Development and identification of short stalked wheat-Thinopyrum ponticum translocation lines

Dong-Hai Yu, Hong-Gang Wang* , Jing Li, Xiao-Dong Jiang and Ju-Rong Gao

College of Agronomy, Shandong Agricultural University, Taian city 271018, Shandong, P.R.China

Summary

From two dwarfing Triticum aestivum-Thinopyrum ponticum addition lines Shannong31504 and Shannong315O5, two cytologically stable and short stalked translocation lines, named as Shannong31504-1 and Shannong31505-1, were developed. Their chromosome numbers in root tip cells were 2n=42, and 21 bivalents can be observed at PMC MI. Quadrivalent was observed in PMC Ml of F₁ hybrid between Shannong31504-1 and different common wheat variety. Biochemical identification showed that the dwarfing translocation lines contained Th. ponticum chromatin, and three RAPD markers designated as S36₁₈₀₀, S37₇₂₀ and S97₄₉₀ from 112 random primers, which can be used to detect the Th.ponticum chromatin in the translocation lines, were screened.

Key words: wheat, Thinopyrum ponticum, translocation line, dwarfing, identification

Introduction
During past several decades, the incorporation of dwarf genes into common wheat has resulted in dramatic yield increments. Now with the popularization of intensive farming system, more dwarfing or semi-dwarfing wheat cultivars with excellent agronomic characters will be urgently needed. Using dwarf genes to breed dwarfing or semi-dwarfing varieties is the most economical and effective approach to suit this needs. Until now, the fact that dwarfism is mainly controlled by major gene has been proved. Twenty-one major dwarf genes have been discovered and nine of them located on specific chromosome arms (Yang 1993). Among the twenty-one major dwarf genes, seventeen genes originated from common wheat and the others came from durum wheat But only several dwarf genes, such as Rht1, Rht2 (coming from Norin 10 source) and Rht8, Rht9 (coming from Akakomugi source), have been successfully utilized in wheat breeding program, and the others are of little practical value as they severely reduce the plant height as well as grain yield (Gale 1985). It is, therefore, essential to search for additional source of dwarfism to improve wheat yields further and broaden the genetic bases of dwarfism.

Thinopyrum ponticum (= Elytrigia elongata = Agropyron elongatum = Elymus elongatus = Lophopyrum e!ongatum, 2n=lOx=70) is one of the most important resources for wheat improvement (Li 1985). For it have many useful traits such as resistance to stem rust, leaf rust, wheat streak mosaic virus and barley yellow dwarf virus, high tolerance to salinity and aridity. Due to these useful traits and good crossing ability with common wheat, a number of useful genes have been transferred from this species to common wheat through wide cross, and several useful wheat germplasms and cultivars have also been produced. But there are still no reports about the transfer of dwarf gene from Th. ponticum to common wheat. In this paper, two wheat-Th. ponticum short stalked translocation lines, which came from the selfed progenies of two dwarfing T. aestivum-Th. ponticum addition lines Shannong31504 and Shannong31505, were bred. The biochemical methods and RAPD assay were used to detect the introgression of the Th. ponticum chromatin into the translocation lines.