Uncovering Hidden Phenotypes to Accelerate Domestication in Perennial Ryegrass for Seed Production

Abstract

Seed dispersion, shattering, shedding, and lack of retention, all refer to the same dispersal mechanism in which reproductive organs detach from plant inflorescences upon maturity. This separation, or disarticulation, is mainly attributed to the development of an abscission layer which is genetically programmed. However, such detachment is just part of the seed dispersal phenomenon determined by a network of interactions between biotic and abiotic agents allowing gene flow over space and time. Understanding the genetics underlying seed dispersal has ecological and agricultural implications; while this phenomenon grants an evolutionary advantage to wild plants, it affects crop productivity and domestication of species with economic potential by severely reducing seed yield. In consequence, variation for dispersal-related traits has been selected over millennia through improving seed retention and yield, thus allowing the development of agriculture and consequent human societies. Nevertheless, genetic correlations among traits can limit the progress of selecting for a dispersal trait and generate unfavorable trade-offs. The presence of these correlations can be attributed to (i) the univariate approach that characterizes both selection methods and the study of multivariate phenotypes like inflorescence architecture and seed dispersal, and (ii) our limited ability to perceive and quantify the multidimensional phenotypic reality. These are the two foci of this introductory chapter, in which I use perennial ryegrass (Lolium perenne L.) as an example to discuss the need for a holistic understanding of the relationships between inflorescence morphology and seed dispersal, with an ultimate goal to improve seed yield and plant domestication.