influenciada por el genotipo. Por tal razón solo se transforma de manera rutinaria y eficiente en el cultivar 60444. La posibilidad de transformación de distintos cultivares de yuca permitirá explotar la enorme variabilidad del cultivo, invitándonos a aumentar los esfuerzos para mejorar y universalizar los protocolos de transformación de yuca.

The cassava (Manihot esculenta Crantz) crop has a very important role as a food, feed and a raw material in developing countries; therefore it is a priority to develop technologies oriented to the solution of problems and agronomic improvement of the crop. The genetic transformation of cassava was developed 15 years ago by producing friable embryogenic callus (FEC) from somatic embryos as target tissue for transformation. In the present work we evaluated the induction of somatic embryos by using three different synthetic auxins and the production of FEC from both SG107-35 and BRA685 cassava cultivars; both are resistant to cassava bacterial blight caused by Xanthomonas axonopodis pv. manihotis, the most important bacterial disease affecting the crop. Our results showed that in both cultivars gave rise to somatic embryos in media containing Picloram at a concentration of 12 mg/l being more efficient than using 2,4-D or Dicamba. Additionally the cultivar BRA685 produced regenerative FEC giving rise to plants through somatic embryogenesis. However compared to the model cultivar 60444, FEC production was greatly lower. This work shows new efforts to increase the number of transformable cultivars of cassava and take advantage of the enormous genetic variability of the crop.

Carbon source dependent somatic embryogenesis and plant regeneration in cotton, Gossypium hirsutum L. cv. SVPR2 through suspension cultures.

Highly reproducible and simple protocol for cotton somatic embryogenesis is described here by using different concentrations of maltose, glucose, sucrose and fructose. Maltose (30 g/l) is the best carbon source for embryogenic callus induction and glucose (30 g/l) was suitable for induction, maturation of embryoids and plant regeneration. Creamy white embryogenic calli of hypocotyl explants were formed on medium containing MS basal salts, myo-inositol (100 mg/l), thiamine HCI (0.3 mg/l), picloram (0.3 mg/l), Kin (0.1 mg/l) and maltose (30 g/l). During embryo induction and maturation, accelerated growth was observed in liquid medium containing NH3NO4 (1 g/l), picloram (2.0 mg/l), 2 ip (0.2 mg/l), Kin (0.1 mg/l) and glucose (30 g/l). Before embryoid induction, large clumps of embryogenic tissue were formed. These tissues only produced viable embryoids. Completely matured somatic embryos were germinated successfully on the medium fortified with MS salts, myo-inositol (50 mg/l), thiamine HCl (0.2 mg/l), GA3 (0.2 mg/l), BA (1.0 mg/l) and glucose (30 g/l). Compared with earlier reports, 65% of somatic embryo germination was observed. The abnormal embryo formation was highly reduced by using glucose (30 g/l) compared to other carbon sources. The regenerated plantlets were fertile but smaller in height than the seed derived control plants.