Isozymes, secondary compounds and experimental cultures of Australian seagrasses in Halophila, Halodule, Zostera, Amphibolis and Posidonia

Abstract

Systematic and ecological implications were shown for Australian seagrasses by studies of isozymes, secondary compounds and experimental cultures. In Halophila, small- and large-leaved plants which occur sympatrically from northern Queensland to New South Wales and were referred to H. ovalis (R.Br.) Hook. f. differed in isozymes and secondary compounds and maintained leaf size differences in experimental cultures. The small-leaved plants should be referred to a different species. In Halodule, narrow-leaved plants that were referred to H. uninervis (Forsk.) Aschers. and H.pinifolia (Miki) Den Hartog were examined. In experimental cultures, narrow-leaved plants from Thursday Island produced both tridentate and rounded serrulate leaf tips and differed in isozymes and secondary compounds from wide-leaved plants. The narrow- leaved plants should be referred to H. pinifolia and the wide-leaved plants to H. uninervis. In Zostera, small- and large-leaved forms of Z. capricorni Aschers. which occur sympatrically in Queensland and New South Wales have similar isozymes that differ from those of Z. muelleri Irmisch. ex Aschers. of South Australia. Experimental cultures of Z. capricorni continued to produce 5-nerved leaves and those of Z. muelleri, 3- nerved leaves. In Amphibolis, cultures of A. antarctica (Labill.) Sonder & Aschers. and A. griffithii (J. M. Black) Den Hartog continued to show leaf differences but were similar in secondary compounds and isozymes, differing in only one of eight enzyme systems. In Posidonia, wide-leaved plants of P. australis Hook. f. continued to produce leaves in culture that differed in width from those of P. sinuosa Cambridge & Kuo but were similar in secondary compounds and isozymes, differing only in one of eight enzyme systems. The chemical evaluations and experimental cultures suggested wide differences in Halophila and in Halodule but indicated only narrow differences in the other three genera.

Photosynthesis and Metabolism in Seagrasses at the Cellular Level

“…A similar approach in temperate Australia by Nicholls et al (1982) showed that the lipids, comprising up to 7.6% dry weight, of P. australis and Heterozostera tasmanica, had patterns of monocarboxylic, dicarboxylic and hydroxy acids sufficiently different to allow even detritus of these two species to be distinguished. Taxonomic questions at the species level in seagrasses have also been approached chemically by McMillan et al (1981) and McMillan (1983) using secondary products such as the flavonones and their sulphonated derivatives from Amphibolis, Halodule, Halophila, Posidonia and Zostera.…”

Hybridisation in a tropical seagrass genus, Halodule (Cymodoceaceae), inferred from plastid and nuclear DNA phylogenies

“…An isozyme study of Halodule showed a clear difference between samples from the western tropical Atlantic and the Indo-Pacific (McMillan et al 1981, McMillan 1991. A molecular phylogeny based on the ITS of nDNA also showed two clusters, one from the western tropical Atlantic and the other from the western Pacific (Waycott & Barnes unpublished).…”

The In Vitro Antioxidant and Anti-Inflammatory Activities of Selected Australian Seagrasses

“…It is common knowledge that fruits, vegetables, and other plants are a rich source of vitamins, minerals, and bioactive secondary metabolites (metabolic products that are not necessary for growth, development, and reproduction, but are essential for ecological and other interactions), many of which have anti-inflammatory properties [ 7 , 8 ]. In addition to commonly consumed plant materials, phytochemical analyses of many seagrasses including Halophila stipulacea [ 9 ], Thalassodendron ciliatum [ 9 ], Halodule uninervis [ 9 ], Halodule pinifolia [ 10 , 11 ], Halophila ovalis [ 10 ], Syringodium isoetifolium [ 10 , 11 ], Thalassia hemprichii [ 11 , 12 ], Cymodocea rotundata [ 11 ], Enhalus acoroides [ 11 ], Cymodocea serrulate [ 11 ], and Zostera muelleri [ 13 , 14 ] have indicated seagrasses are also natural reservoirs of phenolics, flavonoids, sterols, alkaloids, saponins, tannins, terpenoids, and other bioactive secondary metabolites.…”