Pak. J. Bot., 47(5): 1817-1824, 2015. UV-B IRRADIATION EFFECTS ON BIOLOGICAL ACTIVITIES AND CYTOLOGICAL BEHAVIOR OF SAINFOIN (ONOBRYCHIS VICIIFOLIA SCOP.) GROWN IN VIVO AND IN VITRO SADEGH MOHAJER* 1 , ROSNA MAT TAHA 1 , MINOO MOHAJER 2 , AND IMAN YOUSEFI JAVAN 3 1 Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia 2 Department of Plant Biology, Faculty of Biological Sciences, Kharazmi University, Tehran 15719-14911, Iran 3 Department of Science and Technology for Agriculture, Forestry, Nature and Energy, University of Tuscia, 01100 Viterbo, Italy *Corresponding author email: mohajer.ae@gmail.com Abstract To investigate the feasibility of UV-B irradiation (312 nm), seeds of Onobrychis viciifolia were exposed to five different intensities for determining the effectiveness of cellular behavior, nutritional constituents and biological activities in In vivo and In vitro growth cultures. The atomic spectroscopy analysis confirmed that concentrations of two macronutrients (P and N) improved after UV-B exposure as compared with control plants. Near infrared radiation conducted on both In vivo and In vitro plants showed significant differences on dry matter digestibility (DMD) and crude fiber (CF). Flavonoid and phenolic compounds were increased in both growth cultures by 40% intensity of UV-B irradiation, although In vitro plants had the higher compounds than intact plants. Increasing the UV-B irradiation intensity was also found to yield positive effect on anthocyanin. Observations on cellular behavior such as determination of nuclear and cell areas, mitotic index and chromosomal aberrations were proven to be essential in deducing the effectiveness of UV-B irradiation to induce somaclonal variation in sainfoin. Key words: Sainfoin, UV-B irradiation, Macronutrients, Pigment, Cytology, Phenolic, Flavonoid. Introduction Sainfoin (Onobrychis viciifolia Scop. syn. Onobrychis sativa L.) is one of the most important forage legumes, which is favoured by farmers due to high nutritional value properties. Forage quality is the ability of pasture to produce a desired livestock response, which has direct relation with nutritional constituents (Mohajer et al., 2012). The potential of chlorophyll to absorb the light energy across a wide visible range helps the optimum photosynthesis efficiency in plants. Approximately, 8-9% of total solar radiation consists of ultraviolet radiation (UV), which is a part of non- ionizing electromagnetic spectrum (Frederick, 1993). Plants are regularly exposed to UV irradiation by sunlight as a requirement for photosynthesis. It was also reported that UV-B irradiation could promote growth, morphological, physiological and biochemical responses in plants (Zhang et al., 2003; He et al., 2003). However, excessive UV-B irradiation has been proven to have a negative impact on most of the crops or plant species (Agrawal et al., 2006). The high intensity of UV irradiation has been shown to perturb protein synthesis (Xiuzher, 1994; Kang et al., 2012), and affect the balance of hormones (Rabie et al., 1996), enzyme activity, water exchange (Stoeva et al., 2001) and gas exchange in plant leaves (Stoeva & Bineva, 2001). Some researchers have also demonstrated that exposure to UV light can result in significant changes in photosynthetic pigments by the composure of chlorophylls and carotenoids (Teramura & Ziska, 1996) and impairing their photosynthetic function (Grzymski et al., 2001). Response to UV-B irradiation differs between species, whereby distinctive mechanisms were employed, such as inhibition of free radicals due to exposure of seeds to UV irradiation, involving peroxidase and antioxidants (Rogozhin et al., 2000; Ahmad et al., 2013). The inhibition of free radicals is a biochemical defense mechanism utilizing flavonoids and carotenoids. Liang et al. (2006) stated that flavonoids played a significant role to guard against UV-B damage in plants, whereby flavonoids would act as a UV filter by absorbing irradiation with wavelengths between 280-320 nm, while carotenoids function reacts as an internal filter. Moreover, irradiation of UV-B was widely used in tissue culture systems, where it can be used to induce somatic variation and to deduce the varieties of interest and evaluation of genetic resource (Run et al., 1999). UV light can also affect the cellular activity, such as changing the chromosomal function without resulting in cytoplasmic damage and shifting of chromosomes after exposure on cells (Bradshaw et al., 1995). Along this line, the chromosomes were found to move passed the equator to the non-irradiated pole and lose the capacity of division (Sinha & Hader, 2002). The present study was designed with the following objectives; to investigate the feasibility of UV-B irradiation on seeds to improve the expression of biological activities without mutation, to determine the appropriate irradiation intensity for induction of somaclonal variation; subsequently verified by means of cytological study. Materials and Methods UV-B treatment: Seeds of Onobrychis viciifolia were exposed to five different levels (100% down to 20%) of UV-B (312nm) irradiation by Spectroline Transilluminator (TVC-312R, six 15-watt UV-B tubes, 120V, 60Hz, 2.0 AMPS) for 15 min per day of a week.