Genetic Variability as a Means to Improve Seedling Emergence and Early Developmental Phases in Crop Plants

Embryogenesis, germination and the early phases of seedling growth represent critical phases in the plant life cycle and are probably the most important events in determining the success of an annual plant. In the perspective of a more sustainable agriculture, we aim to achieve a robust seedling phase with improved resistance to abiotic as well as biotic environmental stress. Genetic improvement has forced the developmental pathway of crop plants toward the realization of highly productive species in which resource allocation processes are optimized at the expense of defense processes. In this context the discovery of key factors underlying the developmental process and at the same time playing an important role in the interplay between the young individuals and the environment is crucial for designing future gene manipulation approaches. Among the different aspects affecting seedling development, the two that will be analyzed in this chapter also play an important role in the interplay with the environment. Hormones are endogenous signals governing seedling growth and architecture establishment but at the same time are able to induce plant responses to environmental stress. Wax deposition is required for determining correct embryo and seedling development, and provides, besides that, a protective barrier that plants produce in their early developmental phases to defend themselves from pathogens as well as from variation in environmental abiotic components, such as temperature and water availability. We will explore the genetic, biochemical and physiological factors implicated and highlight the most significant aspects that might be taken into consideration in future breeding programs.

Keywords: Abiotic stress, Biotic stress, Cuticle, Cuticular wax, Embryogenesis, Germination, Heterosis, Phytohormones, Seedling growth, Transgenic plants.