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Many metal transporters in plants are promiscuous, accommodating multiple divalent cations including some which are toxic to humans. Previous attempts to increase the iron (Fe) and zinc (Zn) content of rice endosperm by overexpressing different metal transporters have therefore led unintentionally to the accumulation of copper (Cu), manganese (Mn) and cadmium (Cd). Unlike other metal transporters, barley Yellow Stripe 1 (Hv YS1) is specific for Fe. We investigated the mechanistic basis of this preference by constitutively expressing Hv YS1 in rice under the control of the maize ubiquitin1 promoter and comparing the mobilization and loading of different metals. Plants expressing Hv YS1 showed modest increases in Fe uptake, root-to-shoot translocation, seed accumulation and endosperm loading, but without any change in the uptake and root-to-shoot translocation of Zn, Mn or Cu, confirming the selective transport of Fe. The concentrations of Zn and Mn in the endosperm did not differ significantly between the wild-type and Hv YS1 lines, but the transgenic endosperm contained significantly lower concentrations of Cu. Furthermore, the transgenic lines showed a significantly reduced Cd uptake, root-to-shoot translocation and accumulation in the seeds. The underlying mechanism of metal uptake and translocation reflects the down-regulation of promiscuous endogenous metal transporters revealing an internal feedback mechanism that limits seed loading with Fe. This promotes the preferential mobilization and loading of Fe, therefore displacing Cu and Cd in the seed. [ABSTRACT FROM AUTHOR]

Malnutrition is a prevalent and entrenched global socioeconomic challenge that reflects the combined impact of poverty, poor access to food, inefficient food distribution infrastructure, and an over-reliance on subsistence mono-agriculture. The dependence on staple cereals lacking many essential nutrients means that malnutrition is endemic in developing countries. Most individuals lack diverse diets and are therefore exposed to nutrient deficiencies. Plant biotechnology could play a major role in combating malnutrition through the engineering of nutritionally enhanced crops. In this article, we discuss different approaches that can enhance the nutritional content of staple crops by genetic engineering (GE) as well as the functionality and safety assessments required before nutritionally enhanced GE crops can be deployed in the field. We also consider major constraints that hinder the adoption of GE technology at different levels and suggest policies that could be adopted to accelerate the deployment of nutritionally enhanced GE crops within a multicomponent strategy to combat malnutrition. [ABSTRACT FROM AUTHOR]

Antioxidants are protective molecules that neutralize reactive oxygen species and prevent oxidative damage to cellular components such as membranes, proteins and nucleic acids, therefore reducing the rate of cell death and hence the effects of ageing and ageing-related diseases. The fortification of food with antioxidants represents an overlap between two diverse environments, namely fortification of staple foods with essential nutrients that happen to have antioxidant properties (e.g. vitamins C and E) and the fortification of luxury foods with health-promoting but non-essential antioxidants such as flavonoids as part of the nutraceuticals/functional foods industry. Although processed foods can be artificially fortified with vitamins, minerals and nutraceuticals, a more sustainable approach is to introduce the traits for such health-promoting compounds at source, an approach known as biofortification. Regardless of the target compound, the same challenges arise when considering the biofortification of plants with antioxidants, that is the need to modulate endogenous metabolic pathways to increase the production of specific antioxidants without affecting plant growth and development and without collateral effects on other metabolic pathways. These challenges become even more intricate as we move from the engineering of individual pathways to several pathways simultaneously. In this review, we consider the state of the art in antioxidant biofortification and discuss the challenges that remain to be overcome in the development of nutritionally complete and health-promoting functional foods. [ABSTRACT FROM AUTHOR]

Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas (CRISPR-associated system) has become the multipurpose tool to manipulate plant genome via their programmable sequence recognition, binding, and cleavage activities. Efficient plant genome modification often requires robust plant transformation. For most plant species, the CRISPR/Cas reagents are delivered into plants as plasmids by Agrobacterium-mediated T-DNA transfer or biolistic approaches. However, these methods are generally inefficient, heavily genotype dependent, and low throughput. Among the alternative plant transformation approaches, the protoplast-based transformation holds the potential to directly deliver DNA, RNA, or protein molecules into plant cells in an efficient and high-throughput manner. Here, we presented a robust and simplified protocol for protoplast-based DNA/ribonucleoprotein (RNP )-mediated genome editing in the model species Nicotiana benthamiana. Using this protocol, we have achieved the gene editing efficiency at 30-60% in protoplasts and 50-80% in regenerated calli and plants. The edited protoplasts can be readily regenerated without selection agents owing to highly efficient DNA or preassembled RNP transformation frequency. Lastly, this protocol utilized an improved culture media regime to overcome the complex media composition used in the previous studies. It offers quick turnaround time and higher throughput to facilitate the development of new genetic engineering technologies and holds the promise to combine with other genetic and genomic tools for fundamental and translational plant research., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Genetic improvement of rice is crucial to achieve global food security as rice is an important staple crop for more than half of the global population. One of the methodologies for genetic improvement is biolistic delivery of genetic components into plant cells. In this chapter, we describe steps involved in introducing plasmid DNA carrying gene of interest into rice mature embryos using Biolistic ® PDS-1000/He particle delivery system. We also provide information required for recovery of transformed plants and production of transgenic seed for next generation analysis. Using this protocol, typical 50-70 putative independent transgenic callus lines can be generated from 100 bombarded embryos. Transgenic rice plantlets can be produced within 2 months after the initiation of seed germination for transformation.