EXPRESSION OF THE COLD-INDUCED WHEAT GENE WCS120 AND ITS HOMOLOGS IN RELATED SPECIES AND INTERSPECIFIC COMBINATIONS

Low-temperature response was measured at the whole plant and at the mo lecular level in wheat-rye amphiploids and in other interspecific comb inations. Cold tolerance of interspecifics whose parents diverged wide ly in hardiness levels resembled the less hardy higher ploidy level wh eat parent. Expression of the low-temperature induced Wcs120 gene of w heat (Triticum aestivum L. em. Thell.) has been associated with freezi ng tolerance and was used here to study mRNA and protein accumulation in interspecific and parental lines during cold acclimation. Northern and Western analyses showed that homologous mRNAs and proteins were pr esent in all the related species used in the experiments. Cold-toleran t rye (Secale cereale L.) produced a strong mRNA signal that was susta ined throughout the entire 49-day cold-acclimation period. The wheats produced a mRNA signal that had diminished after 49 days of low-temper ature exposure. The wheat-rye triticales did not exhibit the independe nt accumulation kinetics of the cold-tolerant rye parent but, rather, more closely resembled the wheat parent in that the mRNA signal was gr eatly diminished after 49 days of low-temperature exposure. The influe nce of the rye genome was manifest in slightly greater mRNA and protei n accumulation in earlier stages of acclimation. Protein accumulations in the triticales were also maintained to a somewhat greater extent t han found in the wheats at the end of the 49-day acclimation period. P rotein accumulations in the wheat-crested wheatgrass (Agropyron crista tum L. Gaertner) interspecific resembled that of the wheat parent. The influence of the higher ploidy level wheats of the expression of homo logous gene families from wheat-related hardy diploids in interspecifi c combinations may in part explain the poor cold tolerance observed.