THE EFFECTS OF ANTI-MITOTIC AGENTS ON DIHAPLOIDIZATION AND FERTILITY IN WINTER SQUASH (Cucurbita maxima Duch.) AND PUMPKIN (Cucurbita moschata Duch.) ANDROGENIC HAPLOIDS

Abstract

Double-haploidization (DH) is one of the favorable techniques to obtain 100% pure double haploid plants (DH's) for generating the new F 1 cultivars in a short time. The fecundity of this technique depends on the high quantity of haploids and also fertile DH's. However, there are no comprehensive reports on the chromosome doubling and fertility (fruit and seed-set) of winter squash and pumpkin haploids, currently. Thus, to obtain high frequency and fertile DH's, the efficiency of different anti-mitotic agents (colchicine, amiprophos methyl, trifluralin and oryzalin) was tested at various concentrations and exposure times for both in vitro and in vivo conditions. Haploid plantlets recovered from anther cultures of winter squash and pumpkin lines were used for DH program. The haploid plants were wholly immersed in aqueous solutions of antimitotic agents in vitro and apical parts of haploid plantlets were treated with anti-mitotic agents three times in vivo. Since some plants remained haploid, and the highest DH efficiency was obtained from multiple treatments of colchicine to shoot tips of haploid plants in the rate of 93.3%. In vivo multiple treatments of 1% colchicine for an hour was found to be the best doubling procedure for the recovery of high-frequency fertile DH's in our winter squash and pumpkin breeding program.

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“…DOI: 10.24326/asphc.2018.5.1 Table 1. The effects of anti-mitotic agents, and their doses (D) and durations (DR) on ploidy status of winter squash and pumpkin in vitro Each value followed by different letters indicates a significant difference (P < 0.05) to (DMRT) C: control; TR: treatments; TE: number of treated explants; SR: survival rate; CL: colchicine; APM: amiprophos methyl; TF: trifluralin; OR: oryzalin Kurtar, E.S. (2018).…”

“…Hortorum Cultus, 17(5), 3-14. DOI: 10.24326/asphc.2018.5.1 Each value followed by different letters indicates a significant difference (P < 0.05) to (DMRT) C: control; TR: treatments; TE: treated explants Kurtar, E.S. (2018).…”

“…Traditional breeding methods are highly labor and time-consuming, and lines still are not 100% homozygous [Germana 2006]. Currently, doubled haploid (DH) technique is used for the recovery of 100% pure dihaploid lines (DH's) in lots of plant species [Kurtar andBalkaya 2010, Galazka andNiemirowicz-Szczytt 2013]. In vitro androgenesis, gynogenesis and parthenogenesis are the unique methods for the recovery of fertile homozygous DH's.…”

“…Nevertheless the importance of the DH's, this unique technology has some limitations in large-scale breeding efforts, such as genotype dependency, low haploid frequency, requirement for labour-intensive works (detection and extraction of embryos, acclimatization etc.) and production of fertile plants (lack of efficient doubling methods) [Kurtar andBalkaya 2010, Kurtar et al 2016]. Therefore, to produce an efficient dihaploidization method with high-level of fertile DH's, sterile haploids should be subjected to some anti-mitotic agents with convenient dose and durations, because the fertility (fruit-set and seed-set) is a key factor for maintaining the dihaploid lines in a DH breeding effort.…”

“…Colchicine is the mainly used anti-mitotic agent [Lim and Earle 2009, Galazka and Niemirowicz-Szczytt 2013, Aslam et al 2017 along with chromosome duplication methods categorized as immersion of whole plantlets or nodal explants Abak 1996, Caglar andAbak 1997], treatment on apical meristems [Nikolova and Niemirowicz-Szczytt 1996], shoot tips Sari 2003, Solmaz et al 2011] and lateral shoots in Cucurbits. Trifluralin, amiprophos methyl, and oryzalin have been reported as alternative antimitotic agents for colchicines due to less phytotoxicity, high efficiency at low concentration, and insignificantly morphological abnormalities [Grzebelus and Adamus 2004, Alan et al 2007, Chen et al 2016.…”