Molecular analysis of the expression of a crtB transgene and the endogenous psy2-y 1 and psy2-y 2 genes of cassava and their effect on root carotenoid content

Abstract

A conventional breeding program was established to transfer the bacterial phytoene synthase transgene-crtB-from a transgenic, white-rooted cassava to yellow-rooted cassava plants carrying the endogenous phytoene synthase alleles named psy2-y and/or psy2-y. Combining endogenous phytoene synthase enzymes (PSYs) with CRTB in a single cassava plant would allow the molecular dissection of individual allele contributions to carotenoid synthesis and/or accumulation in cassava roots. The simultaneous expression of the crtB transgene and psy2-y in individuals planted in the field coincided with higher total, HPLC-quantified carotenoid content in roots, although the variability among replications (plants) precluded the detection of statistically significant differences. Nevertheless, the highest total carotenoid content in roots within a family coincided with one individual of the F1 progeny carrying both psy2-y and crtB genes. The results also indicated the presence of at least one more key gene-different from psy or crtB-which too is necessary for the synthesis and/or accumulation of Pro-Vitamin A carotenoids in cassava roots.

Integrated transcriptomics and metabolomics analyses of the effects of bagging treatment on carotenoid biosynthesis and regulation of Areca catechu L.

“…In the yellowish fruit landrace Huang Song of tomato, the expression of crtB compensates for the deficiency in phytoene synthesis due to the decreased activity of PSY1 ( Lin et al., 2021 ). The insertion of synthase crtB into a white cassava plant resulted in the accumulation of β-carotene ( Chavarriaga-Aguirre et al., 2017 ). Besides, crtZ plays a key role in α-carotene, β-carotene and subsequent production of zeaxanthin in a range of pathways.…”

Advances in Genetic Engineering in Improving Photosynthesis and Microalgal Productivity

“…IPP or DMAPP, a five-carbon precursor, is synthesized through the methylerythritol 4-phosphate (MEP) pathway from pyruvate and glyceraldehydes-3-phosphate, and condensation of such C5 units produces different C10, C15, and C20 polyprenyl units, one of which is geranylgeranyl pyrophosphate (GGPP) [100]. Phytoene synthase (PSY) is an enzyme that catalyzes the reaction of two GGPP molecules to form a 40-carbon phytoene, which is the first limited step in carotenoid biosynthesis and a common precursor of other carotenoids in microalgae [101,102]. Phytoene is converted to lycopene by carotenoid isomerase (CRITISO), ζ-carotene desaturase (ZDS), and phytoene desaturase (PDS).…”

Carotenoid composition and sequestration in cassava (Manihot esculentumCrantz) roots

“…Biofortification of cassava has been a recent approach implemented by programs such as HarvestPlus (www.harvestplus.org) through conventional breeding, which utilised the genetic variability already present in landraces (Iglesias et al ., 1997; Chavez et al ., 2000; Ceballos et al ., 2013). More recently, genetic transformation with bacterial carotenoid genes was utilised to increase the levels of β-carotene to 60-75 µg/g DW (Chavarriaga-Aguirre et al ., 2017; Beyene et al ., 2018). Genetic assessment of selected genotype panels enabled the elucidation of underlying genes involved in high β-carotene content (e.g.…”