Exclusive Preferential Transmission of an Alien Chromosome in Common Wheat1
- S. S. Maan2
Aegilops longissima S. & M. and Ae. sharonenis Eig were crossed with Triticum dicoccum Schrank ‘Khapli’ pollen, and F1 hybrids were crossed several times with T. aestivum L. em. Thell. pollen to substitute the T. aestivum nucleus into the cytoplasm of these Aegilops species. Partially male and female-sterile plants having a monosomic substitution (20″+2′) or a monosomic addition (21″+1′) were obtained from these nuclear-substitution backcrosses. These plants had normal anther extrusion, abundant pollen, and incomplete scattered seed set on bagged or crossed heads, and the reciprocal cross with euploid T. aestivum as a female gave complete seed set. Euploid, 21” plants were not obtained from crosses in either direction, most offspring having again 20″+2′ or 20″+1′, and having abundant pollen but partial seed set on bagged heads. All the selfed progeny of plants with a monosomic substitution or monosomic addition had a disomic substitution or disomic addition, respectively, and were fertile. Evidently, male and female gametes with one Aegilops chromosome were functional, and those without the Aegilops chromosome did not function.
There was thus an apparent gametocidal action of the sporophyte having an Aegilops chromosome, on the gametes lacking this chromosome. Occasionally malesterile euploid T. aestivum plants with Ae. sharonensis cytoplasm were obtained as a result of rare functional female gametes without the critical Ae. sharonensis chromosome.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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