Soybean is an important cash crop and its productivity is significantly hampered by salt stress. High salt imposes negative impacts on growth, nodulation, agronomy traits, seed quality and quantity, and thus reduces the yield of soybean. To cope with salt stress, soybean has developed several tolerance mechanisms, including: (i) maintenance of ion homeostasis; (ii) adjustment in response to osmotic stress; (iii) restoration of osmotic balance; and (iv) other metabolic and structural adaptations. The regulatory network for abiotic stress responses in higher plants has been studied extensively in model plants such as Arabidopsis thaliana. Some homologous components involved in salt stress responses have been identified in soybean. In this review, we tried to integrate the relevant works on soybean and proposes a working model to describe its salt stress responses at the molecular level.Key words: abiotic stress; Glycine max; ion homeostasis; osmotic adjustment; reactive oxygen species scavenging; salt tolerance; soybean. HM (2008). Salt tolerance in soybean. J. Integr. Plant Biol. 50(10), 1196-1212. Available online at www.jipb.net Due to its high protein and oil content, soybean is an important cash crop for human diet, animal feeds, and biodiesel. It is also used as raw material for many human health and industrial products. Therefore, the demand for soybean is ever increasing worldwide. Phang TH, Shao G, LamSalt stress is one of the abiotic stresses that significantly reduce the yield of soybean. Soybean germplasms display a spectrum of salt tolerance capability. A vast collection of soybean genotypes was screened in order to identify genetic materials showing high tolerance to salt stress (Shao et al. 1986). Currently, breeding is the major strategy to improve the salt tolerance of soybean. However, the efficiency of traditional breeding is low because of the long breeding cycle, incompatible fertilization, and close linkage between abiotic stress tolerance loci and undesirable characters (e.g. low yield) (Wang et al. 2003). Received 18 Mar. 2008 Accepted 18 Jun. 2008 Supported by the Hong Kong RGC Earmarked Grant CUHK4434/04M and the Hong Kong UGC AoE Plant and Agricultural Biotechnology Project AoE-B-07/09 (to H.M. Lam).* Author for correspondence. Molecular breeders suggest a concept of "breeding by design" as a targeted, efficient, and comprehensive strategy to elevate the salt tolerance of soybean (Peleman and Dvan der Voort 2003;Wan 2006). A better understanding of salt stress response and the underlying tolerance mechanism is important for implementation of such a tactic.This review aims to summarize the current understanding on the salt stress responses and tolerance mechanisms in soybean. Effects of Salt Stress on Growth, Agronomy Traits and Seed Quality of SoybeanSoybean is classified as a moderately salt-tolerant crop and the final yield of soybean will be reduced when soil salinity exceeds 5 dS/m (Ashraf 1994). It was shown that the average production of 20 soybean cultivars under nonsal...