|SCHEURING, C - Texas A&M University|
Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2009
Publication Date: 7/24/2009
Citation: Larson, S.R., Scheuring, C., Kaur, P., Cliften, P.F., Mott, I.W., Bushman, B.S., Dong, J.J., Zhang, Y., Zhang, X., Wang, R. 2009. BAC Library Development for Allotetraploid Leymus (Triticeae) Wildryes Enable Comparative Genetic Analysis of Lax-Barrenstalk1 Orthogene Sequences and Growth Habit QTLs. Plant Sci. 177:427-438. doi:10.1016/j.plantsci.2009.07.006.
Interpretive Summary: Basin wildrye (Leymus cinereus) and creeping wildrye (Leymus triticoides) are two of the largest native perennial grasses in western North America. Hybrids of basin wildrye and creeping wildrye display a combination of traits, including tall plant height and a profusion lateral rhizome- and tiller-stem branches, which may be useful for biomass production. We developed genomic DNA libraries from a creeping x basin wildrye hybrid, using bacterial artificial chromosomes (BACs) as the cloning vector, which contain 405,888 clones with an estimated average length of 150,000 nucleotide-base-pairs of plant DNA per clone. Thus, we estimate that this library contains about 6.1 copies of the Leymus wildrye genome and should include at least one copy of most genes. The lax-barrenstalk1 gene controls the initiation of lateral branches in rice and maize but was not previously isolated from cool-season grasses such as wheat, barley, or the Leymus wildryes. As part of this study, DNA sequences from the lax-barrenstalk1 gene of maize and rice hybridized to 12 of the Leymus wildrye BAC clones. Deduced amino acid sequences and genetic map positions from at least seven BAC clones were highly conserved with the rice and maize lax-barrenstalk1 genes. Mutations of the lax-barrenstalk1 orthogene were detected in creeping wildrye and are located in a chromosome region that controls tiller and rhizome proliferation in families derived from the basin and creeping wildrye hybrids. These BAC libraries and gene sequences provide new resources to investigate growth habit and other key traits in large-statured perennial grasses.
Technical Abstract: Tall caespitose basin wildrye (Leymus cinereus) and rhizomatous creeping wildrye (Leymus triticoides) are two of the largest native grasses in western North America and the interspecific hybrids display a heterotic combination of traits. The rice lax panicle and maize barrenstalk1 orthogenes are transcription factors responsible for induction of axillary branches. Sequences orthologous to the lax-barrenstalk1 orthogene were not previously identified in Triticeae or other cool-season grasses despite many available ESTs. We developed BamHI and Mbo1 bacterial artificial chromosome (BAC) libraries from a creeping x basin wildrye hybrid including 405,888 clones with an estimated average length of 150.5 kb per insert, which represents 6.1 haploid genome-equivalents of these allotetraploid Leymus wildryes. Degenerate PCR primers designed from the lax-barrenstalk1 orthogene were used to amplify homologous sequences from Leymus. Overgo probes designed from these Leymus sequences hybridized to 12 BAC clones. Deduced amino acid sequences and linkage map positions from at least seven BAC clones were highly conserved with the rice and maize lax-barrenstalk1 orthogenes. Nonsense mutations of the lax-barrenstalk1 orthogene were detected in creeping wildrye and possible associations with Leymus tiller and rhizome QTLs were investigated. These BAC libraries and gene sequences provide new resources to investigate growth habit and other key traits in large-statured perennial grasses.