Genetic control of self-incompatibility and reproductive development in flowering plant (1994) p. 386
Gametophytic competition and selection
J. I. Hormazza and M. Herrero

Isozyme analysis of backcross progeny of Lycopersicon esculentum (cold sensitive) and Lycopersicon hirsutum (cold tolerant) derived from pollinations at normal and low temperature showed that gametes with a particular chromosomal segment from L. hirsutum were favored over those with the corresponding L. esculentum segment in fertilization at low temperatures (Zamir et al. 1982). Further work (Zamir and Vallejos 1983) showed that the selection pressure was higher during pollen tube growth than during pollen development. Finally, Zamir and Gadish (1987) demonstrated that progeny from crosses made at low temperatures had better cold adaptation, evaluated by root growth, than progeny from crosses made at higher temperatures. Using pollen mixtures of several Lycopersicon species, Lyakh (1992) has shown that pollen from cold tolerant species is more competitive for fertilization at low temperatures than pollen from cold sensitive species. Schön et al. (1991) crossed winter and spring Hordeum cultivars and compared control F2's with F2's derived from F1 plants self‑pollinated at low temperatures. Segregation distortion in favor of the cold tolerant cultivar was observed at one locus although further studies are necessary to determine if that segregation distortion is correlated with an increase of sporophytic cold tolerance.