Development of Stable Homozygous Wheat/Amblyopyrum muticum (Aegilops mutica) Introgression Lines and Their Cytogenetic and Molecular Characterization

Abstract

Wheat is one of the world’s most important sources of food. However, due to its evolution its genetic base has narrowed, which is severely limiting the ability of breeders to develop new higher yielding varieties that can adapt to the changing environment. In contrast to wheat, its wild relatives provide a vast reservoir of genetic variability for most, if not all, agronomically important traits. Genetic variation has previously been transferred to wheat from one of its wild relatives, Ambylopyrum muticum (previously known as Aegilops mutica). However, before the genetic variation available in this species can be assessed and exploited in breeding and for research, the transmission of the chromosome segments introgressed into wheat must first be stabilized. In this paper we describe the generation of 66 stably inherited homozygous wheat/Am. muticum introgression lines using a doubled haploid procedure. The characterisation and stability of each of these lines was determined via genomic in situ hybridization and SNP analysis. While most of the doubled haploid lines were found to carry only single introgressions, six lines carried two. Three lines carried only complete Am. muticum chromosomes, 43 carried only small or very small introgressions and the remainder carried either only large introgressions or a large plus a small introgression. The strategy that we are employing for the distribution and exploitation of the genetic variation from Am. muticum and a range of other species is discussed.

Generation of Doubled Haploid Wheat-Triticum urartu Introgression Lines and Their Characterisation Using Chromosome-Specific KASP Markers

“…The DH production procedure used was as described by Laurie and Reymondie (1991) and used previously to generate wheat- Am. muticum DH lines ( King et al, 2019 ). In summary, wheat spikes were emasculated and then pollinated with maize (cultivars Northern Extra Sweet, Prelude and Sundance).…”

The Resurgence of Introgression Breeding, as Exemplified in Wheat Improvement

“…Given that the success rate in inducing introgressions is quite low, and that conventional cytological methods are not capable of distinguishing between large and small introgression segments, pioneering attempts to achieve this goal were largely unsuccessful. Recent advances with respect to both chromosome manipulation and particularly in genetic marker technology, however, are changing this picture (Winfield et al, 2016;King et al, 2017King et al, , 2019Koo et al, 2017). A list of successful examples is presented in Table 2.…”

Chromosome Pairing in Polyploid Grasses

“…One of the key components for the successful utilization of wide hybridization in plant breeding is the control of homoeologous chromosome associations. In countless studies, the ph1b mutant of wheat has been used to induce homoeologous chromosome recombinations between chromosomes of wheat and related species, for transferring desirable traits into the wheat genome ( Marais et al., 2010 ; Niu et al., 2011 ; Ayala-Navarrete et al., 2013 ; Rey et al., 2015a ; Rey et al., 2015b ; Han et al., 2016 ; King et al., 2019 ). After the introgression of the chromosomal segment from a related species, it is necessary to immediately re-activate the Ph1 gene to avoid risking the rapid elimination of the segment.…”