ABSTRACT

 A study was carried out to determine the biochemical composition of and genetic diversity among ten maize (Zea mays L.) varieties assessed by Rapid Amplified Polymorphic DNA (RAPD) markers. Grains of ten maize varieties grown in Eastern part of Nigeria were collected from National Seed Company of Nigeria Umuahia and investigated for their nutritive value to assess their dietary value for humans. Proximate composition shows moisture content in the range of (9.85-11.3 %), ether extract (3.17 - 4.09 %), protein (10.72 - 12.33 %), crude fiber (1.84 -2.06 %) and carbohydrates (68.73-72.17 %), starch (59.72-71.14 %), sugar (7.53-8.78 %). The data indicate that seeds of these varieties vary greatly in protein, fats and crude fibre contents as well as in carbohydrate, sugar and starch contents. ART/98/SW1-1 and SDM-2 varieties were found to contain higher protein content (>12 %) while SUWAN-l-SR-Y and SDM-2 contain high fats content of (>4%). TZPB-SR-W and BR9943-DMR-SR-W contain higher starch content. In minerals the level of sodium is (61.77-180.68 mg/lOOg), K (315.71-342.78 mg/lOOg), Ca (163.77 -180.68 mg/lOOg), Fe (2.79 - 3.46 mg/lOOg), Mg (136.87 -146.91 mg/lOOg) and P (260.78- 285.78 mg/lOOg). The leaves of the maize varieties were also evaluated for their chlorophyll and carotene contents. The result of the analysis of variance showed high significant differences among the varieties. SI'WAN-1 -SR-Ywas found to have highest significant amount of chlorophyll a, b and total chlorophyll (a + b) as well as in carotenoid. The result of the correlation analysis also showed that there was statistically significant correlations (P<0.01) between chlorophyll a, b, total chlorophyll (a + b) and carotenoA study was also earned out to compare the concentration, purity and quality of the extracted DNA from maize seed varieties. The result indicated that TZPB-SR-W (260.18 mg/lOOg) had significantly (P<0.05) higher DNA concentration while DNA concentration in MDV-3 variety (233.07 mg/lOOg) was the lowest. DNA purity was significantly (P<0.05) higher in SUWAN-l-SR-Y variety (1.93g) while varieties OB-98, MDV-3 and TZPB-SR-W with no significant differences had the least value (1.68) for purity. The quality of DNA was significantly higher in SAMMAZ-28 (2.18) while SUWAN-l-SR-Y showed the least value (2.07). This result established that differences existed in concentration, purity and quality of extracted DNA in different varieties of maize seeds. The Random Amplified Polymorphic DNA (RAPD) profiles of ten maize varieties were separately compared to find out the differences among them by the occurrence of polymorphic bands. Using different primer combinations, specific RAPD fingerprinting profiles were obtained for each of the maize variety. Of the 20 primer combinations screened, 10 were reliable. The RAPD profiling of the 10 maize varieties revealed polymorphic bands ranging in size from 200bp for OPD - 17 and OPE-18 to 500bp OPB - 02, OPH02 and OPD11. A total of 102 scorable bands or fragment length was produced in ten maize varieties with primers. A high level of polymorphism of 82.39% was detected among the ten varieties. Based on the RAPD markers, a dendrogram was constructed using the UPGMA method. From the dendogram Oba super-2 and SDM-2 are 0.825 (82.5%) genetically identical followed by SAMMAZ and MDV-3 0.8 (80%) and the lowest 0.65 (65%) was observed between ART/98/SW1-1 and BR-9943-DMR-SRW. The RAPD led to a clear distinction among the six varieties and the other four varieties.