Effects and characterization of the conditioning medium that increase colony formation from barley (Hordeum vulgare L.) protoplasts

Barley (Hordeum vulgare L.) protoplasts isolated from four suspensions and from microspore derived proembryos improved their colony formation when supplied with conditioned medium from barley suspensions. Up to 11 % of the protoplasts formed colonies larger than 200 μm. Data were obtained on pH of the conditioning media, their protein profile on SDS-PAGE, contents of IAA and zeatin/zeatin derivatives and the growth rate of the medium producing suspensions.

The effect on colony formation from treatment of the conditioned media with heat, acid or base depended on the combination of protoplasts and conditioner. Ultrafiltration showed that the molecular weight of the conditioning factors was larger than 10,000 daltons. Among the six suspensions used for conditioning, two suspensions derived from liquid cultures of protoplasts had the best conditioning ability..