Effect of in vitro and in vivo colchicine treatments on pollen production and fruit set of melon plants obtained by pollination with irradiated pollen

Abstract

Haploid/doubled haploid (DH) technology can aid plant breeding programs by accelerating production of homozygous lines, provided enough viable DH progeny can be obtained from diverse haploid genotypes. In cases where there is a low frequency of spontaneous doubling, chromosome doubling procedures are required to achieve fecundity. We produced 63 parthenogenetic melon plantlets via pollination with c-irradiated pollen, cloned them by nodal cuttings, and tested the effects of in vitro and in vivo colchicine treatment on survival, ploidy, pollen production, and fruit recovery. The most effective procedure was in vitro exposure of 3 cm shoot tip explants to 500 mg/l colchicine for 3 h. This treatment gave 83% survival of explants and 26% conversion to diploidy. Fruit recovery rate was 60% among plants with good pollen production. In vivo exposure of the tops of young plants to 5000 mg/l for 2 and 4 h yielded some fruits but also resulted in less survival and more morphological abnormalities. Strategies for recovery of progeny from parthenogenetic melon plants are recommended. To our knowledge, this study represents the first comprehensive study of recovery of fruits and viable seeds from parthenogenetic melon plants.

Enhanced recovery of doubled haploid lines from parthenogenetic plants of melon (Cucumis melo L.)

“…The plant materials and general methods used are described in Lim and Earle (2008). Haploid/mixoploid parthenogenetic melon (Cucumis melo L.) plantlets were obtained from seeds produced after pollination with irradiated pollen and were maintained in Magenta boxes of E20A medium (Sauton and Dumas de Vaulx 1987) solidified with 0.8% Phytoblend (Caisson Laboratories, Inc., North Logan, UT).…”

“…Pollen from plants that flowered in vitro and/or in the greenhouse was examined as described in Lim and Earle (2008). All the anthers from a flower were teased apart in a 40 lL drop of Alexander's stain (Alexander 1969).…”

“…Haploid melon plants have been obtained (at low frequencies) from seeds recovered after pollination with irradiated pollen (Sauton and Dumas de Vaulx 1987;Sauton 1988;Sauton et al 1989;Cuny et al 1993;Sari and Abak 1994;Doré et al 1995;Ficcadenti et al 1995Ficcadenti et al , 1999; Lotfi et al 2003;Lim and Earle 2008), Such parthenogenetic haploids rarely show spontaneous doubling so chromosome doubling using colchicine or other antimitotic agents is required to obtain fruit set and DH seeds. Various strategies for colchicine treatment of parthenogenetic melon plants have been described (Caglar and Abak 1997;Koksal et al 2002;Yashiro et al 2002;Lotfi et al 2003) with widely disparate rates of conversion to diploidy (from 0 to 100%, often with small sample sizes); however, information about fruit set and seed germination after doubling is very limited (Lotfi et al 2003;Lim and Earle 2008).…”

“…Various strategies for colchicine treatment of parthenogenetic melon plants have been described (Caglar and Abak 1997;Koksal et al 2002;Yashiro et al 2002;Lotfi et al 2003) with widely disparate rates of conversion to diploidy (from 0 to 100%, often with small sample sizes); however, information about fruit set and seed germination after doubling is very limited (Lotfi et al 2003;Lim and Earle 2008).…”

“…We previously described the production of parthenogenic haploids from melon breeding lines carrying multiple disease resistances as well as effects of in vitro and in vivo colchicine treatments on ploidy, pollen production, and fruit set (Lim and Earle 2008). The in vitro treatments applied 500 or 1,000 mg/L colchicine to shoot tip or nodal explants for 3 h. Exposure of 3 cm shoot tips to 500 mg/L colchicine gave the best results: 83% plant regeneration from treated explants; 22% conversion of regenerated plants to diploidy.…”