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Black rot caused by Xanthomonas campestris pv. campestris (Xcc) poses a threat to cruciferous crops worldwide. Here, we report the genome sequences including both the chromosome and plasmid sequences of four Xcc isolates, which were assembled using a combination of Nanopore long-read and MGISEQ-2000 short-read sequences. The assembled genomes of the four Xcc isolates collected in Dingxi (DX, Gansu Province), Ji’nan (JN, Shandong Province), Tianjin (TJ, Tianjin Municipality) and Yixing (YX, Jiangsu Province), are 5,186,378 bp, 5,183,344 bp, 5,229,476 bp and 5,148,143 bp in size, respectively, and harbor 4,766, 4,760, 4,821 and 4,691 protein-coding genes. These genome data provide valuable resources for studies that will enrich our understanding of genomic evolution and genetic diversity of Xcc isolates, and the molecular basis of Xcc-host interactions, thereby assisting the development of novel strategies for effectively controlling the disease caused by Xcc.

Members of the Fusarium graminearum species complex (FGSC) cause extensive yield losses in cereal production worldwide, and food safety concerns due to the accumulation of Fusarium toxins in infected grains. Among these pathogens, F. meridionale is responsible for Fusarium head blight of wheat and rice, ear and stalk rot of maize, and pod blight of soybean. Here, we present an improved genome assembly of F. meridionale strain SR5 isolated from rice in China based on PacBio long-read sequencing and Illumina short-read sequencing technology. The assembled genome of SR5 has a total size of 36.82 Mb, an N50 scaffold length of 7.82 Mb, nine scaffolds, and encodes 12,409 predicted genes. These high-quality data expand FGSC genomic resources and provide a valuable resource for better understanding their genetic diversity and the molecular basis of pathogenesis, which will facilitate the development of an effective control strategy. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

The performance of a structurally dissipating rock-shed (SDR) depends largely on the capacity of its energy dissipators. At present, most energy dissipators are made of metals, which dissipate energy by unrecoverable plastic deformation. Therefore, they are not able to recover their energy-dissipation capacity after deformation under rockfall impact. However, a rockfall usually disintegrates into pieces when it rolls down from a higher position and results in multiple rockfall impacts. An energy dissipator with self-recovery capability is therefore more suitable for ensuring the safety of SDRs. Replacing metal with polyurethane (a hyperelastic material with remarkable self-recovery capability) can provide self-recovery capability for energy dissipators, making them more suitable for resisting multiple rockfall impacts. In this work, polyurethane was manufactured into two types of energy dissipators: cylindrical and cubical. Full-scale falling rock impact tests and dynamic numerical simulations were conducted to study the mechanical response of the energy dissipators. In addition, in order to ensure the accuracy of the simulation, the dynamic mechanical properties of the polyurethane were tested and its dynamic constitutive model was established. The experimental and simulation tests have clarified the advantages of the polyurethane energy dissipator. We also summarized the practical considerations in the design of energy dissipators.

As a common phenomenon in granular flow, grain segregation plays a great role in affecting the behavior of granular soil by causing a great change of grain-void distribution in granular soil. This paper presents an experimental study on the influence of grain segregation on the behavior of sand, by a number of triaxial tests to interpret the characteristic behavior, friction and dilatancy behavior, excess pore water pressure behavior and critical state behavior of sand incorporating grain segregation. An index - grain segregation index Igs was proposed to quantify grain segregation. Grain segregation affected greatly the characteristic behavior of sand, causing the movement of void ratio-dilatancy relation of sand towards the increase of void ratio and dilatancy of sand. In the drained tests, the mobilized friction angle of sand showed a decrease followed by an increase but the mobilized dilatancy angle of sand increased, with increasing grain segregation index. An increase in grain segregation index impaired the basic friction of sand. In the undrained tests, the mobilized friction angle of sand showed an increase followed by a decrease with increasing grain segregation index. However, grain segregation caused an increase of the mobilized dilatancy of sand followed by a different development. An increase in grain segregation resulted in a higher summit of the dilatancy of sand but with a faster decrease along axial strain. In the q-p′ plane, grain segregation caused a reciprocating rotation of the dilatancy line and failure line of sand. Grain segregation resulted in enhancement of the peak-state dilatancy of sand, affecting greatly peak-state friction angle and peak-state basic friction angle of sand as well as the normalized excess pore water pressure. The excess friction angle of sand showed an increase followed by a decrease in the drained tests but increased linearly in the undrained tests, with increasing grain segregation index. The excess friction angle-over-maximum dilatancy angle of sand decreased in up convexity while increasing grain segregation index. Grain segregation resulted in rotation and translation of the critical state line of sand in the e-p′α=0.7 plane. However, in the q-p′ plane, the critical state line of sand showed an anticlockwise rotation followed by a clockwise rotation with increasing grain segregation index.

