Plant Gene and Trait 2025, Vol.16, No.4, 142-151 http://genbreedpublisher.com/index.php/pgt 143 2 Rootstock Technology in Tomato Cultivation 2.1 Historical development and adoption of rootstock use in tomato Tomato grafting technology was initially developed to address soil-borne diseases and environmental stress issues. Later, with the development of greenhouse cultivation and soilless cultivation, the use of rootstocks became increasingly common. Nowadays, rootstocks can not only resist diseases, but also help tomatoes better cope with adverse environments such as saline-alkali, drought and high temperature, and at the same time increase yield and fruit quality (Lee et al., 2023; Mohamed et al., 2024). This technique is particularly common in greenhouse and saline-alkali land cultivation and is also regarded as an important means for stable yield increase (Singh et al., 2020; Fu et al., 2022; Alqardaeai et al., 2024). 2.2 Types of rootstocks: vigorous, disease-resistant, and dwarfing Some “strong rootstocks”, such as Maxifort and GFS-16, perform well in high-temperature or saline-alkali environments. They can make tomatoes grow more vigorously, produce more fruits and have a higher yield (Balliu et al., 2024; Hashem et al., 2024; Mohamed et al., 2024). There is also a kind of “disease-resistant rootstock”, usually wild tomatoes or other solanaceae plants, such as wild tomatoes S. pimpinellifolium, S. habrochaites or eggplants. These rootstocks can effectively prevent soilborne diseases and viral infections (Singh et al., 2020; De Moura Guerra and Da Silva Rodrigues, 2024). In recent years, dwarfing rootstocks have also become increasingly popular. Its main advantages are that it can control the height of the plant, is suitable for close planting, is convenient for management, and is more suitable for mechanized operation. At the same time, it can also ensure yield and fruit quality. Many studies have found that dwarfing rootstocks perform well when cultivated at high density in greenhouses. 2.3 Grafting techniques and compatibility issues When grafting tomatoes, the commonly used methods include “split grafting” and “insertion grafting”. The survival and subsequent growth after grafting are related to the “affinity” between the rootstock and the scion (Latifah et al., 2023). If the affinity is good, tomatoes will grow fast, have strong absorption capacity and good stress resistance (Balliu et al., 2024). However, if the affinity is poor, not only is the grafting not likely to succeed, but there may also be problems such as the plant not growing and even dying prematurely (De Moura Guerra and Da Silva Rodrigues, 2024). Therefore, selecting a suitable combination of rootstocks and scions with complementary traits is a crucial step in achieving high-yield and high-quality tomato cultivation (Fu et al., 2022; Lee et al., 2023). 3 Characteristics and Classification of Dwarfing Rootstocks 3.1 Definition and physiological features of dwarfing rootstocks Dwarfing rootstocks are a type of rootstock that can make tomatoes grow shorter and more compact. They can regulate the growth of scions, making tomatoes mature earlier, with better fruit quality, and also more drought-resistant and disease-resistant. This type of rootstock is often used for close planting and also helps to increase yield (Figure 1) (Hayat et al., 2021; Hayat et al., 2023a). This effect is mainly due to the fact that they can affect the hormones within plants, such as auxin, cytokinin, abscisic acid, gibberellin and brassinolide, etc. In addition, dwarfing rootstocks can also alter the efficiency of photosynthesis, the transport efficiency of water and nutrients, as well as the structure of the root system and stems. Through the “mutual cooperation” with the scion, they regulate the growth rhythm and plant structure of tomatoes, thereby enabling tomatoes to grow normally and bear more fruits even when planted closely. 3.2 Genetic background and breeding sources The genetic background of these rootstocks is rather complex. Some come from the dwarfism variations of tomatoes themselves, and many are from wild relatives, such as Solanum pennellii or Solanum torvum. These wild plants usually have stronger drought resistance and root vitality. If they are hybridized with tomatoes, these advantages can be “passed on” to tomatoes. For instance, the offspring of tomatoes and S. pennellii, “RF4A”, can retain water better and grow more robustly in arid environments (Khapte et al., 2022). Furthermore, there are currently many studies looking for genes and molecular markers related to “dwarfism”, which can help breeders screen out good dwarfing rootstocks more quickly (Hayat et al., 2021; Hayat et al., 2023a).
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