Agronomy and Horticulture, Department of


First Advisor

Sally A. Mackenzie

Date of this Version


Document Type



Ketumile D., 2017. Msh1-mediated non-genetic phenotypic variation in plants: Prospects for epigenetic breeding in Sorghum bicolor. Master's Thesis, UNL.


A Thesis Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfilment of Requirements For the Degree of Master of Science, Major: Agronomy, Under the Supervision of Professor Sally A. Mackenzie. Lincoln, Nebraska: August, 2017

Copyright (c) 2017 Dikungwa Ketumile


Sorghum is the fifth most important cereal crop grown in the world, and is the primary staple food for many people in developing countries. Like other major crops, its improvement is constrained by depletion of genetic diversity within breeding germplasm. Investigated in this study is the unique creation of non-genetic phenotypic variation through altering MutS Homolog1 (MSH1), a plant-specific gene, and the potential it presents for sorghum improvement. Suppression of MSH1 results in non-genetic developmental reprogramming. The derived MSH1 memory lines, when used in crossing, result in heritable phenotypic variation that enhances plant vigor and agronomic performance. A previous study of MSH1-suppression effects in TX430 sorghum inbred revealed dramatic phenotypic variation. However, a proportion of the phenotypic effect was found to be genetic, resulting from spontaneous reversion of dwarfing gene dw3 to produce plant height variability. In this study, the possibility that MSH1 suppression influenced dw3 reversion was investigated; however, no evidence of increased dw3 reversion was found. F2 progeny derived from F1 parents pre-screened for dw3 reversion showed enhanced phenotypic variation in plant height, days to flowering, tillering and grain yield relative to the wildtype. A large proportion of the F2 families showed tendency to be taller and delayed in flowering, while about 10% of families outperformed the wildtype in tillering and grain yield. The observed MSH1 induced range of phenotypic variation in agronomic traits presents an opportunity for selection and potential for breeding in crops.

Advisor: Sally A. Mackenzie