This paper presents a laboratory experimental study on particle breakage of sand subjected to friction and collision, by a number of drum tests on granular materials (silica sand No. 3 and ceramic balls) to investigate the characteristics of particle breakage and its effect on the characteristics of grain size distribution of sand. Particle breakage increased in up convexity with increasing duration of drum tests, but increased linearly with increasing number of balls. Particle breakage showed an increase, followed by a decrease while increasing the amount of sand. There may be existence of a characteristic amount of sand causing a maximum particle breakage. Friction tests caused much less particle breakage than collision tests did. Friction and collision resulted in different mechanisms of particle breakage, mainly by abrasion for friction and by splitting for collision. The fines content increased with increasing relative breakage. Particle breakage in the friction tests (abrasion) resulted in a sharper increase but with a smaller total amount of fines content in comparison with that in the collision tests (splitting). For the collision tests, the fines content showed a decrease followed by an increase as the amount of sand increased, whereas it increased in up convexity with increasing number of balls. The characteristic grain sizes D 10 and D 30 decreased in down convexity with increasing relative breakage, which could be described by a natural exponential function. However, the characteristic grain sizes D 50 and D 60 decreased linearly while increasing the relative breakage. In addition, the coefficients of uniformity and curvature of sand showed an increase followed by a decrease while increasing the relative breakage.

Fusarium oxysporum f. sp. conglutinans is the causal agent of Fusarium wilt of cabbage (Brassica oleracea var. capitata L.), which results in severe yield loss. Here, we report a high-quality genome sequence of a race 1 strain (IVC-1) of F. oxysporum f. sp. conglutinans, which was assembled using a combination of PacBio long-read and Illumina short-read sequences. The assembled IVC-1 genome has a total size of 71.18 Mb, with a contig N50 length of 4.59 Mb, and encodes 23,374 predicted protein-coding genes. The high-quality genome of IVC-1 provides a valuable resource for facilitating our understanding of F. oxysporum f. sp. conglutinans–cabbage interaction. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

This paper presents an experimental investigation of mobility and deposition characteristics of dry granular flow, by a number of flume tests on silica sand no. 3 and silica sand no. 7, to interpret the effects of angle of slope, granular volume, cushion, granular structure, and granular size on the mobility and deposition characteristics of granular flow. Along a given slope, an increase of the amount of sand impaired its mobility. However, for a given amount of sand along a slope, an increase of the angle of slope resulted in a V-shaped change of the angle of mass center movement, implying the existence of a characteristic combination of the angle of slope and the amount of sand to yield the maximum mobility of granular flow. The angle of mass center movement increased while increasing the thickness of cushion, showing that the cushion impaired the mobility of granular flow. Granular structure using the mixed structures of silica sand no. 3 and silica sand no. 7 affected greatly the mobility of granular flow, by showing an inverted structure in the near runout area with the deposition of the materials in the upper half of original grading structure in the far runout area for the inverse grading structure and normal grading structure. The mobility of granular flow increased with the change in turn of the inverse grading structure, the uniform structure, and the normal grading structure. The increase of the grain sizes of granular material enhanced its mobility. In addition, the angle of mass center movement showed a more reliable assessment for the mobility of granular flow in comparison with the angle of maximum mass movement.

