Introgression of chromosome segments from multiple alien species in wheat breeding lines with wheat streak mosaic virus resistance

Abstract

Pyramiding of alien-derived Wheat streak mosaic virus (WSMV) resistance and resistance enhancing genes in wheat is a costeffective and environmentally safe strategy for disease control. PCR-based markers and cytogenetic analysis with genomic in situ hybridisation were applied to identify alien chromatin in four genetically diverse populations of wheat (Triticum aestivum) lines incorporating chromosome segments from Thinopyrum intermedium and Secale cereale (rye). Out of 20 experimental lines, 10 carried Th. intermedium chromatin as T4DL*4Ai#2S translocations, while, unexpectedly, 7 lines were positive for alien chromatin (Th. intermedium or rye) on chromosome 1B. The newly described rye 1RS chromatin, transmitted from early in the pedigree, was associated with enhanced WSMV resistance. Under field conditions, the 1RS chromatin alone showed some resistance, while together with the Th. intermedium 4Ai#2S offered superior resistance to that demonstrated by the known resistant cultivar Mace. Most alien wheat lines carry whole chromosome arms, and it is notable that these lines showed intra-arm recombination within the 1BS arm. The translocation breakpoints between 1BS and alien chromatin fell in three categories: (i) at or near to the centromere, (ii) intercalary between markers UL-Thin5 and Xgwm1130 and (iii) towards the telomere between Xgwm0911 and Xbarc194. Labelled genomic Th. intermedium DNA hybridised to the rye 1RS chromatin under high stringency conditions, indicating the presence of shared tandem repeats among the cereals. The novel small alien fragments may explain the difficulty in developing well-adapted lines carrying Wsm1 despite improved tolerance to the virus. The results will facilitate directed chromosome engineering producing agronomically desirable WSMV-resistant germplasm.

CENH3 morphogenesis reveals dynamic centromere associations during synaptonemal complex formation and the progression through male meiosis in hexaploid wheat

“…The role of presynaptic centromere associations and their transition to homologous pairing Individual chromosome pairs visualized by in situ hybridization (Schwarzacher et al, 1992) can be studied in alien introgression lines of hexaploid wheat, carrying whole chromosomes or chromosome arms from a related species (Moln ar et al, 2015;Ali et al, 2016). A study on a wheat-rye translocation line revealed that cognition of homologous chromosome partners initiates at the centromeres in meiotic interphase and, subsequently, homologous chromosome segments align in leptotene with synapsis starting at the telomeres (Schwarzacher, 1997).…”

Biodiversity in Ethiopian linseed (Linum usitatissimum L.): molecular characterization of landraces and some wild species

“…Selection may be related to agronomic performance and also regional use differences (Worku et al 2005(Worku et al , 2012. Previously, Ali et al (2016) showed clusters of variation between the Ethiopian linseed landraces and non-native cultivars for majority of morphological traits. Noormohammadi et al (2015) reported wild L. austriacum L. populations at intermediate altitudes have greater diversity than populations at lower and higher altitudes.…”

Association Mapping of Root Traits for Drought Tolerance in Bread Wheat

“…A total of 102 PCR-based markers were applied aiming to understand their genetic structure and to identify molecular markers that are closely associated to quantitative trait loci (QTLs) of important root traits ( Table 2). Plant germination, DNA extraction and PCR proiling followed previously published standard procedures [32]. Further, population structure of these lines was analyzed with general linear model (GLM) and mixed linear model (MLM) approaches using TASSEL software with their default seting for identiication of QTLs associated with important root traits.…”