Minimally altering a critical kinase for low-phytate maize

An Overview of Targeted Genome Editing Strategies for Reducing the Biosynthesis of Phytic Acid: an Anti-nutrient in Crop Plants

Anti-nutrients are substances either found naturally or are of synthetic origin, which leads to the inactivation of nutrients and limits their utilization in metabolic processes. Phytic acid is classified as an anti-nutrient, as it has a strong binding affinity with most minerals like Fe, Zn, Mg, Ca, Mn, and Cd and impairs their proper metabolism. Removing anti-nutrients from cereal grains may enable the bioavailability of both macro- and micronutrients which is the desired goal of genetic engineering tools for the betterment of agronomic traits. Several strategies have been adopted to minimize phytic acid content in plants. Pursuing the molecular strategies, there are several studies, which result in the decrement of the total phytic acid content in grains of major as well as minor crops. Biosynthesis of phytic acid mainly takes place in the seed comprising lipid-dependent and lipid-independent pathways, involving various enzymes. Furthermore, some studies show that interruption of these enzymes may involve the pleiotropic effect. However, using modern biotechnological approaches, undesirable agronomic traits can be removed. This review presents an overview of different genes encoding the various enzymes involved in the biosynthetic pathway of phytic acid which is being targeted for its reduction. It also, highlights and enumerates the variety of potential applications of genome editing tools such as TALEN, ZFN, and CRISPR/Cas9 to knock out the desired genes, and RNAi for their silencing.

Effect of fermentation using different lactic acid bacteria strains on the nutrient components and mineral bioavailability of soybean yogurt alternative

Introduction

Analysis of the composition of yogurt alternatives (YAs) during fermentation provides critical information for evaluating its quality and nutritional attributes.

Method

We investigated the effects of homotypic (HO) and heterotypic (HE) lactic acid bacteria on the nutritional and mineral bioavailabilities of soybean YA (SYA) during fermentation.

Result

The acidic amino acid (Glu, Asp) and organic acid contents in HO-fermented YA were increased from 2.93, 1.71, and 7.43 mg/100 g to 3.23, 1.82, and 73.47 mg/100 g, respectively. Moreover, both HO and HE lactic acid bacteria fermentation enhanced mineral absorptivity. They altered the molecular speciation of minerals from a large molecular type (2,866 Da) to a small molecular type (1,500 Da), which was manifested in a time-dependent manner. Furthermore, YA substantially increased the bone mass in a zebrafish osteoporosis model, further highlighting the potential of lactic acid bacterial fermentation for mineral bioavailability.

Discussion

This study provides a foundation for understanding the effects of fermentation conditions on the composition and bioavailability of minerals in YA and can assist in its production.

Genomic approaches for improving grain zinc and iron content in wheat

More than three billion people worldwide suffer from iron deficiency associated anemia and an equal number people suffer from zinc deficiency. These conditions are more prevalent in Sub-Saharan Africa and South Asia. In developing countries, children under the age of five with stunted growth and pregnant or lactating women were found to be at high risk of zinc and iron deficiencies. Biofortification, defined as breeding to develop varieties of staple food crops whose grain contains higher levels of micronutrients such as iron and zinc, are one of the most promising, cost-effective and sustainable ways to improve the health in resource-poor households, particularly in rural areas where families consume some part of what they grow. Biofortification through conventional breeding in wheat, particularly for grain zinc and iron, have made significant contributions, transferring important genes and quantitative trait loci (QTLs) from wild and related species into cultivated wheat. Nonetheless, the quantitative, genetically complex nature of iron and zinc levels in wheat grain limits progress through conventional breeding, making it difficult to attain genetic gain both for yield and grain mineral concentrations. Wheat biofortification can be achieved by enhancing mineral uptake, source-to-sink translocation of minerals and their deposition into grains, and the bioavailability of the minerals. A number of QTLs with major and minor effects for those traits have been detected in wheat; introducing the most effective into breeding lines will increase grain zinc and iron concentrations. New approaches to achieve this include marker assisted selection and genomic selection. Faster breeding approaches need to be combined to simultaneously increase grain mineral content and yield in wheat breeding lines.

Optimization of Protein Quality Assay in Normal, opaque-2, and Quality Protein Maize

The development of quality protein maize (QPM) was considered a significant leap toward improvement in the nutritional status of rural masses in developing countries. The nutritional quality of QPM is attributed to the higher concentration of essential amino acids, particularly lysine and tryptophan, in its kernel endosperm. However, the similarity in the grains of QPM and normal maize necessitates the development of a standard protocol to assess the protein quality of maize. The present study aimed at improving the protocol of protein quality assessment in QPM. For this purpose, endosperm defatting and protein estimation procedures were restandardized and optimized with respect to the protocol duration and its amenability for high-throughput analysis. Unlike normal maize, QPM and opaque-2 mutants were completely defatted within a 48 h period. It was observed that the tryptophan content, calculated at each defatting interval, increased in the samples defatted for a longer duration. No significant differences were observed in the tryptophan content analyzed in the samples defatted for 48 and 72 h. Moreover, the endosperm protein estimated by using the Bradford method with certain modifications strongly correlated with the micro-Kjeldahl method (r = 0.9). Relative to the micro-Kjeldahl method, the Bradford method was found to be precise, rapid, and hazard-free. The present findings enable a testing protocol of reduced time duration that can be used in resource-poor settings for the determination of a protein quality assay in QPM. Overall, the present study effectively helped in reducing the defatting time by 24 h and protein estimation by 3 h as compared to the already established International Maize and Wheat Improvement Center protocol. This is expected to enable the aggregation of high-protein-quality maize to facilitate its commercialization.

Current Advancements and Limitations of Gene Editing in Orphan Crops

Gene editing provides precise, heritable genome mutagenesis without permanent transgenesis, and has been widely demonstrated and applied in planta. In the past decade, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated proteins (Cas) has revolutionized the application of gene editing in crops, with mechanistic advances expanding its potential, including prime editing and base editing. To date, CRISPR/Cas has been utilized in over a dozen orphan crops with diverse genetic backgrounds, leading to novel alleles and beneficial phenotypes for breeders, growers, and consumers. In conjunction with the adoption of science-based regulatory practices, there is potential for CRISPR/Cas-mediated gene editing in orphan crop improvement programs to solve a plethora of agricultural problems, especially impacting developing countries. Genome sequencing has progressed, becoming more affordable and applicable to orphan crops. Open-access resources allow for target gene identification and guide RNA (gRNA) design and evaluation, with modular cloning systems and enzyme screening methods providing experimental feasibility. While the genomic and mechanistic limitations are being overcome, crop transformation and regeneration continue to be the bottleneck for gene editing applications. International collaboration between all stakeholders involved in crop improvement is vital to provide equitable access and bridge the scientific gap between the world's most economically important crops and the most under-researched crops. This review describes the mechanisms and workflow of CRISPR/Cas in planta and addresses the challenges, current applications, and future prospects in orphan crops.