Plant roots mechanically enhance the strength of soil and improve slope stability through anchoring. Given the popularization of ecological slope-protection technology, a quantitative study of how roots help to anchor soil is highly pertinent. The object of the present study is thus to investigate how roots and soil combine to affect the mechanical properties of the root-soil interface. Toward this end, pullout experiments of cedar roots of different diameters in soils of different density were conducted. The experimental results show that the maximum pullout force increases significantly with increasing root diameter, but only slightly increases with increasing soil density, which indicates that the root diameter has a greater impact on the maximum pullout force than soil density. Next, based on studies of fiber-reinforced composites, a root-soil pull-out model was proposed to study the evolution of shear stress on root-soil interface. This approach ensures that the model accurately reflects the dynamic stress distribution evolution at the root-soil interface and can calculate the pullout process of embedded root from soil. The accuracy of the model is verified by comparing the calculated results with experimental results. Finally, how soil density and root diameter affect the anchoring force was analyzed. The results indicate that the maximum anchoring force increases linearly with increasing root diameter, but nonlinearly with increasing soil density until reaching a fixed value. These results show that the root soil pull-out model has significant practical value in slope protection.

The members of myeloblastosis transcription factor (MYB TF) family are involved in the regulation of biotic and abiotic stresses in plants. However, the role of MYB TF in phosphorus remobilization remains largely unexplored. In the present study, we show that an R2R3 type MYB transcription factor, MYB103, is involved in phosphorus (P) remobilization. MYB103 was remarkably induced by P deficiency in cabbage (Brassica oleracea var. capitata L.). As cabbage lacks the proper mutant for elucidating the mechanism of MYB103 in P deficiency, another member of the crucifer family, Arabidopsis thaliana was chosen for further study. The transcript of its homologue AtMYB103 was also elevated in response to P deficiency in A. thaliana, while disruption of AtMYB103 (myb103) exhibited increased sensitivity to P deficiency, accompanied with decreased tissue biomass and soluble P concentration. Furthermore, AtMYB103 was involved in the P reutilization from cell wall, as less P was released from the cell wall in myb103 than in wildtype, coinciding with the reduction of ethylene production. Taken together, our results uncover an important role of MYB103 in the P remobilization, presumably through ethylene signaling.

Industrialization is one way to achieve a sustainable route out of poverty. During the implementation of industry-based poverty alleviation projects, rural households’ livelihood responses to change are crucial. A stronger livelihood response is conducive to multidimensional poverty relief due to industry-based poverty alleviation projects. Effective poverty alleviation can also stimulate stronger household responses. There is a positive cycle between livelihood response and multidimensional poverty relief effects that can help achieve sustainable poverty alleviation goals. Using a synergistic perspective on the relationship between “people–industry–land”, this paper explains the poverty alleviation logic connecting livelihood response, multidimensional poverty relief, and sustainable routes out of poverty by constructing a four-dimensional livelihood response measurement system with three elements of intensity. We analyzed survey data collected from 2363 households from 4 sample counties in 4 contiguous poverty-stricken areas, and measured and compared the characteristics of rural households’ livelihood responses and the factors influencing poverty alleviation projects. Rural households’ livelihood responses in four sample counties were moderate. The four dimensions of responses were ranked as livelihood strategy response, livelihood space response, livelihood output response, and livelihood capital response. The three intensities indicated that the perception and willingness elements of livelihood response were very similar, but there was a big gap between those elements and livelihood response actions. At the group level, poor households had higher and more consistent livelihood response than non-poor households. External environment factors (such as location, industry type, village organizational ability, and village atmosphere) and internal family factors (such as resource endowment, income sources, health, education, labor quantity, policy trust, credit availability, and social networks) had a significant impact on households’ livelihood response. However, this impact varied across different dimensions and had different intensities. This paper proposes a multidimensional poverty relief mechanism and suggests sustainable routes out of poverty.

