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.).

Genetic diversity and population structure of watermelon (Citrullus sp.) genotypes.

Genetic polymorphism amid plant species is a crucial factor for plant improvement and maintaining their biodiversity. Evaluation of genetic diversity amongst plant species is significant to deal with the environmental stress conditions and their effective involvement in the breeding programs. Hence, in present study, an attempt has been made towards the genetic assessment of individual and bulked populations of 25 watermelon genotypes, belonging to Citroides (citron watermelon) and Lanatus (dessert watermelon) group from Konya, Thrace, Turkmenistan, Saudi Arabia and Turkey. The employed Random Amplified Polymorphic DNA (RAPD) and Inter-Simple Sequence Polymorphism (ISSR) marker systems provided 69.4 and 95.4% polymorphisms, respectively. Different clustering methods showed clear grouping of the genotypes based on the geographical origin and species. Citron genotypes from Turkmenistan stood apart from all the Turkish Lanatus genotypes. However, Saudi Arab Lanatus genotype grouped with native Turkish varieties indicating the genetic linkage. Among all the Turkmenistan Citron genotypes, Turkmenistan-11 was the most distinct form. Moreover, sufficient genetic variation was found between the commercial and native Lanatus genotypes of Turkey as well as Citron genotypes of Turkmenistan. Hence, it will be beneficial to include these genotypes in the future breeding programs to transfer disease-resistant alleles from Citron to Lanatus genotypes.