Nicotiana benthamiana XYLEM CYSTEINE PROTEASE genes facilitate tracheary element formation in interfamily grafting

Grafting is a plant propagation technique widely used in agriculture.A recent discovery of the capability of interfamily grafting in Nicotiana has expanded the potential combinations of grafting.In this study,we showed that xylem connection is essential for the achievement of interfamily grafting and investigated the molecular basis of xylem formation at the graft junction.Transcriptome and gene network analyses revealed gene modules for tracheary element(TE)formation during grafting that include genes associated with xylem cell differentiation and immune response.The reliability of the drawn network was validated by examining the role of the Nicotiana benthamiana XYLEM CYSTEINE PROTEASE(NbXCP)genes in TE formation during interfamily grafting.Promoter activities of NbXCP1 and NbXCP2 genes were found in differentiating TE cells in the stem and callus tissues at the graft junction.Analysis of a Nbxcp1;Nbxcp2 loss-of-function mutant indicated that NbXCPs control the timing of de novo TE formation at the graft junction.Moreover,grafts of the NbXCP1 overexpressor increased the scion growth rate as well as the fruit size.Thus,we identified gene modules for TE formation at the graft boundary and demonstrated potential ways to enhance Nicotiana interfamily grafting.

An AGAMOUS-like factor is associated with the origin of two domesticated varieties in Cymbidium sinense (Orchidaceae)

Cymbidium has been artificially domesticated for centuries in Asia,which produced numerous cultivated varieties.Flowers with stamenoid tepals or those with multiple tepals have been found in different species of Cymbidium;however,the molecular basis controlling the formation of these phenotypes is still largely unknown.Previous work demonstrated that AGAMOUS/AG lineage MADS genes function in floral meristem determinacy as well as in reproductive organs development in both dicots and monocots,indicating a possible relationship with the origin of two flower varieties in Cymbidium.Here,we characterized and analyzed two AG lineage paralogues,CsAG1 and CsAG2,from Cymbidium sinense,both of which were highly expressed in the gynostemium column of a standard C.sinense.Interestingly,we detected ectopic expression of CsAG1 rather than CsAG2 in all floral organs of a stamenoid-tepal variety and significant down-regulation of CsAG1 in a variety with multiple tepals.Over-expression of CsAG1 in wild type Arabidopsis resulted in petal-to-stamen homeotic conversion,suggesting a conserved C-function of CsAG1 in the development of Cymbidium flower.Altogether,our results supported a hypothesis that disruption of a single AG-like factor would be associated with the formation of two domesticated varieties in C.sinense.

Combination of genetic analysis and ancient literature survey reveals the diverge nee of traditional Brassica rapa varieties from Kyoto, Japan

Since ancient times,humans have bred several plants that we rely on today.However,little is known about the divergence of most of these plants.In the present study,we investigated the divergence of Mibuna(Brassica rapa L.subsp.nipposinica L.H.Bailey),a traditional leafy vegetable in Kyoto(Japan),by combining genetic analysis and a survey of ancient literature.Mibuna is considered to have been bred 200 years ago from Mizuna,another traditional leafy vegetable in Kyoto.Mibuna has simple spatulate leaves,whereas Mizuna has characteristic serrated leaves.The quantitative trait loci(QTL)and gene expression analyses suggested that the downregulation of BrTCP15 expression contributed to the change in the leaf shape from serrated to simple spatulate.Interestingly,the SNP analysis indicated that the genomic region containing the BrTCP15 locus was transferred to Mibuna by introgression.Furthermore,we conducted a survey of ancient literature to reveal the divergence of Mibuna and found that hybridization between Mizuna and a simple-leaved turnip might have occurred in the past.Indeed,the genomic analysis of multiple turnip cultivars showed that one of the cultivars,Murasakihime,has almost the same sequence in the BrTCP15 region as Mibuna.These results suggest that the hybridization between Mizuna and turnip has resulted in the establishment of Mibuna.

Carbon Nanobelts:Brief History and Perspective

Carbon nanotubes(CNTs)are an emerging nanomaterial because of their outstanding performance in various applications.In recent years,the segment molecules of CNTs,referred to as carbon nanorings(CNRs)or carbon nanobelts(CNBs),have gained attention for their unique structures and properties,as well as their potential as seed molecules for the precise synthesis of CNTs.CNBs are rigid and thick segments of CNTs whose synthesis has been addressed by scientists fascinated by the uniqueness of CNBs long before the discovery of CNTs.After 60 years of efforts by synthetic chemists all over the world,the synthesis of the first CNB,(6,6)CNB,was achieved by our group in 2017.Since this milestone,diverse types of nanobelts have been synthesized through various synthetic routes,thereby demonstrating their photophysical,magnetic,and redox properties derived from rigid belt structures.The applications of CNBs have also been introduced recently.The formation of the host−guest complex,transformation to three-dimensional molecules,and measurement of conductivity have been reported for CNBs.This paper summarizes the brief history and perspective of CNBs.Further synthetic campaigns and aggressive application of CNBs would create novel and groundbreaking scenes in materials science.

