Portieria hornemannii (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

1. habit vegetative thallus; 2 & 3, details of apical portions; 4, detail of inrolled tip; 5, cross-section of vegetative thallus; 6, detail of central axial cell, medulla and cortex; 7, detail of outer cortex with gland cells; 8, cystocarpic nemathecia; 9, longitudinal section through cystocarpic nemathecia; 10, cross-section through tetrasporangial nemathecium.

Portieria hornemannii (Lyngb.) P.C. Silva

Protologue: Smithsonian Contr. Mar. Sci. 27: 39, 129 (1987).

Family: Rhizophyllidaceae

Chromosome number: 2n= unknown

Synonyms

• Desmia hornemannii Lyngb. (1819),
• Chondrococcus hornemannii (Lyngb.) F. Schmitz (1895).

Origin and geographic distribution

P. hornemannii is common in the tropical Indian and Pacific Oceans. In South-East Asia it has been recorded from northern Burma (Myanmar), Malaysia, Indonesia, the Philippines and Papua New Guinea.

Uses

P. hornemannii is a source of carrageenan related to lambda carrageenan and which can be 35% of dry weight. It is also used for human food as vegetable salad.

Production and international trade

There are no available estimates of production of P. hornemannii from the wild for food or medicinal use.

Properties

P. hornemannii contains the terpenes chondrocole A & B (recently changed in name to apakaochtodene A & B) and the oxygenated compound chondrolactone. Especially apakaochtodene B is an effective deterrent against herbivores. A pentahalogenated monoterpene (halomon or prehalomon) from this alga shows cytotoxic activity against human tumour cells. This compound may be sequestered in gland cells distributed in the cortex of this alga and is only present in some of the samples. Most plants emit a pungent odour.

Description

• Thalli up to 20 cm tall, usually smaller, bright orange to red, composed of several erect, overlapping flattened branches arising from small discoid holdfasts.
• Branching in one plane, irregularly pinnate-alternate, in up to 5(-7) orders, forming rounded axils; diameter of primary branches not exceeding 7 mm; terminal branches at distal portion of thalli with slightly expanded curved or inrolled tips; lower lateral branchlets with simple acute teeth.
• Central axis in cross-section clearly visible, rather narrow, surrounded by large-celled pseudo-parenchymatous medulla and cortex of smaller cells; outer cortex in parts of thalli with many slightly larger gland cells.
• Two forms may coexist in the same habitat: a rigid cartilaginous form and a more flexuous, gelatinous form with finer branches.
• Life cycle diplo-haplontic, triphasic and isomorphic.
• Tetrasporangia and spermatangia in pale patches on surface of fertile thalli; cystocarps in wart-like nemathecia, mostly concentrated along thallus edges.
• Tetrasporangia forming solid layer without interspersed sterile cells; sporangia zonately divided, 6 μm × 45 μm.
• Gametophytes monoecious.
• Female nemathecia with semi-globose cystocarps developing several gonimolobes separated by thin sterile partitions; released carpospores globose, 9 μm in diameter.
• Spermatangia superficial, in pustule-like areas very similar to pale tetrasporangial patches.

Growth and development

The growth pattern of P. hornemannii is uniaxial. There are indications that cystocarpic thalli occur in the Philippines all year round.

Ecology

The thalli of P. hornemannii form bright orange-red bunches strongly attached to coralline rocks at the upper subtidal zones of the reef margin or rocky shore exposed to strong wave-action, or on other algae, especially the crustose coralline Peysonnelia spp. Its habitat is limited to areas characterized by clear water.

Propagation and planting

P. hornemannii is not grown in phycoculture.

Diseases and pests

Aplysiid snails have been observed grazing voraciously on P. hornemannii.

Yield

In wild P. hornemannii beds in the Philippines, the alga exhibits a patchy distribution, with a density of up to 2 thalli per 0.25 m² and an average biomass of about 1.74 g (wet weight) on such a surface. This provides an average of about 6.9 g (wet weight) potential harvest from 1 m².

Handling after harvest

Thalli of P. hornemannii are sold fresh or are sun-dried.

Prospects

The recorded presence of halogenated compounds in P. hornemannii may be worth looking into for their possible importance in medicine and in plant protection against herbivores. The available carrageenan has not yet been used for exploitation.

Literature

• Burreson, B.J., Woolard, F.X. & Moore, R.E., 1975. Chondrocole A and B, two halogenated dimethyl hexahydrobenzofurans from the red alga Chondrococcus hornemannii (Mertens) Schmitz. Tetrahedron Letters 1975: 2155-2158.
• Fuller, R.W., Cardellina, J.H. II., Kato, Y., Brinen, L.S., Clardy, J., Snader, K.M. & Boyd, M.R., 1992. A pentahalogenated monoterpene from the red alga Portieria hornemannii produces a novel cytotoxicity profile against a diverse panel of human tumor cell lines. Journal of Medical Chemistry 35: 3007-3011.
• Matlock, D.B., Ginsburg, D.W. & Paul, V.J., 1999. Spatial variability in secondary metabolite production by the tropical red alga Portieria hornemannii. Hydrobiologia 398/399: 267-273.
• Meñez, E.G., Calumpong, H.P., Newman, D.J. & West, J.A., 1996. An account of the red alga, Portieria hornemannii (Gigartinales, Rhizophyllidaceae), from the Philippines. In: Prasad, A.K.S.K., Nienow, J.A. & Rao, V.N.R. (Editors): Contributions in phycology. Volume in honour of Professor T.V. Desikachary. Beihefte Nova Hedwigia 112: 161-170.
• Semesi, A.K. & Mshigeni, K.E., 1977. Studies on the yield and IR spectra of phycocolloids from Chondrococcus hornemannii and Sarconema filiforme from Tanzania. Botanica Marina 20: 271-276.
• Woolard, F.A. & Moore, R.E., 1978. The structure and absolute configuration of chondralactone, a halogenated monoterpene from the red alga Chondrococcus hornemannii and a revised structure for chondrocole A. Tetrahedron Letters 1978: 2367-2370.

Sources of illustration

Okamura, K., 1923. Icones of Japanese algae. Vol. 4. Okamura, Tokyo, Japan. Pl. 190 (cross-sections vegetative thallus, nemathecia); Stegenga, H., Bolton, J.J. & Anderson, R.J., 1997. Seaweeds of the South African West coast. Contributions from the Bolus Herbarium 18: Plate 112, p. 319 (detail of apical portion 3, cross-section 6); Trono, G.C. & Ganzon-Fortes, E.T., 1980. An illustrated seaweed flora of Calatagan, Batangas, Philippines. University of the Philippines Marine Science Center & Filipinas Foundation, Manila, The Philippines. Fig. a & b, p. 65 (habit and detail apical portion 2). Redrawn and adapted by P. Verheij-Hayes.

Authors

• G.C. Trono Jr