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Wheat Information Service
Number 75: 14 - 20 (1992)


Cytogenetic study on the origin of some special Chinese landraces of common wheat

Wu-Yun Yang, Chi Yen and Jun-Liang Yang


Triticeae Research Institute, Sichuan Agricultural University, Dujiangyan City, 611830 Sichuan, China


Summary

Tibetan Weedrace, Yunnan Hulled Wheat, Sichuan White Wheat complex (including Chinese Spring) and Xinjiang Rice Wheat are four special landraces of Triticum aestivum L. which were found in China. Genomic analysis showed that they were different from T. aestivum L. var. spelta by one to two pairs of chromosomes. These four Chinese landraces could be classified into two groups, with the Xinjiang Rice Wheat in one group and all the remaining in the other. These two groups were found to be distinguished by two pairs of chromosomes and one of them was identified as chromosome 6B. Cytogenetic analysis showed that these two groups of common wheat landraces might be independently originated in China via pollination of different accessions of the cultivated wheat tetraploid by the Aegilops tauschii accessions which has been discovered as a native species in the northwestern China and as a weed in the central China as well.


Introduction

The Xinjiang Rice Wheat (XR) is a Polish-wheat-like landrace collected from Xinjiang. The Tibetan Weedrace (TW) is a brittle-rachis weedrace in barley field found in Tibet and the nearby northwestern Sichuan as a weed. The Yunnan Hulled Wheat (YH) is a glume-hulled landrace growing in Yunnan. The Sichuan White Wheat complex (SW) are a group of cultivated common wheat with multifloret spikelets, rounded glume and lemma. All these four special wheat landraces have been so far only found in China. Morphological and cytogenetic studies showed that they all had the AABBDD genome (Chen 1980; Lu and Zhang 1983; Yao 1983; Chen et al 1988; Yen et al 1988). However, these Chinese landraces have some primitive traits that distinguish them from T. aestivum var spelta (SP) and the common wheat of the East Mediterranean origin (Yao 1983; Chen et al 1988; Yen et al 1988). Based on these evidences, they were considered to be originated in China (Riley et al 1967; Chen 1985; Chen et al 1988; Yen et al 1988). However, the problems of how and where they originated still remain unanswered.

In this paper, we describe the results of the cytogenetical analysis of these four special Chinese common wheat landraces. The origin of these four landraces are also discussed.


Materials and methods

The plant materials used in this study are listed in
Table1. They are all maintained in Triticeae Research Institute, Sichuan Agricultural University.

Interspecific hybrids were obtained by the conventional crossing method through immature hybrid embryo culture on N6 medium. The hybrid plants were moved to Barkam, Sichuan in August to survive the summer and moved back and grown in Triticeae Research Institute of Sichuan Agricultural University at Dujiangyan City in October.

Mitotic analysis were made in root-tip cells fixed in the 3 : 1 ethanol(95%)-glacial acid solution and stained by the Feulgen procedure. Meiotic analysis were done in pollen mother cells (PMCs) fixed and stained as the root-tip cells.

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