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Wheat Information Service
Number 89: 7-12 (1999)
Research article

Characterization of dwarf trait in the tetraptoid wheat landrace, Aiganfanmai

Z. S. Peng^1,2, Z. X. Su¹ and K. C. Cheng<sup>2

1</sup>Department of Biology, Sichuan Normal College, Nanchong. Sichuan 637002,China
²School of Life Science, Lanzhou University, Lanzhou, Gansu 730000, China

Summary

Aiganfanmai is a dwarfing tetraploid wheat (Triticum turgidum L.) landrace native to China. Genetic analysis on the dwarf trait of Aiganfanmai was carried out by crossing with the tall tetraploid wheat landrace Fenzhilanmai. Chi² analysis revealed that F₂ population from the cross between Aiganfanmai and Fenzhilanmai segregated into a ratio of 1 (dwarf) : 3 (tall), which means that the dwarf trait of Aiganfanmai was controlled by a single recessive Rht (reduced height) gene. This conclusion was confirmed by the backcross test that showed 1 : 1 segregation in BC₁ progeny (F₁ x Aiganfanmai). The dwarf subpopulation in F₂ was significantly different from Aiganfanmai in the mean and variance of modified plant height, indicating that some modifiers for dwarfism existed. In addition, the reaction of seedlings of Aiganfanmai to the hormone gibberellic acid (GA) was investigated by using the GA-insensitive variety, Tom Thumb as cheek material. The measures of coleoptile and the first leaf of seedlings after GA-treatment indicated that the dwarf trait of Aiganfanmai was GA-sensitive. Based on these results, the usage of Aiganfanmai in lodging resistance breeding was discussed.

Key words: Dwarf, Landrace, Rht gene, Tetraploid wheat, Triticum turgidum

Introduction

The development of short-straw high-yielding varieties to avoid lodging has been an important objective of breeding programs in wheat (Triticum aestivum L.) (Lupton 1987). This is partly because short-straw wheats allow further increases of yield to be obtained by their ability to utilize higher level of artificial fertilizer. The use of dwarf germplasm in breeding have contributed very much to the 'Green Revolution' of improved wheat production in the world. Nevertheless, the creation of and research on new dwarf germplasm is still very interesting to present wheat breeders.

Some changes in chromosome number could cause short-straw wheat (Law et al. 1987; Xue et al. 1991). However, they were of little use in high-yield breeding programs because of their poor agronomic performance. Contrarily, the dwarf germplasm that carried some major reducing height (Rht) genes were important in agriculture. Up to now, 26 Rht genes were found and studied in dwarf wheat (McIntosh et al. 1998). But none of them intrinsically belonged to tetraploid wheat (T. turgidum) species. Breeders were compelled to use hexaploid wheat dwarf materials in tetraploid wheat lodging-resistance breeding by interspecies crossing, which needs many times of artificial backcrossing with tetraploid wheat to eliminate the genetic constitution of hexaploid wheat other than the Rht gene and thus is ineffective. So dwarf germplasm. have been ardently desired at the tetraploid level. Gale et al. (1981) reported the semi-dwarfism in tetraploid wheat which Rht genes were introduced from hexaploid wheat Norin 10. Borner et al (1987) identified GA insensitive tetraploid wheats carrying Rht gene(s) from hexaploid wheat. On the other hand it should be emphasized that there exists dwarf tetraploid landrace native to Chian, Aiganfanmai.

Aiganfanmai is a dwarfing tetraploid wheat landrace that possessed normal chromosome number and normal chromosome constitution (Peng 1998). This paper describes experiments designed to investigate the inheritance of dwarf trait in Aiganfanmai, and the reaction to the hormone gibberellic acid (GA).

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