A symbiotic relationship with fungi allows Berseem clovers to grow more healthily in salty soil due to the fungi's arbuscular mycorrhiza network that controls the uptake and distribution of salt ions.

Salty soil represents an extremely harsh environment for plant growth. It causes, among other challenges, an osmotic imbalance that prevents water uptake by roots, prevents the uptake of vital nutrients like nitrogen and phosphorous, and prevents the ability to maintain a proper sodium/potassium balance in the plant cells. Mycorrhiza is the fungal net that forms on and in the roots of many plants as a mutualistic symbiote. Certain mycorrhiza allow the host plant, like the berseem clover (Trifolium alexandrinum), to grow in soil that would normally be too salty for it in its pure state. They effectively allow the plant to uptake water, nitrogen, phosphorous, and potassium using a number of biochemical means such as storing excess salt ions in vacuoles (internal storage spaces), putting the breaks on the transport of salt ions within the host plant, and tapping the surrounding soil for nutrients by extending the fungal network through a greater volume of soil than would be possible for the plant roots alone.

References

"The role of arbuscular mycorrhizal fungi in alleviating salt stress is well documented. This paper reviews the mechanisms arbuscular mycorrhizal fungi employ to enhance the salt tolerance of host plants such as enhanced nutrient acquisition (P, N, Mg and Ca), maintenance of the K+ : Na+ ratio, biochemical changes..., physiological changes..., molecular changes..., and ultra-structural changes...Salinization of soil is a serious problem and is increasing steadily in many parts of the world, in particular in arid and semi-arid areas. Saline soils occupy 7% of the earth’s land surface and increased salinization of arable land will result in to 50% land loss by the middle of the 21st century...it affects the establishment, growth and development of plants leading to huge losses in productivity..." (Heikham et al. 2009:1)

"Arbuscular mycorrhizal fungi (AMF) are associated with the roots of over 80% terrestrial plant species including halophytes, hydrophytes and xerophytes. In this respect, biological processes such as mycorrhizal application to alleviate salt stress would be a better option." (Heikham et al. 2009:2)

"Several studies investigating the role of AMF in protection against salt stress have demonstrated that the symbiosis often results in increased nutrient uptake, accumulation of an osmoregulator, an increase in photosynthetic rate and water-use efficiency, suggesting that salt-stress alleviation by AMF results from a combination of nutritional, biochemical and physiological effects." (Heikham et al. 2009:5)

"Mycorrhizal inoculation can increase P [phosphorous] concentration in plants by enhancing its uptake facilitated by the extensive hyphae of the fungus which allows them to explore more soil volume than the non-mycorrhizal plants. It is estimated that external hyphae deliver up to 80% of a plant’s P requirements...higher accumulation of N [nitrogen] [is found] in shoots of mycorrhizal Sesbania grandiflora and S. aegyptiaca than non-mycorrhizal control plants. The extra-radical mycelia take up inorganic nitrogen from the soil in the form of nitrate and assimilated it via nitrate reductase, located in the arbuscule-containing cells." (Heikham et al. 2009:6)

Journal article
Arbuscular mycorrhizal symbiosis modulates antioxidant response in salt-stressed Trigonella foenum-graecum plantsMycorrhizaOctober 11, 2013
Heikham Evelin, Rupam Kapoor

Journal article
Arbuscular mycorrhizal fungi in alleviation of salt stress: a reviewHeikham E; Kapoor R; Giri B

No link available.

Living System/s

Organism
Egyptian CloverTrifolium alexandriumSpecies