Evaluation of allicin content and botanical traits in Iranian garlic (Allium sativum L.) ecotypes
Introduction
Garlic (Allium sativum L.) is one of the most important bulb vegetables grown and used as spice and flavoring agent for foods (Velisek et al., 1997). The center of origin of garlic has been considered to be central Asia. From the center of origin, garlic has been spread west, south and east (Etoh et al., 2001).
Garlic is also cultivated for its medicinal properties and this aspect is steadily increasing in the world. It has benefits in lowering total plasma cholesterol, reducing blood pressure and decreasing platelet aggregation (Mayeux et al., 1998, Sterling and Eagling, 2001). Garlic products have become popular in recent years and a variety of culinary and pharmaceutical preparations are now available in market (Velisek et al., 1997).
In Iran cultivation and consumption of garlic has a long history and areas under its cultivation is estimated about 10 000 ha. At present six pharmaceutical garlic products exist in the Iranian markets under license of the health ministry.
The constituents of garlic are divided into two main groups: sulfur-containing compounds and non-sulfur-containing compounds. Most of the medicinal effects of garlic are referable to a sulfur compound known as allicin (Schulz, 1998). The intact garlic clove does not contain allicin but rather its precursor, the non-protein amino acid alliin. Alliin is converted to allicin, pyruvate and ammonia by the enzyme allinase, when the bulb is cut or crushed (Rabinkov et al., 1994).
The amount of allicin in fresh garlic is highly variable (Schulz, 1998). It has been known that allicin content, which released from garlic samples from various regions, is very variable (Iberl et al., 1990, Ueda et al., 1991, Schulz, 1998). Furthermore agronomic parameters also cause variations in phytomedical levels (Mayeux et al., 1998). According to British pharmacopoeia (1998), the minimum allicin content to ensure pharmaceutical and economical viability of garlic powder products should be 4.5 mg/g. Hence it is important to standardize garlic, i.e. breeding a garlic clone with suitable content of allicin and agronomical traits which are needed for the large-scale culture and drug production.
Garlic is a sterile species and reproduces only by vegetative propagation. A series of different ecotypes have been established over time in various areas of cultivation. Considerable morphological and biochemical variations between and within ecotypes are displayed (Bradley et al., 1996, Avato et al., 1998). These differences were described with the objective of selection the best quality of active substance (Avato et al., 1998).
Based on the previous information, it is first time that a research program has been considered in order to evaluate genetic diversity of Iranian garlic ecotypes. In our study 24 ecotypes were collected from the main production regions. Since the study of genetic variability in different traits of available ecotypes is a prelude to crop improvement, genetic variation and diversity for different traits including botanical characteristics, allicin content (before and after culture) and molecular studies were conducted.
The present article is the result of botanical and phytomedical pre-culture studies. In the next stage of the research (field experiment), we will evaluate morpho-physiological characters including the presence or absence of floral stem, low temperature requirement for auxiliary bud differentiation, day length threshold for bulb enlargement, number and size of inflorescence bulbils and clove dormancy (Messiaen et al., 1993, Lallemand et al., 1997). These will help to delimit varietal groups in Iranian garlic ecotypes.
Section snippets
Plant material
A total of 24 garlic clones were collected from different areas. This sampling was done according to the information of local agricultural extension offices and producers from all over Iran (Fig. 1). Geographical origins of the 24 garlic ecotypes are listed in Table 1. A sample of 20 bulbs per ecotype was randomly chosen and then evaluated for variability of three botanical characteristics: mean bulb weight, mean clove weight and clove number per bulb.
Allicin determination
An HPLC method using butyl
Botanical evaluation
Quantitative characteristics are listed in Table 2. Clove and bulb mean weight varied from 0.7 to 5.44 and 16 to 62.34 respectively. The range of variation for clove number per bulb varied from 7 in Ge11 to 40 in Ge22. There was a significant positive correlation between clove mean weight and bulb mean weight (P < 0.01 and r = +0.8) as well as negative correlations between clove mean weight and clove number (P < 0.05 and r = −0.4; Table 3). The color of the external bracts in almost all the
Conclusion
The analysis of genetic divergence plays an important role in breeding programs. Garlic is sterile species with variability in desirable morphological and physiological characteristics. The vegetative mode of multiplication of the species restricts breeding methods. A solution is sought in the use of domestic ecotypes, which are fully adapted to local conditions and are important genetic resources and initial breeding material (Gvozdanovic-Vagar et al., 2002). The preliminary analysis of the
Acknowledgments
We gratefully acknowledge the excellent laboratory work of Mr. Erfatpoor. Further we express our thanks to Mr. K. Larijani for his co-operation in HPLC analysis.
References (14)
- et al.
Agronomic evaluation and essential oil content of garlic (Allium sativum) ecotypes grown in southern Italy
Adv. Hort. Sci.
(1998) - et al.
Classification of Australian garlic cultivars by DNA fingerprinting
Aust. J. Exp. Agric.
(1996) - et al.
RAPD variation of garlic clones in the center of origins and the western area of distribution
Mem. Fac. Agric. Kagoshima Univ.
(2001) - Gvozdanovic-Vagar, J., Vasic, M., Cervenski, J., 2002. Variability of characteristics of garlic (Allium sativum)...
- et al.
Quantitative determination of allicin and alliin from garlic by HPLC
Planta Med.
(1990) - et al.
Delimitation of varietal groups in garlic (Allium sativum L.) by morphological, physiological and biochemical characters
Acta Hort.
(1997) - Messiaen, C.M., Cohat, J., Pichon, M., Leroux, J.P., Beyries, A., 1993. Les Allium alimentaries reproduits par voie...
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