Microspore embryogenesis and plant regeneration from anthers of barley cultured through meiosis

Abstract

A technique has been developed which allows the culture of barley cv. Igri anthers in isolated spikes and spikelets through meiosis until the mid-late uninucleate microspore stage. Light microscopical analyses and measurements of the duration of the individual substages of meiosis and microsporogenesis revealed a developmental sequence indistinguishable from that observed in vivo. Embryogenesis was induced in microspores at the mid-late uninucleate stage, when anthers from cultured spikes and spikelets were plated on induction medium and green plants were regenerated from the embryoids. Among different media tested for their ability to sustain a normal development of the microsporocytes and the microspores, modified Murashige and Skoog (MS) and Kao media solidified with agarose yielded optimal growth of the isolated spikes and spikelets. On a modified MS medium with 100 g/1 maltose and 1 mg/1 6-benzylaminopurine (BAP) 62 % of the anthers survived. Fifty-one percent of these anthers responded with microspore embryogenesis and a mean of 2.4 green plants were regenerated per responding anther. The albino to green plant ratio was 0.5. The significance of this culture system for establishing a transformation system with gene targeting mediated by homologous meiotic recombination is discussed.