2 New Zealand Garden Journal, 2004, Vol.7 (1) Anthurium ‘Montana’, an A. amnicola hybrid Anthurium aristocracy Vern Collette1 The anthurium is a unique A. andraeanum Linden is widely followed by a generative or ornamental plant that has been accepted as the progenitor of the reproductive phase. In the juvenile dubbed the aristocrat of the plant anthurium cut flower cultivars phase, vegetative buds emerge in world, commanding attention and commercially propagated today, and the axils of the leaves, while in the generating considerable interest is the highlight of this article. Since generative phase, inflorescence buds wherever it is displayed. Its estimated its discovery in Colombia it has been can be found in the leaf axils world trade exceeds US$20 million. bred and cultivated extensively for (Christensen, 1971). Once the This places it second in trade and its brilliantly coloured and patterned juvenile phase has passed, flowers economic value only to spray flowers. However, A. andraeanum are produced in an alternating cycle orchids, and makes it a thriving itself represents a hybrid population, with leaves throughout the year lucrative industry in many parts of and the wide variation in size, colour, (Kamemoto and Nakasone, 1963). the world, including several and growth form of anthuriums in When the flower emerges in the leaf Caribbean countries, Taiwan, cultivation is a consequence of axil, the spathe may or may not be Singapore, Thailand, Japan, and the extensive interspecific hybridisation. highly coloured, but it is tightly curled Philippines. However, Holland around the immature spadix. It takes remains the world's largest grower, an average of 6-9 weeks from the and by virtue of its extensive time of its emergence, for the breeding programme, this country is Anthurium flowers peduncle to be fully extended and the primary source of new colours the spathe fully expanded, exposing The term "flower" is used to refer to and cultivars to the international a mature spadix. For A. andraeanum, the commercial product, made up market. While Holland supplies the spathe is cordate and simple, of the spathe, spadix and peduncle mainly the European market, Hawaii with very prominent veins that (flower stalk). The anthurium spathe remains the chief supplier to the originate at the spadix-spathe is actually a modified bract that United States, and over the years junction. These run in arcs along the subtends the protruding cylindrical has developed as the epicentre for surface of the spathe, and converge inflorescence rachis, called the published research on various at its apex (Higaki et al., 1984). The spadix (Higaki et al., 1984). The aspects of anthurium genetics, spathe is also characterised by a surface of the spadix is made up of propagation and improvement. thick cuticle on the upper and lower fused segments, each being the point Recently, the anthurium has been a epidermis. The epidermis (both upper from which the true flower emerges. popular feature in the ornamental and lower) is one cell layer thick, and The true flowers are minute, arena of New Zealand and Australia. beneath this is a single or double hermaphroditic and protogynous (the There is a uniquely strong market for layer of similar sized, hypodermal female parts of the flower develop the anthurium as a pot plant in both cells. In anthurium, flower colour first) in development, making these countries, whereas in many pigment generally accumulates only anthurium highly outcrossing other countries the predominant in the hypodermal cells of both the (Campbell, 1900). The flowers are economic focus is the cut flower upper and lower epidermis. invisible to the naked eye and are industry. insect pollinated. Once fertilised the ovary enlarges and forms a single The genus Anthurium belongs to the berry with one or two seeds inside, family Araceae, which includes other Flower colour in a process that completely well known ornamental genera, such disfigures the spadix. Once mature, The main colours in anthurium as Spathiphyllum, Zantedeschia, these detach from the spadix. spathes are red/pink, orange/coral, Philodendron, and Monstera. While and white. A few cases of green, and the taxonomic literature describes The growth of the anthurium plant is even brown, coloured spathes are as many as 1,000 Anthurium species, divided into a juvenile phase, also known. Some white lines can 1 AgResearch Grasslands, Tennent Drive, Private Bag 11008, Palmerston North; [email protected] New Zealand Garden Journal, 2004, Vol.7 (1) 3 develop a pink blush as the flower flavone C-glycosides comprised These authors proposed that gene matures giving a patterned 82% of the major flavonoids. Flavone M controls the production of cyanidin arrangement to the spathe. Blues mono-C and di-C-glycosides along 3-rutinoside, and that gene O and yellows are notably absent, and with O-glycosyl derivatives were all controls the production of while varied shades of red and represented. pelargonidin 3-rutinoside. Although orange are present, these are not M and