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Wheat Information Service
Number 84: 13-18 (1997)
Research article


Production, fertility and cytology of tetrageneric hybrids involving Triticum, Agropyron, Haynaldia and Secale

Wen-Ye Yuan^1,2, Shan-Cheng Sun², Shao-Xiang Liu², Yu Sun², Motonori Tomita1 and Yoshimasa Yasumuro<sup>1

1</sup>Laboratory of Plant Genetics and Breeding, Faculty of Agriculture, Tottori University, Tottori 680, Japan
²Institute of Crop Genetics, Shanxi Academy of Agricultural Sciences, Taiyuan 030031, China


Summary

Tetrageneric hybrids involving Triticum, Agropyron, Haynaldia and Secale were synthesized by means of immature embryo rescue. They can be used: (1) to transfer multi-disease resistance to wheat; (2) to demonstrate the behaviour of each parental chromosome in hybrid cells and rearrangement of the hybrid genomes. Twelve plants of the tetrageneric hybrids were obtained from 53 rescued embryos in 2831 pollinated florets and grew normally with characters inherited from the 4 genera. Seed setting percentage of the hybrid plants was 1.2%, varying from infertile to low-fertile. Most of the hybrids in the cross combination of (TS6xO (AABBRR) x TH6xL (AABBVV)) x TA6xA₂ (AABBEE) had 39 chromosomes. Many selfed derivatives have been obtained from the tetrageneric hybrids.

Key words: wheat, intergeneric hybrids, embryo culture


Introduction

Distant hybridization has been practised widely in wheat breeding to transfer chromosome segments with useful genes. Agropyron, Secale, Haynaldia and other wild relatives of wheat are important genetic resources to improve wheat varieties. Among them, Agropyron intermedium is known to possess genes conferring resistance to barley yellow dwarf virus (BYDV) (Xin et al. 1988) and rusts (Knott 1989), and Haynaldia villosa and Secale cereale are different resistant resources against powdery mildew. Up to now, more than 10 trigeneric hybrids and few tetrageneric hybrids have been produced in the Triticeae (Kimber and Sallee 1979; Sharma and Gill 1983; Fernandez-Escobar and Martin 1988, 1989; Li and Dong 1993). Most of the papers reported many useful data about chromosome pairing at metaphase I (MI) of meiosis involving multi-genera of wheat wild relatives (Fernandez-Escobar and Martin 1985; Stoinva 1994; Sun et al. 1995). In recent years, molecular analyses have been used to identify alien chromosomes in the studies of trigeneric hybrids (Islam-Faridi and Mujeeb-Kazi 1995; Svitashev et al. 1995). In order to introduce alien genes for multidisease resistance and to study the relationship of different alien chromosomes, tetrageneric hybrids involving Triticum spp., A. intermedium, H. villosa and S. cereale were developed by means of immature embryo culture, and F₃ generation plants were successfully obtained in the present report.

This paper presents data on the production, morphology, cytology and fertility of two tetrageneric hybrids and their derivatives involving Triticum, Secale, Haynaldia and Agropyron. The results of molecular analyses will be reported in another paper.


Materials and methods

The plant materials used consisted of following amphidiploids: TS6x1330 and TS6xO (Both are hexaploid Triticale, 2n=6x=42, AABBRR); TH6xL and TH6xH (hexaploid Haynatriticum, 2n=6x=42, AABBVV); TA6xA₂ (hexaploid Agrotriticum, 2n=6x=42, AABBEE) and TA8x16-3 (octoploid Agrotriticum, 2n=8x=56, AABBDDEE). They were selected or synthesized from intergeneric hybridization (Sun 1981; Liu et al.1988; Chen and Huang 1991). Trigeneric hybrids TS6xO/TH6xL and TS6x1330/TH6xH obtained as reported (Yuan et al. 1993) were used as a female parent, TA6xA₂and TA8x16-3 as male parents, respectively.

The hybrid embryo was rescued 15-20 days after pollination. The basic culture medium was MS with whole ingredients. The culture media for the induced callus and callus relay were: (1) MS + 200mg/1 glutamine + 1 00mg/1 asparagine + 600mg/1 hydrolytic facto- albumin + 2mg/1 2,4-D + 0.1mg/1 KT; (2) MS + lmg/1 2,4-D + lmg/1 NAA + 0.1mg/1 KT. Culture medium for differentiation was MS + 3mg/1 BA. Sugar was 3%, agar 0.6%, pH5.6, photoperiod 14hr/day and culture temperature 25 + or - 1C. Regenerated plantlets were transplanted to pots.

Root-tip cells were pre-treated for 24hr at 0C, fixed in ethanol/glacial acetic acid (3:1) and kept in 70% alcohol, then stained with acetic carmine for somatic chromosome counting.

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