Introduction from the Wild and Growth Characterization of Three Provenances of Calotropis procera (Ait) in a Domesticated State in Dry lands of South Eastern Kenya

Calotropis procera is a wild species that is drought-resistant and important in production of wool, fibre, biomass among other uses. There exist high demand of the wool in Asian countries and collection from the wild has been going on in Kenya and other countries. However, this collection does not meet the quantity required. Domestication of the species may be the key in bridging the quality and quantity demands for the wool. A study is being undertaken to evaluate growth, phenology and wool productivity of selected provenances of C. procera in dry lands of S. Eastern Kenya. The research site is situated between 01.313580S, 037.755460 E and 01.314220S, 037.755760E and elevation of 1173m a.s.l in South Eastern Kenya University (SEKU), Kitui County, Kenya. The research started in January 2015 with the main focus on monitoring the growth, phenological characteristics and wool productivity of the species in a typical farm setting. This paper focuses on growth characterization of three provenances of C. procera under different spacings (1.5mx1.5m, 2mx2m and 3mx3m). Results indicate that the species can be domesticated, it is hardy and capable of achieving an average field survival of over 97%. The species is multi-stemmed with Tharaka provenance showing highest mean branching of 13.25 followed by Baringo (12.22) then Kibwezi (11.98). Kibwezi recorded a slightly higher DBH growth of 3.90cm followed by Baringo (3.83) then Tharaka (3.82). Tharaka had highest mean height of 187.89cm, Baringo (184.25) and Kibwezi (182.63). Test of homogeneity of variances showed significant statistical differences (P<0.5) with Kibwezi being the least significant (0.043), Baringo (0.01) and Tharaka (0.000). All provenances showed a strong positive correlation (Pearson, P<0.01, n = 12) of branching, DBH and Height with Kibwezi recording rs = 0.975, Baringo (rs = 0.988) and Tharaka (rs = 0.996). Differences in spacing levels started affecting growth parameters from the age of ten months with 3x3 showing highest DBH followed by 2x2 then 1.5x1.5. In terms of height, 1.5x1.5 has the highest (182.85cm), 2x2 (172.42) and 3x3 (168.65). 3x3 was not statistically significant (0.806, P<0.05) while 2x2 and 1.5x1.5 had significance of 0.001 and 0.000 respectively. All spacing levels showed strong positive correlations (Spearman, P<0.01, n = 12) of the study parameters where 1.5x1.5 had rs = 0.614, 2x2 (rs = 0.972) and 3x3 (rs = 0.986) all at P<0.01. The study can authoritatively conclude that the species can establish and grow well in a typical farm setting in dry lands. Spacing affects growth parameters from the age of 10 months. Baringo provenance and 2x2 spacing have performed best. The study recommends analysis of wool productivity to justify the best provenance and spacing. Keywords: Calotropis procera, Domestication, Kibwezi Provenance, Tharaka Provenance, Baringo provenanc

Genetic diversity and gene flow revealed by microsatellite DNA markers in some accessions of African Plum (Dacryodes edulis) in Cameroon

Dacryodes edulis is a multipurpose tree integrated in the cropping system of Central African region still dominated by subsistence agriculture. Some populations grown are wild which can provide information on the domestication process, and could also represent a potential source of gene flow. Leaves samples for DNA extraction were collected from wild forms in Mbakwa supe region and from cultivated forms in Yaounde and Santchou region. Six microsatellites DNA markers were employed in genotyping to analyze population structure and gene flow. Amplification rate was high and genotyping revealed high level of genetic variation. The overall polymorphic level at the six loci was also high with average expected heterozygosity of 0.53; polymorphism of 0.46; mean allelic diversity of 0.5 and mean allele number of 8.33. There were no clear differences with only 1% variation among the three populations and 6% variation among individuals within populations. In contrast, the rate of heterozygosis was high in all the three populations. Both the number of migrant per generation (Nm=20) and the Wright’s Fstatistics (FST=0.012) suggest that there was substantial gene flow among the populations. These findings indicate that D. edulis possess a great potential of pollen dispersal and dominant crosspollination within populations. Most of the loci with private alleles (45%) were found in wild individuals which could be a source of pollen for crossing their cultivated relatives.Key words: Dacryodes edulis, domestication, genetic diversity and structure

Draft genomes of two Artocarpus plants, jackfruit (A. heterophyllus) and breadfruit (A. altilis)

Two of the most economically important plants in the Artocarpus genus are jackfruit (A. heterophyllus Lam.) and breadfruit (A. altilis (Parkinson) Fosberg). Both species are long-lived trees that have been cultivated for thousands of years in their native regions. Today they are grown throughout tropical to subtropical areas as an important source of starch and other valuable nutrients. There are hundreds of breadfruit varieties that are native to Oceania, of which the most commonly distributed types are seedless triploids. Jackfruit is likely native to the Western Ghats of India and produces one of the largest tree-borne fruit structures (reaching up to 45 kg). To-date, there is limited genomic information for these two economically important species. Here, we generated 273 Gb and 227 Gb of raw data from jackfruit and breadfruit, respectively. The high-quality reads from jackfruit were assembled into 162,440 scaffolds totaling 982 Mb with 35,858 genes. Similarly, the breadfruit reads were assembled into 180,971 scaffolds totaling 833 Mb with 34,010 genes. A total of 2822 and 2034 expanded gene families were found in jackfruit and breadfruit, respectively, enriched in pathways including starch and sucrose metabolism, photosynthesis, and others. The copy number of several starch synthesis-related genes were found to be increased in jackfruit and breadfruit compared to closely-related species, and the tissue-specific expression might imply their sugar-rich and starch-rich characteristics. Overall, the publication of high-quality genomes for jackfruit and breadfruit provides information about their specific composition and the underlying genes involved in sugar and starch metabolism

Genetic Diversity and Population Structure of Canarium tramdenum Dai and Yakovl. in Northern Vietnam

Canarium tramdenum occurs naturally in subtropical and tropical regions of Indochina and China. The wood is used for making high quality furniture and the fruit and leaves are used in traditional medicine. However, a lack of information on genetic diversity and population structure has handicapped the genetic conservation and domestication of this high-value species. This study evaluated genetic variation within and among four C. tramdenum populations. Sixty individuals were collected from four natural populations in Vietnam in the provinces of Ninhbinh, Bacgiang, Nghean, and Backan. Genetic diversity and genetic structure were determined using 20 ISSR markers. A total of 192 DNA fragments with sizes ranging from 110 bp to 3,000 bp were detected, of which 154 segments (80.2%) were polymorphic and 38 segments (19.8%) were monomorphic. The ISSR data indicated a moderate degree of genetic diversity for the species (h = 0.252). The four populations were separated into three genetic clusters with low levels of genetic distance between them. AMOVA result showed that most (78%) of the genetic variation was within the populations. The moderate to high genetic diversity of C. tramdenum and the low genetic differentiation among populations suggested that all existing natural populations in the particular regions needed to be preserved to protect the genetic diversity of this species