Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Genetic Association Between Winter Hardiness And Sugar Content In Perennial Ryegrass (Lolium perenne L.)

Toshihiko Yamada¹ , Sohei Kobayashi² , Hiroshi Hisano¹ , Ken-ichi Tamura² , Yasuharu Sanada² , Pankaj K. Bhowmik¹ , Midori Yoshida² , Ian P. Armstead³ , Mervyn O. Humphreys³

¹  Hokkaido University, Kita 11, Nishi 10, Kita, Sapporo, Hokkaido, 060-0811, Japan

²  National Agricultural Research Center for Hokkaido Region, Hitsujigaoka 1, Sapporo, Hokkaido, 062-8555, Japan

³  Institute of Grassland and Environment Research, Plas Gogerddan, Aberystwyth, SY23 3EB, Wales, UK

Perennial grasses must survive periods of protracted snow cover and low temperature during the winter in the northern biosphere. Sugar metabolism is one of the important factors involved in winter hardiness. The F₂ (Aurora x Perma) genetic map population of perennial ryegrass was used to identify QTL for traits relating to winter hardiness as well as sugar content. Scores of winter survival were measured in the deep snow environment at Sapporo using fungicide control regime of snow mould fungi, and QTL were identified on LGs 2, 4, 6 and 7. QTL for content of high molecular fructan were observed on LGs 1, 2 and 4. QTL for winter survival in LGs 2 and 4 are close to QTL for fructan content. Freezing tolerance in tillers was also evaluated and QTL for this trait was observed on LGs 5 and 6. QTL for sucrose content on LG 5 was closed to one QTL for freezing tolerance. Fructosyltransferase genes involved in fructan biosynthesis such as 1-SST, 6-SFT and 6G-FFT were mapped to the genetic map, but failed to show coincidence with any fructan content QTL. Sucrose synthase gene was also mapped on LG 7. Allelic variation in regulatory genes such as those for the CBF transcription factor may contribute to the QTL for winter survival and content of cold inducible sugar. CBF genes were isolated, characterized and mapped on LG5. We will discuss the genetic basis of winter hardiness in grasses based on comparative genomic information of Triticeae.