Timopheevi Cytoplasm Research Articles

Cross Breeding Male‐Sterile Wheat (Triticum Aestivum L.) and Rye (Secale Spp.)1

Seed set on male‐sterile wheat (Triticum aestivum L.), T. timopheevi cytoplasm, pollinated by rye (Secale) in field crossing blocks was less than 2%. Seed set on male sterile wheat/rye F1's was negligible when backcrossed to rye, 0.37% when backcrossed to wheat, and 0.96% when crossed to 6X Triticale. The partial fertility of two 56‐ chromosome amphiploids arising spontaneously on malesterile wheat/rye F1's pollinated by rye indicate that some ryes possess fertility restoration factors that interact with those of male‐sterile wheat to restore pollen fertility. F1 progenies of cytoplasmic male‐sterile wheat‐rye F1's crossed to 6X Triticale were frequently partially fertile. Malesterile wheat may be a useful breeding tool for making interspecific crosses involving rye.

Genetic Influence of Male Sterile Cytoplasms and Fertility-Restoring Genes on Performance of Common Wheat Varieties

The cytoplasm of Ae. ovata delays heading by 13 days on an average in common wheat varieties, whereas T. timopheevi cytoplasm did not show such effect. Ovata cytoplasm also increases plant height, number of tillers and number of spikelets per spike ; on the other hand nucleus substitution lines with timopheevi cytoplasrn did not deviate greately from the normals. The influence of two fertility-restoring genes, Rfc1 and Rf3, was strikingly identical.

DISTRIBUTION OF FERTILITY-RESTORlNG GENES IN HEXAPLOID WHEATS FOR AE. OVATA AND T. TIMOPHEEVI CYTOPLASMS. I

Ninety-two varieties (or strains) of hexaploid wheat were tested as to fertility-restoration in two male-sterile cytoplasms derived frcurl Ae, ovata and T, timopheevi. In total eight effective restorers were found, i. e., P168, P170, P171, P173, P174, ABD-1 and ABE-16 for Ae. ovata cytoplasm and T. spelta var. duhamelianum for T, timopheevi cytoplasm. A few restorers were found among 6x cultivars, though none of them was very effective. All the restorers functioned only in either Ae. ovata or T. timopheevi cytoplasm.

MONOSOMIC ANALYSIS OF <i>TRITICUM SPELTA</i> VAR. <i>DUHAMELIANUM</i>, A FERTILITY-RESTORER FOR <i>T. TIMOPHEEVI</i> CYTOPLASM

Chromosomal location of genes for fertility-restoration, awnlessness, spelta-type ear and red coleoptile color of Triticum spelta var. duhamelianum, an effective fertility- restorer for the timopheevi cytoplasm, was determined by monosomic analysis. The results can be summarized as follows:T. spelta var. duhamelianum carries a dominant fertility-restoring gene Rf3 on its chromosome 1B. Chromosome 7D exerts a weak suppressing effect to this gene. Awnlessness is mainly due to an epistatic inhibitor B1 in chromosome 5A, while chromosome 6D has a promoting effect on awn development. As to the ear type, chromosome 5A carries a spelta gene q1, whereas chromosomes 2D and 3D possess some modifiers to this gene. Red coleoptile color is produced by genes in chromosomes 7A and 7D, while five other chromosomes, 2A, 2B, 2D, 3B and 6A, carry weak suppressors.