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Pak. J. Bot., 45(2): 375-381, 2013.

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INFLUENCE OF SALT STRESS ON GROWTH AND ANTIOXIDANT RESPONSES OF TWO MALUS SPECIES AT CALLUS AND PLANTLET STAGES

KAI WANG¹, LIXIN ZHANG^1*, MEI GAO¹, LIXIA LV², YONGGUI ZHAO¹, LINSEN ZHANG³, BINZHI LI³, MINGYU HAN³ AND ASHOK K. ALVA⁴

Abstract: Soil salinization has become a major threat to apple (Malus domestica L.) production in some regions of China. In this study, we investigated the effects of salt stress i.e. 150 mM NaCl on growth and antioxidant responses of 15-d old callus and plantlets of two Malus species i.e., rootstock Malus robusta Rehd (Rehd) and scion Malus domestica Borkh. cv. Fuji (Fuji) grown on Murashige and Skoog (MS) medium. Salt stress induced an increase in activities of superoxide dismutase (SOD), peroxidase (POD) and glutathione reductase (GR) in two Malus species, while a decrease in catalase (CAT) activity in Fuji and unchanged pattern in that in Rehd species respectively at callus and plantlets stages. Additionally, salt stress led to an increase in hydrogen peroxide (H₂O₂) and superoxide radicals (O₂^{• −}) contents, along with an enhanced accumulation of malondialdehyde (MDA) resulting in a decrease in relative growth rate (RGR) of both species. The activities of SOD, POD, CAT and GR of both  species at plantlets stage were greater while H₂O₂, O₂^{• −} and MDA contents lower than those at callus stage. The two Malus species showed similar accumulation of MDA and RGR at both differentiation stages, although they showed different patterns of H₂O₂ and O₂^{• −} accumulation and their corresponding scavenging capacity. The results of this study suggested that callus of both species was more sensitive to salt stress than plantlets. The responses of two Malus species to salt stress were similar at a given differentiation stage. Therefore, callus stage is more appropriate for evaluation of plant responses to salt stress. The scion (Fuji) can be matched with rootstock (Rehd) to adapt to soil salinity stress.

¹College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, P.R. China

²College of Forestry, Northwest A&F University, 712100, Yangling, Shaanxi, P.R. China

³ College of Horticulture, Northwest A&F University, 712100, Yangling, Shaanxi, P.R. China

⁴USDA-ARS-Vegetable and Forage Crops Research Unit, 99350, Prosser, WA, USA

^*Corresponding author’s e-mail address: zhanglixinyangling88@yahoo.com.cn