Members of the

Squamosa promoter-binding protein-like (SPL) is a major family of plant-specific transcription factor, which is involved in multiple biological processes, such as plant growth and development, hormone response, light response and stress response. Therefore, it has been profoundly significant to systematically analyze the SPL Transcription Factors family in Brassica oleracea. In this study, a total of 33 BoSPLs were identified in the B. oleracea genome, and they were further divided into six subgroups based on the phylogenetic tree constructed from the SPL proteins of B. oleracea, B. rapa and Arabidopsis thaliana. The expression profile of BoSPLs in different organs/tissues showed that a large number of BoSPLs were expressed in the callus, root, stem, leaf, bud, flower and silique. In addition, the expression levels of two BoSPLs (BoSPL9b and BoSPL10b) were up-regulated in chilling tolerance cabbage ‘CT-923’ at 6 h after chilling stress when compared with normal treatment (mock), while two BoSPLs (BoSPL9b and BoSPL15a) in chilling sensitive cabbage ‘CS-D9’, five BoSPLs (BoSPL1, -9a, -9b, -10b, -11b) in ‘CT-923’ and two BoSPLs (BoSPL9b and BoSPL16a) in ‘CS-D9’ were up-regulated after 24 h chilling stress, indicated that these genes may play an important role in the chilling-tolerance of cabbage. We analyzed the characteristics of BoSPLs and provided the basis for further functional research.

This paper presents a review of particle breakage in granular soils by comprehensively summarizing the measurement of particle breakage, the fundamentals of particle breakage, the soil mechanics on...

The E3 ubiquitin ligases are key regulators of protein ubiquitination, which have been shown to be involved in a variety of cellular responses to both biotic and abiotic stresses in eukaryotes. However, the E3 ubiquitin ligase homologues in the soil-borne plant pathogen Plasmodiophora brassicae, the causal agent of clubroot disease of crucifer crops worldwide, remain largely unknown. In this study, we characterized secreted E3 ubiquitin ligases, a group of proteins known to be involved in virulence in many pathogens, in a plasmodiophorid P. brassicae. Genome-wide search in the P. brassicae genome retrieved 139 putative E3 ubiquitin ligases, comprising of 115 RING, 15 HECT, 1 HECT-like, and 8 U-box E3 ubiquitin ligases. Among these E3 ubiquitin ligases, 11 RING, 1 U-box, and 3 HECT were found to harbor signal peptide. Based on published RNA-seq data (Schwelm et al. in Sci Rep 5:11153, 2015), we found that these genes were differentially expressed in distinct life stages including germinating spores, maturing spores, and plasmodia. We characterized one potential secreted E3 ubiquitin ligase, PbRING1 (PBRA_000499). Yeast invertase assay showed that PbRING1 harbors a functional N-terminal signal peptide. PbRING1 also harbors a really interested new gene (RING) domain at its C terminus, which was found to display the E3 ligase activity in vitro. Collectively, this study provides a comprehensive insight into the reservoir of putative secreted E3 ligases in P. brassicae.

The main aim of this paper is to define an elastic wave velocity threshold for rainfall-induced landslide prediction and early warning. To achieve this goal, several key questions need to be addressed, such as what threshold of wave velocity should be employed for issuing early warning? And how such thresholds should be selected? In an attempt to answer these questions, a total of 32 centrifuge experiments were conducted on model slopes. We first determined the critical deformation prior to initiation of shear failure. Then, the corresponding wave velocities at the critical deformation were compiled to establish a threshold of wave velocity to be used for early warning of landslides. Finally, a large-scale slope model test was performed to confirm the proposed threshold of elastic wave velocity. Based on the wave monitoring results, a warning is proposed to be issued at normalized elastic wave velocity of 0.9, and the slope toe is preferable for wave monitoring.

Clubroot caused by Plasmodiophora brassicae is an economically important disease of crucifer crops throughout the world and is a major threat to the quality and yield of cabbage (Brassica oleracea ...

Background Brassica oleracea includes several morphologically diverse, economically important vegetable crops, such as the cauliflower and cabbage. However, genetic variants, especially large structural variants (SVs), that underlie the extreme morphological diversity of B. oleracea remain largely unexplored. Results Here we present high-quality chromosome-scale genome assemblies for two B. oleracea morphotypes, cauliflower and cabbage. Direct comparison of these two assemblies identifies ~ 120 K high-confidence SVs. Population analysis of 271 B. oleracea accessions using these SVs clearly separates different morphotypes, suggesting the association of SVs with B. oleracea intraspecific divergence. Genes affected by SVs selected between cauliflower and cabbage are enriched with functions related to response to stress and stimulus and meristem and flower development. Furthermore, genes affected by selected SVs and involved in the switch from vegetative to generative growth that defines curd initiation, inflorescence meristem proliferation for curd formation, maintenance and enlargement, are identified, providing insights into the regulatory network of curd development. Conclusions This study reveals the important roles of SVs in diversification of different morphotypes of B. oleracea, and the newly assembled genomes and the SVs provide rich resources for future research and breeding.

