FAN, CHUANZHU* and (Jenny) Qiu-Yun Xiang. Department of Botany, North Carolina State University, Campus box 7612, Raleigh, NC 27695-7612. - Systematic Affinities of Two Enigmatic African Families, Grubbiaceae and Hydrostachyaceae - Evidence from Nuclear 26S rDNA Sequence Data.
Various chloroplast DNA data suggested Cornales including two
enigmatic monotypic African families Grubbiaceae and Hydrostachyaceae.
Forty species representing all major groups of Cornales, including two
of three species Grubbia, and four samples representing three of 22
species Hydrostachys, were sequenced for 26S rDNA containing
approximate 3300bp in the present study. Phylogenetic analyses using
both parsimony and maximum likelihood methods identified Grubbia as
the sister of another African genus Curtisia with high bootstrap
support congruent with previous findings based on rbcL & matK sequence
data. These two genera were allied with the nyssoids in the parsimony
analysis, but were recognized as sister of a monophyletic group
consisting of nyssoids, matixioids, Cornus, and Alangium in the ML
analysis. The four sequences of Hydrostachys were missing approximate
1000 bp near the 5’ end. Those four samples of Hydrostachys formed a
strongly supported, long-branched monophyletic group sister to the
remainder of Cornales. However, this placement was not strongly
supported in the parsimony tree. Moreover, this 26S rDNA-based
relationship of Hydrostachys differs from that suggested by some
earlier analyses of chloroplast genes
Key words: