Abscisic acid in preservation of Taraxacum pieninicum in the form of synthetic seeds in slow growth conditions

Taraxacum pieninicum Pawł. is listed as critically endangered species, for which currently applied protection methods are insufficient. The aim of this study was to investigate the possibility of T. pieninicum storage in the form of synthetic seeds under slow-growth conditions in combination with ABA treatment, as one of the ex situ protection methods of this species. The obtained results indicated that darkness was much more favorable condition for synseed storage and did not generate additional stress during cold exposure in contrast to the light conditions. The preculture of shoot tips on the medium supplemented with ABA led to a decrease in the shoots proliferation rate and inhibition of their growth. ABA clearly inhibited growth of the encapsulated shoot tips also during cold storage. Biochemical parameters showed that ABA effectively reduced the negative effect of the cold stress, what was found on the basis of analyzes of H2O2 and TBARS levels in the stored material. Moreover, synseeds stored under light conditions and treated with ABA exhibited decreased level of endogenous jasmonic acid what indicated interaction between those two phytohormones at a low temperature. The study also demonstrated that in vitro culture, cold storage and ABA treatment had no effect on the flowering process of this species after acclimatization to ex vitro conditions.

SEM observation of pollen grains and fruits of the Pieniny Mountains Polish endemic species Taraxacum pieninicum (Asteraceae)

Taraxacum pieninicum Pawł. (Asteraceae) is an endemic species, growing only in Pieniny Mts. The aim of the presented work was to investigate its pollen morphology as well as its ultrastructural traits of achene pericarp. Pollen grains of this species were of medium size, echino-lophate and 3-zonocolporate. The external surface of the achene body was of scale sculpture, covered with the spikes. Pappus hairs were not branched, built of a few tubular cells, with acute, protruding ends.