Additional file 1: Figure S1. Morphology of cauliflower Koroso_1401 and pointed cabbage OX-heart_923. Figure S2. Genome size estimation using flow cytometry analysis for cauliflower Korso and cabbage OX-heart. Figure S3. Chromosome conformation capture of cauliflower Korso and pointed cabbage OX-heart. Figure S4. Pairwise comparisons of the pseudo-chromosomes among cauliflower Korso, cabbage OX-heart and broccoli HDEM. Figure S5. Distribution of estimated insertion times of intact LTR retrotransposons in Korso, OX-heart and B. rapa (v3.0) genomes. Figure S6. Distribution of centromeric satellite repeats CentBr 1 and CentBr 2 on the nine chromosomes of Korso and OX-heart. Figure S7. Segmental collinearity between the A. thaliana genome and genomes of Korso, OX-heart and B. rapa. Figure S8. Subgenomes in Korso and OX-heart. Figure S9. Detected SVs between the genomes of Korso and the OX-heart. Figure S10. Significantly enriched GO terms in genes overlapping with detected SVs in their gene body and/or promoter regions. Figure S11. Distribution of SV genotyping rates in 271 B. oleracea accessions. Figure S12. Population analysis of the 271 B. oleracea accessions using SNPs. Figure S13. Manhattan plot displaying the -log(q-value) of allele variations between cabbage and cauliflower for SVs across the Korso genome. Figure S14. Expression profiles of genes potentially involved in curd maintenance and floral arrest.

Xinmo landslide buried the village and caused many casualties and property damage. After the landslide, a deformed block came into being on the left side of the landslide. Researchers mainly concentrated on the main body and the causes of the landslide without a systematic analysis of this block. This work is to discuss this block based on field investigation and UAV images. In the investigation, four scarps and three cracks were found. The lower two scarps indicated a downslope movement of the foot of the block, while the other two scarps and three cracks showed that main displacement of the block was towards to the free face formed in the landslide. Combined previous researches, it can be inferred that bedrock in the lower two scarps was the locking section, which stopped the movement of the block and the formation of the block can be divided into three stages. Then, two potential slipping direction were concluded and the FOS (Factor of Safety) were calculated with the Finite Element Method (FEM). Results show that the slip is more easily towards the free face which would do less harm. But it cannot be excluded that it would slip down the slope which could do much harm to the village and the road. So, monitoring is recommended on the foot of the block to get an advanced notice.

This paper presents a laboratory experimental investigation of the behavior of coral sands. The investigation incorporated particle breakage to interpret its influence on consolidation and ...

This paper presents a laboratory experimental study to comprehensively investigate the characteristics of particle breakage using numerous triaxial tests on a coral sand. Coral is a highly crushable granular material which fills the gaps between more crushable and less crushable granular materials. The monotonic tests and cyclic tests were terminated at the designated axial strains and the designated cyclic numbers, respectively. The grain size distributions were measured by sieve analyses of the specimens after the triaxial tests were performed. The relative breakage and relative fractal dimension were used to quantify the particle breakage. The cause of particle breakage that increased with increasing isotropic consolidation stress was shown to be isotropic stress. An almost linear increase in particle breakage in relative breakage was found as axial strain increased, whereas the increase in particle breakage in relative fractal dimension showed upward convexity. More particle breakage occurred in denser samples. During consolidation to the identical mean effective stress, the anisotropic stress state played a bigger role in particle breakage than the isotropic stress state, but during shearing particle breakage occurred more sharply in the triaxial tests with the isotropic consolidation to the higher confining pressure. In the cyclic shearing, the particle breakage in relative breakage and relative fractal dimension increased in upward convexity as the cyclic number increased, but in upward concavity with increasing axial strain. A hyperbolic model was proposed to correlate the relative fractal dimension with the relative breakage for use with both monotonic and cyclic tests. In the monotonic tests, a hyperbolic model was proposed to correlate the particle breakage in relative breakage and relative fractal dimension with the plastic work per unit volume. It is proposed that the loading-mode-induced (i.e., monotonic loading and cyclic loading) different mechanism of particle breakage meant that this model could not be applicable in the cyclic tests. The results suggested that the hyperbolic correlation of the particle breakage in relative fractal dimension and the plastic work per unit volume is the most reliable method of interpreting the energy consumption characteristics of particle breakage. This approach takes the fractal nature of soil into consideration. A microscopic view of particle breakage is also effective for observing the evolution of particle breakage. (C) 2018 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.

