Age-related Induced Resistance Effect on Tomato Seedlings for Producing Tomato Yellow Leaf Curl Virus (TYLCV)-Free Plants and High-quality Seeds

Abstract

Egypt is facing a major problem in the field of tomato seed production, as infection with the yellow tomato leaf curl virus (TYLCV) is one of the most important factors in the success of this important production process, which has an impact on national food security, in addition to facing the steady increase in the costs of importing tomato seeds in particular vegetable crop seeds in general. Therefore, the main objective of the current study is to study plant age-related induced resistance (ARIR) against tomato yellow leaf curl virus (TYLCV) in tomato plants. Several research points were studied, respectively: first, the effect of plant age on resistance to TYLCV virus in tomato plants that is transmitted by whitefly. Second, the detection and identification of tomato yellow leaf curl virus (TYLCV) in seeds obtained from seedlings of different ages (35 and 90 days old). Third, study the behavior of the whitefly in terms of the number of eggs and larvae, the percentage of the number of infected plants that showed symptoms of infection with the virus, and its relationship to the age of the seedlings. The results of this study proved that the age of the plant is closely related to the ability of the plant to withstand infection with the tomato yellow leaf curl virus (TYLCV). The DNA of the tomato yellow leaf curl virus (TYLCV) was identified from a sample of seeds obtained from plants obtained from 35-day-old seedlings. On the contrary, the DNA of tomato yellow leaf curl virus (TYLCV) was not detected in the seed sample obtained from plants produced from 90-day-old seedlings that were cultivated and adapted inside the nursery. The results also showed that in both protocols, using or without insecticides did not prevent the white fly from laying eggs and producing larvae on the plants. The increase was also gradual in the numbers of eggs and larvae of the white fly, as this activity peaked in the third week of transferring the seedlings to the open field, then those numbers decreased after the third week. This study also demonstrated the effect of positive seedling age (90 days old) on morphological traits related to vegetative growth, fruit production, and seed yield. Among the important benefits obtained was the ability to obtain seeds free of TYLCV in tomato plants, as well as the ability to remove nursery plants that showed early symptoms of the virus, and thus reduce the economic losses caused by the whitefly through the spread of the virus in the open fields.