Genes controlling plant growth habit in Leymus (Triticeae): maize barren stalk1 ( ba1 ), rice lax panicle, and wheat tiller inhibition ( tin3 ) genes as possible candidates

Leymus cinereus and L. triticoides are large caespitose and rhizomatous perennial grasses, respectively. Previous studies detected quantitative trait loci (QTL) controlling rhizome spreading near the viviparous1 ( vp1 ) gene markers on linkage groups LG3a and LG3b in two families, TTC1 and TTC2, derived from Leymus triticoides × Leymus cinereus hybrids. The wheat tiller inhibition gene ( tin3 ) is located on Triticum monococcum chromosome 3 A m L near vp1 . Triticeae group 3 is reportedly collinear with rice chromosome 1, which also contains the maize barren stalk1 and rice lax branching orthogene near vp1 . However, previous studies lacked cross-species markers for comparative mapping and showed possible rearrangements of Leymus group 3 in wheat- Leymus racemosus chromosome addition lines. Here, we developed expressed sequence tag (EST) markers from Leymus tiller and rhizomes and mapped sequences aligned to rice chromosome 1. Thirty-eight of 44 informative markers detected loci on Leymus LG3a and LG3b that were collinear with homoeologous sequences on rice chromosome 1 and syntenous in homoeologous group 3 wheat- Leymus and wheat- Thinopyrum addition lines. A SCARECROW-like GRAS-family transcription factor candidate gene was identified in the Leymus EST library, which aligns to the Leymus chromosome group 3 growth habit QTL and a 324-kb rice chromosome 1 region thought to contain the wheat tin3 gene.