Genetic diversity assessment of ancient mulberry (Morus spp.) in Lebanon using morphological, chemical and molecular markers (SSR and ISSR)
From Firenze University Press Journal: Advances in Horticultural Science
A. Kadri, Lebanese Agricultural Research Institute, Tal Amara Station, Department of Plant Biotechnology, Plant Genetic Resources Unit
S. Saleh, Lebanese University, Faculty of Sciences I, Applied Plant biotechnology, Hadath, Lebanon.
A. Elbitar, Lebanese Agricultural Research Institute, Tal Amara Station, Department of Plant Biotechnology, Plant Tissue Culture Unit
A. Chehade, Lebanese Agricultural Research Institute, Tal Amara Station, Department of Plant Biotechnology, Plant Genetic Resources Unit
Mulberry belongs to the genus Morus of the family Moraceae. It is a multipurpose tree with a significant ecological, nutritional and economical high value. Mulberries are highly adaptable species in different soil and climatic conditions. They are generally quite tolerant to drought, pollution and poor soil. Therefore, they can be found in a wide area of tropical, subtropical, and temperate zones in Asia, Europe, North America, South America, and Africa (Kafkas et al., 2008).
The genus Morus regroups 24 species (Thabti et al., 2014). The most widespread species in the Mediterranean climate areas are: Morus alba with fruit colors ranging from white to dark red, Morus rubra with mainly red/purple fruits and Morus nigrawith dark purple to black fruits (Gerasopouls and Stravroulakis, 1997). Mulberry fruits have remarkable potential for providing various valuable industrial products of high economic value for human beings. They are used for direct fruit consumption (Morus alba, Morus indica, Morus nigra, and Morus laevigata).
Most of mulberry species have distinct flavor with juicy and acidic characteristics making them attractive for use in the processing industry for products such as fruit juice, ice cream, jelly, and jam (Ercisli and Orhan, 2007). Interest in mulberry has increased considerably over the last 20 years as a healthy fruit. Morus species have great antioxidant potential due to their high content in phenolic compounds including flavonoids, anthocyanins, and carotenoids (Zhang and Ma, 2018). Mulberries present anticancer and antiinflammatory properties and show as well significant effect on many chronic diseases like diabetes (Nakamura et al., 2009; Kwon et al., 2015; Qian et al., 2015).
Mulberry is an economically important plant used for sericulture. It is the sole food plant for the domesticated silkworm, Bombyx mori (Zhao et al., 2009). The genus Morus, is cultivated extensively in East, Central and South Asia for silk production (Awasthi et al., 2004). Hence, mulberry is one of the most important components that decide the sustainability of this industry (Liu et al., 2009). At the turn of the century, Lebanon was known for its highquality silk industry. Bestowed with an ideal climate and a fertile soil, mulberries were planted everywhere in Lebanon and mulberry production flourished (Firro, 2009).
The silk tradition in Lebanon is more than two thousand years old. It goes back to the period of the famous purple dye (Ourjouan) extracted from the Murex shell by the Phoenicians of Sidon and Tyre and used to produce imperial purple silk (Khater, 2009). In the 19th century, silk industry constituted almost 80% of Lebanon’s economy. By the early 20th century, 70% to 80% of the cultivable land of the country mountainous regions (Mount Lebanon) became devoted to mulberry orchards. Due to the high demands in silk production, mulberry tree has an unsurpassed economic impact on rural communities. After 1940’s, when silk began to be imported from the Far East, the sericulture industry declined sharply. Mulberry cultivation became marginalized.
However, Lebanon still has very old rainfed mulberry trees which are the remnants of the abundant orchards that were once shaping the landscape of many villages. Mulberry trees are found in different Lebanese villages, mostly located at orchards periphery or in small gardens. In Lebanon, mulberry genotypes are very diverse, as they were sometimes obtained in the past from seeds or from cuttings. This process has led to a great number of landraces adapted to different conditions and different uses throughout the country. In Lebanon, there are many local traditional accessions but no named cultivars. Mulberries are distinguished and denominated according to the fruit color: “Abyad” (white mulberry), “Mwachah” (purple mulberry), “Shami” and “Aswad” (black mulberries). Mulberry genetic diversity is progressively being lost in farmers’ fields and in nature.
The threat results from the interaction of several factors and is processing at an alarming rate. The most crucial factors are urbanization, climatic changes, out breaks of new diseases and pests, and the frequent occurrence of natural calamities. Little information is available about the genetic diversity of Lebanese mulberries. To protect mulberry in Lebanon, a marginalized species, conservation programs should be initiated. In this study, we have collected local mulberry accessions from different geographical regions of Lebanon and assessed their genetic diversity by using agromorphological traits as well as molecular markers (SSR and ISSR).
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