Flower color mutation caused by spontaneous cell layer displacement in carnation (Dianthus caryophyllus).

A change of layer arrangement of shoot apical meristem (SAM) organized by three cell layers (L1, L2 and L3) is thought to be one of the provocations of bud sport, which often induces changes in phenotypic colors in periclinal chimeras. This paper describes a cell layer rearrangement which is the cause of spontaneous flower color mutation by using two carnation (Dianthus caryophyllus L.) cultivars that are presumably periclinal chimeras, 'Feminine Minami' (deep pink flower) and its recessive sport 'Tommy Minami' (pinkish red flower). The genotype of the acyl-glucose-dependent anthocyanin 5-glucosyltransferase (AA5GT) which is responsible for the color change of red to pink, in each cell layer was deduced by genomic analysis using tissues originated from specific cell layer and investigation of partial petal color mutations. In the results, the genotype of the L1 of 'Feminine Minami' was heterozygous for functional AA5GT and non-functional AA5GT carrying retrotransposon Ty1dic1 (AA5GT-Ty1dic1), and its inner cell layer hid red flower genotype, whereas AA5GT-Ty1dic1 of the L1 of 'Tommy Minami' became homogenic in absence of the insertion of a new Ty1dic1. Our outcomes concluded that the L1 of 'Tommy Minami' harboring the recessive AA5GT alleles are attributed to the inner cell layer of 'Feminine Minami' possessing red flower genotype.

In vitro growth and single-leaf photosynthetic response of Cymbidium plantlets to super-elevated CO2 under cold cathode fluorescent lamps.

To examine the effectiveness of super-elevated (10,000 micromol mol(-1)) CO(2) enrichment under cold cathode fluorescent lamps (CCFL) for the clonal propagation of Cymbidium, plantlets were cultured on modified Vacin and Went (VW) medium under 0, 3,000 and 10,000 micromol mol(-1) CO(2) enrichment and two levels of photosynthetic photon flux density (PPFD, 45 and 75 micromol m(-2) s(-1)). Under high PPFD, 10,000 micromol mol(-1) CO(2) increased root dry weight and promoted shoot growth. In addition, a decrease in photosynthetic capacity and chlorosis at leaf tips were observed. Rubisco activity and stomatal conductance of these plantlets were lower than those of plantlets at 3,000 micromol mol(-1) CO(2) under high PPFD, which had a higher photosynthetic capacity. On the other hand, plantlets on Kyoto medium grown in 10,000 micromol mol(-1) CO(2) under high PPFD had a higher photosynthetic rate than those on modified VW medium; no chlorosis was observed. Furthermore, growth of plantlets, in particular the roots, was remarkably enhanced. This result indicates that a negative response to super-elevated CO(2) under high PPFD could be improved by altering medium components. Super-elevated CO(2) enrichment of in vitro-cultured Cymbidium could positively affect the efficiency and quality of commercial production of clonal orchid plantlets.