Anther Culture in Cucurbita Species.

Production of homozygous pure parental lines is the first stage of hybrid vegetable breeding. Unfortunately, producing pure lines takes a long time by classical breeding methods, especially in open-pollinated vegetable species, and this period can be up to 8-10 years. Recently, doubled haploid (DH) technology, as a set of biotechnological methods, has emerged as an alternative to classical breeding methods and allows for the generation of 100% homozygous pure double haploid lines in 1 or 2 years. Although haploid plants were successfully produced via irradiated pollen technique and gynogenesis in some Cucurbita species, haploid plants have not been obtained from some lines due to genotype dependency, and haploidy frequency is still not sufficient for use in a breeding program. Thus, anther culture technique has emerged as an alternative technique in the DH process. The main objective of this chapter is to provide explanatory information on anther culture technique applied in the Cucurbita genus. For this purpose , key points and details of methods and protocols of the anther culture technique are described in summer squash (Cucurbita pepo L.), pumpkin (Cucurbita moschata Duch.), and winter squash (Cucurbita maxima Duch.).

Gynogenesis in Cucurbita Species.

The development of F1 hybrid vegetable varieties emerges as a result of a great effort, long time, investment, knowledge, and advanced technology. The first stage of hybrid vegetable breeding is obtaining pure lines. It is possible to obtain homozygous parent lines used in the production of hybrid varieties with traditional breeding methods. This period takes 8-10 years, especially in some vegetables which are highly open-pollinated, such as Cucurbita spp. Androgenetic- and/or gynogenetic-based dihaploidization methods provide 100% homozygous pure haploid lines in 1-2 years and save time and effort.The DH frequency by irradiated pollen technique and anther culture strongly depends on the genotypic response, whereby their practical use in a breeding program is still limited. As a possible alternative technique, gynogenesis (unfertilized ovule/ovarium cultures) switches on to produce haploid plants in some Cucurbita species. In the Cucurbita genus, gynogenesis has been one of the most studied and popular DH techniques and presented remarkable results in recent years.

Induction of Parthenogenesis by Irradiated Pollen in Cucurbita Species.

Due to their many superior agronomic traits (high yield and fruit quality, resistance/tolerance to biotic and abiotic stress factors, etc.), hybrid vegetable cultivars are widely used in vegetable production all over the world. The first stage of hybrid vegetable breeding is to obtain homozygous pure parental lines. Unfortunately, producing pure lines takes a long time by classical breeding methods, especially in open-pollinated vegetable species, and this period can be up to 8-10 years. Recently, doubled haploid (DH) technology, as a biotechnological method, has emerged as an alternative to classical breeding methods and allows for the generation of pure (100% homozygous) DH lines in one or two years.However, the DH technique needs labor-intensive efforts and experiences as well as the use of appropriate production technologies. The main objective of this chapter is to provide explanatory information on the technique of induction of parthenogenesis by irradiated pollen applied to several species of the Cucurbita genus. For this purpose , key points and details of methods and protocols of this technique are described in summer squash (Cucurbita pepo L.), pumpkin (Cucurbita moschata Duch.), and winter squash (Cucurbita maxima Duch.).

Screening of Cucurbita maxima and Cucurbita moschata Genotypes for Resistance Against Meloidogyne arenaria, M. incognita, M. javanica, and M. luci.

The host response of fifteen winter squash (Cucurbita maxima) and five pumpkin (Cucurbita moschata) dihaploid genotypes to Meloidogyne arenaria, M. incognita, M. javanica, and M. luci was screened in pot experiments. Root galling and nematode reproduction were detected in all combinations of plant genotype and nematode species. Ten genotypes of C. maxima and three genotypes of C. moschata were considered highly resistant (<10% of the susceptible genotype) or moderately resistant (<50% of the susceptible genotype) to one or more Meloidogyne species based on nematode reproduction as a percentage of the most susceptible genotype. Genotypes 55CA15-A3 and G14-IP1 of C. maxima were highly resistant to M. luci and M. arenaria, respectively. Both 14BO01-O2 and G9-A4 genotypes of C. moschata were considered highly resistant to M. arenaria. However, these genotypes still allowed significant nematode reproduction because egg number per plant was higher than initial number of eggs used as inoculum, indicating that all genotypes were hosts.