Basic helix&ndash, loop&ndash, helix (bHLH) transcription factor (TF) family is commonly found in eukaryotes, which is one of the largest families of regulator proteins. It plays an important role in plant growth and development, as well as various biotic and abiotic stresses. However, a comprehensive analysis of the bHLH family has not been reported in Brassica oleracea. In this study, we systematically describe the BobHLHs in the phylogenetic relationships, expression patterns in different organs/tissues, and in response to chilling stress, and gene and protein characteristics. A total of 234 BobHLH genes were identified in the B. oleracea genome and were further clustered into twenty-three subfamilies based on the phylogenetic analyses. A large number of BobHLH genes were unevenly located on nine chromosomes of B. oleracea. Analysis of RNA-Seq expression profiles revealed that 21 BobHLH genes exhibited organ/tissue-specific expression. Additionally, the expression of six BobHLHs (BobHLH003, -048, -059, -093, -109, and -148) were significantly down-regulated in chilling-sensitive cabbage (CS-D9) and chilling-tolerant cabbage (CT-923). At 24h chilling stress, BobHLH054 was significantly down-regulated and up-regulated in chilling-treated CS-D9 and CT-923. Conserved motif characterization and exon/intron structural patterns showed that BobHLH genes had similar structures in the same subfamily. This study provides a comprehensive analysis of BobHLH genes and reveals several candidate genes involved in chilling tolerance of B. oleracea, which may be helpful to clarify the roles of bHLH family members and understand the regulatory mechanisms of BobHLH genes in response to the chilling stress of cabbage.

The current study was undertaken to investigate the mechanism underlying Boron (B)-alleviated phosphate (P) deficiency in Arabidopsis thaliana. Furthermore, we were interested to explore whether this alleviation of P deficiency by B could extend to Brassica crops. Arabidopsis thaliana or Brassica oleracea plants were grown under P-sufficient or -deficient condition with or without extra B for 7 days, then shoots and roots of B. oleracea were sampled for analysis of soluble P content while those of A. thaliana were harvested for analysis of total P content, soluble P content and nitric oxide (NO) as well as for cell wall extraction and RNA isolation. A. thaliana plants showed reduced root growth and decreased P content in the root under P-deficient conditions, but improved root growth when supplemented with additional B. Further analysis revealed that exogenous B elevated the cell wall pectin content and facilitated the release of P in P-deficient seedlings, thus more soluble P was available to sustain growth under P deficiency. Furthermore, B supplement also increased soluble P in P-deficient cabbage (Brassica oleracea var. capitata L.), an economically important vegetable crop. P deficiency alone was sufficient to induce NO accumulation, and in combination with B application further enhanced NO accumulation, while exogenous application of NO scavenger c-PTIO [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide] counteracted this positive effect of B, indicating that NO is positively involved in B-mediated alleviation of P deficiency. Our study reveals the critical role of B in improving the growth of P-deficient plants, and also provides evidence implicating the involvement of NO signal.

