ThePartnership no. 15

Gearing up for future

Gearing up for future circumstances Science factors explained For the western part of Europe, 2018 was a memorable year for meteorologists: an unusual long period of drought, hot weather and a record number of warm days over 20 degrees Celsius. One can argue about the cause, but most will agree that the world climate is changing. For growers, periods with extreme weather is yet another challenge to deal with. To be able to feed a world inhabited by some 10 billion people in 2050, agricultural production needs to double, with a reduced input of fertilizer. At the same time, growing crops will be exposed to more extreme weather conditions, and those crops need to be grown in areas where fresh water might become increasingly scares. Although, at first side, a bleak future, researchers and breeders are gearing up to provide the high yielding varieties that will still be able to thrive under these circumstances. 24 | The Partnership Abiotic stress factors “Selecting vegetables for resistance to many different kinds of pathogens, so-called biotic stress, has been and will remain the major focus of much of the breeding activities,” explains Manager Research and Applications Gert-Jan de Boer. “But research and breeding activities will also encompass more attention towards creating new varieties that can withstand abiotic stress such as climate extremes.” Abiotic stress or non-living factors that have an adverse effect to plant growth and development, include amongst others high and low temperatures, salinity, lack of essential minerals like phosphate starvation, drought and flooding. De Boer: “These factors might have overlapping effects on the vitality of the plant, but their effect can also be very (crop) specific. Increasing salinity of the soil or water, for example due to large-scale irrigation, has a greater impact on Curcurbitae species than for example on tomato. In fact, some species related to tomato, such as S. pennellii, turn out to actually benefit from living on high saline soils. Although, these types of so-called halophytic species have long held much promise to increase salt tolerance in crop plants, very little progress has been achieved.” Salt tolerance Plant salt tolerance has long been studied in model species such as Arabidopsis (thale cress), which is also a salt sensitive species. A number of genes from this plant play a crucial role in the uptake of sodium from the soil. Reducing the activity of some of these genes, like SOS 1,2 &3 & HKT1, results in improved tolerance or hypersensitivity to salt. “In a collaborative study with researchers from the University of Amsterdam, we discovered that an increase in salt tolerance of lettuce could be achieved by introducing genes from a wild lettuce species, namely L. serriola, and that the HKT1 gene from this species was amongst one of them.” Collaborative research Although tomato is able to withstand higher levels of salt than many other vegetable crops, it also has its Achilles heel with respect to abiotic stresses. This weak spot is exposure to prolonged periods of high temperatures. Elevating the temperature above 31 degrees Celsius during the day and 25 degrees at night is sufficient to significantly reduce the fruit set of most commercial tomato cultivars. “This is due to a reduction in the number of pollen formed and a decrease in viability of the pollen. An effort to identify tomato cultivars that are more tolerant The Partnership | 25