Expression ofphytoene synthase1and Carotene DesaturasecrtIGenes Result in an Increase in the Total Carotenoids Content in Transgenic Elite Wheat (Triticum aestivumL.)

Abstract

Dietary micronutrient deficiencies, such as the lack of vitamin A, are a major source of morbidity and mortality worldwide. Carotenoids in food can function as provitamin A in humans, while grains of Chinese elite wheat cultivars generally have low carotenoid contents. To increase the carotenoid contents in common wheat endosperm, transgenic wheat has been generated by expressing the maize y1 gene encoding phytoene synthase driven by a endosperm-specific 1Dx5 promoter in the elite wheat (Triticum aestivum L.) variety EM12, together with the bacterial phytoene desaturase crtI gene from Erwinia uredovora under the constitutive CaMV 35S promoter control. A clear increase of the carotenoid content was detected in the endosperms of transgenic wheat that visually showed a light yellow color. The total carotenoids content was increased up to 10.8-fold as compared with the nontransgenic EM12 cultivar. To test whether the variability of total carotenoid content in different transgenic lines was due to differences in the transgene copy number or expression pattern, Southern hybridization and semiquantitative reverse transcriptase polymerase chain reaction analyses were curried out. The results showed that transgene copy numbers and transcript levels did not associate well with carotenoid contents. The expression patterns of endogenous carotenoid genes, such as the phytoene synthases and carotene desaturases, were also investigated in wild-type and transgenic wheat lines. No significant changes in expression levels of these genes were detected in the transgenic endosperms, indicating that the increase in carotenoid transgenic wheat endosperms resulted from the expression of transgenes.

The colours of durum wheat: a review

“…2): (i) early in the pathway, for the synthesis of phytoene; (ii) for lycopene cyclisation; and (iii) for carotene hydroxylation. Since in wheat the PSY-catalysed reaction has been reported as the rate-limiting step of the biosynthesis pathway, it is feasible that this reaction has a role in the regulation of carotenoid accumulation (Lindgren et al 2003;Cong et al 2009). …”

A novel phytoene synthase paralog from halophytic Salicorniaconfers salinity tolerance in plants

“…Golden rice is a glaring example of this promotion (Ye et al, 2000;Paine et al, 2005). Other metabolically manipulated plants for carotenoid improvement are tomato (Fray et al, 1995) canola (Shewmaker et al, 1999), wheat (Cong et al, 2009), potato (Romer and Fraser, 2005), and soybean (Kim et al, 2012). However, knowledge about the role of genes involved in carotenoids biosynthesis for induction of salt tolerance and their expression analyses remained obscure.…”

Transgenic Pro-Vitamin A Biofortified Crops for Improving Vitamin A Deficiency and Their Challenges

“…For instance, maize would be more important in Sub-Saharan Africa whereas rice and wheat in South Asia at a whole population level, not specifically for children due to data limitation. For transgenic pVA enhancement in crops, identification of the carotenogenesis pathway and its regulating genes in plants and bacteria enabled ectopic expression of specific carotenoids in edible parts of crops [38]. Briefly, carotenogenesis begins with the formation of geranylgeranyl-diphosphate (GGPP) followed by condensation of two GGPPs (Fig.…”

“…Moreover, 94% of wheat currently grown is bread wheat (T. aestivum) which was selected for white flour with little pVA carotenoid [44]. Cong et al (2009) showed bread wheat grains could produce high levels of carotenoids by introducing the maize PSY1 and bacterial carotene desaturases (CrtI) genes [37]. Their transgenic wheat endosperm increased carotenoid contents 10.8 folds compared with the non-transgenic counterpart [37].…”