A comparison of barley isolated microspore and anther culture and the influence of cell culture density.

Comparisons were made between the efficiency of barley plant regeneration from anther culture (AC) and isolated microspore culture (IMC) for the European winter cultivar `Igri' and the spring F1 Australian breeder's hybrid Amagi Nijo×WI2585. In both cases, IMC produced a higher number of green regenerant plantlets per anther than AC. For `Igri' there was a 100- to 200-fold improvement and for Amagi Nijo×WI2585 there was a five- to ninefold improvement of IMC over AC. To improve the consistency and reliability of the IMC method, we investigated several parameters, including maltose concentration, subculture protocol, microspore plating density and colony plating density. Subculturing during the liquid culture phase produced no significant improvement in the number of microspores developing into colonies. The optimal concentration of maltose in the liquid induction medium was found to be 90 g l-1. Both microspore plating density and colony plating density were found to influence plant regeneration. Microspores produced the highest numbers of colonies when plated at densities greater than 5×104 ml-1, and colonies produced optimal numbers of green plantlets when plated at 12.5-25 colonies/cm2.