Molecular characterization of sour orange (Citrus aurantium) accessions and their relatives using SSR and SRAP markers.

Citrus production with its many varieties is of importance since it provides economically important products for Turkish exports. Sour orange is a rootstock commonly used for propagating the different scion varieties. Knowledge of the genetic diversity of the rootstock accessions would be useful in order to improve citrus breeding programs. We studied genetic relationships and diversity of 51 accessions of sour orange (Citrus aurantium) and their relatives using SSR (simple sequence repeat) and SRAP (sequence-related amplified polymorphism) molecular markers. Twenty-one SRAP primer combinations were tested on these accessions and relatives, producing 167 polymorphic fragments, with a mean of 8.0 and a mean polymorphism information content value of 0.47. Seventeen SSR primers also produced 30 polymorphic fragments, with a mean of 1.4 per primer and a mean polymorphism information content value of 0.39. The unweighted pair-group method with arithmetic average analysis using combined SSR and SRAP data showed a similarity range from 0.71 to 1.00 among the accessions. In the cluster analysis, sour orange relatives were indicated as a separate group from sour orange. 'Macrophylla' and 'Mexican lime' were the accessions most distinct (0.71) from the others. We conclude that genetic diversity in these sour orange accessions is lower and some of them were identical.

Genetic diversity among melon accessions (Cucumis melo) from Turkey based on SSR markers.

Melon (Cucumis melo) is an important vegetable crop in Turkey, where it is grown in many regions; the most widely planted lines are local winter types belonging to the var. inodorous. We examined 81 melon genotypes collected from different provinces of Turkey, compared with 15 reference melon genotypes obtained from INRA/France, to determine genetic diversity among Turkish melons. Twenty polymorphic primers were used to generate the SSR markers. PCR amplification was performed and electrophoresis was conducted. SSR data were used to generate a binary matrix. For cluster analysis, UPGMA was employed to construct a clustering dendrogram based on the genetic distance matrix. The cophenetic correlation was compared with the similarity matrix using the Mantel matrix correspondence test to evaluate the representativeness of the dendrogram. A total of 123 alleles were amplified using the 20 SSR primer sets. The number of alleles detected by a single primer set ranged from 2 to 12, with an average of 6.15. The similarity ranged from 0.22 to 1.00 in the dendrogram developed from microsatellite analysis. Based on this molecular data, we concluded that genetic diversity among these Turkish accessions is relatively high.

Gelling agents and culture vessels affect in vitro multiplication of banana plantlets.

Agar is the most commonly used gelling agent in media for plant tissue culture. Because of the high price of tissue-culture-grade agar, attempts have been made to identify suitable alternatives. The type of culture vessel and lid also affects the gaseous composition inside the vessel as well as light penetration. In turn, the vessel affects growth parameters, such as shoot elongation, proliferation and fresh weight, as well as hyperhydric degradation processes. We examined the effects of different culture vessels, including commercial glass jars, magenta boxes, and disposable containers, as well as different gelling agents (agar-agar, Agargel, Phytagel, and plant agar) on the micropropagation of Dwarf Cavendish bananas in an effort to find a combination that yields large numbers of high-quality seedlings. The different culture vessels did not significantly affect seedling culture success. The medium significantly affected shoot weight. Phytagel resulted in the highest shoot weight (overall mean = 2.4 g), while agar, Agargel and plant agar resulted in 1.7, 2.2 and 2.2 g, respectively. Disposable container/Phytagel and Magenta/Agargel combinations yielded the highest shoot weights (2.9 and 3.0 g, respectively). Mean shoot length increased progressively with subculture (four subcultures were made). The highest mean shoot length was obtained with Phytagel and Agargel media (6.4 and 6.3 cm, respectively). Shoot number was significantly affected by medium only at subculture 4. Overall, the highest mean shoot length was obtained with the Magenta/Agargel combination (8.5 cm). Phytagel and plant agar gave higher mean shoot number than agar and Agargel (2.1, 2.1 and 1.7 and 1.9, respectively). The costs of the media and of the culture vessels need to be taken into account for final choice of the banana shoot culture system.