MOLECULAR AND PHENOTYPIC RESISTANCE OF GROUNDNUT VARIETIES TO LEAF SPOTS DISEASE IN GHANA

Groundnut yield is constrained in most cases by early and lateleaf spots diseases. Selection and breeding for resistance will enhance yields. Therefore, this study was conducted in Crop Research Institute, Fumesua-Kumasi, Ghana to screen 20 groundnut varieties for leaf spots resistance using both molecular and phenotypic tools. Differences in disease incidence among individual plants, severity score, lesion diameter and defoliation across the 20 genotypes were highly significant (p<0.01) under phenotypic screening. Fourteen genotypes were moderately resistant while six genotypes were susceptible. The SSR markers pPGseq2F5(280), pPGseq2B10(280/290), pPGPseq17F6(120/140/150), PMc588(180/220) and PM384(100) confirmed most resistant genotypes at the molecular level. The resistant genotypes confirmed by the markers were 'ICG7878', 'Obolo', 'Oboshie', 'Jenkaar', 'Adepa', 'Nkosour', 'Azivivi', 'Nkatekokoo', 'Behenase', 'Manipinta', 'Otuhia', 'GK7', 'Nkatiesari' and 'Sumnut22'. Genotypes '55-437', 'Yenyawoso', 'Bremawuo', 'Kumawu', 'Konkoma' and 'Shitaochi' were susceptible. Hence, resistance to leaf spots exists among commercially grown groundnuts in Ghana. Both morphological descriptors and DNA molecular could be used for identification of resistant genotypes.