Corrigendum: A promoter toolbox for tissue-specific expression supporting translational research in cassava ().

[This corrects the article DOI: 10.3389/fpls.2022.

A promoter toolbox for tissue-specific expression supporting translational research in cassava ().

There is an urgent need to stimulate agricultural output in many tropical and subtropical countries of the world to combat hunger and malnutrition. The starchy crop cassava (), growing even under sub-optimal conditions, is a key staple food in these regions, providing millions of people with food. Cassava biotechnology is an important technique benefiting agricultural progress, but successful implementation of many biotechnological concepts depends on the availability of the right spatiotemporal expression tools.

Mutations in DNA polymerase δ subunit 1 co-segregate with CMD2-type resistance to Cassava Mosaic Geminiviruses.

Cassava mosaic disease (CMD) suppresses cassava yields across the tropics. The dominant CMD2 locus confers resistance to cassava mosaic geminiviruses. It has been reported that CMD2-type landraces lose resistance after regeneration through de novo morphogenesis.

Novel rice iron biofortification approaches using expression of ZmYS1 and OsTOM1 controlled by tissue-specific promoters.

Intrinsic improvement of iron (Fe) concentration in rice grains, called rice Fe biofortification, is a promising countermeasure against widespread human Fe deficiency. In this study, two novel rice Fe biofortification approaches are reported. The first approach (Y approach) involved the expression of maize YELLOW STRIPE 1 controlled by the HEAVY METAL ATPASE 2 promoter.

Natural Variation in Vitamin B and Vitamin B Contents in Rice Germplasm.

Insufficient dietary intake of micronutrients contributes to the onset of deficiencies termed hidden hunger-a global health problem affecting approximately 2 billion people. Vitamin B (thiamine) and vitamin B (pyridoxine) are essential micronutrients because of their roles as enzymatic cofactors in all organisms. Metabolic engineering attempts to biofortify rice endosperm-a poor source of several micronutrients leading to deficiencies when consumed monotonously-have led to only minimal improvements in vitamin B and B contents.

The haplotype-resolved chromosome pairs of a heterozygous diploid African cassava cultivar reveal novel pan-genome and allele-specific transcriptome features.

Background: Cassava (Manihot esculenta) is an important clonally propagated food crop in tropical and subtropical regions worldwide. Genetic gain by molecular breeding has been limited, partially because cassava is a highly heterozygous crop with a repetitive and difficult-to-assemble genome.

Findings: Here we demonstrate that Pacific Biosciences high-fidelity (HiFi) sequencing reads, in combination with the assembler hifiasm, produced genome assemblies at near complete haplotype resolution with higher continuity and accuracy compared to conventional long sequencing reads.

Efficient Genetic Transformation and Regeneration of a Farmer-Preferred Cassava Cultivar From Ghana.

Cassava is an important staple crop that provides food and income for about 700 million Africans. Cassava productivity in Africa is limited by viral diseases, mainly cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). Genetic barriers such as high heterozygosity, allopolyploidy, poor seed set, and irregular flowering constrain the development of virus-resistant cassava varieties conventional breeding.

Current progress and challenges in crop genetic transformation.

Plant transformation remains the most sought-after technology for functional genomics and crop genetic improvement, especially for introducing specific new traits and to modify or recombine already existing traits. Along with many other agricultural technologies, the global production of genetically engineered crops has steadily grown since they were first introduced 25 years ago. Since the first transfer of DNA into plant cells using Agrobacterium tumefaciens, different transformation methods have enabled rapid advances in molecular breeding approaches to bring crop varieties with novel traits to the market that would be difficult or not possible to achieve with conventional breeding methods.

Diurnal dynamics of the Arabidopsis rosette proteome and phosphoproteome.

Plant growth depends on the diurnal regulation of cellular processes, but it is not well understood if and how transcriptional regulation controls diurnal fluctuations at the protein level. Here, we report a high-resolution Arabidopsis thaliana (Arabidopsis) leaf rosette proteome acquired over a 12 hr light:12 hr dark diurnal cycle and the phosphoproteome immediately before and after the light-to-dark and dark-to-light transitions. We quantified nearly 5,000 proteins and 800 phosphoproteins, of which 288 fluctuated in their abundance and 226 fluctuated in their phosphorylation status.

Multiplying the efficiency and impact of biofortification through metabolic engineering.

Ending all forms of hunger by 2030, as set forward in the UN-Sustainable Development Goal 2 (UN-SDG2), is a daunting but essential task, given the limited timeline ahead and the negative global health and socio-economic impact of hunger. Malnutrition or hidden hunger due to micronutrient deficiencies affects about one third of the world population and severely jeopardizes economic development. Staple crop biofortification through gene stacking, using a rational combination of conventional breeding and metabolic engineering strategies, should enable a leap forward within the coming decade.

Genome Wide Analysis of the Transcriptional Profiles in Different Regions of the Developing Rice Grains.

