Salinity is a major abiotic stress which affects crop plants around the world, resulting in substantial loss of yield and millions of dollars of lost revenue. High levels of Na + in shoot tissue have many adverse effects and, crucially, yield in cereals is commonly inversely proportional to the extent of shoot Na + accumulation. We therefore need to identify genes, resistant plant cultivars and cellular processes that are involved in salinity tolerance, with the goal of introducing these factors into commercially available crops. Through the use of an Arabidopsis thaliana mapping population, we have identified a highly significant quantitative trait locus (QTL) linked to Na + exclusion. Fine mapping of this QTL identified a protein kinase (AtCIPK16), related to AtSOS2, that was significantly up-regulated under salt stress. Greater Na + exclusion was associated with significantly higher root expression of AtCIPK16, which is due to differences in the gene's promoter. Constitutive overexpression of the gene in Arabidopsis leads to plants with significant reduction in shoot Na + and greater salinity tolerance. amiRNA knock-downs of AtCIPK16 in Arabidopsis show a negative correlation between the expression levels of the gene and the amount of shoot Na + . Transgenic barley lines overexpressing AtCIPK16 show increased salinity tolerance.

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Maize tolerance potential to oil pollution was assessed by growing Zea mays in soil contaminated with varying levels of crude oil (0, 2.5 and 5.0 % v/w basis). Crude oil contamination reduced soil microflora which may be beneficial to plant growth. It was observed that oil pollution caused a remarkable decrease in biomass, leaf water potential, turgor potential, photosynthetic pigments, quantum yield of photosystem II (PSII) (Fv/Fm), net CO2 assimilation rate, leaf nitrogen and total free amino acids. Gas exchange characteristics suggested that reduction in photosynthetic rate was mainly due to metabolic limitations. Fast chlorophyll a kinetic analysis suggested that crude oil damaged PSII donor and acceptor sides and downregulated electron transport as well as PSI end electron acceptors thereby resulting in lower PSII efficiency in converting harvested light energy into biochemical energy. However, maize plants tried to acclimate to moderate level of oil pollution by increasing root diameter and root length relative to its shoot biomass, to uptake more water and mineral nutrients.