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University of Khartoum (2015)

Estimation of Genetic Diversity in Acacia Seyal Varieties from Some Ecological Zones of the Sudan

Abdalla, Thorayia Musa Mohammed

Titre : Estimation of Genetic Diversity in Acacia Seyal Varieties from Some Ecological Zones of the Sudan

Auteur : Abdalla, Thorayia Musa Mohammed

Université de soutenance : University of Khartoum

Grade : Doctor of Philosophy (PhD) 2015

Résumé
The study aimed to investigate the genetic diversity using morphometric characters and at the DNA among geographical sources of var. seyal and var. fistula). The assessed morphometric characters were seed morphology, seed germination and early seedling growth. Seeds were collected from geographical sources that represent the natural range in Sudan. Var. seyal sources were Alfola, Almerum and Kadugli in South Kordofan State, Alhawata, Alrawashda, Srfsaed, and Wdbasher in Gedaref State, Singa in Sinnar State, Al-Damazen in Blue Nile State and Khartoum State and leaves were collected from Shendi in River Nile State. For A.seyal var. fistula seeds were collected from Almigrih and Alhawata in Gadaref State. Seed samples were taken from each source and seed length, width and weight were measured. Seeds from each source were planted under nursery conditions, and germination was recorded periodically. Seedling growth parameters were measured after one, two and three months from date of sowing. Random Amplified Polymorphic DNA (RAPD) marker procedure was used to estimate DNA diversity. DNA was extracted from newly fresh leaves of 60 seedlings from each geographical of the two varieties. Bands were generated using four primers (OPA9, OPC9, OPA8 and OPA17). Genetic variations within and among populations of A. seyal were estimated using PAST software, Un-weighted Pair Group Method Arithmetic Average (UPGMA) and principal Coordinate analyses (PCoA) were carried. Significant differences were observed between Almigrih and Alhawata sources of var. fistula in seed weight and seed width (P<0.003), and germination rate (P<0.0063). Differences in seed length, and germination percentage were not significant. On the other hand var. seyal showed significant variation among the 10 sources in seed length, width and weight (P<0.0001), germination rate (P<0.0001) and germination percentage (P<0.0001). Differences between the two sources of var. fistula in seedling growth traits increased with seedling age. After one month from seed sowing the differences were only significant for shoot length (P<0.021) and root weight (P<0.0053. However, After the second month the differences were significant for root length, and shoot, root and leaf weight (P<0.001), and after three months, there were significant differences in shoot length, root length, shoot weight, root weight and leaf weight (P< 0.0096). As for var. seyal the differences among the sources in the second and third month from seed sowing were significant in root, shoot and leaf or in total weight (P<0.0001). The RAPD procedure showed significant variations among the geographical sources of each variety and between the two varieties. The variations among var. seyal sources in seed and seedling growth traits and at the DNA level were associated with variations in environmental conditions, especially annual rainfall. The sources should similar clustering for the morphological traits and at the DNA. The following clusters were identified : 1) Alhawata, Alrawashda, Srfsaed, and Wdbasher, 2) Singa and Al-Damazen, 3) Alfola, 4) Almerum and Kadugli, 5) Khartoum, and 6) Shendi. These results indicate that seed traits and seedling growth traits of Acacia seyal are adaptive traits with genetic basis. Also, Movement of seeds from distant sources should be restricted. Also, the results of the study revealed distinct differences between var. seyal and var. fistula in seed traits, germination rate, germination percentage, seedling growth and at the DNA level, confirming that they are two distinct sub-taxa.

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Page publiée le 23 août 2016, mise à jour le 20 juin 2017