How Convolutional Neural Networks Diagnose Plant Disease

Deep learning with convolutional neural networks(CNNs)has achieved great success in the classification of various plant diseases.However,a limited number of studies have elucidated the process of inference,leaving it as an untouchable black box.Revealing the CNN to extract the learned feature as an interpretable form not only ensures its reliability but also enables the validation of the model authenticity and the training dataset by human intervention.In this study,a variety of neuron-wise and layer-wise visualization methods were applied using a CNN,trained with a publicly available plant disease image dataset.We showed that neural networks can capture the colors and textures of lesions specific to respective diseases upon diagnosis,which resembles human decision-making.While several visualizationmethods were used as they are,others had to be optimized to target a specific layer that fully captures the features to generate consequential outputs.Moreover,by interpreting the generated attention maps,we identified several layers that were not contributing to inference and removed such layers inside the network,decreasing the number of parameters by 75%without affecting the classification accuracy.The results provide an impetus for the CNN black box users in the field of plant science to better understand the diagnosis process and lead to further efficient use of deep learning for plant disease diagnosis.

A member of the ALOG gene family has a novel role in regulating nodulation in Lotus japonicus

Legumes can control the number of symbiotic nodules that form on their roots, thus balancing nitrogen assimilation and energy consumption. Two major pathways participate in nodulation: the Nod factor(NF)signaling pathway which involves recognition of rhizobial bacteria by root cells and promotion of nodulation, and the autoregulation of nodulation(AON) pathway which involves long-distance negative feedback between roots and shoots. Although a handful of genes have a clear role in the maintenance of nodule number, additional unknown factors may also be involved in this process. Here, we identify a novel function for a Lotus japonicus ALOG(Arabidopsis LSH1 and Oryza G1) family member, LjALOG1,involved in positively regulating nodulation. LjALOG1 expression increased substantially after inoculation with rhizobia, with high levels of expression in whole nodule primordia and in the base of developing nodules. The ljalog1 mutants, which have an insertion of the LORE1 retroelement in LjALOG1, had significantly fewer nodules compared with wild type, along with increased expression of LjCLE-RS1(L. japonicus CLE Root Signal 1), which encodes a nodulation suppressor in the AON pathway. In summary,our findings identified a novel factor that participates in controlling nodulation, possibly by suppressing the AON pathway.

Excited-state conformation capture by supramolecular chains towards triplet-involved organic emitters

Nowadays,the development of trip let-involved materials becomes a hot research topic in solid-state luminescence fields.However,the mechanism of trip let-involved emission still remains some mysteries to conquer.Here,we proposed a new concept of excited-state confo rmation capture for the const ructio ns of different types of trip let-involved materials.Firstly,excited-state conformation could be trapped by supramolecular chains in crystal and fo rm a new optimum excited-state structure which is different from that in solution or simple rigid environment,leading to bright thermally activated delayed fluorescence(TADF) emission.Based on excited-state conformation capture methodology,next,we obtained roomtemperature phosphorescence(RTP) by introducing Br atoms for the enhancement of intersystem crossing.It could be concluded from experime ntal results that TADF may originate from aggregate effect while RTP may derive from monomers.Finally,heavy-atom free RTP and ultra RTP were achieved by eliminating aggregate effect.This wo rk could not only exte nd the design methodology of triplet-involved materials but also set clear evidences for the mechanism of triplet-involved emissions.

Chemical Synthesis of Carbon Nanorings and Nanobelts

CONSPECTUS:The discovery and creation of new forms of carbon have always transformed the scientific landscape.For example,the discoveries of fullerenes,carbon nanotubes(CNTs),and graphenes have opened doors to the science of nanometersized carbon allotropes,otherwise known as nanocarbons.Since then,researchers worldwide have unveiled their outstanding physical and chemical properties,and a number of applications and technologies have arisen in not only materials science but also biological research fields.The synthesis and study of this privileged class of“single-molecule”compounds has become one of the most engaging subjects in chemistry and holds huge promise to establish new fields in molecular science.However,there have been huge gaps between established small-molecule chemistry and nanocarbon science.In the particular case of CNTs,it is still not possible to access structurally uniform CNTs.Although a wide range of synthetic methods have been reported,CNTs are generally accessed as a mixture of various structures.One logical strategy to achieve full synthetic control over CNTs is to build up from a template molecule with structural precision(the so-called“growth-from-template”strategy),where a short CNT segment molecule represents an initial synthetic target.To this end,organic synthesis techniques are our most powerful tools to synthesize short CNT segments such as carbon nanorings and carbon nanobelts.This Account highlights our 16-year campaign in the synthesis and application of carbon nanorings and carbon nanobelts.The first topic is the synthesis of carbon nanorings(cycloparaphenylenes)as substructures of CNTs.The second topic is the synthesis of armchair and zigzag carbon nanobelts,which consist solely of fully fused hexagonal rings and provide a continuous double-stranded cylindrical framework.The third topic is the synthesis of methylene-bridged cycloparaphenylene,an aromatic belt containing nonhexagonal rings,in which the cyclic paraphenylene chain is ladderized by methylene bridges.This nonalternant aromatic belt can be regarded as segments of nonconventional CNTs.During our extensive investigation,we found that the careful design of strainless macrocyclic precursors is crucial to the success of the synthesis of these curvedπ-conjugated nanorings and nanobelts.In the final section,some of the representative size-dependent properties of these nanorings/belts,including their HOMO−LUMO energies,strain energies,and photophysical properties,are summarized.In addition to basic properties,the utilization of these compounds as supramolecular hosts and organic materials is also briefly introduced.We hope this Account will inspire the development of new forms of nanocarbon molecules that would open doors to new fields and applications.