Insights into the Genetic Relationships and Breeding Patterns of the African Tea Germplasm Based on nSSR Markers and cpDNA Sequences.
Africa is one of the key centers of global tea production. Understanding the genetic diversity and relationships of cultivars of African tea is important for future targeted breeding efforts for new crop cultivars, specialty tea processing, and to guide germplasm conservation efforts. Despite the economic importance of tea in Africa, no research work has been done so far on its genetic diversity at a continental scale. Twenty-three nSSRs and three plastid DNA regions were used to investigate the genetic diversity, relationships, and breeding patterns of tea accessions collected from eight countries of Africa. A total of 280 African tea accessions generated 297 alleles with a mean of 12.91 alleles per locus and a genetic diversity (H S) estimate of 0.652. A STRUCTURE analysis suggested two main genetic groups of African tea accessions which corresponded well with the two tea types Camellia sinensis var. sinensis and C. sinensis var. assamica, respectively, as well as an admixed "mosaic" group whose individuals were defined as hybrids of F2 and BC generation with a high proportion of C. sinensis var. assamica being maternal parents. Accessions known to be C. sinensis var. assamica further separated into two groups representing the two major tea breeding centers corresponding to southern Africa (Tea Research Foundation of Central Africa, TRFCA), and East Africa (Tea Research Foundation of Kenya, TRFK). Tea accessions were shared among countries. African tea has relatively lower genetic diversity. C. sinensis var. assamica is the main tea type under cultivation and contributes more in tea breeding improvements in Africa. International germplasm exchange and movement among countries within Africa was confirmed. The clustering into two main breeding centers, TRFCA, and TRFK, suggested that some traits of C. sinensis var. assamica and their associated genes possibly underwent selection during geographic differentiation or local breeding preferences. This study represents the first step toward effective utilization of differently inherited molecular markers for exploring the breeding status of African tea. The findings here will be important for planning the exploration, utilization, and conservation of tea germplasm for future breeding efforts in Africa.
Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China; Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China; College of Life Science, University of Chinese Academy of SciencesKunming, China; Genetic Resources Unit, World Agroforestry CentreNairobi, Kenya; Tea Research Institute, Kenya Agricultural and Livestock Research OrganizationKericho, Kenya.
Moses C
MC
Wambulwa
Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China; Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China; College of Life Science, University of Chinese Academy of SciencesKunming, China; Genetic and Plant Breeding Division, Coconut Research InstituteLunuwila, Sri Lanka.
Muditha K
MK
Meegahakumbura
Tea Research Institute, Kenya Agricultural and Livestock Research Organization Kericho, Kenya.
Samson
S
Kamunya
Genetic Resources Unit, World Agroforestry Centre Nairobi, Kenya.
Alice
A
Muchugi
Department of Science, Royal Botanic Garden Edinburgh Edinburgh, UK.
Michael
M
Möller
Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences Kunming, China.
Jie
J
Liu
Genetic Resources Unit, World Agroforestry CentreNairobi, Kenya; Centre for Mountain Ecosystems, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China.
Jian-Chu
JC
Xu
Centre for Mountain Ecosystems, Kunming Institute of Botany, Chinese Academy of Sciences Kunming, China.
Sailesh
S
Ranjitkar
Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China; Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China; College of Life Science, University of Chinese Academy of SciencesKunming, China.
De-Zhu
DZ
Li
Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences Kunming, China.
Lian-Ming
LM
Gao
African tea germplasm; Camellia sinensis; breeding improvement; cpDNA regions; genetic diversity; nSSR markers