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Genetic diversity of cassava (Manihot esculenta Crantz) introduced in the oceanic - 83 islands islands of Vanuatu, Melanesia, - Population : 200, 000 South Pacific - 3 Official Languages : English, French, Bislama Julie Sardos, Roger Malapa, Doyle McKey, -+ 100 local languages Jean-Louis Noyer and Vincent Lebot - Diet based on root crops (traditionally yam and taro)

CASSAVA IN VANUATU THE AIM OF THIS STUDY: - Conduct a survey of the different named • Introduced in the 1850s (« sweet » cultivars only) varieties and have an estimation of • Quickly fully adopted by population cassava’s diversity • Now cultivated from north to south - Compare phenotypic and genetic diversity • Eaten boiled, roasted or made into laplap (traditional pudding) - Determine the implication of sexual events • Leaves are not consumated • Vegetatively propagated (stem cuttings) in generation of the observed variability • Polymorphic • Its diversity has never been studied in Vanuatu

1 Materials and Methods Materials and Method • Description of cultivars by farmers • A survey in 10 • DNA extraction from dried leaves villages located on a different island : • Neutral and co-dominant markers : 12 collection of Single Sequence Repeat (SSR) cultivated varieties • Analysis: population description: Hexp, => A large panel of Hobs, Wright’s fixation index (Fis ecological and values) and construction of a cultural situations neighbour-joining tree based on the dissimiliraty matrix (genetic groups determination)

RESULTS A global collection of 109 different varieties - max. / village: 21 - min. / village: 5 + 8 plants issued from seeds

2 Fis Fis RESULTS Locus 1 -0.087 Locus 7 -0.169 Locus 2 0.093 Locus 8 -0.048 Locus 3 -0.197 Locus 9 0.029 • Molecular data: 3 to 8 alleles / locus Locus 4 -0.203 Locus 10 -0.097 with an average of 5.92 alleles / locus Locus 5 -0.066 Locus 11 -0.018 Locus 6 0.036 Locus 12 -0.188 • H = 0.6632 and H = 0.7162 exp obs For 9 of the 12 loci, Fis values are negative => The population presents an excess of heterozygotes

Dendrogram based on dissimilarities calculated from the SSR data set Dendrogram based on dissimilarities calculated from the SSR data set on named

on named cassava varieties in Vanuatu. Karicassava varieties in Vanuatu. kari Napound wes Awat Kari Kari kari Ngoï ngoï Napound wes Kari Awat Tamatsina Kari Kari Ngoï ngoï Yellow Kari Naï tom poun Tamatsina Kari Kari Yellow Kari Varieties collected Naï tom poun Yellow Kari Kari Tongoa Raïri Kari Kouï kouï mpaï mpaï Yellow Noulngon mori in Santo : Kari Seedling 3 Raïri Seedling 2 Kouï kouï mpaï mpaï Nagoh raplèn Noulngon mori Tanna Seedling 3 Seedling 2 Guilguil Nagoh raplèn Mahe Tanna Pango Erakor Ila Guilguil Biskit Mahe Mango Pango Lastik laplap Ila Seedling 5 Biskit Tri hundred Mango Nawanu mayok white Lastik laplap Polis Seedling 5 Kovehak Tri hundred Katiba Nawanu mayok white Seedling 6 Polis Seedling 7 Kovehak Sava nehvowi Katiba Seedling 8 Seedling 6 Seedling 4 Seedling 7 Mandaï Sava nehvowi Savar Seedling 8 Mariango Seedling 4 Anytime Mandaï Unnamed 9 Savar Unnamed 2 Mariango Tawera mwele Anytime Presence of Nivila gbaou gbaou No geographical Unnamed 9 Found along the river Unnamed 2 Cotten Tawera mwele Vila Nivila gbaou gbaou Bisroe Found along the river White sand Cotten Tanna pau Vila genetic groups Mwétari structure of Bisroe Unnamed 8 White sand "Seed of ""Malekula""" Tanna pau Lorum Mwétari Unnamed 5 Unnamed 8 Metcha "Seed of ""Malekula""" Unnamed 6 Lorum Sava èn tanna genetic diversity Unnamed 5 Mariango red Metcha Unnamed 6 lulu Sava èn tanna Rice Mariango red Sikis ma nis Atchin Tavuo Malakula lulu Rice Seedling 1 Sikis manis Matsohorten Tavuo Betongmoat Seedling 1 Auloua Matsohorten Unnamed 4 Betongmoat Epi Auloua Potokar Unnamed 4 Unnamed 3 Epi Dik Potokar Pasglass Unnamed 3 One peny Dik Unnamed 10 Pasglass Nasem One peny Rice Unnamed 10 Ralava Nasem Rice Rice Kaé malatin Ralava Takara Rice Nissis lokouven Kaé malatin Nissis taman Takara Tounoé mbaï mbaï Nissis lokouven Nipni mokven Nissis taman Unnamed 7 Tounoé mbaï mbaï Temit Nipni mokven Unnamed 11 Unnamed 7 Rice Temit Fijian Unnamed 11 Wot levit Rice Rice Fijian Flower manioc Wot levit Salomon Rice Rice Flower manioc Belli Salomon Rice Rice Borouwo Belli Melmel Rice Ramatsino Borouwo Espel Melmel Sapa Ramatsino Kaoui Espel M. glaziovii Sapa M. glaziovii Kaoui Unnamed 12 M. glaziovii Wes M. glaziovii Plastic tongoa Unnamed 12 Unnamed 1 Wes Agrikaltja Plastic tongoa Unnamed 1 Agrikaltja

