From Mendel’s discovery on pea to today’s plant genetics and breeding

In 2015, we celebrated the 150th anniversary of the presentation of the seminal work of Gregor Johann Mendel. While Darwin’s theory of evolution was based on differential survival and differential reproductive success, Mendel’s theory of heredity relies on equality and stability throughout all stages of the life cycle. Darwin’s concepts were continuous variation and “soft” heredity; Mendel espoused discontinuous variation and “hard” heredity. Thus, the combination of Mendelian genetics with Darwin’s theory of natural selection was the process that resulted in the modern synthesis of evolutionary biology. Although biology, genetics, and genomics have been revolutionized in recent years, modern genetics will forever rely on simple principles founded on pea breeding using seven single gene characters. Purposeful use of mutants to study gene function is one of the essential tools of modern genetics. Today, over 100 plant species genomes have been sequenced. Mapping populations and their use in segregation of molecular markers and marker–trait association to map and isolate genes, were developed on the basis of Mendel's work. Genome-wide or genomic selection is a recent approach for the development of improved breeding lines. The analysis of complex traits has been enhanced by high-throughput phenotyping and developments in statistical and modeling methods for the analysis of phenotypic data. Introgression of novel alleles from landraces and wild relatives widens genetic diversity and improves traits; transgenic methodologies allow for the introduction of novel genes from diverse sources, and gene editing approaches offer possibilities to manipulate gene in a precise manner

Phylogenomic analyses of the Photinia complex support the recognition of a new genus Phippsiomeles and the resurrection of a redefined Stranvaesia in Maleae (Rosaceae)

Photinia and its morphologically similar allies in Maleae (Rosaceae) consist of five currently recognized genera: Aronia, Heteromeles, Photinia, Pourthiaea, and Stranvaesia, and 68 species, distributed in Asia and North and Central America. Despite previous efforts to clarify relationships in this group, the generic delimitations have remained uncertain. Our goals were to reconstruct a robust phylogeny of Photinia and its close allies to test the monophyly of the currently recognized genera, especially Photinia and Stranvaesia, and the hybrid origin hypothesis of Photinia bodinieri. This study employs complete plastomes and the entire nuclear ribosomal DNA (nrDNA) repeats assembled from the genome skimming approach with a broad taxon sampling of 81 species in 30 genera of Rosaceae, especially Maleae. Based on three datasets, including the whole plastome, coding sequence, and nrDNA repeats, the results of maximum likelihood and Bayesian inference analyses showed that the previously circumscribed Stranvaesia and Photinia were each non-monophyletic. Six clades have been recovered herein within Photinia and its allied genera: Aronia, Heteromeles, Photinia s.s., Pourthiaea, Stranvaesia, and a new genus Phippsiomeles consisting of the Central American species formerly placed in Photinia. The strong conflicts between the plastome and nrDNA phylogenies of Phippsiomeles and Stranvaesia tomentosa suggest the possibility that they may have each originated involving hybridization events, while no incongruence among datasets was detected to support the hybrid origin of Photinia bodinieri. We provide 12 new combinations, to transfer eight taxa of the New World Photinia into Phippsiomeles and clarify the generic placements of several species of Photinia and Stranvaesia