Genetic Characterization of Selected Macadamia Germplasm and the Implications on Breeding and Conservation in Kenya

Gitonga, Lucy; Wanjala, Bramwel W.; Muigai, Anne W. T.; Ngamau, Kamau; Kahangi, E. M.; Gichuki, S.; Kairichi, M.

doi:10.17660/actahortic.2011.918.116

Cited by 1 publication

(1 citation statement)

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“…Over the last few decades, several marker technologies have been developed for macadamia, primarily for the study of genetic diversity. Some of the important markers used in macadamia are isozyme [ 17 ], randomly amplified DNA fingerprinting (RAF) [ 18 , 19 ], random amplified polymorphic DNA (RAPD) [ 20 , 21 ], amplified fragment length polymorphism (AFLP) [ 22 , 23 ], randomly amplified microsatellite fingerprinting (RAMiFi) [ 24 ] and microsatellite [ 25 – 27 ] markers. Limitations associated with these marker systems include low marker density, poor genome coverage, and less cost-effectiveness.…”

Section: Introductionmentioning

confidence: 99%

Ultra-high-throughput DArTseq-based silicoDArT and SNP markers for genomic studies in macadamia

Alam

Neal²,

O’Connor

et al. 2018

PLoS ONE

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Macadamia (Macadamia integrifolia, M. tetraphylla and hybrids) is an Australian native nut crop and has a significant economic value in the food industries worldwide. Long juvenility along with traditional breeding strategies impede quick genetic improvement of this crop. The existing cultivars constitute only second to fourth generation of the wild germplasm in the rainforest. The utilisation of molecular markers for genomic selection and genome-wide association studies may accelerate genetic gains. Identification of a robust, reproducible, and cost-effective marker system is instrumental in increasing the efficiency of genomic studies. This study is the first to report the potential of two ultra-high-throughput diversity array technology (DArT) markers (silicoDArT and SNP) in macadamia. Both markers were used to identify the genetic diversity and population structure in 80 macadamia cultivars. Parentage analysis of 25 scions in a rootstock trial was conducted to confirm plant identity where recorded identities did not corroborate with phenotypic field observations. A total of 22,280 silicoDArT and 7,332 SNP markers were reported, of which 11,526 silicoDArT and 3,956 SNP markers were used for analyses after screening with quality control parameters including >95% call rate, >95% reproducibility, and >0.05 one ratio. The average polymorphic information content (PIC) values of silicoDArT and SNP markers were 0.29 and 0.21, respectively. Genetic variance among the cultivars ranged from 0.003 to 0.738 in silicoDArT and 0.004 to 0.412 in SNP markers. Four distinct population groups were identified from SNP data analysis. Most of the accessions used in this study were descended from two or more populations. Cluster analysis clearly separated genotypes of distinct origins, such as the Hawaii Agricultural Experiment Station and Hidden Valley Plantation accessions. Two wild accessions of Macadamia jansenii and M. ternifolia were found to be distantly related to the cultivars. Wild germplasm individuals and their hybrids with cv. ‘660’ formed separate clusters, suggesting that crossing between wild and cultivated genepools can extend genetic diversity. DArTseq-based SNP markers were successfully utilized to confirm the genetic identity of 25 scions in a rootstock trial. Our study suggests that DArT platforms are a robust system for the facilitation of genomic studies with regard to macadamia.

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