|Keywords||Heat Resistance, Virus Resistance|
|Current development stage||General list: Choose current TRL level|
|Collaboration Opportunity||Licensing of Technology|
The major tomato growing regions are experiencing increasingly hot climates (Middle East, Northwest Africa, Southwest Europe, Central Asia, Southeast Asia, Australia, Southeast and Southwest USA, Brazil). Tomatoes plants cease to flower and set fruits above 35 0C in open fields. Furthermore, in these hot regions, tomatoes are under threat from viruses belonging to the Tomato yellow leaf curl virus (TYLCV) family, a virus transmitted by the whitefly Bemisia tabaci, which often destroys the entire crop. Therefore, it is highly desirable to be able to grow tomato varieties, which combine resistance to TYLCV with tolerance to temperatures above 40 0C.
The researchers used classical breeding to develop varieties of tomatoes that combine resistance to TYLCV and tolerance to extreme heat.
The lines (coined 770), are a determinate type of tomato for open field cultivation. They show a high level of resistance against TYLCV (no symptoms and yields similar to uninfected plants). They are also tolerant to heat: flowering and fruit setting routinely occur at temperatures around 40 0C (ambient temperatures reaching 45 °C). Under high temperature, the plants produce a very nice round shape fruit with an average weight of 200 grams. Fruits do not show any malformation due to heat stress.
The researchers crossed two lines, a TYLCV-resistant tomato line which, was very susceptible to heat (developed in-house), and a tomato landrace that was tolerant to extreme heat, but was very susceptible to TYLCV infection. Over several generations of selection in TYLCV-infested fields and at extreme outdoor temperatures, stable lines were obtained with the desired combination of TYLCV resistance and heat tolerance. The breeding and selection took place in an open field in the Jordan Valley, on the Jordanian and the Israeli side of the border, during the peak of the summer hot season.
Pictures below: (A) and (B): F3 and F4 populations of 770 plants under field conditions (TYLCV infection and extreme heat).
Tomato varieties combining resistance to TYLCV and tolerance to heat are currently not available on the market. These will be the first varieties of this kind available. These lines provide tremendous commercial as well as environmental advantages:
- Tomatoes are able to grow and yield in the field under extreme virus and heat stresses, a great opportunity for the tomato processing industry.
- Reverses the present trend to protect plants from extreme heat (cooling) and virus (insecticides) by growing tomatoes indoors, in insect-proof cooled greenhouses (remarkable energy savings).
- Allows reclaiming of fields abandoned because virus and heat did not permit proper tomato cultivation on a commercial scale.
- Allows extending the tomato-growing season outdoors, which is presently limited to the mild weather months.
- Permits a better coordination between farming and the processing industry.
- These lines will constitute the basic germplasm from which to produce virus and heat resistant lines for greenhouses.
- These lines could be adapted to produce local varieties with specific needs, worldwide.