Development of pure lines by ovary culture in watermelon (Citrullus lanatus L.)

In this study, it was aimed to obtain haploid plants from the genetic resources of Türkiye by ovary culture and to make them double haploid in order to accelerate breeding studies in watermelon, which is widely consumed in the world and in Türkiyey and has high economic value. Within the scope of the research, twelve morphologically diverse and high quality watermelon genotypes (Kar 17, Kar 22, Kar 37, Kar 48, Kar 68, Kar 88, Kar 116, Kar 165, Kar 180, Kar 192, Kar 340, Kar 341) selected from Cucurbit Genetic Resources Collection of Horticulture Department of Çukurova University (Adana, Türkiye) and collected from different regions and provinces of Türkiye and three commercial varieties (Sturbust F1, Ersin and Emerald) were used. Four different nutrient media (A: Murashige and Skoog (MS), 30 g L-1 sucrose, 7 g L-1 agar, 0.04 mg L-1 TDZ; B: MS, 30 g L-1 sucrose, 7 g L-1 agar, 0.15 mg L-1 2,4-D, 1.5 mg L-1 Kinetin; C: MS, 30 g L-1 sucrose, 7 g L-1 agar, 0.1 mg L-1 2,4-D, 1 mg L-1 BAP; D: MS, 30 g L-1 sucrose, 7 g L-1 agar, 0.1 mg L-1 2,4-D, 1 mg L-1 Kinetin) were tested. As regeneration medium; MS medium including 0.2 mg L-1 BAP and 0.05 mg L-1 NAA was used. In the study, pre- applications [temperature (35°C/48 hours), cold shock (4°C/24 hours) and no pre- application] were applied to the ovaria in the induction medium and their effects on development were examined. Flow cytometry analysis, stomal examinations, morphological and cytological observations were performed to determine the ploidy levels of the plants obtained. In vitro and in vivo colchicine applications were made to the plants determined as haploid. Molecular analyses were made to the plants determined as double haploid and their homozygosity was examined. As a result of the study, it was determined that the most suitable induction medium was C and the most suitable pre-application was keeping the temperature at 35°C for 48 hours. It was determined that 67 plants were haploid and 33 plants were double haploid out of 100 plants on which flow cytometry analysis was perfomed. The most successful colchicine application was determined to be keeping in 0.5% colchicine solution for 4 hours with a success rate of 63.014%. The number of plants obtained by ovary culture and was 294 and 34 lines were obtained.