, Volume 48, Issue 5, pp 483-497

The reproductive biology and genetic diversity of Potamophila parviflora R. Br.

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Abstract

Potamophila parviflora, a wild relative ofdomestic rice, is endemic to the north-eastern river systemsof New South Wales, Australia. It is the only member of the genus,and is habitat specific. Several new sites were found, mostly in theUpper Clarence catchment. Florets of P.parviflora were found to be 86%female-only, while 14% contained mature malereproductive parts, which occurred more often in the middle sectionof the panicle. Pollen was found to be necessary for the developmentof mature fruits. RAPD data showed that there is very little geneticvariation between individual plants, or between differentpopulations. An embryological study showed several irregularities inmegasporogenesis and megagametogenesis. No tetrads were observed inmegasporogenesis and the ovule is vacuolate at the megaspore mothercell stage. Megagametogenesis proceeded rapidly, nuclei within theovule were sometimes not spherical and varied in size, and sometimesthe antipodal cells doubled in number with a corresponding halving insize of the nuclei. Chromosome number varied between 2n = 24and 2n = 25, between and within populations. These resultsindicate that P. parvifloracould be a diplosporous apomict of the Antennaria type, althoughfurther works are required to provide conclusive proof.