Singlet oxygen generation and photo-oxidation reactions in supercritical fluid carbon dioxide

Oxygen is remarkable in that it has a triplet ground state, a 3Σg state, with its first two excited states being of singlet multiplicity (1Δg and 1Σg+, lying 94 kJ mol-1 and 158 kJ mol-1 above the ground state, respectively). Relaxation of the singlet state to the ground state is consequently spin forbidden, resulting in a long lifetime for singlet oxygen: Singlet oxygen is a highly reactive species and is responsible for oxidative damage in a number of systems. In this study, singlet oxygen quantum yields, ΦΔ, have been measured at varying temperatures and pressures, as a function of oxygen concentration, in supercritical fluid carbon dioxide. [Continues.

Zygotic embryo in vitro culture of Cocos nucifera L. (sv. East African Tall variety) in the coastal lowlands of Kenya

In vitro embryo culture of Cocos nucifera L. was carried out with the aim of determining whether it can be applied as an alternative coconut propagation tool to address the lack of planting materials in Kenya. Zygotic embryos excised from mature healthy pyrenes of high yielding Cocos nucifera L. (sv. East African Tall, a coconut variety from Kenya) were cultured using Murashige and Skoog (MS) culture medium supplemented with plant growth regulators (PGRs) namely 6-benzyl aminopurine (BAP) (0.5 mg/l), naphthalene acetic acid (NAA) (0.5 mg/l), 2,4 dichlorophenoxyacetic acid (2,4-D) (1.7 mg/l) and indole butyric acid (IBA) (1.7 mg/l). Germination of 84 and 27% embryos were recorded in liquid and semi-solid MS medium, respectively. Embryo cultured in liquid medium and incubated in darkness during the initial four weeks resulted in a germination percentage of 80% while incubation in light resulted in only 30% germination. MS medium was also supplemented with 100, 25, 15 and 0% (v/v) coconut water (CW). Embryo germination was 60% in medium supplemented with 15% (v/v) coconut water although 0% (v/v) gave the highest germination rate at 67%. Medium supplementation by 1.7 mg/l 2,4-D PGR resulted in germination of 30% when plant growth regulator was co-autoclaved and 84% when plant growth regulator was sterilized by microfiltration. The results presented in this study indicate that in vitro micropropagation of the Kenyan variety of Cocos nucifera L. is a feasible alternative.Keywords: Cocos nucifera L., in vitro embryo culture, east African tall (EAT) Kenyan variety, zygotic embryoAfrican Journal of Biotechnology Vol. 12(22), pp. 3435-344

Assessment of the genetic diversity of Kenyan coconut germplasm using simple sequence repeat (SSR) markers

Genetic diversity and relationship among 48 coconut individuals (Cocos nucifera L.) collections from the Coastal lowland of Kenya were analyzed using 15 simple sequence repeat (SSR) primer pairs. Diversity parameters were calculated using Popgene Software version 1.31. The gene diversity values ranged from 0.0408 (CAC68) to 0.4861 (CAC23) with a mean value of 0.2839. The polymorphic information content (PIC) values ranged from 0.0400 to 0.3680 with a mean value of 0.2348. Marker CAC23 had the highest PIC and revealed highest gene diversity values in this study. Analysis of the molecular variation indicated that within individual variation was 98% while among materials, variation was low at 2% suggesting that molecular variation was not defined by region of production. Cluster analysis was constructed using DARwin program version 6.0. Forty eight (48) coconut individuals were clustered into three groups.Keywords: Coconut palm (Cocos nucifera L., Arecaceae), germplasm, simple sequence repeat (SSR) markers, cluster analysis, diversit