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Wheat Information Service
Number 93: 5-8 (2001)
Research article


A one-gene system of cytoplasmic male sterility-fertility in durum wheat

S. S. Maan and S. F. Kianian

Department of Plant Sciences, North Dakota State University, Fargo, North Dakota, U.S.A.


Summary

The nuclear genome of durum wheat (Triticum turgidum L.) is incompatible with Aegilops longissima cytoplasm [(lo) cytoplasm] and nucleocytoplasmic compatibility is improved by a species cytoplasm specific (scst) nuclear gene located on chromosome 1A of durum. The resulting durum line having (lo) cytoplasm and one copy of the (scst) gene is male-sterile and when crossed to normal durum produces plump and viable seeds carrying scst, while seeds without scst are shriveled and non-viable. Our objectives were (1) to transfer the scst gene from (lo) male-sterile durum to the cytoplasmic background of normal durum, (2) to determine if the euplasmic durum. with a scst/scst gene pair is fertile, and (3) to use the selected euplasmic durum line (if fertile) as a recurrent male parent to propagate a (lo) male-sterile durum line. We crossed a 1D(1A) disomic-substitution line of euplasmic Langdon durum as a female to a male fertile line having (lo) cytoplasm and scstscst + ViVi (vitality) gene pairs. The resulting 1A+1D double-monosomic F1's were partially fertile. The F2's were cytologically examined. One euploid F2 plant was obtained. It was male fertile and when crossed to the (lo) scst male-sterile durum produced all plump seeds and male-sterile progeny, indicating that F2 plant had a scstscst gene pair and no Vi. Thus, an euplasmic F2-derived line carrying a scstscst pair was produced and used as a maintainer B-line to produce a cytoplasmic male-sterile A-line having (lo) cytoplasm and a scstscst gene pair.

Key words:scst, Vi, cytoplasmic male sterility


Introduction

A cytoplasmic male sterility system (CMS) derived from Triticum timpheevi Zhuk., used in research for producing hybrid cultivars of common wheat (T. aestivum L.), can also be used for producing hybrid cultivars of durum wheat (T. turgidum L). This CMS system requires labor intensive selection procedures for breeding male fertility restoring lines (R-lines) with a potential to produce fully fertile hybrid wheats, because the native wheat genes that are expressed as sterility in the alien cytoplasmic background also affect fertility in the hybrid wheat cultivars.

The Triticum species differ in regards to compatibility with the cytoplasm from some related species (Maan 1983; Sasakuma and Maan 1978). For example, the nuclear genomes of common wheat and T. timopheevi are compatible with the cytoplasm of Aegilops longissima or Ae. uniaristata [(lo) or (un) cytoplasm, respectively], and the resulting alloplasmic common wheat lines have normal fertility and plant vigor (Maan 1975). In contrast, the nuclear genome of durum wheat is incompatible with the (lo) or (un) cytoplasm (Maan 1992a, b, 1994).
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