Genetic analysis of the influence of the maternal environment on tomato seed and seedling performance

Quality of seeds is strongly affected by their genetic make-up, the environment during seed development and maturation and also the interaction between the genome and the environment. In this thesis, I tried to dissect the genetic basis of tomato seed quality by a combined study of physiology, genetics and genomics in relation to the maternal environment. Chapter 1 of the thesis (General introduction) describes the definition and different aspects of seed and seedling quality and the factors influencing them, with the emphasis on the maternal environment. Additionally background on the used genetic tools with emphasis on the generalized genetical genomics (GGG) approach is provided. Finally, integration of large ‘omics’ technology driven datasets is suggested as an approach to assist in the identification of the genes underlying QTLs. Seed performance traits, such as seed dormancy and germinability, can be influenced by different maternal nutritional environmental conditions. In Chapter 2 I investigated the effect of different maternal nutritional environments on the quality of seeds from two tomato species (S. lycopersicum and S. pimpinellifolium). I showed that different phosphate and nitrate levels available for mother plants influences seed and seedling quality traits especially in stressful germination environments. Correlation analysis was done between physiological traits and metabolic changes caused by the different maternal environments in tomato and interesting positive and negative correlations were identified which shed light on the molecular regulation of seed quality in different maternal environments. High quality seed is defined by high levels of seed germination and seedling establishment, especially under sub-optimal conditions. Seed quality however, is acquired during seed maturation and therefore in addition to the mother plant’s genetic background can be strongly influenced by the maternal environment in which the seeds develop. Chapter 3 of the