Characterization of three date palm cultivars based on RAPD fingerprints and fruit chemical composition

Abstract EN

The interspecific and intergenetic relationships of three date palms (Phoenix dactylifera L.) cultivars (namely : Yellow Sukkary, Red Sukkary, and Naptet Sukkary) were investigated.

The chemical analysis included the fruit antioxidants activity and efficiency, total bound and free phenolics, flavonoids and carotenoids contents.

Data showed that antioxidant extraction with ethanol : water (1 : 1) solvent gave the highest antioxidant activity ("Oxygen Radical Absorbance Capacity" values) (ORAC FL) and highest antioxidant efficiency (AE).

"Red Sukkary" cultivar showed significantly higher values of bound protocatechuic, caffeic, coumaric, ferulic, hydroxy benzoic, and hydroxy cinnamic acids.

Whereas "Yellow Sukkary" cultivar contained significantly higher values of free protocatechuic, vanillic, syringic, and hydroxy benzoic acids compared with all other cultivars.

No free vanillic acid was detected in "Red Sukkary", whereas no free protocatechuic acid was detected in "Naptet Sukkary" cultivar.

The highest content of flavonoids was presented in "Red Sukkary" (4.47 mg / 100 g fresh weight), followed by "Naptet Sukkary" (2.26 mg / 100g fresh weight) and "Yellow Sukkary" (2.13 mg / 100g fresh weight).

In addition, total carotenoids contents in fresh date fruits of both "Red Sukkary" and "Naptet Sukkary" cultivars were significantly higher than those of "Yellow Sukkary".

The suitability of randomly amplified polymorphic DNA (RAPD) fingerprints as a genetic marker in date palm was tested.

Three date palm cultivars (Red Sukkary, Yellow Sukkary, and Naptet Sukkary) were subjected to DNA fingerprint analysis.

From 40 primers tested, only 16 were selected as reproducible, giving 115 bands.

The RAPD profiles obtained were successfully used to differentiate the genotypes.

Based on the pairwise comparison of amplification products, the genetic similarity was estimated.

The three date palm cultivars showed variation at the DNA level.

The genetic similarity among all date palm cultivars ranged from 81 to 87 %.

Naptet Sukkary was quite distant from other cultivars.

A dandrogram was constructed using UPGMA analysis.

On the basis of this analysis, the populations were clustered into two clusters : cluster I contained Red Sukkary and Yellow Sukkary cultivars, and cluster II contained Naptet Sukkary cultivar.

Therefore.

the polymorphism detected and its reproducibility suggest that RAP Dmarkers can be used successfully for varietals identification and for studying the genetic diversity of cultivars.