The 21st century is marked by global scarcity of water resources, environmental pollution and increased salinisation of soil and water. Amongst the various environmental stresses such as high winds, extreme temperatures, soil salinity, drought and flood that are impacting the production and cultivation of crops, soil salinity is one of the most devastating, causing significant reductions in arable land, crop productivity and quality. It has been estimated that worldwide 20% of total cultivated and 33% of irrigated agricultural lands are afflicted by high salinity. Salinised areas are increasing at a rate of 10% annually due to low precipitation, high surface evaporation, weathering of native rocks, irrigation with saline water, and poor cultural practices. It has been estimated that more than 50% of arable land will be salinised by the year 2050 (Jamil et al., 2011).
A small tomato, Solanum pimpinellifolium, commonly known as the currant tomato is helping scientists to understand plant responses to salt stress, vital to the development of resilient crop varieties. A study entitled, Deciphering salt stress responses in Solanum pimpinellifolium through high-throughput phenotyping, by Julkowska et. al. (Plant Journal 2024) found that this tomato, holds untapped genetic secrets thanks to its extensive diversity (phenotypic variations).
Solanum pimpinellifolium is a wild species of tomato, native to Ecuador and Peru which has naturalised elsewhere, such as the Galápagos Islands. Commonly grown in gardens as a domesticated heirloom tomato, but it is considered to be wild species.
The scientists discovered that this currant tomato plants had a wide and varied response to salinity stress, with the greenhouse tested plants surviving salinity if they transpired more efficiently, and the field plants performing better if they had a greater shoot mass. Reportedly, the plants grew vigorously plants grew, with strong, bushy growth that developed quickly, withstanding the saltier soils better than the 2700 varieties tested.
The researchers assumed the Solanum pimpinellifolium accumulated fewer sodium ions in their leaves, suggesting that salt-resilient plants have a way of avoiding excessive uptake from the soil. But in fact, they found that the healthier plants held plenty of sodium ions in their tissues. They think that while the larger, healthier plants do take up salt from the soil, they can spread it more evenly over their larger leaf network, dispersing the effects.
Through a Genome Wide Association Study, the researchers also identified candidate genes not previously associated with salt stress, highlighting the power of high-throughput phenotyping in uncovering novel aspects of plant stress responses. This study contributes to theunderstanding of salt stress tolerance in S. pimpinellifolium and lays the groundwork for further investigations into the genetic basis of these traits, ultimately informing breeding efforts for salinity tolerance in tomato and other crops.