Variation of phenotype, ploidy level, and organogenic potential of in vitro regenerated polyploids of Pyrus communis

Abstract

A wide range of phenotypic variation was observed among neopolyploids obtained from the diploid pear cultivar 'Fertility' by in vitro colchicine treatment. The variant plantlets had alterations in leaf characteristics. Neopolyploids had significantly different ratios of leaf length to leaf width compared to the diploid control. Shoot regeneration from leaf explants and rooting ability from in vitro shoots of neopolyploids was examined. Regeneration frequencies of shoots from leaf explants of seven of the nine neopolyploids were significantly decreased compared to the diploid control. The organogenic potential of neopolyploids was highly genotypedependent for both shoots and roots. Tetraploid clone 4x -4 failed to regenerate shoots from leaf explants and the pentaploid clone 5x -2 failed to root from in vitro shoots. The results suggest that polyploidization caused the decrease in or loss of in vitro organogenic potential. Regenerated shoots derived from neopolyploids showed different phenotypes, depending on the ploidy of the donor plant.

Phenotypic and genome size changes (variation) in synthetic tetraploids of daylily (Hemerocallis) in relation to their diploid counterparts

“…Similar phenotypic variation was noted among neotetraploids of Pyrus communis induced in vitro with colchicine (Sun et al 2011). The variant plantlets had alterations in leaf characteristics.…”

“…Joshi and Verma (2004) also reported that newly obtained polyploid plants were slower in growth initially but later surpassed in growth parameters their diploid counterparts. In turn, a decrease in the in vitro Pyrus communis shoot and root organogenic potential was found by Sun et al (2011). Such decrease of in vitro organogenic ability of polyploids was attributed to the difficulty of normal completion of mitosis or the tendency to produce aneuploid cells during mitosis.…”

“…Therefore, synthetic polyploidisation has been utilised for breeding for many years. Recently, in vitro polyploidisation techniques have been developed for Salix viminalis (Wojciechowicz 2009), Humulus lupulus (TrojakGoluch and Skomra 2013), Miscanthus (Głowacka et al 2010), tulip (Podwyszyńska 2011), Centella asiatica (Kaensaksiri et al 2011), Pyrus communis (Sun et al 2011), and Gerbera jamesonii (Gantait et al 2011).…”

ROOTING SHOOTS OF APPLE VARIETIES AND THEIR TETRAPLOIDS OBTAINED BY THE in vitro TECHNIQUE

“…The above-mentioned authors also observed that in vitro produced neo-tetraploid shoots are generally shorted and have wider leaves darker colour compared to diploid ones. Shoot regeneration potential from leaves in pear [Gantait et al 2011] and shoot multiplication rate in gerbera [Sun et al 2011] were significantly lower in tetraploids compared to diploids. In gerbera, shoots of tetraploids required longer period to produced roots and the roots were shorter and less numerous compared to those of diploids.…”

“…Differences in phenotype and in vitro growth behaviour between diploids and their neotetraploids were reported for several plant species, e.g. watermelon [Compton et al 1993], gerbera [Gantait et al 2011] and pear [Sun et al 2011]. The above-mentioned authors also observed that in vitro produced neo-tetraploid shoots are generally shorted and have wider leaves darker colour compared to diploid ones.…”