3 Dendrogram based on dissimilarities calculated from the SSR data set on named cassava varieties in Vanuatu.

Kari kari Napound wes Discussion Awat Kari Ngoï ngoï Kari Tamatsina Kari Group A Yellow Naï tom poun - Loci which are polymorphic and presence of genetic Kari Tongoa Kari Yellow Kari Raïri K ouï kouï mpa ï mpaï Group B groups: Noulngon mori Seedling 3 See dling 2 Nagoh raplèn Tanna Erakor Guilguil Mahe Pango Ila => several different genotypes introduced Biskit Mango Lastik laplap Se edling 5 Tri hundred Nawanu mayok white Polis Kovehak Katiba See dling 6 Seedling 7 Sava nehvowi Seedling 8 Seedling 4 Mandaï Sav ar Mariango Anytime Unnamed 9 Unnamed 2 Tawera mwele - No geographical organization of genetic diversity: Nivila gbaou gbaou Found along the river Cotten Vila Bisroe White sand Tanna pau Mwétari Unnamed 8 "Seed of ""Malekula""" Lorum => circulation of cultivars throughout the country Unnamed 5 Metcha Unnamed 6 Sava èn tanna Finally: 91 different Mariango red Atchin Malakula lulu Rice Sikis manis Tavuo Seedling 1 genotypes in this Matsohorten Betongmoat Auloua Unnamed 4 Epi Potoka r Unnamed 3 population Dik Pasglass One peny - A large number of different genotypes: Unnamed 10 Nasem Rice Ralava Rice Kaé malatin Takara Nissis lokouven Nissis taman Tounoé mbaï mbaï Nipni mokven => somatic mutation on SSR loci Unnamed 7 Temit Unnamed 11 Rice Fijia n Wot levit Rice Flower manioc Salomon Rice => participation of sexual events in generation of Belli Rice Borouwo Melmel Ramatsino Espel Sapa diversity Kaoui M. glaz iov ii M. glaziovii « Wild » Unnamed 12 Wes Plastic tongoa Unnamed 1 Agrikaltja

Discussion Discussion - Excess of heterozygotes in the population: Presence of genetic clones collected in different => selection of heterozygotes issued islands: from seeds by farmers => particular clones appreciated by farmers are clonally propagated and well conserved Heterozygosity confers advantage to seedlings which favour their retention, Low rate of clonemates (rakes) on the multiplication and adoption as new dendrogram: clones => common varieties which are clonally Inadvertent or deliberate selection ? propagated might be melted with incorporated plants issued from seeds

4 CONCLUSION CONCLUSION • Since their introduction, cassava’s • Human selection, perhaps bolstered by clones have circulated widely natural selection, has favoured throughout the country heterozygous genotypes • Despite vegetative propagation by • Study of genetic diversity within named farmers, it appears that incorporation varieties and study of variation among of volunteer plants occurs commonly villages on a single island would give enough to have affected genotypic more insights into the structure and diversity dynamics of the diversity of cassava in Vanuatu

Thank you [email protected] Vanuatu Agricultural Research and Training Center

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