Vernalization in Lolium temulentum L.: Responses of In Vitro Cultures of Mature and Immature Embryos, Shoot Apices and Callus

Response of vernalization to low temperature (2°C) was studied in a winter-annual form of Lolium temulentum L., using imbibed seeds, excised mature and immature embryos, shoot apical meristems and callus tissue. Excised embryos, as early as 5 days after anthesis, and excised shoot apices could be vernalized as effectively as imbibed seeds. Cold treatment of developing embryos within the ear, however, appeared to have no vernalizing effect. Plants derived from callus by somatic embryogenesis showed varying degrees of vernalization response. The vernalization response in L. temulentum, as in winter annual cereals, appears to be located in the shoot apical meristem and the vernalized condition can be transmitted to new axillary meristems formed from it.