Interspecies grafting is an economically relevant technique that allows beneficial shoot and root combinations from separate species to be combined. One hypothesis for the basis of graft compatibility revolves around taxonomic relatedness. To test how phylogenetic distance affects interspecific graft compatibility within the economically important Solanaceae subfamily, Solanoideae, we characterized the anatomical and biophysical integrity of graft junctions between four species: tomato (Solanum lycopersicum), eggplant (Solanum melongena), pepper (Capsicum annuum), and groundcherry (Physalis pubescens). We analyzed the survival, growth, integrity, and cellular composition of the graft junctions. Utilizing various techniques, we were able to quantitatively assess compatibility among the interspecific grafts. Even though most of our graft combinations could survive, we show that only intrageneric combinations between tomato and eggplant are compatible. Unlike incompatible grafts, the formation of substantial vascular reconnections between tomato and eggplant in the intrageneric heterografts likely contributed to biophysically stable grafts. Furthermore, we identified 10 graft combinations that show delayed incompatibility, providing a useful system to pursue deeper work into graft compatibility. This work provides new evidence that graft compatibility may be limited to intrageneric combinations within the Solanoideae subfamily. Further research amongst additional Solanaceous species can be used to test the extent to which our hypothesis applies to this family.

ABSTRACTInterspecies grafting is a technique that allows beneficial shoot and root combinations from separate species to be combined into a single organism. Despite its relevance to agricultural production, little is known about the determinants of graft compatibility. One hypothesis for compatibility revolves around the taxonomic degree of relatedness between the two plants. To test how phylogenetic distance affects interspecific graft compatibility within the economically important Solanaceae sub-family, Solanoideae, we characterized the anatomical and biophysical integrity of graft junctions for graft combinations made between four species: tomato (Solanum lycopersicum), eggplant (Solanum melongena), pepper (Capsicum annuum), and groundcherry (Physalis pubescens). We analyzed the survival, growth, and junction integrity via bend tests, and imaged the cellular composition of the graft junctions in order to deduce the status of vascular connectivity across the junction. Utilizing these techniques, we were able to quantitatively assess the degree to which each interspecific combination exhibits compatibility. Despite the fact that most of our graft combinations exhibited high survival rates, we show that only tomato and eggplant heterografts are truly compatible. Unlike incompatible grafts, the formation of reconnected vascular tissue within the tomato and eggplant heterografts contributed to biophysically stable grafts that were resistant to snapping. Furthermore, we identified 10 graft combinations that show delayed incompatibility, providing a useful, economically relevant system to pursue deeper work into genetic and genomic determinants of graft compatibility. This work provides new evidence indicating that graft compatibility may be limited to intrageneric combinations within the Solanoideae subfamily. Further research using more extensive graft combinations amongst Solanaceous species can be used to test whether our hypothesis broadly applies to this family.

Petunia hybrida is a hybrid ornamental that serves as one of the most popular bedding plants in the world. Numerous petunia seeds are distributed on an annual basis, which requires labor-intensive hybrid-breeding. The Dof (DNA-binding with one finger) transcription factor family is a plant-specific member of the zinc finger superfamily. Dofs play diverse roles in regulating plant developmental processes; however, their functions during flower development are not well characterized, especially in ornamental species. In this study, we used genome-wide analysis to identify 35 Dof genes that are encoded in the P. inflata reference genome. These Petunia Dofs (PiDofs) can be organized into five distinct phylogenetic groups, based on the sequences of their highly conserved Dof domains. Expression analysis using quantitative-RT-PCR identified several PiDofs that exhibit unique expression patterns during reproductive development. Many of these reproductive PiDofs were expressed in all four floral whorls throughout flower development, while other PiDofs exhibited developmental stage and/or organ specific expression patterns. RNAi was used to knock-down the expression level of PiDof14, an anther-specific Dof. Reduced expression of PiDof14 promoted tapetum degradation and depressed meiotic divisions in the microsporocytes, ultimately leading to a male-sterile phenotype. The organ- and stage-specific expression patterns of many of the other PiDof genes indicate that additional members of this family may play specific roles in regulating male and female fertility. This work provides insight into a novel regulator of male-fertility in Petunia, and lays the foundation for targeted genome engineering of the larger Dof family in order to generate an efficient hybrid breeding system for P. hybrida.

The rapid development of high-throughput sequencing techniques has led biology into the big-data era. Data analyses using various bioinformatics tools rely on programming and command-line environments, which are challenging and time-consuming for most wet-lab biologists. Here, we present TBtools (a Toolkit for Biologists integrating various biological data-handling tools), a stand-alone software with a user-friendly interface. The toolkit incorporates over 130 functions, which are designed to meet the increasing demand for big-data analyses, ranging from bulk sequence processing to interactive data visualization. A wide variety of graphs can be prepared in TBtools using a new plotting engine ("JIGplot") developed to maximize their interactive ability; this engine allows quick point-and-click modification of almost every graphic feature. TBtools is platform-independent software that can be run under all operating systems with Java Runtime Environment 1.6 or newer. It is freely available to non-commercial users at https://github.com/CJ-Chen/TBtools/releases.

SummaryVascular plants are wired with a remarkable long‐distance communication system. This network can span from as little as a few centimeters (or less) in species like Arabidopsis, up to 100 m in the tallest giant sequoia, linking distant organ systems into a unified, multicellular organism. Grafting is a fundamental technique that allows researchers to physically break apart and reassemble the long‐distance transport system, enabling the discovery of molecular signals that underlie intraorganismal communication. In this review, we highlight how plant grafting has facilitated the discovery of new long‐distance signaling molecules that function in coordinating developmental transitions, abiotic and biotic responses, and cross‐species interactions. This rapidly expanding area of research offers sustainable approaches for improving plant performance in the laboratory, the field, the orchard, and beyond.