Morphological and Molecular Characterisation of Nineteen (19) Tomato Cultivars from Northern Nigeria

Tomato is an autogamous vegetable crop whose genetic variability has been reduced by selection and breeding processes. Characterisation of tomato germplasm, therefore, aids the documentation of the genetic variability existing in a population. To morphologically characterise tomato varieties from Northern Nigeria, and molecularly characterise the varieties using (Simple Sequence Repeat (SSR) markers, nineteen (19) tomato varieties were collected from major markets in seven states in Northern Nigeria using a purposive sampling method. Tomato seeds were extracted, prepared, sowed in screen houses and morphologically characterised using cross-sectional shapes, core, pericarp, matured fruit colour, overall fruit shape, size and firmness. Leaves of tomato seedlings four weeks after sowing were pooled and used for genomic DNA extraction. The polymerase chain reaction (PCR) was performed and PCR products were visualized through electrophoresis. SSR fragment analysis was scored as the presence or absence of a specific fragment size from the Electropherograms.

Results showed that 44% of the colour of tomato core was white, 17% were red and pink, 5% were orange and yellow and 11% were variants of other colours, showing wide variations in the qualitative traits. Similarities among the nineteen tomato samples ranged from 14 (Dan India with Derica sweet, Kaduna Tangino, Nassarawa Roma 1 and 2, Niger Roma2, UTC01 and UTC 02) to 86% (between Mai mara and Derica small). SSR gave three unique SSR bands that identified and characterised the cultivars.

The result of this study revealed genetic diversity within a group of tomato genotypes of different origins cultivated in Northern Nigeria using molecular (SSR) analysis. This confirmed the efficacy of the SSR markers as highly variable markers that detect the codominant single locus and are suitable to distinguish between the genetically related cultivars.