Table 1: Outcomes of transgenic provitamin A (pVA) production or enhancement in wheat, maize and potato are summarized; genes, varieties, and changes in pVA levels are presented.

Crop Gene Cultivar or Line Outcomes Publication
pVA production increase or narrative indication Compound level
(Transgenic vs. control) #
Wheat Maize PSY * and CrtI * Variety EM12 - ~ * 10.8 folds increase in total carotenoids with expression of yellow grain color in transgenic lines - 4.96 μg g-1 DW * vs. 0.46 [37]
CrtB *, CrtI Cultivar Bobwhite - ~ 8 folds increase in total carotenoids with expression of red/yellow grain color in transgenic lines - 4.06 ± 0.49 μg g-1 DW vs. 0.58 ± 0.02 [21]
- ~ 76 folds increase in pVA content § - 3.21± 0.37 μg g-1 DW vs. 0.05±0.01
Wheat
LCYb *
Chinese Spring - β-carotene decrease by silenced LCYb gene - 0.09 μg g-1 DW vs. 0.22 [43]
Wheat
CCDs *
Tetraploid Kronos and hexaploid line UC1041 - β-carotene decrease by CCD1 cleaving and degrading β-carotene; indicated from increased ratio of β,ε- and β,β-branch carotenoids in endosperm - No numerical data provided [44]
Maize Maize PSY and CrtI White
kernel Hi-II
- ~ 34 folds increase in total carotenoids with preferential accumulation of pVA - 33.6 mg g-1 DW vs. 1.01 [45]
- ~ 25 folds increase in pVA - 9.8 mg g-1 DW vs. 0.39
Zmpsy1 *,
PacrtI *, Gllycb *
, Glbch *
, ParacrtW *
South African elite white variety M37W - ~ 142 folds increases in total carotenoids with both Zmpsy1and PacrtI expression - 156.14 mg g-1 DW vs. 1.01 [46]
- Zmpsy1 and PacrtI genes needed for changes in carotenoids and color from white to yellow, orange, red - No numerical data provided
Maize PSY, CrtI South African elite white variety M37W - ~ 169 folds increase in β-carotene with orange color endosperm - 59.32 mg g-1 DW vs. 0.35 [47]
Potato CrtI Cultivar Desiree - ~ 6.3 folds increase in tuber total carotenoids - 35 lg g-1 DW vs. 5.6 [48]
- β-carotene increase from undetectable levels - 10.30 lg g-1 DW vs. negligible level
LCYe * - ~ 14 folds increase in tuber β-carotene by silenced LCYe - 43.56 ng g-1 DW vs. 3.17 [41]
CHY1, CHY2 - ~ 4.5 folds increase in tuber total carotenoids by silencing CHYs - 21758.57 ng g-1 DW vs. 4887.95 [49]
- ~ 35 folds increase in tuber β-carotene by silencing CHYs - 85.3 ng g-1 DW vs. 2.25
CrtB, CrtI, CrtY * - ~20 folds increase in total carotenoids - 114.4 mcg g-1 DW vs. 5.8 [50]
- 3600 folds increase in β-carotene - 47 mcg g-1 DW vs. 0.013
CrtB, CrtI, CrtY - ~ 20 folds increase in total carotenoids
- 50% of total carotenoids as pVA carotenoids resulting from their favorable shift
- Shown in graphical charts [42]
Cauliflower Or (Orange) gene - ~ 10 folds increase in total carotenoids during
storage vs. starting point in fresh tubers
- ~ 20 folds increase in β-carotene during
storage vs. starting point in fresh tubers
- Shown in graphical charts [51]
* ~: up to, DW: dry weight PSY: phytoene synthases, CrtI: bacterial carotene desaturases, CrtB: bacterial phytoene synthase, LCYb: Lycopene β-cyclase gene, CCDs: Carotenoid cleavage dioxygenases, DW: seed dry weight, Zmpsy1: maize phytoene synthase 1, PacrtI: Pantoea ananatis phytoene desaturase, Gllycb: Gentiana lutea lycopene b-cyclase, Glbch: G. lutea β-carotene hydroxylase, ParacrtW: Paracoccus β-carotene ketolase, LCYe: lycopene ε-cyclase, CHY: non-heme β -carotene hydroxylases, CrtY: lycopene β-cyclase.
§ As sum of α-carotene, β-carotene, and β-cryptoxanthin.
# Highest levels among transgenic lines when given specific numerical data; otherwise without numerical data, shown in bar charts or graphs for graphical comparisons.