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Cassava is a staple food used in many countries around the world, despite deficiencies in micronutrients such as provitamin A carotenoids. Unfortunately, improvement of the cassava nutritional content by use of conventional breeding is slow and difficult. Therefore, there is an urgent need to develop and standardize protocols using biotechnological tools to improve cassava. The Alliance of Biodiversity International and the International Center for Tropical Agriculture (CIAT) have worked on cassava genetic transformation over the last 30 years. Here, we describe, step by step, the procedures used for genetic transformation of cassava variety TMS60444, to improve carotenoids and other traits. This protocol includes stock setup, reagents, media preparation, materials, and equipment, for the genetic transformation of embryogenic tissues. The main expected output in publishing this protocol is to provide the basis for a reproducible and reliable method to genetically modify and/or gene edit Latin American and Asian cassava varieties.

The CRISPR gene-editing (GE) breeding method is used to increase the resilience of high-yielding tomato cultivars against pests and diseases, reducing crop protection requirements. This study investigated consumers’ willingness to buy CRISPR GE tomatoes in a repeated discrete-choice experiment. We observed a strong positive effect of providing information on the CRISPR breeding technology, while the sensory experience of the CRISPR GE tomatoes in a visit to a greenhouse had a rather weak, predominantly negative effect on the participants’ willingness to buy CRISPR GE tomatoes. We found that roughly half of the 32 participants demonstrated constant CRISPR GE tomato choices during the experiments, and these participants were mainly employed as scientists. However, the rest of the participants changed their CRISPR GE tomato choices, with the majority showing an increase in their willingness to buy CRISPR GE tomatoes; these “changers” were dominated by non-scientists. Science communication on CRISPR GE breeding technology should target people with little knowledge about the technology, and consumers of organic tomatoes seem to have more specified, stable preferences regarding the technology. Further, scientific information about the CRISPR GE methodology should preferentially be provided when new technology and information about it are not yet widespread and people have not yet formed a strong opinion about the technology.

The CRISPR gene-editing (GE) breeding method is used to increase the resilience of high-yielding tomato cultivars against pests and diseases, reducing crop protection requirements. This study investigated consumers’ willingness to buy CRISPR GE tomatoes in a repeated discrete-choice experiment. We observed a strong positive effect of providing information on the CRISPR breeding technology, while the sensory experience of the CRISPR GE tomatoes in a visit to a greenhouse had a rather weak, predominantly negative effect on the participants’ willingness to buy CRISPR GE tomatoes. We found that roughly half of the 32 participants demonstrated constant CRISPR GE tomato choices during the experiments, and these participants were mainly employed as scientists. However, the rest of the participants changed their CRISPR GE tomato choices, with the majority showing an increase in their willingness to buy CRISPR GE tomatoes; these “changers” were dominated by non-scientists. Science communication on CRISPR GE breeding technology should target people with little knowledge about the technology, and consumers of organic tomatoes seem to have more specified, stable preferences regarding the technology. Further, scientific information about the CRISPR GE methodology should preferentially be provided when new technology and information about it are not yet widespread and people have not yet formed a strong opinion about the technology.

Plant specialized metabolites are often synthesized and stored in dedicated morphological structures such as glandular trichomes, resin ducts, or laticifers where they accumulate in large concentrations. How this high productivity is achieved is still elusive, in particular, with respect to the interface between primary and specialized metabolism. Here, we focus on glandular trichomes to survey recent progress in understanding how plant metabolic cell factories manage to balance homeostasis of essential central metabolites while producing large quantities of compounds that constitute a metabolic sink. In particular, we review the role of gene duplications, transcription factors and photosynthesis.

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.

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.