O may be the two major genes always in a desirable genetic Anthocyanin pigments have also affecting spathe colour in anthurium, background. Cultivars with a red been found in the leaves, peduncle, Kamemoto et al. (1988) suggested spathe usually have a bright yellow stipules, roots, and stems of several other genes operate to spadix, while the colour of the spadix anthurium. In petals of other flowers, provide the diversity of flower varies from orange to red in cultivars anthocyanins are nearly always found colours. However, these have not with a pink spathe. In the orange in epidermal cells, while in vegetative yet been identified and further spathe group, spadices are either tissue they tend to be located sub- experiments are being conducted to orange or yellow, whereas in cultivars epidermally (Kay et al., 1981; identify all the genetic factors with a white spathe, there can be Hrazdina, 1982). However, controlling pigment production in the attractive matches with pink to bright Wannakrairoj and Kamemoto (1990) anthurium spathe. red spadices. Other colours such as found that in the anthurium spathe, purple, bronze and green are also the location of anthocyanin differed Anthurium amnicola, one of the more found in the spadix (Kamemoto and from species to species and could recent additions to the anthurium Kuehnle, 1996). be located in the epidermis, genus, was discovered in Panama hypodermis and/or mesophyll. In in 1972. Its most beneficial feature In Anthurium (and in the family anthurium cultivars, anthocyanins is the ease with which it can be Araceae in general), the major colour were found exclusively in the crossed with other species, and it pigments in the spathe are hypodermal layers on both the upper has been used in numerous anthocyanin derivatives. Carotenoid and lower surfaces of the spathe interspecific crosses with A. pigments are also present, but only (Higaki et al., 1984). andraeanum to produce slight in spadix tissue where they are variations in flower colour. While responsible for the bright yellow In A. amnicola Dressler, peonidin 3- conventional plant breeding has been colour of this organ. All other spadix rutinoside was reported in addition the standard approach for developing colours are flavonoid-based. to pelargonidin and cyanidin new colours in anthurium, it is limited Chlorophyll also contributes to glycosides. In combination with in scope. A molecular approach to spathe colour, either alone, giving a cyanidin 3-rutinoside, this compound modifying anthurium flower colour completely green spathe, or in accounts for the lavender spathe has been initiated in response to the combination with other anthocyanin and purple spadix of this species increasing demand for novel spathe pigments to give a brown spathe (Marutani et al., 1987). The colours. Several genes involved in (Kamemoto and Kuehnle, 1996). distribution of anthocyanins, the flower colour pathway in however, in A. amnicola is restricted anthurium have been isolated, and Pelargonidin and cyanidin derived to the lower and upper epidermis. studies of their expression over time anthocyanins are the main colour in various tissues have revealed a pigments in the anthurium spathe. unique expression pattern. Results These are usually glycosylated with Breeding new also suggest that there is diurnal glucose and rhamnose, forming anthuriums rhythm to the expression of one of pelargonidin and cyanidin 3- these genes (Collette, 2002). The rutinoside (Iwata et al., 1979; 1985). Plant breeding has provided isolated genes are currently being The presence of one or both significant information concerning used to design genetic constructs pigments, as well as their different the inheritance of flower colour in for various experiments to modify concentrations, determines the anthurium (Kamemoto et al., 1988). colour. New paths are being explored spathe colour (Iwata et al., 1985). The current hypothesis is that two to discover the possibility of Flavones are the other main flavonoid genes, M and O, are responsible for producing yellow and even the pigments in the anthurium spathe. anthocyanin production in anthurium, elusive blue anthurium. In a leaf survey of 142 species from and that there is recessive epistasis 58 genera of the family Araceae, of the O locus over the M locus. Williams et al. (1981) found that 4 New Zealand Garden Journal, 2004, Vol.7 (1) Growing References anthuriums Campbell, D.H. (1900). Studies in the Araceae. I. Ann. Bot. 14: 2-25. Christensen, O.V. (1971). Morphological studies on the growth and formation of Anthurium andraeanum is a slow Anthurium scherzerianum Schott and Anthurium andraeanum Lind. Tiddsskrift growing perennial requiring shady, for Planteavl. 75: 793-798. humid conditions, such as might be Collette, V.E. (2002). A molecular analysis of flower colour development in an ornamental found in a tropical rainforest. In monocot (Anthurium andraeanum). PhD thesis, Massey University, Palmerston North. addition to A. andraeanum, other Higaki, T., Rasmusan, H.P. and Carpenter, W.J.