Plant Archives Volume 20 No. 2, 2020 pp. 9669-9681 e-ISSN:2581-6063 (online), ISSN:0972-5210 PHYSIOLOGICAL AND MOLECULAR STUDIES ON WILD BARLEY (HORDEUM SPONTANEUM) UNDER SALT STRESS Shaimaa R. M. Khalil* 1 , Ahmed Ashoub* 2 & 3, Basita A. Hussein 4 , Wolfgang Brüggemann 3 , Ebtissam H. A. Hussein 4 and Mohamed S. Tawfik 1 1* Oil Crops Biotechnology Lab, Agricultural Genetic Engineering Research Institute (AGERI), Agricultural Research Center (ARC), 9 Gamaa Street, 12619, Giza, Egypt. 2* Agricultural Genetic Engineering Research Institute (AGERI), Agricultural Research Center (ARC), 9 Gamaa Street, 12619, Giza, Egypt 3 Institute of Ecology, Evolution, and Diversity, Goethe University Frankfurt am Main, 13 Max-von-Laue-Straße, 60438, Frankfurt am Main, Germany 4 Department of Genetics, Faculty of Agriculture, Cairo University, Giza, Egypt Abstract Salinity is a major threat to plant survival and productivity worldwide. Wild barley (Hordeum spontaneum) is the progenitor of the cultivated barley (Hordeum vulgare L.) and one of the known species for tolerance to excess of salinity in soil and irrigating water. We evaluated some of the physiological and molecular variations resulting from germinating wild barley seeds on different salinity levels. Chlorophyll fluorescence parameters (OJIP, Fv/Fm and PI) were measured in wild barely seedling growing in the presence of ten different NaCl levels (0, 25, 50, 75, 100, 125, 150, 175, 200, 225, and 250 mM) for 4 weeks. Chloroplast photosynthesis efficiency begins to be negatively affected at 125 mM NaCl concentration and above. Molecular analysis using DDRT-PCR technique on wild barley seedlings growing at 0, 125 and 200 mM NaCl levels, revealed the upregulation of several fragments. Sequencing revealed that the fragments belongs to seven genes (thi4, shmt, lhc3, B2, vps29, oee1 and sbt). Real-time PCR analysis was performed to validate our results and out of the seven identified genes, B2 was the most upregulated gene followed by shmt and oee1 genes. Key words: H. spontaneum, salinity, chlorophyll fluorescence, DDRT-PCR and real-time PCR analysis Introduction Dehydration-inducing conditions are major abiotic stresses affecting plant distribution, productivity, and survival worldwide (Hernández, 2019). Salinity is a limiting factor affecting plants’ growth and yield in different areas worldwide (Munns, 2005; Munns and Tester, 2008 and Hasegawa, 2013). Soil salinization occurs naturally in areas close to/surrounding see-shores and salty lakes, or due to wrong agricultural practices, usage of poor-quality irrigation water, lack of proper drainage system, and extensive use of fertilizers (FAO, 2009). Salinization of soil is a problem in different regions worldwide, and salinization of lands is estimated to reach up to 50% of the world’s arable land by 2050 (Wang et al., 2003; Jamil et al., 2011 and Shrivastava and Kumar, 2015), therefore hindering efforts towards increasing food production for the growing world population. H. spontaneum is commonly known as wild barley or spontaneous barley. It is originated in the fertile crescent area (Turuspekov et al., 2014), and believed to be the origin that gave rise to commercially available cereal barley (H. vulgare L.) (El-Hashash and El-Absy, 2019). Economically important crops-wild relatives are the genetic source for various traits involved in biotic and abiotic tolerance (Mondal et al., 2018 and Pandotra et al. , 2020). The domestication process of many commercial crops led to the marked truncation of the wild population, leading to loss of the genetic pool available to breeders (Ellis et al., 2000 and Kumar et al., 2020). Therefore, different workers in the field of plant biology have used wild barley for the discovery of new genes (Ames et al., 2015; Nishantha et al., 2018 and Liu et al., 2020a). *Author for correspondence : E-mail : moh4mon@gmail.com, shaimaa.rm@gmail.com, ashoub@em.uni-frankfurt.de