Background The MYB transcription factor (MYB TF) family has been reported to be involved in the regulation of biotic and abiotic stresses in plants. However, the involvement of MYB TF in phosphate remobilization under phosphate deficiency remains largely unexplored. Results Here, we showed that an R2R3 type MYB transcription factor, MYB103, was involved in the tolerance to P deficiency in Arabidopsis thaliana . AtMYB103 was induced by P deficiency, and loss function of AtMYB103 significantly enhanced sensitivity to P deficiency, as root and shoot biomass and soluble P content in the myb103 mutant were significantly lower than those in wild-type (WT) plants under the P-deficient condition. Furthermore, the expression of Pi deficiency -responsive genes was more profound in myb103 than in WT. In addition, AtMYB103 may also be involved in the cell wall-based P reutilization, as less P was released from the cell wall in myb103 than in WT, which was in company with a reduction of the ethylene production. Conclusions These findings uncover the role of MYB103 in the P remobilization, presumably through ethylene signaling.

In analyzing seismic stability of a slope with upper bound limit analysis method, the slip surface is often assumed as a log-spiral or plane slip surface. However, due to the presence of a weak layer and unfavorable geological structural surface or a bedrock interface with overlying soft strata, the preexisting slip surface of the slope may be irregular and composed of a series of planes rather than strictly log-spiral or plane shape. A computational model is developed for analyzing the seismic stability of slopes with pre-existing slip surfaces. This model is based on the upper bound limit analysis method and can consider the effect of anchor bolts. The soil or rock is deemed to follow the Mohr-Coulomb yield criterion. The slope is divided into multiple block elements along the slip surface. According to the displacement compatibility and the associated flow rule, a kinematic velocity field of the slope can be obtained computationally. The proposed model allows not only calculation of the rate of external work owing to the combined effect of self-weight and seismic loading, but also that of the energy dissipation rate caused by the slip surface, interfaces of block elements and anchorage effect of the anchors. Considering a direct relationship between the rate of external work and the energy dissipation rate, the expressions of yield acceleration and permanent displacement of anchored slopes can be derived. Finally, the validity of this proposed model is illustrated by analysis on three typical slopes. The results showed that the proposed model is more easily formulated and does not need to solve complex equations or time consuming iterations compared with previous methods based on the conditions of force equilibrium.

A great deal of triaxial tests were conducted under various influence factors on the Silica sand No.5 with the purpose of investigating the characteristics of particle breakage. Particle breakage was measured by sieve analysis conducted at the different axial strain level after the tests to obtain relevant grain size distribution curves which were quantified by relative breakage. It was found that the particle breakage in relative breakage increases with increasing axial strain and confining pressure. Particle breakage was also caused during consolidation. Denser sample was revealed to cause more particle breakage. Initial stress anisotropy was found to result in more particle breakage during anisotropic consolidation than that during isotropic consolidation but during shearing the higher confining pressure resulted in more particle breakage than the initial stress anisotropy with a relatively lower confining pressure. Particle breakage was found to increase in up convexity with increasing cycle number of cyclic loading but in up concavity with increasing additional axial strain. A hyperbolic model was proposed to correlate the particle breakage in relative breakage with the plastic work per unit volume for the monotonic and cyclic triaxial tests.

This article presents a laboratory experimental study on the state-dependent behavior of a crushable sand that was crushed progressively in a number of the drained triaxial tests. The critical state line of sand showed a straight line in the e-logp′ plane, in the e-p′α=0.7 plane and in the q-p′ plane despite of involving the progressive particle breakage. It showed a family of the relations between stress ratio and dilatancy factor rather than a unique stress-dilatancy relation. While increasing the initial void ratio or the initial confining pressure, the peak-state friction and maximum dilatancy angles of sand showed a decrease, but the peak-state basic friction angle of sand increased. Linear representation was revealed for the relations of the maximum dilatancy angle - the peak-state stress ratio and the peak-state basic friction angle - the peak-state stress ratio. An increase in the peak-state state parameter resulted in a linear decrease of the peak-state friction and dilatancy angles of sand, but a linear increase of the peak-state basic friction angle of sand. It revealed a unique linear friction-dilatancy relation of sand incorporating the progressive particle breakage. The peak-state volumetric strain and deviator strain of sand increased while increasing the initial void ratio or the initial confining pressure or the peak-state state parameter, but decreased with increasing the peak-state stress ratio. The peak-state dilatancy factor d incorporating the progressive particle breakage decreased linearly with increasing the peak-state stress ratio, but linearly increased along the increase of the peak-state state parameter. Dilatancy of sand should be dependence of the pressure and density of sand as well as the progressive particle breakage.

