Dynamic regulation of plasmodesmatal permeability and its application to horticultural research

Effective cell-to-cell communication allows plants to fine-tune their developmental processes in accordance with the prevailing environmental stimuli.Plasmodesmata(PD)are intercellular channels that span the plant cell wall and serve as cytoplasmic bridges to facilitate efficient exchange of signaling molecules between neighboring cells.The identification of PD-associated proteins and the subsequent elucidation of the regulation of PD structure have provided vital insights into the role of PD architecture in enforcing crucial cellular processes,including callose deposition,ER–Golgi-based secretion,cytoskeleton dynamics,membrane lipid raft organization,chloroplast metabolism,and cell wall formation.In this review,we summarize the emerging discoveries from recent studies that elucidated the regulatory mechanisms involved in PD biogenesis and the dynamics of PD opening-closure.Retrospectively,PDmediated cell-to-cell communication has been implicated in diverse cellular and physiological processes that are fundamental for the development of horticultural plants.The potential application of PD biotechnological engineering represents a powerful approach for improving agronomic traits in horticultural crops in the future.

Genome-wide identification and characterization of the abiotic-stress-responsive lipoxygenase gene family in diploid woodland strawberry(Fragaria vesca)

Lipoxygenase(LOXs)is a kind of dioxygenase without heme and iron,which plays an important role in the development and adaptation of many plants to the environment.However,the study of strawberry LOX gene family has not been reported.In this study,14 LOX genes were identified from the diploid woodland strawberry genome.The phylogenetic tree divides the FvLOX gene into two subfamilies:9-LOX and 13-LOX.Gene duplication event analysis showed that whole-genome duplication(WGD)/segmental duplication and dispersed duplication effectively promoted the expansion of strawberry LOX family.QRT-PCR analysis showed that FvLOX genes were expressed in different tissues.Expression profile analysis showed that FvLOX1 and FvLOX8 were up-regulated under low temperature stress,FvLOX3 and FvLOX7 were up-regulated under drought stress,FvLOX6 and FvLOX9 were up-regulated under salt stress,FvLOX2,FvLOX3 and FvLOX6 were up-regulated under salicylic acid(SA)treatment,FvLOX3,FvLOX11 and FvLOX14 were up-regulated under methyl jasmonate(MeJA)treatment,FvLOX4 and FvLOX14 were up-regulated under abscisic acid(ABA)treatment.Promoter analysis showed that FvLOX genes were involved in plant growth and development and stress response.We analyzed and identified the whole genome of strawberry FvLOX family and characterized a variety of FvLOX candidate genes involved in abiotic stress response.This study laid a theoretical and empirical foundation for the response mechanism of strawberry to abiotic stress.

Metabolite variation in hybrid corn grain from a large-scale multisite study

Metabolite composition is strongly affected by genotype,environment,and interactions between genotype and environment,although the extent of variation caused by these factors may depend upon the type of metabolite.To characterize the complexity of genotype,environment,and their interaction in hybrid seeds,50 genetically diverse non-genetically modified(GM) maize hybrids were grown in six geographically diverse locations in North America.Polar metabolites from 553 harvested corn grain samples were isolated and analyzed by gas chromatography–mass spectrometry and 45 metabolites detected in all samples were used to generate a data matrix for statistical analysis.There was moderate variation among biological replicates and across genotypes and test sites.The genotype effects were detected by univariate and Hierarchical clustering analyses(HCA) when environmental effects were excluded.Overall,environment exerted larger effects than genotype,and polar metabolite accumulation showed a geographic effect.We conclude that it is possible to increase seed polar metabolite content in hybrid corn by selection of appropriate inbred lines and growing regions.

Epigenetic Modifications and Plant Hormone Action

The action of phytohormones in plants requires the spatiotemporal regulation of their accumulation and responses at various levels. Recent studies reveal an emerging relationship between the function of phytohormones and epigenetic modifications. In particular, evidence suggests that auxin biosynthesis, transport, and signal transduction is modulated by microRNAs and epigenetic factors such as histone modification, chromatin remodeling, and DNA methylation. Furthermore, some phytohormones have been shown to affect epigenetic modifications. These findings are shedding light on the mode of action of phytohormones and are opening up a new avenue of research on phytohormones as well as on the mech- anisms reaulatino eoioenetic modifications.

