Genomics and molecular markers for rice grain quality: a review

Rice grain quality is a benchmark of rice breeding success. Current rice breeding programs consider grain characteristics that are preferred by consumers in the rice value chain. Specific traits of quality that suit the demands of stakeholders must be targeted before, during and after breeding of new varieties. Therefore, screening tools that are environmentally independent, cheap, robust and easy to use, such as molecular markers, are needed to facilitate timely and accurate selection of traits. As a multifaceted overall phenotype and consisting of several parameters ranging from physical, textural, aroma and increasingly nutritional properties, the selection for quality has not only become about which trait(s) to focus on but is rather an issue of the combination of traits that can be incorporated into a dream variety. The more traits that are available, the more markers we need to capture these traits and feed them into the breeding and selection pipelines. This chapter reviews progress made on genomics and the molecular markers developed for quality traits of rice grains. In addition, this chapter presents the increasing need for novel phenotypes in the form of metabolites that can be traced back to the genome of rice

Proline Metabolism and Its Functions in Development and Stress Tolerance

Proline takes an exceptional place among the proteinogenic amino acids by its specific accumulation in pollen and in response to multiple types of stress. Despite the more than 50 years of research, the biochemical pathways of proline biosynthesis and degradation still await their complete characterization in plants. Also, the molecular and physiological functions of proline metabolism in plant development and defense against stress are not yet fully understood. This chapter focuses on the current knowledge about the biochemical pathways of proline metabolism in plants, on its tissue-specific regulation and subcellular compartmentation, and on still open questions. Furthermore, we will summarize what is known about the influence of proline metabolism on plant development under optimal growth conditions and how it may support continued development despite the impact of stress. The cognate chapter “Regulation of Proline Accumulation and its molecular and physiological Functions in Stress Defense” will focus on the possible beneficial functions of proline metabolism and accumulation in the defense response against diverse stresses. With these two cohesive chapters, we aim to provide a comprehensive picture of the current knowledge and the open research questions in proline-dependent stress defense