Biotechnological Studies of Date Palm: Micropropagation of Inflorescence, Molecular Biology and Secondary Metabolites

Abstract

The study was performed during the period of 1999 to 2003 in the laboratory of plant tissue culture, Agriculture Development Systems project (ADS), Ministry of Agriculture. The best method to surface sterilize the female spathe of date palm 'Zaghloul' was using HgCh solution at 0.1% for 5 min. The morphological survey of different types of buds within the date palm head was carried out. It is recommended that date palm spikes at 2.5 em in length would be oriented to somatic embryogenesis as a main target. Nutrient medium (3f4MS and 40 gm r1 sucrose) supplemented with 2.5 mg 1- 1 2,4-D + 0.5 mg r1 IBA + 0.2 mg r1 2ip, some of the small florets which existed on the spikes formed direct shoots or roots. At the same time, some florets swelled and formed ball-like structures. The direct proembryos were formed within these structures. Generally, 73.0 % of spike segments were able to form embryos whether directly or indirectly after subculture 3. In respect to date palm spikes at 7.0 em in length, it is suspected that they must instruct to direct shoot formation (caulogenesis). Only 33.0 %of middle spikes produced direct shoots (vegetative buds) after subculture 2 when they were cultured onto the basal nutrient medium (MS and 50 gm 1" 1sucrose) supplemented with 2.5 mg 1"1 2,4-D + 0.5 mg 1"1 IBA+ 0.2 mg r1 2ip. Also, the same result was obtained with the nutrient medium which contained 0.5 mg r1 2,4-D + 0.5 mg r1 IBA + 0.2 mg r1 2ip. Moreover, the majority of spike explants tend to form direct proembryos better than preceding age. Regarding the spikes in late age of growth and development (20.0 em in length), no considerable response was recorded. Subsequently, it is not preferable to use an inflorescence as a desirable source for explant in date palm micropropagation at later age of growth (29.0 em in length). All major amplified DNA fragments of date palm cv. Zaghloul, generated by PCR amplification using the random primers OPD2; OPB18 and OPC14, were detected in all samples, to ensure the genetic stability in the three samples (donor mother plant; in vitro propagated plantlets and ex vitro plants grown in the greenhouse). The growth of embryogenic callus that used to produce the flavonoids was steadily decreased by increasing the flavonoids content as indicated by the increasing value. It is suggested that spraying with particular substances including ethrel and other promoting substances after traditional offshoots separation is beneficial to secrete more amounts of flavonoids and their relative compounds to improve the natural defense within the palm tree against pathogens invading. Administration rats with 40 mg ethanolic extract of flavonoids incorporated into 100 gm of a diet caused considerable responses in the gain of body weight, organs weight, total lipids, total cholesterol, serum glucose level, and liver and kidney functions as a result of increasing the health of hyperglycemic rats. Key words: Phoenix dactylifera L., Inflorescence, Tissue culture, Somatic embryogenesis, Secondary metabolites, Hyperglycemia.