Arabidopsis LEC1 and LEC2 Orthologous Genes Are Key Regulators of Somatic Embryogenesis in Cassava

High genotype-dependent variation in friable embryogenic callus (FEC) induction and subsequent somaclonal variation constitute bottlenecks for the application and scaling of genetic transformation (GT) technology to more farmer- and industry-preferred cassava varieties. The understanding and identification of molecular factors underlying embryogenic development in cassava may help to overcome these constraints. Here, we described the Arabidopsis thaliana LEAFY COTYLEDON (LEC) LEC1 and LEC2 orthologous genes in cassava, designated as MeLEC1 and MeLEC2, respectively. Expression analyses showed that both, MeLEC1 and MeLEC2, are expressed at higher levels in somatic embryogenic (SE) tissues in contrast with differentiated mature tissues. The rapid expression increase of MeLEC genes at early SE induction times strongly suggests that they are involved in the transition from a somatic to an embryonic state, and probably, in the competence acquisition for SE development in cassava. The independent overexpression of the MeLEC genes resulted in different regenerated events with embryogenic characteristics such as MeLEC1OE plants with cotyledon-like leaves and MeLEC2OE plants with somatic-like embryos that emerged over the surface of mature leaves. Transcript increases of other embryo-specific regulating factors were also detected in MeLECOE plants, supporting their mutual interaction in the embryo development coordination. The single overexpression of MeLEC2 was enough to reprogram the vegetative cells and induce direct somatic embryogenesis, which converts this gene into a tool that could improve the recovery of transformed plants of recalcitrant genotypes. The identification of MeLEC genes contributes not only to improve our understanding of SE process in cassava, but also provides viable alternatives to optimize GT and advance in gene editing in this crop, through the development of genotype-independent protocols

Seguridad alimentaria y nutricional en Colombia

Por su posicion y fisiografia, Colombia presenta una gran diversidad de zonas climaticas y cuenta con abundantes recursos agricolas y de agua dulce, una biodiversidad excepcional y gran riqueza en recursos naturales. La agricultura se caracteriza por monocultivos tecnificados por region (v.gr. cana de azucar, cafe, flores, algodon, platano, banano, sorgo, maiz, arroz, palma africana, papa y yuca, entre otros). Hay cultivos para consumo interno y se exportan cultivos de alto valor como cafe, banano, cana de azucar y palma africana. La agricultura en Colombia se vera afectada seriamente por el cambio climatico, tanto en seguridad alimentaria, como en la socioeconomia agricola. En relacion con seguridad alimentaria y nutricional (SAN) Colombia ocupa el decimo lugar en el Indice de Sostenibilidad Alimentaria y el noveno en agricultura sostenible (2016 Food Sustainability Index) y, si bien los porcentajes de desnutricion se han reducido, aun persiste en poblaciones de bajos ingresos asi como en indigenas. El 12,5% de la población se encuentra subalimentada. El pais muestra una transicion nutricional de su poblacion, y presenta problemas de deficit y exceso de peso en todos los grupos de poblacion. Se han asumido actividades de mitigacion y adaptacion al cambio climatico para enfrentar los retos de la produccion agricola sostenible. Colombia cuenta con capacidades cientificas y tecnologicas con trayectoria de larga data a pesar de la reduccion actual en el presupuesto de ciencia y tecnologia, y hay desarrollos en alternativas de solucion para el incremento en la productividad agricola en los diversos sistemas de cultivo con consideraciones territoriales. Se busca promover el incremento de la oferta agropecuaria para garantizar la seguridad alimentaria, promover las exportaciones agropecuarias y propender por el bienestar de los agricultores. Entre muchas de las iniciativas articuladas se destacan: la “Estrategia Colombia Siembra”, la “Mision para la Transformacion del Campo Colombiano” y la estrategia de “Crecimiento Verde”

Food and Nutrition Security in Colombia

As a result of its position and physiography, Colombia has an enormous diversity of climate zones, together with abundant agricultural and fresh water resources, an exceptional biodiversity and a wealth of natural resources. Its agriculture is characterized by technified monocultures by region (such as sugar cane, coffee, flowers, cotton, banana, banana, sorghum, maize, rice, African palm, potato and cassava). There are crops for domestic consumption, while highvalue crops such as coffee, sugar cane and African palm are exported. Agriculture in Colombia will be seriously affected by climate change, both in terms of food security and agricultural socioeconomics. In relation to food and nutritional security (SAN), Colombia ranks 10th in the Food Sustainability Index and the ninth in sustainable agriculture (2016 Food Sustainability Index), and although the percentages of malnutrition have decreased, they still persist in lowincome as well as indigenous populations. A total of 12,5% of the population is undernourished. The country reflects the nutritional transition of its population, and has problems of both underweight and overweight in all the population groups. Climate change mitigation and adaptation activities have been undertaken to address the challenges of sustainable agricultural production. Despite the current budget reduction for Science and Technology, colombian scientific and technological capacities are solid, with a long history, and there have been developments in alternative solutions to boost agricultural productivity in the diverse farming systems with territorial considerations. The aim is to boost the agricultural supply to guarantee food security and promote agricultural exports and farmers’ welfare. The many initiatives implemented include: The Colombia Plants Strategy; the Mission for the Transformation of the Colombian Countryside and the Green Growth strategy

A simple hydroponic hardening system and the effect of nitrogen source on the acclimation of in vitro cassava (Manihot esculenta Crantz)

Peer Revie

The potential of using biotechnology to improve cassava: a review

The importance of cassava as the fourth largest source of calories in the world requires that contributions of biotechnology to improving this crop, advances and current challenges, be periodically reviewed. Plant biotechnology offers a wide range of opportunities that can help cassava become a better crop for a constantly changing world. We therefore review the state of knowledge on the current use of biotechnology applied to cassava cultivars and its implications for breeding the crop into the future. The history of the development of the first transgenic cassava plant serves as the basis to explore molecular aspects of somatic embryogenesis and friable embryogenic callus production. We analyze complex plant-pathogen interactions to profit from such knowledge to help cassava fight bacterial diseases and look at candidate genes possibly involved in resistance to viruses and whiteflies—the two most important traits of cassava. The review also covers the analyses of main achievements in transgenic-mediated nutritional improvement and mass production of healthy plants by tissue culture and synthetic seeds. Finally, the perspectives of using genome editing and the challenges associated to climate change for further improving the crop are discussed. During the last 30 yr, great advances have been made in cassava using biotechnology, but they need to scale out of the proof of concept to the fields of cassava growers

Molecular analysis of the expression of a crtB transgene and the endogenous psy2-y1 and psy2-y2 genes of cassava and their effect on root carotenoid content

Peer Revie