Letters in 2019

Niche differentiation has been theorized to occur in plants, but experimental validation of this mechanism of species coexistence is lacking. This study finds selection and phenotypic plasticity to be the main drivers of differentiation.

Two novel orthologous lectin receptor kinases are identified in barley. They specifically confer quantitative resistance to leaf rust pathogens that are not adapted to different cereal hosts.

A study sequenced the genome of a museum specimen of Egyptian emmer wheat chaff dated back to 3,000 years ago. The genome reveals the unique genetic diversity contained in this ancient sample as well as the domestication and dispersal history of emmer wheat.

The vascular cambium contains meristem cells that produce secondary xylem and phloem in the stems and roots of many plants. Its activity largely determines wood formation. Now, a genome-wide transcript profiling of Arabidopsis thaliana root cambium is presented to unlock the complex network that regulates cambium development and activity.

The remarkable diversity of plant leaf shapes raises a question: what is the biological relevance of the different shapes? Now researchers have discovered the preference of a leaf-processing herbivore for non-lobed leaves, indicating that leaf shape is an adaptive trait.

Climate change is projected to warm higher latitudes at an increasing rate, probably causing more forest fires and altering native boreal forest composition. Alaskan conifer trees could decline in importance relative to deciduous broadleaf trees, modifying feedback loops within the entire forest ecosystem and with the climate.

A sex determination gene, FrBy, is identified in the dioecious kiwifruit and demonstrated to maintain male functions across angiosperm species. FrBy and the known female suppressor gene, SyGI, support the evolution of dioecy via the ‘two-mutations’ model.

Tropical carbon stocks are essential for proper accounting of global carbon budgets, but difficult to monitor on a large scale. L-band microwave observations used here enable direct and spatially explicit accounting of annual carbon fluxes from different types of land surface.

Analyses of the single-cell 3D genome structures of rice eggs, sperm and unicellular zygotes reveal plant-specific 3D genome features and a compact silent centre in the egg and unicellular zygote that may be involved in regulating zygotic genome activation.

In moss, a subgroup of uncharacterized AP2/ERF transcription factors called STEMIN promotes stem cell formation and regeneration, specifically through a repressive chromatin mark on its target genes.

By map-based cloning and knockout experiments, a study identified and validated ZmDMP to be one of the two genes known to control haploid induction in maize. A single-nucleotide mutation in ZmDMP causes a 2–3-fold increase in the haploid induction rate.

Volatile organic compounds from plants are an integral part of atmospheric chemistry and ecosystem interactions, especially in an Arctic region impacted by climate change. Observed increases in insect herbivores leads to a substantial increase in VOC emissions, showing a link between warming and plant impacts.

Calcium (Ca²⁺) is one of the most important second messengers in plant signalling, but high-level accumulation in cytosol causes toxicity. Now, a chloroplast calcium uniporter has been found to mediate Ca²⁺ influx from cytosol to chloroplast and, interestingly, regulate plant responses to osmotic stress.

A study reports the crystal structures of the Arabidopsis thaliana cytochrome P450 monooxygenase CYP90B1—a rate-limiting enzyme of the brassinosteroid biosynthetic pathway—complexed with its substrate or inhibitors for brassinosteroid biosynthesis, providing insights into its function.

Tomato breeding with a desirable MADS-box mutation to improve harvesting can often result in unwanted traits due to negative epistatis with cryptic mutations. A dosage mechanism involving a duplication of a second gene to overcoming the negative epistasis is dissected, enabling the design of gene editing strategies to predictably improve harvesting.

Cotton fibre grows in a protective boll that becomes a barrier for researchers when tracking the growth dynamics. Now, the cytoskeleton in elongating cotton fibres has been visualized by live-cell imaging. The cytoskeleton organization and dynamics shed light on the elongation mode of cotton fibre.

A study reports a regulatory system that boosts transgene expression in the plastids of potato tubers. This system employed an RNA-binding protein PPR10 variant to bind a cognate cis-element of a plastid transgene, encoding GFP, and activate its expression.

Using de novo root regeneration from a detached Arabidopsis leaf as a model system, the authors show that jasmonates are a crucial signalling step from wounding to a local auxin response.

A study using base editing generated transgene-free wheat with mutations that confer resistances to multiple herbicides, and developed a selectable marker that could facilitate co-editing of herbicide resistance and other target traits of interest.

Efficient genome editing using DNA-free systems remains challenging in most plant species. Now, a new genome-editing system achieves efficient DNA- and selectable-marker-free gene editing by direct delivery of Cas9–guide RNA ribonucleoproteins into rice zygotes.