Abstract
Aegilops geniculata Roth has been used as a donor of disease-resistance genes, to enrich the gene pool for wheat (Triticum aestivum) improvement through distant hybridization. In this study, the wheat–Ae. geniculata alien disomic substitution line W16998 was obtained from the BC1F8 progeny of a cross between the common wheat ‘Chinese Spring’ (CS) and Ae. geniculata Roth (serial number: SY159//CS). This line was identified using cytogenetic techniques, analysis of genomic in situ hybridization (GISH), functional molecular markers (Expressed sequence tag-sequence-tagged site (EST–STS) and PCR-based landmark unique gene (PLUG), fluorescence in situ hybridization (FISH), sequential fluorescence in situ hybridization–genomic in situ hybridization (sequential FISH–GISH), and assessment of agronomic traits and powdery mildew resistance. During the anaphase of meiosis, these were evenly distributed on both sides of the equatorial plate, and they exhibited high cytological stability during the meiotic metaphase and anaphase. GISH analysis indicated that W16998 contained a pair of Ae. geniculata alien chromosomes and 40 common wheat chromosomes. One EST–STS marker and seven PLUG marker results showed that the introduced chromosomes of Ae. geniculata belonged to homoeologous group 7. Nullisomic–tetrasomic analyses suggested that the common wheat chromosome, 7A, was absent in W16998. FISH and sequential FISH–GISH analyses confirmed that the introduced Ae. geniculata chromosome was 7Mg. Therefore, W16998 was a wheat–Ae. geniculata 7Mg (7A) alien disomic substitution line. Inoculation of isolate E09 (Blumeria graminis f. sp. tritici) in the seedling stage showed that SY159 and W16998 were resistant to powdery mildew, indeed nearly immune, whereas CS was highly susceptible. Compared to CS, W16998 exhibited increased grain weight and more spikelets, and a greater number of superior agronomic traits. Consequently, W16998 was potentially useful. Germplasms transfer new disease-resistance genes and prominent agronomic traits into common wheat, giving the latter some fine properties for breeding.
Highlights
Given ongoing population growth and conflicting resource demands, improvement of wheat (Triticum aestivum L.) yield is increasingly challenging
Pm13 is derived from Ae. longissima Schweinf. and Muschl. [12], Pm57 is derived from Ae. searsii Feldman and Kislev [13], and Pm43 is derived from Thinopyrum intermedium (Host) Barkworth and D.R.Dewey [14]
The result was that, there, two chromosomes exhibited strong green hybridization signals in the root tip cells (Figure 2). These results indicate that W16998 comprised two Ae. geniculata chromosomes and 40 common wheat chromosomes
Summary
Given ongoing population growth and conflicting resource demands, improvement of wheat (Triticum aestivum L.) yield is increasingly challenging. Accurate evaluation and effective utilization of resistant germplasms are prerequisites for the development of resistant cultivars. This is necessary to improve wheat disease resistance, enable screening of large germplasm resources, and enable the transfer and polymerization of resistance genes. It is an increasingly important approach for enriching common wheat with beneficial genes derived from related species by distant hybridization [3,4,5]. Many powdery mildew resistance genes are derived from wild relatives of wheat, and have been introduced to common wheat by additions, substitutions, and translocations of chromosomes. The introduction of resistance genes from wild relatives is imperative and effective approach for broadening the genetic background of wheat
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