Characterization of wheat-Thinopyrum bessarabicum genetic stock for stripe rust and Karnal bunt resistance

Utilization of modern breeding techniques for developing high yielding and uniform plant types ultimately narrowing the genetic makeup of most crops. Narrowed genetic makeup of these crops has made them vulnerable towards disease and insect epidemics. For sustainable crop production, genetic variability of these crops must be broadened against various biotic and abiotic stresses. One of the ways to widen genetic configuration of these crops is to identify novel additional sources of durable resistance. In this regard crops wild relatives are providing valuable sources of allelic diversity towards various biotic, abiotic stress tolerance and quality components. For incorporating novel variability from wild relative’s wide hybridization technique has become a promising breeding method. For this purpose, wheat-Th. bessarabicum amphiploid, addition and translocation lines have been screened in field and screen house conditions to get novel sources of yellow rust and Karnal bunt resistant. Stripe rust screening under field conditions has revealed addition lines 4JJ and 6JJ as resistant to moderately resistant while addition lines 3JJ, 5JJ, 7JJ and translocation lines Tr-3, Tr-6 as moderately resistant wheat-Thinopyrum-bessarabicum genetic stock. Karnal bunt screening depicted addition lines 5JJ and 4JJ as highly resistant genetic stock. These genetic stocks may be used to introgression novel stripe rust and Karnal bunt resistance from the tertiary gene pool into susceptible wheat backgrounds.

Development of RNA-seq-based molecular markers for characterizing Thinopyrum bessarabicum and Secale introgressions in wheat

Sequence-based markers have added a new dimension in the efficiency of identifying alien introgressions in wheat. Expressed sequence tag-sequence tagged sites (EST-STS) markers have proved useful in tracing alien chromatin. In this study, we report the development of Thinopyrum bessarabicum- and Secale anatolicum-specific EST-STS markers and their application in tracing respective alien chromatin introgressions in wheat. The parental lines, Chinese Spring (CS), ISR991.1 (CS/Th. bessarabicum amphidiploid), and ISR1049.2 (CS/Secale anatolicum amphidiploid), were used as core experimental materials. Using comparative analysis of RNA-Seq data, 10 903 and 10 660 candidate sequences specific to Th. bessarabicum and S. anatolicum, respectively, were assembled and identified. To validate the genome specificity of these candidate sequences, 68 and 64 EST-STS markers were developed from randomly selected candidate sequences of Th. bessarabicum and S. anatolicum, respectively, and tested on sets of alien addition lines. Fifty-five and 53 markers for Th. bessarabicum and S. anatolicum chromatin, respectively, were assigned to chromosomal location(s), covering all seven chromosomes. Approximately 83% of S. anatolicum-specific markers were transferable to S. cereale. The genome-specific candidate sequences identified and the EST-STS markers developed will be valuable resources for exploitation of Th. bessarabicum and Secale species diversity in wheat and triticale breeding.

Novel Sources of Variation in Grain Yield, Components and Mineral Traits Identified in Wheat Amphidiploids Derived from Thinopyrum bessarabicum (Savul. & Rayss) Á. Löve (Poaceae) under Saline Soils in India

Salt-affected soils constrain wheat production globally. A wild wheat species, Thinopyrum bessarabicum (Savul. & Rayss) Á. Löve (Poaceae), and its derivatives are tolerant of high external NaCl concentrations but have not been tested yet in field conditions. The aim of this study was to study the performance of amphidiploids derived from T. bessarabicum for grain yield (GYD), yield components and grain mineral composition traits under normal and saline soil conditions. Field experiments were conducted at Karnal (pH(water) = 7.3) and Hisar (pH(water) = 8.3) sites in 2014–2015 and 2015–2016 in India. Grain samples were analysed using inductively coupled plasma–mass spectrometry (ICP-MS). Yield and yield component traits of amphidiploids were typically greater at Karnal than Hisar. The GYD was greater at Karnal (1.6 t ha−1) than Hisar (1.2 t ha−1) in 2014–2015. However, GYD was greater at Hisar (1.7 t ha−1) than Karnal (1.1 t ha−1) in 2015–2016. Mean grain zinc (Zn) concentration of eight amphidiploids, averaged across sites and years, varied from 36 to 43 mg kg−1. Some amphidiploids derived from T. bessarabicum showed greater GYD and grain Zn concentration under saline soils (Hisar) than normal soils (Karnal). These might be potential new sources for the development of salt-tolerant wheat varieties with increased grain Zn concentration under salt-affected soils.

Copy Number Variation of Transposable Elements in Thinopyrum intermedium and Its Diploid Relative Species

Diploid and polyploid wild species of Triticeae have complex relationships, and the understanding of their evolution and speciation could help to increase the usability of them in wheat breeding as a source of genetic diversity. The diploid species Pseudoroegneria spicata (St), Thinopyrum bessarabicum (Jb), Dasypyrum villosum (V) derived from a hypothetical common ancestor are considered to be possible subgenome donors in hexaploid species Th. intermedium (JrJvsSt, where indices r, v, and s stand for the partial relation to the genomes of Secale, Dasypyrum, and Pseudoroegneria, respectively). We quantified 10 families of transposable elements (TEs) in P. spicata, Th. bessarabicum, D. villosum (per one genome), and Th. intermedium (per one average subgenome) using the quantitative real time PCR assay and compared their abundance within the studied genomes as well as between them. Sabrina was the most abundant among all studied elements in P. spicata, D. villosum, and Th. intermedium, and among Ty3/Gypsy elements in all studied species. Among Ty1/Copia elements, Angela-A and WIS-A showed the highest and close abundance with the exception of D. villosum, and comprised the majority of all studied elements in Th. bessarabicum. Sabrina, BAGY2, and Angela-A showed similar abundance among diploids and in Th. intermedium hexaploid; Latidu and Barbara demonstrated sharp differences between diploid genomes. The relationships between genomes of Triticeae species based on the studied TE abundance and the role of TEs in speciation and polyploidization in the light of the current phylogenetic models is discussed.

Molecular-cytogenetic analysis of diploid wheatgrass Thinopyrum bessarabicum (Savul. and Rayss) A. Löve

Thinopyrum bessarabicum (T. Săvulescu & T. Rayss, 1923) A. Löve, 1980 is diploid (2n=2x=14, JJ or EbEb), perennial self-fertilizing rhizomatous maritime beach grass, which is phylogenetically close to another diploid wheatgrass species, Agropyron elongatum (N. Host, 1797) P. de Beauvois, 1812. The detailed karyotype of Th. bessarabicum was constructed based on FISH with six DNA probes representing 5S and 45S rRNA gene families and four tandem repeats. We found that the combination of pAesp_SAT86 (= pTa-713) probe with pSc119.2 or pAs1/ pTa-535 allows the precise identification of all J-genome chromosomes. Comparison of our data with the results of other authors showed that karyotypically Th. bessarabicum is distinct from A. elongatum. On the other hand, differences between the J-genome chromosomes of Th. bessarabicum and the chromosomes of hexaploid Th. intermedium (N. Host, 1797) M. Barkworth & D.R. Dewey, 1985 and decaploid Th. ponticum (J. Podpěra, 1902) Z.–W. Liu & R.–C. Wang, 1993 in the distribution of rDNA loci and hybridization patterns of pSc119.2 and pAs1 probes could be an indicative of (1) this diploid species was probably not involved in the origin of these polyploids or (2) it could has contributed the J-genome to Th. intermedium and Th. ponticum, but it was substantially modified over the course of speciation