SELECTION AND EVALUATION OF GENETIC DIVERSITY IN POMEGRANATE. I- Some criteria for studying the progenies of selfing, open-pollination and hybrid between Nab-El Gamal and El- Tahrir Cultivars

Abstract

Pomegranate breeding program was initiated in 2004 in the Horticulture Research Institute, Agriculture Research Center, Egypt. Breeding objectives are dedicated predominantly by the demands of the European markets and exploit the principal advantages of the Egyptian cultivars. It was initiated by crossing between the main cultivars (Manfaloty, Nab-El Gamal, El-Tahrir and Bader), selfing and open pollination for each cultivar. The aim of this study was to develop very early ripening genotypes of high productivity, dwarfing habit and good quality of fruits. About 200 progenies resulting from open, self-pollination and crossing among these cultivars were planted in Shandawel, Sohag Governorate in 2008. The progenies were studied to examine the inheritance of important traits. Some trees of these progenies flowered and gave fruits in 2012 and 2013 seasons; from which, nine trees were selected on the basis of the yield. The present investigation studied the polymorphism variance based on vegetative growth, flowering, fruit characters and yield of these progenies. DNA fingerprinting was determined through ISSR technique, using five primers to identify unique molecular markers characterizing the progenies under study. Some progenies, such as the hybrid between El-Tahrir × Nab-El Gamal (tree No 9) exhibited a yield of 22.5 Kg/tree. Trees (No 7 and No 9) of the hybrid between El-Tahrir ♀ × Nab El-Gamal ♂ gave the best ratio of T.S.S/Acidity of 31.96 and 29.86 respectively, as compared to the other progenies. The hybrid tree (No 7) between the same two cultivars was the smallest tree compared with all the progenies under study. Open pollination progeny of Nab-El Gamal gave the highest number of pomegranate grains in 100 g, while the self pollination progeny of El-Tahrir gave the highest juice percentage. A dark color of the grains was detected for the hybrid (El-Tahrir ♀ × Nab El-Gamal ♂) in the two seasons. The results of molecular analysis of genomic DNA of the nine trees (progenies) of pomegranate showed that the total number of amplicons amplified by the five primers was 57 with an average of 11.4/primer. The polymorphism ranged from 50% to 93.3%. The size of the amplified band varied between the used primers, ranging from 115 to 128 bp. Genetic similarity value was very low among the three tested hybrids ranging between 0.0 to 0.06. The variations observed in the genetic similarity could be attributed to the effect of pollen grains on the genetic structure of the resulting genotypes. On the other hand, a high value of genetic similarity was observed in the self and open pollination progenies of Nab-El Gamal, while the self and open pollination progenies of El-Tahrir cultivar exhibited intermediate values of genetic similarity. This polymorphism renders these markers useful for further genetic studies in pomegranate progenies.