Agronomy and Horticulture Department



Madhav Bhatta

First Advisor

P. Stephen Baenziger

Date of this Version



Bhatta, M. 2018. Identification of genes/genomic regions controlling resistance to biotic and abiotic stresses in synthetic hexaploid wheat. Ph.D. dissertation. Univ. of Nebraska-Lincoln.


A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Agronomy and Horticulture (Plant Breeding and Genetics), Under the Supervision of Professor P. Stephen Baenziger. Lincoln, Nebraska: November, 2018.

Copyright (c) 2018 Madhav Bhatta


Synthetic hexaploid wheat (SHW; 2n=6x=42, AABBDD, Triticum aestivumL.) is produced from an interspecific cross between durum wheat (2n=4x=28, AABB, T. turgidumL.) and goat grass (2n=2x=14, DD, AegilopstauschiiCoss.). It is reported to have a considerable amount of genetic diversity and is a potential source of novel alleles controlling abiotic and biotic stresses resistance and improving wheat quality. Therefore, the first study was to understand the genetic diversity and population structure of SHWs and compare the genetic diversity of SHWs with elite bread wheat (BW) cultivars. The result of this study identified a wide range of genetic diversity within the SHWs. The genetic diversity of the ABD and D-genome of SHWs were 50% and 88.2%, respectively, higher than that found on the respective genome in a sample of elite BW cultivars. The second study was to identify novel genomic regions and underlying genes associated with grain yield and yield-related traits under two drought-stressed environments. This study identified 90 novel genomic regions and haplotype blocks associated with improving grain yield and yield-related traits with phenotypic variance explained of up to 32.3%. The third study was to identify common bunt resistance genotypes, genomic regions and underlying genes conferring resistance to common bunt. This study identified 29 resistant SHWs and 15 genomic regions (five were novel) conferring resistance to common bunt. The fourth study to explore the genetic variation of 10-grain minerals (Ca, Cd, Co, Cu, Fe, Li, Mg, Mn, Ni, and Zn) and grain protein concentration (GPC); identify marker-trait associations and candidate genes associated with grain minerals using a genome-wide association study (GWAS). A wide range of genetic variation identified within SHWs for GPC and grain mineral concentrations. A GWAS identified 92 genomic regions (60 were novel and 40 were within genes) associated with increasing beneficial grain mineral concentration and decreasing concentration of toxic compound such as Cd. The results from this research will be valuable for broadening the genetic base of wheat and could assist in further understanding of the genetic architecture of traits under biotic and abiotic stresses.

Advisor: P. Stephen Baenziger