Meiotic chromosome pairing, isozyme analyses and ferritin expression in a red clover mutant capable of somatic embryogenesis

Abstract

Red clover genotypes capable of regenerating plantlets in vitro from non-meristem-derived callus are rare. A previous study identified a pair of near isogenic lines which were derived from a single seed but differed in regenerative ability. The callus-derived plants of this clone were highly regenerative when reintroduced to culture whereas the epicotyl-derived plants produced non-regenerative callus cultures. The objective of the present study was to observe meiotic chromosome pairing and to compare isozyme profiles and ferritin gene expression in regenerative and non-regenerative plants and cultures from the clone. Meiotic cells exhibited normal homologous chromosome pairing. Starch gel zymograms from glasshouse-grown regenerative (F49R) and non-regenerative (F49M) plants failed to show somaclonal variation for alcohol dehydrogenase, glutamate dehydrogenase, esterase or peroxidase. Isoelectric focusing of callus cultures from regenerative and non-regenerative plants revealed that regeneration was accompanied by a reduction in staining intensity and numbers of peroxidase bands compared to non-regenerative cultures. A unique cathodic peroxidase band (pI 7.6) was associated with non-regenerative cultures. Ferritin expression was greater in callus than in fresh petiole tissue. Ferritin expression remained high in non-regenerative callus cultures but declined in regenerative cultures as regeneration progressed.