Population genetics of the mangrove Rhizophora stylosa in northern Australia

Starch gel electrophoresis was used to examine genetic variation in five widely separated populations of the mangrove Rhizophora stylosa Griff. Shoots containing leaves and well developed apical buds were collected between March and August 1987 from Darwin, the Daintree River, 2 sites at Missionary Bay (Hinchinbrook Island), Chunda Bay (Cape Ferguson) and Lardelli Creek (Ayr). No two trees at each sampling site were separated by more than 1km, except for the Daintree River site, which was sampled over 2km.A suitable extraction buffer was developed by modifying a buffer developed by Dr Gavin Moran (CSIRO) for eucalypts and acacias.Twenty eight enzymes were investigated for the Rhizophora stylosa samples (ACP, ACON, AK, ADH, ALD, AAT, EST(FL), FH, BetaGAL, G6PD, GPI, GDH, GSR, GAPDH, HK, IDH, LAP, LGGP, LTP, LPP, MDH, ME, MDR, PER, PGM, 6PGD, SKDH, TPI). Fourteen enzymes were resolved adequately for these samples (ACON, AAT, GPI, GDH, GSR, HK, IDH, LAP, LTP, MDH, ME, PER, 6PGD, TPI).Other Rhizophoraceae successfully tested for enzyme activity in leaf and apical bud tissue, using the same methods were Rhizophora apiculata Blume, R. lamarckii Montr., R. mucronata Lamarck, Bruguiera gymnorhiza Lamarck, Ceriops decandra (Griff.) Ding Hou, C. tagal (Perr.) C.B. Rob. var. tagal and C. tagal var. australis C.T. White. Other mangrove species producing clear repeatable results included Lumnitzera racemosa Willdenow, Xylocarpus australasicus Ridley, Sonneratia alba J.E. Smith, Acrostichum speciosum Willdenow, Avicennia marina (Forssk.) Vierh. and A. officinalis Linnaeus.While leaves and buds were chosen initially, due to their year round availability, whole anthers and the plumule of the progagule of Rhizophora stylosa were also successfully tested for enzyme activity. This research was undertaken to:1. develop an effective extraction buffer to counteract the effect of complex secondary metabolites in mangroves, which denature proteins during enzyme extraction.2. develop techniques for the electrophoresis of mangrove tissue and to use these to investigate genetic variability in Rhizophora stylosa and other Rhizophoraceae.