Exclusive Preferential Transmission of an Alien Chromosome in Common Wheat¹

Abstract

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.

Genetic Variation and Its Geographical Distribution in Aegilops caudata L.: Morphology, Hybrid Sterility and Gametocidal Genes

“…The BC 1 F 1 plants distinctly restored their fertility when the F 1 hybrids were backcrossed to the western parents, while their fertility was not restored when they were backcrossed to the eastern parents (Table 6.2 ). A similar sterility has been reported in several Aegilops species as the phenomenon that certain Aegilops chromosomes, gametocidal chromosomes, were preferentially transmitted in the genetic background of common wheat (Endo and Tsunewaki 1975 ;Maan 1975 ;Endo 1990 ). An Ae.…”

Genomic Conflicts that Cause Pollen Mortality and Raise Reproductive Barriers inArabidopsis thaliana

“…Such loci have been documented in animals, especially in Drosophila (Orr et al 2007;Larracuente and Presgraves 2012), and in Ascomycetes (Turner and Perkins 1979;Raju 1994). In plants, after the first description of a PK in a hybrid between two Solanum species (Cameron and Moav 1957), gamete killers (most often PKs) have been reported, especially in hybrids between cultivated plants and their wild relatives, where they often constitute obstacles to the breeding of desirable traits (Maan 1975;Sano 1990). In rice in particular, a number of gamete killers have been described in crosses between cultivated rice (O. sativa) and its wild relatives (Sano 1990;Hu et al 2006;Garavito et al 2010), or between O. sativa subspecies (Oka 1974;Zhang et al 2006).…”

Chromosome damage in early embryo and endosperm development in crosses involving the preferentially transmitted 4S1 chromosome of Aegilops sharonensis

“…A number of workers have shown that certain C and S genome chromosomes are preferentially transmitted when introduced into hexaploid wheat (Endo & Tsunewaki, 1975;Maan, 1975;Miller et al, 1982).…”