A feedback regulation between ARF7-mediated auxin signaling and auxin homeostasis involving MES17 affects plant gravitropism

Gravitropism is an essential adaptive response of land plants.Asymmetric auxin gradients across plant organs,interpreted by multiple auxin signaling components including AUXIN RESPONSE FACTOR7(ARF7),trigger differential growth and bending response.However,how this fundamental process is strictly maintained in nature remains unclear.Here,we report that gravity stimulates the transcription of METHYL ESTERASE17(MES17)along the lower side of the hypocotyl via ARF7-dependent auxin signaling.The asymmetric distribution of MES17,a methyltransferase that converts auxin from its inactive form methyl indole-3-acetic acid ester(MeI AA)to its biologically active form free-IAA,enhanced the gradient of active auxin across the hypocotyl,which in turn reversely amplified the asymmetric auxin responses and differential growth that shape gravitropic bending.Taken together,our findings reveal the novel role of MES17-mediated auxin homeostasis in gravitropic responses and identify an ARF7-triggered feedback mechanism that reinforces the asymmetric distribution of active auxin and strictly controls gravitropism in plants.

GmPIN1-mediated auxin asymmetry regulates leaf petiole angle and plant architecture in soybean

Crop breeding during the Green Revolution resulted in high yields largely due to the creation of plants with semi-dwarf architectures that could tolerate high-density planting.Although semi-dwarf varieties have been developed in rice,wheat and maize,none was reported in soybean(Glycine max),and few genes controlling plant architecture have been characterized in soybean.Here,we demonstrate that the auxin efflux transporter PINFORMED1(GmPIN1),which determines polar auxin transport,regulates the leaf petiole angle in soybean.CRISPR-Cas9-induced Gmpin1abc and Gmpin1bc multiple mutants displayed a compact architecture with a smaller petiole angle than wildtype plants.GmPIN1 transcripts and auxin were distributed asymmetrically in the petiole base,with high levels of GmPIN1a/c transcript and auxin in the lower cells,which resulted in asymmetric cell expansion.By contrast,the(iso)flavonoid content was greater in the upper petiole cells than in the lower cells.Our results suggest that(iso)flavonoids inhibit GmPIN1a/c expression to regulate the petiole angle.Overall,our study demonstrates that a signal cascade that integrates(iso)flavonoid biosynthesis,GmPIN1a/c expression,auxin accumulation,and cell expansion in an asymmetric manner creates a desirable petiole curvature in soybean.This study provides a genetic resource for improving soybean plant architecture.

Negative Isolation of Circulating Tumor Cells Using a Microfluidic Platform Integrated with Streptavidin-Functionalized PLGA Nanofibers

Detection of circulating tumor cells(CTCs)plays an important role in early diagnosis of cancer and personalized therapy.However,isolated CTCs,especially those captured by positive sorting methods,are difficult to culture in subsequent assays because the cells have to be labeled or attached to a substrate for separation.In this study,a negative sorting method has been developed for isolation of CTCs through a microfluidic platform integrated with streptavidin-functionalized electro-spun polylactic-co-glycolic acid nanofibers.Through the specific biotin-streptavidin interaction,the device is able to sort out biotinylated anti-CD45 antibody-labeled white blood cells(WBCs)and enrich A549 human cancer cells from the blood or CTCs from patient suffering non-small cell lung cancer.We demonstrate that the WBC capture efficiency is as high as 97.0%,and the recovery rate of cancer cells reaches up to 97.5%.CTCs are enumerated from blood samples of patients suf-fering lung carcinoma.The number of CTCs increased with the progression of NCCN TNM stages and showed statistically significant difference between stage I and later stages.These results suggest that the integrated negative sorting device is promising to be used for diagnosis of cancer.