Identification of key genes responsible for green and white colored spathes in Anthurium andraeanum (Hort.).

Modern anthuriums, Anthurium andraeanum (Hort.) are among the most popular flowering plants and widely used for interior decoration. Their popularity is largely attributed to the exotic spathes with different colors. Previous studies have reported color development in red spathe cultivars, but limited information is available on key genes regulating white and green colored spathes. This study analyzed anthocyanin, chlorophyll, and carotenoid contents as well as transcript differences in spathes of eight cultivars that differed in spathe colors ranging from red to white and green. Results showed that increased expression of a transcription factor AaMYB2 was associated with elevated levels of anthocyanin in spathes, but decreased expression of AaMYB2 and increased expression of AaLAR (leucoanthocyanidin reductase) and AaANR (anthocyanidin reductase) were accompanied with the accumulation of colorless proanthocyanidin, thus the white spathe. As to the green colored spathe, chlorophyll content in the green spathe cultivar was substantially higher than the other cultivars. Correspondingly, transcripts of chlorophyll biosynthesis-related genes AaHemB (porphobilinogen synthase) and AaPor (protochlorophyllide oxidoreductase) were highly upregulated but almost undetectable in white and red spathes. The increased expression of AaHemB and AaPor was correlated with the expression of transcription factor AaMYB124. Subsequently, qRT-PCR analysis confirmed their expression levels in nine additional cultivars with red, white, and green spathes. A working model for the formation of white and green spathes was proposed. White colored spathes are likely due to the decreased expression of AaMYB2 which results in increased expression of AaLAR and AaANR, and the green spathes are attributed to AaMYB124 enhanced expression of AaHemB and AaPor. Further research is warranted to test this working model.

Profiling of Volatile Compounds and Associated Gene Expression in Two Anthurium Cultivars and Their F1 Hybrid Progenies.

Anthurium is an important ornamental crop in the world market and its floral scent can enhance its ornamental value. To date, studies of the components and formation mechanism of the floral scent of Anthurium are relatively few. In this study, the scent profiles of two Anthurium varieties were measured by gas chromatograph-mass spectrometer (GC-MS). There were 32 volatile organic compounds (VOCs) identified in Anthurium 'Mystral', and the most abundant compound was eucalyptol (57.5%). Extremely small amounts of VOCs were detected in Anthurium 'Alabama'. Compared with A. 'Alabama', most genes related to floral scent synthesis exhibited a higher expression in A.'Mystral', including AaDXS, AaDXR, AaMDS, AaHDS, AaTPS, AaDAHPS, AaADT2, AaPAL1, and AaPAL2. In order to produce new varieties of Anthurium with fragrance, 454 progenies of two crossbred combinations of A. 'Mystral' and A. 'Alabama' were obtained. Four F1 generation plants with different floral scent intensities were selected for further study. The major components of floral scent in the progenies were similar to that of the parental A.'Mystral' plant. The expression patterns of genes related to floral scent synthesis were consistent with the relative contents of different types of VOCs. This study revealed the profiles of volatile compounds and associated gene expression in two Anthurium cultivars and their F1 hybrids, which provided a basis for the floral scent inheritance of Anthurium andraeanum.