Morphological and molecular characterization of maize inbred lines in kenya using simple Sequence repeats

Abstract

Maize (Zea mays L.) is the mam staple food in Kenya with ninety percent of the population depending on it for food and income. Despite its importance, farmers in Kenya harvest less than 2.0 ton/ha compared to world average of 5tonlha. The low productivity is as result of many factors that relate to on farm production constraints and insufficient knowledge on the genetic source of germplasm used for crop improvement. The main objective of this study was to characterize ten elite maize inbred lines using fourteen simple sequence repeats (SSRs) molecular markers and morphological traits in order to better understand germplasm diversity. The field experiment was carried out at Kenya Agricultural Research Institute (KARl) field station at Muguga (2093 meters above sea level). Maize for morphological characterization were planted using thc randomized complete block design and grown for one season. Molecular analysis was carried out using genomic DNA extracted from three weeks old leaves using the modified Cetyltrimethyl-ammonium bromide (CTAB) method at KARl Biotechnology center Nairobi. In total 28 alleles were identified, with a mean of 2.0 alleles per locus. Cluster analysis of morphological traits and SSR markers using unweighted pair group method with arithmetic average (UPGMA) revealed three groups among the inbred lines with distinctive genetic profiles and morphological traits. The phenotypic analysis revealed significant variation with respect to plant and ear height, time to anthesis and silk emergence (50%), anthocyanin coloration and yield. Both morphological and molecular analysis showed that CML206, CML204 and CML312 are related. Likewise CML202 and CML444 clustered together in both analyses. CML395 and CML 442 were also grouped together in both morphological and molecular analysis. The two KARl lines (EMll-133 and EMI2-2IO) were grouped together suggesting a common ancestry. Molecular analysis showed that the line OSU23i is genetically related to the lines EM 11- 133 and EMI2-2IO. However, morphological analysis classified OSU23i as unique as it did not cluster with any inbred line. Both molecular and morphological traits were necessary in grouping the ten maize inbred lines. The SSR primers revealed genetic distance «0.3), which is, a good indication confirming the power of SSR markers to distinguish between closely related inbred lines. As a result of this study breeders will be able to select putative heterotic parents for hybridization and stratify the breeding programs based on the diverse characterization of the inbred lines such as EM 11-133 and CML 204, EM 12-210 and CML 395 and CML 202 and CML 204 with a genetic distance of 1.54. On the other hand breeders should avoid crossing lines which are closely related such as CML 206 and CML 312, EM 11- 133 and CML 395 and CML 444 and CML 442 with genetic distance of 0.154. It will also help in designing sound breeding program and improve management strategy for the ten elite maize lines.