Xigeda formation is a type of hundred-meter-thick lacustrine sediments of being prone to triggering landslides along the trunk channel and tributaries of the upper Yangtze River in China. The Yonglang landslide located near Yonglang Town of Dechang County in Sichuan Province of China, which was a typical Xigeda formation landslide, was stabilized by anti-slide piles. Loading tests on a loading-test pile were conducted to measure the displacements and moments. The uncertainty of the tested geomechanical parameters of the Yonglang landslide over certain ranges would be problematic during the evaluation of the landslide. Thus, uniform design was introduced in the experimental design, and by which, numerical analyses of the loading-test pile were performed using Fast Lagrangian Analysis of Continua (FLAC3D) to acquire a database of the geomechanical parameters of the Yonglang landslide and the corresponding displacements of the loading-test pile. A three-layer back-propagation neural network was established and trained with the database, and then tested and verified for its accuracy and reliability in numerical simulations. Displacement back analysis was conducted by substituting the displacements of the loading-test pile to the well-trained three-layer back-propagation neural network so as to identify the geomechanical parameters of the Yonglang landslide. The neural-network-based displacement back analysis method with the proposed methodology is verified to be accurate and reliable for the identification of the uncertain geomechanical parameters of landslides.

A series of triaxial tests were conducted to investigate the characteristics of the critical state loci (CSLs) of original and pre-crushed sands. The results of the original sand showed that the CSL was divided into two segments by a particle breakage reference stress (0·7 MPa) not only in the e–logp′ plane but also in the q–p′ plane. The results from the pre-crushed sands revealed that particle breakage resulted in a downward translation and an anticlockwise rotation of the CSL in the e–logp′ plane. However, in the q–p′ plane, all the critical state points were on the initial CSL, but with different evolutions against particle breakage for drained and undrained tests.

Background The SWEET proteins are a group of sugar transporters that play a role in sugar efflux during a range of biological processes, including stress responses. However, there has been no comprehensive analysis of the SWEET family genes in Brassica oleracea (BoSWEET), and the evolutionary pattern, phylogenetic relationship, gene characteristics of BoSWEET genes and their expression patterns under biotic and abiotic stresses remain largely unexplored. Results A total of 30 BoSWEET genes were identified and divided into four clades in B. oleracea. Phylogenetic analysis of the BoSWEET proteins indicated that clade II formed first, followed by clade I, clade IV and clade III, successively. Clade III, the newest clade, shows signs of rapid expansion. The Ks values of the orthologous SWEET gene pairs between B. oleracea and Arabidopsis thaliana ranged from 0.30 to 0.45, which estimated that B. oleracea diverged from A. thaliana approximately 10 to 15 million years ago. Prediction of transmembrane regions showed that eight BoSWEET proteins contain one characteristic MtN3_slv domain, twenty-one contain two, and one has four. Quantitative reverse transcription-PCR (qRT-PCR) analysis revealed that five BoSWEET genes from clades III and IV exhibited reduced expression levels under chilling stress. Additionally, the expression levels of six BoSWEET genes were up-regulated in roots of a clubroot-susceptible cabbage cultivar (CS-JF1) at 7 days after inoculation with Plasmodiophora brassicae compared with uninoculated plants, indicating that these genes may play important roles in transporting sugars into sink roots associated with P. brassicae colonization in CS-JF1. Subcellular localization analysis of a subset of BoSWEET proteins indicated that they are localized in the plasma membrane. Conclusions This study provides important insights into the evolution of the SWEET gene family in B. oleracea and other species, and represents the first study to characterize phylogenetic relationship, gene structures and expression patterns of the BoSWEET genes. These findings provide new insights into the complex transcriptional regulation of BoSWEET genes, as well as potential candidate BoSWEET genes that promote sugar transport to enhance chilling tolerance and clubroot disease resistance in cabbage. Electronic supplementary material The online version of this article (10.1186/s12864-019-5454-2) contains supplementary material, which is available to authorized users.