Random Amplified Polymorphic DNA Variation among and within Selected Ixora (Rubiaceae) Populations and Mutants

Random amplified polymorphic DNA (RAPD) analysis was used tostudy variation among and within selectedIxora (Rubiaceae) populationsand mutants. Six populations of I. congesta yielded identicalbanding patterns suggesting genetic uniformity of this species.However, six populations of I. coccinea varieties (three red-flowered,two yellow-flowered and one red-flowered wild-type) exhibitedinfraspecific differences in RAPD profiles. Small and largeleaves of an atavistic mutant cultivar of I. coccinea were alsosubjected to RAPD analysis. An extra band was amplified in thelarge leaves that was absent in small leaves, suggesting thatthe phenotypic alteration in this taxon is due to genetic mutationrather than epigenetic changes. Similarly, an extra band wasdetected in the white sectors of I. Variegated compared to thegreen sectors, suggesting that the shoot apical meristems ofthis cultivar exist as a genetic chimera. DNA gel blot hybridizationwas performed to confirm the specificities of selected bands.Our study indicates that differences among individuals of variouspopulations and mutants may be detected using RAPD markers.Copyright 1999 Annals of Botany Company Ixora L., variegated variety, RAPD fingerprinting, DNA gel blot, intraspecific genetic similarity, atavistic mutant.     

Seed Surface Architecture and Random Amplified Polymorphic DNA Profiles of Paulownia fortunei, P. tomentosa and their Hybrid

The surface patterns of winged seeds of Paulownia fortunei,P. tomentosa and P. fortuneixP. tomentosa were examined by scanningelectron microscopy. The pattern of reticulation on the wingsand seed coat of P. fortunei and the hybrid are comparable,while that on P. tomentosa is different and more elongated.Also, the wings are more extended at the oblong ends of theseeds in the former when compared to the wings of P. tomentosa.Distinct random amplified polymorphic DNA (RAPD) patterns wereobtained for the three taxa and P. kawakamii with five differentrandom oligonucleotide primers, suggesting that the method canyield genetic markers for differentiating the taxa. Also, Southernblot analyses of the RAPD products of the hybrid and the twoparent species revealed shared (inherited) genetic polymorphisms.Copyright 1999 Annals of Botany Company Paulownia species and hybrid, seed surface architecture, reticulated thickening, RAPD markers, Scrophulariaceae.     

Phylogenetic Analysis of Dipterocarps Using Random Amplified Polymorphic DNA Markers

The phylogenetic relationships among 12 species belonging tothree different genera (Shorea, HopeaandAnisoptera) of Dipterocarpaceaewere studied using random amplified polymorphic DNA (RAPD) markers.A modified CTAB DNA extraction protocol was used to obtain tannin-and polysaccharide-free genomic DNA from mature leaves. Clusteranalysis of data from six random primers placed the 12 speciesin three groups corresponding to their respective genera. Fourdistinct nodes ofShoreaspp. and two ofHopeaspp. could be identified.Anisopteramegistocarpaserved as an outgroup, and was unique when comparedto the other genera examined. RAPD profiles of five individualsofH. odoratawith six random primers were identical, suggestingthat there is little intraspecific variation in this species.The RAPD technique can thus be successfully applied for thestudy of phylogenetic relationships of this important groupof tropical timber trees.Copyright 1998 Annals of Botany Company Dipterocarpaceae,Anisopteraspp.,Hopeaspp.,Shoreaspp., RAPD markers, tropical timber trees.     

Analysis of Genetic Diversity amongIxoraCultivars (Rubiaceae) using Random Amplified Polymorphic DNA

We have optimized the genomic DNA extraction method from freshand dry laminas, as well as fresh and dry corolla lobes ofIxoracultivars.Some woody tropical species such as these contain excessiveamounts of phenolic compounds that co-precipitate with DNA resultingin poor or no amplification during the polymerase chain reaction(PCR). Repeated precipitation with CsCl coupled with phenol:chloroformextraction yielded high quality DNA suitable for consistentPCR amplification. The DNA from fresh laminas of 22 cultivarsofIxorawas subjected to random amplified polymorphic DNA (RAPD)analysis. Individual taxa could be identified using specificDNA markers from the RAPD profiles. Cluster analysis of datafrom six primers grouped all 22 cultivars distinctly under twocultivar groups, viz.,IxoraCoccinea andI.Javanica. The percentagegenetic similarity was calculated for all the cultivars basedon the RAPD data. The two cultivar groups and the outgroup plantswere also clearly distinguishable with polar ordination usinga matrix of genetic dissimilarities (one minus similarity).Our data indicate that besides the use of RAPD markers for identificationof particularIxoracultivars within a germplasm collection, thephylogenetic relationships generated by RAPD analysis may beuseful for future breeding programmes. IxoraL. cultivars; Rubiaceae; RAPD fingerprinting; DNA extraction; woody tropical species