Potential male gametophyte competition among camellia sinensis genotypes in isolated biclonal seed orchards

Male fertility of crop plants is a function of pollen production and viability. In breeding, it is a requirement that there be similar fertilities among breeding parents within seed orchards. An in-vitro germination method was used in this study to determine variation in pollen viability among eight tea (Camellia sinensis) genotypes, over three flowering seasons in four isolated biclonal seed orchards located at two sites. The effect of environmental conditions on pollen germination was also studied on two popular genotypes, i.e. AHP SC31/37 (an assamica variety) and GW Ejulu-L (a sinensis variety) that were planted in both sites. Significant variation (P < 0.05) in pollen viability among the eight genotypes indicated a potential for male gametophyte competition. There was significant genotype by environment interaction and positive correlation between pollen viability and temperature. Pollen germination was, however, not affected by rainfall and humidity. The variations in pollen viability may contribute to the variable genetic composition of seed produced in the isolated seed orchards of tea

Estimation of out-crossing rate in a natural breeding population of Warburgia ugandensis using AFLP marker

Warburgia ugandensis Sprague (Canellaceae) occurs in East and Central Africa, and the species is of great medicinal importance to the local communities where it occurs. As the wild populations diminish,planted stands will in future be used as the source of medicinal products as well as germplasm. This study investigated the levels of out-crossing rates to provide knowledge for proper planning in futurecultivation programmes. The mating parameters estimated using the mixed mating model (software MLTR) showed the species to be predominantly out-crossing (89%) with significant levels of selfing.The multi-locus population out-crossing rate was higher than the single-locus population out-crossing rate (tm- ts= 0.023; SE = 0.010), implying that there was less likelihood of mating between relatives (biparental inbreeding). Low values were also obtained for the correlation of paternity, rp(s) = 0.028 (SE = 0.040) and correlation of selfing among family, rs = 0.016 (SE = 0.015). For most loci, allele frequencies of pollen and ovule contributions to the progeny genotypes were significantly different (

Antioxidant capacity of different types of tea products

In the present study, twelve different types of commercial tea samples were assayed to determine their phenolic composition and antioxidant activity. Reverse phase high performance liquid chromatographyusing a binary gradient system was used for the identification and quantification of individual catechins. Subsequently, total phenolic content was determined spectrophotometrically according tothe Folin-ciocalteus method. Total theaflavins and thearubigins were also determined. The radical scavenging behavior of the polyphenols on 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) was also studied spectrophotometrically. The results showed that total polyphenols, total catechins and antioxidant activity were significantly (

Chemical composition and antimicrobial activity of the essential oil of Ocimum gratissimum L. growing in Eastern Kenya

Hydro-distilled volatile oils from the leaves of Ocimum gratissimum L. (Lamiaceae) from Meru district in Eastern Kenya were analysed by gas chromatography-mass spectrometry (GC-MS) and also evaluatedfor antimicrobial activity. The oil was dominated by monoterpens which accounted for 92.48%. This monoterpene fraction was characterized by a high percentage of eugenol (68.8%). The other major monoterpenes were methyl eugenol (13.21%), cis-ocimene (7.47%), trans-ocimene (0.94%), -pinene (1.10%) and camphor (0.95%). The sesquiterpenes present in fairly good amounts were germacrene D(4.25%) and trans-caryophyllene (1.69%). The minor  sesquiterpenes were -farnesene (0.85%) and -bisabolene (0.74%). The antimicrobial activities of the essential oils were evaluated against both Gram positive (Staphylococcus aureus, Bacillus spp.) and Gram negative (Escherichia coli, Pseudomonasaeruginosae, Salmonella typhi, Klebisiella pneumoniae, Proteus mirabilis) bacteria and a pathogenic fungus Candida albicans. The oil had pronounced antibacterial and antifungal activities on all themicrobes

Leaf storage conditions and genomic DNA isolation efficiency in Ocimum gratissimum L. from Kenya

Storage of plant tissues for DNA is important to avoid degradation of DNA. Preliminary studies were conducted on Ocimum gratissimum L. in order to establish the storage conditions for the collected samples before DNA extraction. Secondly, the aim was to determine the best protocol for the extraction of high quality DNA, which would later be used for molecular analysis. DNA was extracted from thesamples one month after field sampling. During the DNA extraction, four protocols were used; the modified hexadecyltrimethyl ammonium bromide (CTAB) mini preparation method described by Doyleand Doyle (1990), with reductants either mercaptoethanol or dithiothreitol; the modified sodium dodecyl sulphate (SDS) mini preparation method of Edwards et al. (1991) with redundant either mercaptoethanol or dithiothreitol. The DNA was purified, treated with RNase, quantified and examined for intactness using gel electrophoresis method. Good quality and high yield DNA  could only be extracted with the buffer containing the detergent SDS and the reducing agent dithiothreiotol