Microspore embryogenesis and programmed cell death in barley: effects of copper on albinism in recalcitrant cultivars.

Albinism remains a major problem in cereal improvement programs that rely on doubled haploid (DH) technology, and the factors controlling the phenomenon are not well understood. Here we report on the positive influence of copper on the production of DH plants obtained through microspore embryogenesis (ME) in recalcitrant cultivars of barley (Hordeum vulgare L.). The presence of copper sulphate in the anther pre-treatment medium improved green DH plant regeneration from cultivars known to produce exclusively albino plants using classical procedures. In plastids, the effect of copper was characterized by a decrease in starch and a parallel increase in internal membranes. The addition of copper sulphate in the ME pre-treatment medium should enable breeders to exploit the genetic diversity of recalcitrant cultivars through DH technology. We examined programmed cell death (PCD) during microspore development to determine whether PCD may interfere with the induction of ME and/or the occurrence of albinism. By examining the fate of nuclei in various anther cell layers, we demonstrated that the kinetics of PCD in anthers differed between the barley cultivars Igri and Cork that show a low and a high rate of albinism, respectively. However, no direct correlation between PCD in the anther cell layers and the rate of albinism was observed and copper had no influence on the PCD kinetic in these cultivars. It was concluded that albinism following ME was not due to PCD in anthers, but rather to another unknown phenomenon that appears to specifically affect plastids during microspore/pollen development.

Inter simple sequence repeat analysis of genetic diversity and relationships in cultivated barley of Nordic and Baltic origin.

This study evaluates putative changes of genetic diversity and relationships of barley in the Nordic and Baltic countries that might have taken place during the last century as a result of commercial breeding. Four ISSR primers were used to analyse 227 accessions, yielding a total of 47 polymorphic loci. Shannon-Weaver diversity values for each locus ranged from 0.012 to 0.693. Overall, there were no significant changes of genetic diversity observed over time. A significant decrease of diversity was, however, observed in material from the southern parts of the Nordic and Baltic countries. In material from the northern parts no decrease of diversity was observed. The genetic diversity of six-rowed barley bred in the middle of the 20th century was low, but there was no significant difference between modern accessions and landraces or old cultivars. The magnitude in changes of genetic diversity differed also in material from different countries of origin. A cluster analysis clearly separated the material into two groups. The first cluster included 86.5% of all six-rowed accessions, whereas the second cluster contained 97.4% of all two-rowed accessions.