Differential Resistance to Stripe Rust (Puccinia striiformis) in Collections of Basin Wild Rye (Leymus cinereus)

Differential resistance to stripe rust (Puccinia striiformis) in a planting of 111 wild collections of Basin wild rye (Leymus cinereus) was noted 2011-2013. In 2011, rust severity was rated on a scale of 1-9. Much lighter infection in 2012 and 2013 was rated as the number of symptomatic leaves per plant divided by plant circumference (to adjust for plant size). Effect of collection was significant in 2011 (P = 0.0042), 2012 (P = 0.0032), and 2013 (P = 0.0095), with a relatively weak (0.23) but significant (P = 0.0149) correlation between 2011 and 2012 and a stronger (0.38) and highly significant (P < 0.0001) correlation between 2012 and 2013. Correlation between results of 2011 and 2013 was near zero and insignificant unless the ratings from 2011 were adjusted for plant size. Representative resistant and susceptible collections will be conserved as accessions in the National Plant Germplasm System. Accepted for publication 19 May 2014. Published 23 June 2014

Development and annotation of perennial Triticeae ESTs and SSR markers

Triticeae contains hundreds of species of both annual and perennial types. Although substantial genomic tools are available for annual Triticeae cereals such as wheat and barley, the perennial Triticeae lack sufficient genomic resources for genetic mapping or diversity research. To increase the amount of sequence information available in the perennial Triticeae, three expressed sequence tag (EST) libraries were developed and annotated for Pseudoroegneria spicata , a mixture of both Elymus wawawaiensis and E. lanceolatus , and a Leymus cinereus × L. triticoides interspecific hybrid. The ESTs were combined into unigene sets of 8 780 unigenes for P. spicata, 11 281 unigenes for Leymus, and 7 212 unigenes for Elymus. Unigenes were annotated based on putative orthology to genes from rice, wheat, barley, other Poaceae, Arabidopsis, and the non-redundant database of the NCBI. Simple sequence repeat (SSR) markers were developed, tested for amplification and polymorphism, and aligned to the rice genome. Leymus EST markers homologous to rice chromosome 2 genes were syntenous on Leymus homeologous groups 6a and 6b (previously 1b), demonstrating promise for in silico comparative mapping. All ESTs and SSR markers are available on an EST information management and annotation database ( http://titan.biotec.uiuc.edu/triticeae/ ).

Molecular genetic linkage maps for allotetraploid Leymus wildryes (Gramineae: Triticeae)

Molecular genetic maps were constructed for two full-sib populations, TTC1 and TTC2, derived from two Leymus triticoides × Leymus cinereus hybrids and one common Leymus triticoides tester. Informative DNA markers were detected using 21 EcoRI–MseI and 17 PstI–MseI AFLP primer combinations, 36 anchored SSR or STS primer pairs, and 9 anchored RFLP probes. The 164-sib TTC1 map includes 1069 AFLP markers and 38 anchor loci in 14 linkage groups spanning 2001 cM. The 170-sib TTC2 map contains 1002 AFLP markers and 36 anchor loci in 14 linkage groups spanning 2066 cM. Some 488 homologous AFLP loci and 24 anchor markers detected in both populations showed similar map order. Thus, 1583 AFLP markers and 50 anchor loci were mapped into 14 linkage groups, which evidently correspond to the 14 chromosomes of allotetraploid Leymus (2n = 4x = 28). Synteny of two or more anchor markers from each of the seven homoeologous wheat and barley chromosomes was detected for 12 of the 14 Leymus linkage groups. Moreover, two distinct sets of genome-specific STS markers were identified in these allotetraploid Leymus species. These Leymus genetic maps and populations will provide a useful system to evaluate the inheritance of functionally important traits of two divergent perennial grass species.Key words: AFLP, perennial grasses, RFLP, STS, SSR.