Construction of transgenic <i>Ipomoea obscura</i> that exhibits new reddish leaf and flower colors due to introduction of β-carotene ketolase and hydroxylase genes

Abstract

Ipomoea obscura, small white morning glory, is an ornamental plant belonging to the family Convolvulaceae, and cultivated worldwide. I. obscura generates white petals including a pale-yellow colored star-shaped center (flower vein). Its fully opened flowers were known to accumulate trace amounts of carotenoids such as β-carotene. In the present study, the embryogenic calli of I. obscura, were successfully produced through its immature embryo culture, and co-cultured with Agrobacterium tumefaciens carrying the β-carotene 4,4′-ketolase (crtW) and β-carotene 3,3′-hydroxylase (crtZ) genes for astaxanthin biosynthesis in addition to the isopentenyl diphosphate isomerase (idi) and hygromycin resistance genes. Transgenic plants, in which these four genes were introduced, were regenerated from the infected calli. They generated bronze (reddish green) leaves and novel petals that exhibited a color change from pale-yellow to pale-orange in the starshaped center part. Especially, the color of their withered leaves changed drastically. HPLC-PDA-MS analysis showed that the expanded leaves of a transgenic line (T 0 ) produced astaxanthin (5.2% of total carotenoids), adonirubin (3.9%), canthaxanthin (3.8%), and 3-hydroxyechinenone (3.6%), which indicated that these ketocarotenoids corresponded to 16.5% of the total carotenoids produced there (530 µg g −1 fresh weight). Furthermore, the altered traits of the transgenic plants were found to be inherited to their progenies by self-crossing.

Fast and High-Efficiency Synthesis of Capsanthin in Pepper by Transient Expression of Geminivirus

“…The study of five cultivars, including the mutant Oranzheva kapia, showed that two hydroxylase genes, encoding CrtZchr03 and CrtZchr06, are present in pepper on chromosomes 3 and 6, and that deletion of the CrtZchr03 gene resulted in an increase in β-carotene accumulation [12]. Cotransformation of the genes responsible for β-carotene, 4,4 -ketolase (CrtW) and β-carotene 3,3 -hydroxylase (CrtZ), has been utilized to engineer transgenic organisms capable of producing astaxanthin, a naturally occurring carotenoid pigment known for its antioxidant properties and vibrant red-orange coloration [13]. In E. coli, the production of zeaxanthin was significantly enhanced by optimizing the codons of the CrtZ, CrtY, and CrtI genes, resulting in a 10-fold increase in zeaxanthin yield [14].…”