Kyeung-Il Park

Genetics and epigenetics in flower pigmentation associated with transposable elements in morning glories.

Among the genus Ipomoea, three morning glories, I. nil (the Japanese morning glory), I. purpurea (the common morning glory), and I. tricolor, were domesticated well for floricultural plants, and many spontaneous mutants displaying various flower pigmentation patterns were isolated. Most of these spontaneous mutations were found to be caused by the insertion of DNA transposable elements in the genes for the anthocyanin pigmentation in flowers, and many of them exhibited variegated flowers, such as white flowers with pigmented spots and sectors. Here, we describe the historical background of the mutants displaying variegated flowers and review the genetic and epigenetic regulation in flower pigmentation associated with transposable elements of these morning glories. The flecked, speckled, r-1, and purple mutations in I. nil were caused by insertions of Tpn1 and its relatives in the En/Spm superfamily, Tpn2, Tpn3, and Tpn4, into the genes for anthocyanin coloration in flowers, i.e., DFR-B, CHI, CHS-D, and InNHX1, respectively. Similarly, the flaked and pink mutants of I. purpurea have distantly related elements, Tip100 and Tip201, in the Ac/Ds superfamily inserted into the CHS-D and F3H genes, respectively. The flower variegation patterns can be determined by the frequency and timing of the excision of these transposons, and their stable insertions produce plain color flowers without generating pigmented spots or sectors; furthermore, both genetic and epigenetic regulation appeared to play important roles in determining the frequency and timing of the excision of the transposons. However, flower variegation is not always associated with the excision of an integrated DNA transposon from one of the genes for anthocyanin pigmentation. The mutant Flying Saucers of I. tricolor displaying variegated flowers was found to have the transposon ItMULE1 inserted into the DFR-B promoter region, but no excision of ItMULE1 from the DFR-B could be detected in the variegated flower lines. The instable pearly-vrg allele in cv. Flying Saucers is likely to be an epiallele because the DNA methylation in the DFR-B promoter appeared to be associated with flower pigmentation.

Identification of r mutations conferring white flowers in the Japanese morning glory (Ipomoea nil)

The wild-type Japanese morning glory [Ipomoea nil (L.) Roth.] exhibits blue flowers with red stems, and spontaneous r mutants display white flowers with green stems. We have identified two r mutations, r1-1 and r1-2, that are caused by insertions of Tpn1-related DNA transposable elements, Tpn3 (5.6xa0kb) and Tpn6 (4.7xa0kb), respectively, into a unique intron of the CHS-D gene, which is responsible for flower and stem pigmentation. Both Tpn3 and Tpn6, which belong to the En/Spm or CACTA superfamily, are nonautonomous elements lacking transposase genes but containing unrelated cellular DNA segments including exons and introns. Interestingly, r1-2 contains an additional 4-bp insertion at the Tpn3 integration site in r1-1, presumably a footprint caused by the excision of Tpn3. The results strengthen the previous notion that Tpn1 and its relatives are major spontaneous mutagens for generating various floriculturally important traits in I. nil. Since I. nil has an extensive history of genetic studies, molecular identification of classical spontaneous mutations would also facilitate reinterpretation of the abundant classical genetic data available.

Changes in Water-soluble Vitamin Contents in Response to Different Processing Methods in Various Paprika Cultivars

The aim of this study was to determine the changes in water-soluble vitamin B1, B2, B3, and C contents in raw and processed materials from different colored paprika cultivars including ‘Cupra’ (red), ‘Maserati’ (yellow), and ‘Boogie’ (orange). We validated the specificity, accuracy, and precision of our vitamin B1, B2, B3, and C analysis method using high-performance liquid chromatography (HPLC). The recovery rate of certified reference material (CRM) was excellent for vitamin B1, B2, B3, and C. We analyzed vitamin B1, B2, B3, and C contents in 33 samples, which ranged from 0 to 0.13 mg/100g, 0.01 to 0.12 mg/100g, 0 to 3.74 mg/100g, and 36.94 to 115.41 mg/100g, respectively. The highest vitamin B1, B2, B3, and C contents were 0.13 mg/100g in raw material from ‘Maserati’ paprika, 0.12 mg/100g in ‘Boogie’ paprika after microwave treatment, 3.74 mg/100g in ‘Cupra’ paprika after grilling treatment, and 115.41 mg/100g in ‘Cupra’ paprika after frying treatment, respectively. Vitamin B1 was only detected in raw materials from ‘Cupra’ and ‘Maserati’. Additional key words: analysis method, HPLC/DAD, HPLC/FLD, processed material, vitamins