Polyamine patterns in haploid and diploid tobacco tissues and in vitro cultures

The aim of this work was to determine PAs levels in pith tissues and callus cultures from haploid and diploid tobacco plants, explanted from the apical and basal regions of the stem. These explants were cultured in an RM-64 medium supplied with IAA and kinetin, under light or in the dark, during successive subcultures. PAs levels followed a basipetal decrease in diploid and an increase in haploid, pith tissues. A similar pattern of total PAs (free + conjugated) was observed for the callus of diploid and haploid plants maintained in the light, and for the haploid callus in the dark, whereas the diploid callus in the dark showed a constant increase in total PAs levels until the end of culture. The PA increase in the diploid callus in the dark was related to free Put levels increase. The ploidy status of the plants could express different PA gradients together with the plant pith and in vitro callus cultures.

A comparative study of initiation and development of embryogenic callus from haploid embryos of several barley cultivars. I. Developmental state of embryo explants and callus potential

Six cultivars of barley (‘Akka’, ‘Bruce’, ‘Klages’, ‘Leger’, ‘Perth’, and ‘York’) were compared for their ability to produce haploid embryos competent to produce embryogenic haploid callus. The capacity to generate such callus from scutellar epidermal cells is different among these cultivars and appears to be correlated with the developmental state–age of the embryo and associated with a rapid growth period. Histological examination of 12-, 14-, and 16-day-old embryos confirmed the meristematic nature of the callus-initiating cells and produced results which correspond well with results obtained from cultures of other similar embryos. Variability among cultivars in embryo development, root initiation from callus, and primary and secondary shoot regeneration was also identified.