Molecular evaluation of Afghan wheat landraces

Abstract

The wheat landraces collected by Dr Hitoshi Kihara et al. from Afghanistan, the place of secondary origin of wheat, are an untapped genetic resource for mining novel alleles. In this study, approximately 400 landraces were collected from seven agroecological zones and characterized using diversity array technology and single-nucleotide polymorphism markers, as well as diagnostic molecular markers at important loci controlling vernalization (Vrn), photoperiod response (Ppd), grain colour (R), leaf rust (Lr), yellow rust (Yr), stem rust (Sr) and Fusarium head blight (Fhb). A genome-wide marker array revealed a large amount of genetic diversity among the landraces, 53% of which were winter types, 43% were either spring types or facultative and 4% were either unknown or had Vrn-A1c – a rare spring allele that needs to be confirmed with additional genotyping and phenotyping. At Ppd, 97% of the lines carried a photosensitive allele. In the case of grain colour, classification based on dominant or recessive allelic combinations revealed that approximately 39% of the population is characterized by white grain. Four gene-specific markers that were targeted to identify loci for rust and Fhb resistance enabled us to identify 17 unique landraces with known resistance genes.

Genome wide association mapping of stripe rust resistance in Afghan wheat landraces

“…In this research we reported the response of 352 KAWLR against yellow rust resistance under diverse environments in Afghanistan and Mexico ( Table 1). The ANOVA results indicated the huge diversity in stripe rust response in the landrace panel in concordance with the previous genetic diversity study on the same materials with molecular markers [10,11]. Sufficient numbers of resistant landraces could be found across environments that could be used to increase the genetic diversity for stripe rust resistance in regions threatened by the breakdown of the resistance gene Yr27.…”

“…Afghan landraces, untapped genetic resources collected and preserved by Dr. Hitoshi Kihara, are among the germplasms never characterized so far to know their potential for contributing stripe rust resistance. The place of origin and the previous study on genotypic characterization offer the possibility to mine new resistance sources for stripe rust [10,11]. Also the recent report showed the Himalayan and surrounding region as centre of origin of Pst virulence races [9].…”

“…The greater number of detected QTL also may be the result of more complex environmental conditions found in the field compared to the controlled environment. This is due to the huge genetic diversity in this germplasm and the prevailing adaptation mechanism of landraces [10,11,32]. Also the combined vision of Pst virulent races origin around Himalayan region and the co-evolution nature of landraces along with stress showed the importance of this study and identification of new resistance sources for stripe rust [9,12] The rust mapper (http://rusttracker.cimmyt.org/) and Hovmoller [9] reported the presence and spreading of new virulence races of stripe rust.…”

Harnessing adult-plant resistance genes to deploy durable disease resistance in crops

“…Vavilov Institute of Plant Genetic Resources (VIR) wheat collections. Through rust screening and genotyping the collections using either the 90K single-nucleotide polymorphism (SNP) or diversity array technology (DArT) platforms, genome-wide association studies (GWAS) enabled the rapid discovery of new quantitative trait loci (QTLs) associated with APR [8][9][10][11]. The recently established gold standard reference genomes of cultivated wheat and its progenitors will accelerate the identification of markers and candidate genes associated with these QTLs [12].…”

Photoperiod and vernalization alleles and their combinations greatly affected phenological and agronomic traits in bread wheat under autumn and spring sowing conditions

“…This implies that different regions require different VRN-1 and PPD-1 combinations to meet local production conditions. In Afghanistan, the PpD-D1a characterized as vast majority (about 97%) of the wheat landraces studied (Manickavelu et al, 2014). The VRN-A1, VRN-B1 , and VRN-D1 dominant alleles were the most widespread in wheat cultivars across India’s various agro-climatic regions (Singh et al, 2013).…”