**Preface to "Plant Genomics 2019—Volume II"**

In recent years, researchers have uncovered the genes and genomic regions responsible for plants' growth, development, and stress responses. This reprint the 'Plant Genomics 2019' Special Issue comprises 57 papers exploring various aspects of plant genomics. These papers delve into gene discovery, genomic prediction, genome editing, plant chloroplast genome sequencing and comparative analysis, microRNA analysis, and comparative genomics.

The studies featured in this Special Issue employ a comprehensive research approach that combines bioinformatics and transcriptome analyses. With this approach, researchers have identified the genes associated with biotic and abiotic stress responses. Studies on the genome-wide identification of gene families, gene characteristics and distributions analysis, and gene expression profiles have shed light on various traits across multiple species.

In addition to gene discovery, the Special Issue also considers microRNAs (miRNAs) and their regulatory roles in gene expression. The roles of miRNAs in plant species have been explored, including the development of an artificial miRNA precursor system for gene silencing and the identification of miRNAs involved in seed development. These findings contribute to our understanding of how miRNA function in plant growth and development, offering potential avenues for crop improvement.

The Special Issue places a significant emphasis on the application of genomic tools for crop improvement. Papers on Chinese winter wheat and flax highlight the effectiveness of genomic prediction and marker-assisted selection in enhancing their yield, salt tolerance, and fruit ripening. Furthermore, the issue explores the revolutionary impact of the CRISPR/Cas9-mediated genome editing of plants, including targeted mutagenesis and gene replacement.

Comparative genomics is another key theme within this Special Issue, providing insights into the evolution of plant species. By comparing genomes, researchers can identify conserved gene families and regulatory elements, shedding light on plants' development and their adaptation to environmental stresses. Comparative genomics can also be used for phylogenetic analyses and resolving relationships between species.

Overall, the 57 papers featured in 'Plant Genomics 2019' exemplify the substantial progress made in understanding plant genetics and genomics. These studies offer valuable insights into the application of genomic tools for crop improvement, sustainable agriculture, and fundamental questions about the evolution and function of plant genes and genomes.

> **Frank M. You** *Editor*
