Isozyme Analyses And Investigation On The Morphological Diversity Of Taxa In Genus Nymphaea

Nymphaeales sensu lato is a perennial aquatic flower,it has high ornamental values owing to its colorful flower and good plant architecture,it is a dispensable aquatic flower in gardens.Thirty three morphological characters were investigated in 60 taxa of Nymphaea.main,component analysis and hierarchical cluster analysis were conducted.In addition,the genetic diversity of 59 taxa of Nymphaea was evaluated by using peroxidase (POD) isozymeand esterase(EST) isozyme.The main results are as follows:1.Morphological investigation showed that the morphological diversity was high among taxa. The average diversity index was 1.446.The diversity index of quantitative traits was overall higher than that of qualitative traits.The average variation coefficient was 36.39%. The trend of the change of the diversity index was opposite to that of the variation coefficient.The principal component analysis showed that the 33 characters were integrated into 5 principal components(PCs) and their accumulative contribution rate amounted to 68.28%.The first and the second principal components represented 28.71% and 18.85%of variance,respectively.Based on the morphological data,the 60 taxa of Nymphaea were clustered into 2 groups,namely,tropical water lily group and hardy water lily group.The 16 taxa included in the tropical water lily group were characterized by apocarpous carpel and tooth leaf.The remaining 44 taxa included in the hardy water lily group had adnation carpel and tooth-absent leaf,no viviparity was observed in them.2.The genetic diversity of 59 taxa in Nymphaea was studied based on the polymorphisms of POD and EST isozymes.Eight isozyme loci were observed,and a total of 12 bands of POD and 6 bands of EST were obtained.3.POD and EST isozymes were analyzed in unexpanded and expand young leaves,mature leaves,petals,buds and petioles in 'Peter Slocum','Masaniello','Texas Dawn'.The polymorphisms were highest in unexpanded and expanded leaves,higher in petioles and buds,lower in the petals and mature leaves in turn.The POD and EST isozymes at vegetative stages were clearer and more regular than those at reproductive stages in 13 cultivars.The content of POD was higher at reproductive stage,while the band pattern were identical to that of vegetative stages.4.The genetic variation of taxa in Nymphaea was very high,and the effective numbers of alleles per locus(A),percentage of polymorphic loci(P) and heterozygosity(Ho) among 59 taxa were on average 1.6852,35.14%and 0.3929,respectively.Above three parameters(A,1.9996;P,80.00%and Ho,0.4999) were highest in 'Fire Crest',while 'Helvola','Persian Lilac',N.stellata,'Star of Siam' and 'Director George T.Moore' had the lowest genetic variation,and their A,P and Ho were 1.2462,0.00%and 0.1975, respectively.5.The UPGMA cluster showed that taxa in Nymphaea can be divided into two groups,the first group includes all taxa hardy water lily and 8 tropical taxa of water lily,the second group consists of the remaining taxa of tropical water lily.The inconsistence in cluster was observed between the results of isozymes analysis and the morphological analysis.6.The band K and L of POD-6 were specific to 'Peach Glow',while the band E of POD-3 was confined to 'Rose Arey' and 'Princess Elizabeth'.These taxa specific bands maybe provide isozyme evidence for taxa identification and protection.