Diseases affecting tomatoes in greenhouses have changed over the past years. Up until 2015, nematodes and TYLCV were the main concern of farmers, yet Fusarium became the most widespread and harmful disease and the first concern for farmers, merchants and agricultural companies. Fusarium is the species that determines the spreadable varieties, as well as the required grafting rootstocks in nurseries and even pesticides and fertilizers.
The main problem with the disease is that it kills the entire plant, thus “zero” production is obtained.
Types of Fusarium that affect tomatoes:
- Coronary Fusarium:
- Caused by Fusarium oxysporium f.sp Radicis-Lycopersici
- It affects the stem at the crown area, for a distance of about 20 cm only. The infection does not extend to the top
- Fusarium root rot:
- It is caused by Fusarium f.sp eumartiim Solani.
- The infection starts from the crown area and extends downwards through the taproot and completely destroys the root. It is caused by an injury induced by a nematode, insect, or agricultural process. Soil temperature helps spread the disease.
- Fusarium vascular wilt:
- It is caused by Fusarium oxysporium f.sp – Lycopersici.
- It is the most common type and has three strains: 0, 1 and 2.
- It affects the stem and spreads upwards. It closes the vessels feeding the leaves, so they become yellow and the plant has a mix of green and yellow colors.
The methods of resistance to this disease have varied. Therefore, we will focus in this research on the method of producing varieties carrying Fusarium-resistant genes. Global companies have already reached this method via crossbreeding between plant parents who possess these genes.
But is hybridization a genetic modification?
The truth is that Hybridization is not considered Genetic modification.
Hybridization is a normal, traditional, but directed and controlled pollination process implemented by humans. It is carried out for more than one plant within the same family, in which each plant possesses specific desirable traits (disease resistance, desirable fruit characteristics, growth strength, etc.) As a result of pollination, we get various genotypes (hybrids) carrying these desired traits, noting that the traits are pure and clear in the first generation (F1). As for the seeds of the second or third generation, genetic isolations occur according to the law of the Austrian scientist Gregor Mendel, and this may lead to serious changes with unknown results. Usually, the productivity and characteristics of the fruit such as the degree of coloring, hardness, shape and homogeneity are affected. However, isolations may occur in other parts.
In 1922, seeds of hybridized corn were sold to farmers for the first time in history.
- Genetic Modification (GMO) is the direct intervention by the chromosomes carrying the traits, and the transfer of the genes or genotypes responsible for a specific trait to other organisms belonging to the same family or to other families. Hence, herein lies the risk, such as introducing an animal trait into the plant kingdom.
To understand genetic modification more clearly, we present the following example: Assuming that we need a variety of wheat that can be grown with soil that is predominantly saline; we intervene genetically and bring a gene that tolerates salinity from marine algae that belongs to a family other than the wheat’s family. We then insert this gene into the genetic map of the wheat variety to obtain the desired salinity-resistant variety.
The problem with genetic modification is that it can produce proteins or other compounds that the body does not recognize or lacks the enzymes necessary to break them down, so they accumulate and become like a strange body inside us, causing endless problems.
Aside from genetic modification, hybridization has worked in providing solutions to many problems in safe ways for humans. It produced varieties with various required and desirable characteristics that do not cause harm to human food.
An example to this is the tomato variety Mandloun, which carries the genes resisting Fusarium and TYLCV. This variety also boasts all the characteristics of the export fruit, and is specifically ordered for the green tomato exporters to the Arabian Gulf, as green fruits have a luxurious and desirable dark metallic luster, and red fruits are solid and dark in color with long and beautiful sepals. The growth system of plants is open, which reduces gray mold, and they have dark green that are desirable in nurseries.