Background: Rice is an important food source for humans worldwide. Because of its nutritional and agricultural significance, a number of studies addressed various aspects of rice grain development and grain filling. Nevertheless, the molecular processes underlying grain filling and development, and in particular the contributions of different grain tissues to these processes, are not understood.

Screening for Resistance in Farmer-Preferred Cassava Cultivars from Ghana to a Mixed Infection of CBSV and UCBSV.

Cassava brown streak disease (CBSD) caused by the (CBSV) and (UCBSV) is a threat to cassava production in Africa. The potential spread of CBSD into West Africa is a cause for concern, therefore screening for resistance in farmer-preferred genotypes is crucial for effective control and management. We multiplied a selection of eleven cassava cultivars grown by farmers in Ghana to test their response to a mixed infection of CBSV (TAZ-DES-01) and UCBSV (TAZ-DES-02) isolates using a stringent top-cleft graft inoculation method.

The Cassava Source-Sink project: opportunities and challenges for crop improvement by metabolic engineering.

Cassava (Manihot esculenta Crantz) is one of the important staple foods in Sub-Saharan Africa. It produces starchy storage roots that provide food and income for several hundred million people, mainly in tropical agriculture zones. Increasing cassava storage root and starch yield is one of the major breeding targets with respect to securing the future food supply for the growing population of Sub-Saharan Africa.

Haplotype-resolved genomes of geminivirus-resistant and geminivirus-susceptible African cassava cultivars.

Background: Cassava is an important food crop in tropical and sub-tropical regions worldwide. In Africa, cassava production is widely affected by cassava mosaic disease (CMD), which is caused by the African cassava mosaic geminivirus that is transmitted by whiteflies. Cassava breeders often use a single locus, CMD2, for introducing CMD resistance into susceptible cultivars.

Symplasmic phloem unloading and radial post-phloem transport via vascular rays in tuberous roots of Manihot esculenta.

Cassava (Manihot esculenta) is one of the most important staple food crops worldwide. Its starchy tuberous roots supply over 800 million people with carbohydrates. Yet, surprisingly little is known about the processes involved in filling of those vital storage organs.

Genetic Transformation of Recalcitrant Cassava by Embryo Selection and Increased Hormone Levels.

Genetic engineering is considered to be an important tool for the improvement of cassava. Cassava is a highly heterozygous crop species for which conventional breeding is a lengthy and tedious process. Robust transformation is based on Agrobacterium-mediated transformation of friable embryogenic callus (FEC).

Enhancement of vitamin B levels in rice expressing Arabidopsis vitamin B biosynthesis de novo genes.

Vitamin B (pyridoxine) is vital for key metabolic reactions and reported to have antioxidant properties in planta. Therefore, enhancement of vitamin B content has been hypothesized to be a route to improve resistance to biotic and abiotic stresses. Most of the current studies on vitamin B in plants are on eudicot species, with monocots remaining largely unexplored.

Linking CRISPR-Cas9 interference in cassava to the evolution of editing-resistant geminiviruses.

Background: Geminiviruses cause damaging diseases in several important crop species. However, limited progress has been made in developing crop varieties resistant to these highly diverse DNA viruses. Recently, the bacterial CRISPR/Cas9 system has been transferred to plants to target and confer immunity to geminiviruses.

Diurnal changes in concerted plant protein phosphorylation and acetylation in Arabidopsis organs and seedlings.

Protein phosphorylation and acetylation are the two most abundant post-translational modifications (PTMs) that regulate protein functions in eukaryotes. In plants, these PTMs have been investigated individually; however, their co-occurrence and dynamics on proteins is currently unknown. Using Arabidopsis thaliana, we quantified changes in protein phosphorylation, acetylation and protein abundance in leaf rosettes, roots, flowers, siliques and seedlings at the end of day (ED) and at the end of night (EN).

A new full-length circular DNA sequencing method for viral-sized genomes reveals that RNAi transgenic plants provoke a shift in geminivirus populations in the field.

We present a new method, CIDER-Seq (Circular DNA Enrichment sequencing) for the unbiased enrichment and long-read sequencing of viral-sized circular DNA molecules. We used CIDER-Seq to produce single-read full-length virus genomes for the first time. CIDER-Seq combines PCR-free virus enrichment with Single Molecule Real Time sequencing and a new sequence de-concatenation algorithm.

Cassava geminivirus agroclones for virus-induced gene silencing in cassava leaves and roots.

Aim: We report the construction of a Virus-Induced Gene Silencing (VIGS) vector and an agroinoculation protocol for gene silencing in cassava ( Crantz) leaves and roots. The African cassava mosaic virus isolate from Nigeria (ACMV-[NOg]), which was initially cloned in a binary vector for agroinoculation assays, was modified for application as VIGS vector. The functionality of the VIGS vector was validated in and subsequently applied in wild-type and transgenic cassava plants expressing the gene under the control of the CaMV 35S promoter in order to facilitate the visualization of gene silencing in root tissues.