The Arrestin-like Protein palF Contributes to Growth, Sporulation, Spore Germination, Osmolarity, and Pathogenicity of Coniella vitis.

Coniella vitis is a dominant phytopathogen of grape white rot in China, significantly impacting grape yield and quality. Previous studies showed that the growth and pathogenicity of C. vitis were affected by the environmental pH. Arrestin-like protein PalF plays a key role in mediating the activation of an intracellular-signaling cascade in response to alkaline ambient. However, it remains unclear whether palF affects the growth, development, and virulence of C. vitis during the sensing of environmental pH changes. In this study, we identified a homologous gene of PalF/Rim8 in C. vitis and constructed CvpalF-silenced strains via RNA interference. CvpalF-silenced strains exhibited impaired fungal growth at neutral/alkaline pH, accompanied by reduced pathogenicity compared to the wild-type (WT) and empty vector control (CK) strains. The distance between the hyphal branches was significantly increased in the CvpalF-silenced strains. Additionally, CvpalF-silenced strains showed increased sensitivity to NaCl, H2O2, and Congo red, and decreased sensitive to CaSO4. RT-qPCR analysis demonstrated that the expression level of genes related to pectinase and cellulase were significantly down-regulated in CvpalF-silenced strains compared to WT and CK strains. Moreover, the expression of PacC, PalA/B/C/F/H/I was directly or indirectly affected by silencing CvpalF. Additionally, the expression of genes related to plant cell wall-degrading enzymes, which are key virulence factors for plant pathogenic fungi, was regulated by CvpalF. Our results indicate the important roles of CvpalF in growth, osmotolerance, and pathogenicity in C. vitis.

Explore the mechanism of Astragalus membranaceus and Poria cocos drug pair in improving immunity based on network pharmacology.

The aim of this study was to investigate the key targets and molecular mechanisms of the drug pair Astragalus membranaceus and Poria cocos (HFDP) in the treatment of immunity. We utilized network pharmacology, molecular docking, and immune infiltration techniques in conjunction with data from the GEO database. Previous clinical studies have shown that HFDP has a positive impact on immune function. We first identified the active ingredients and targets of HFDP from the Traditional Chinese Medicine Systems Pharmacology database and the Swiss Target Prediction database, respectively. Next, we retrieved the differentially expressed genes (DEGs) related to immunity from the GEO databases. The intersection targets of the drugs and diseases were then analyzed using the STRING database for protein-protein interaction (PPI) network analysis, and the core targets were determined through topological analysis. Finally, the intersection genes were further analyzed using the DAVID database for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analyses. Subsequently, by analyzing the expression and prognostic survival of 12 core targets, 5 core target genes were identified, and molecular docking between the hub genes and immunity was performed. Finally, we used the CIBERSORT algorithm to analyze the immune infiltration of immunity genes In this study, 34 effective ingredients of HFDP, 530 target genes, and 568 differential genes were identified. GO and KEGG analysis showed that the intersection genes of HFDP targets and immunity-related genes were mainly related to complement and coagulation cascades, cytokine receptors, and retinol metabolism pathways. The molecular docking results showed that the 5 core genes had obvious affinity for the active ingredients of HFDP, which could be used as potential targets to improve the immunity of HFDP. Our findings suggest that HFDP is characterized by "multiple components, multiple targets, and multiple pathways" in regulating immunity. It may play an essential role in regulating immunity by regulating the expression and polymorphism of the central target genes ESR1, JUN, CYP3A4, CYP2C9, and SERPINE1.

A Simulation Study to Reveal the Epidemiology and Aerosol Transmission Characteristics of Botrytis cinerea in Grape Greenhouses.

Most previously studies had considered that plant fungal disease spread widely and quickly by airborne fungi spore. However, little is known about the release dynamics, aerodynamic diameter, and pathogenicity threshold of fungi spore in air of the greenhouse environment. Grape gray mold is caused by Botrytis cinerea; the disease spreads in greenhouses by spores in the air and the spore attaches to the leaf and infects plant through the orifice. In this study, 120 µmol/L propidium monoazide (PMA) were suitable for treatment and quantitation viable spore by quantitative real-time PCR, with a limit detection of 8 spores/mL in spore suspension. In total, 93 strains of B. cinerea with high pathogenicity were isolated and identified from the air samples of grapevines greenhouses by a portable sampler. The particle size of B. cinerea aerosol ranged predominately from 0.65-3.3 µm, accounting for 71.77% of the total amount. The B. cinerea spore aerosols were infective to healthy grape plants, with the lowest concentration that could cause disease being 42 spores/m3. Botrytis cinerea spores collected form six greenhouse in Shandong Province were quantified by PMA-qPCR, with a higher concentration (1182.89 spores/m3) in May and June and a lower concentration in July and August (6.30 spores/m3). This study suggested that spore dispersal in aerosol is an important route for the epidemiology of plant fungal disease, and these data will contribute to the development of new strategies for the effective alleviation and control of plant diseases.

Uncooled Broadband Photodetection via Light Trapping in Conformal PtTe2-Silicon Nanopillar Heterostructures.

Dirac semimetals have demonstrated significant attraction in the field of optoelectronics due to their unique bandgap structure and high carrier mobility. Combining them with classical semiconductor materials to form heterojunctions enables broadband optoelectronic conversion at room temperature. However, the low light absorption of layered Dirac semimetals substantially limits the device's responsivity in the infrared band. Herein, a three-dimensional (3D) heterostructure, composed of silicon nanopillars (SiNPs) and a conformal PtTe2 film, is proposed and demonstrated to enhance the photoresponsivity for uncooled broadband detection. The light trapping effect in the 3D heterostructure efficiently promotes the interaction between light and PtTe2, while also enhancing the light absorption efficiency of silicon, which enables the enhancement of the device responsivity across a broadband spectrum. Experimentally, the PtTe2-SiNPs heterojunction device demonstrates excellent photoelectric conversion behavior across the visible, near-infrared, and long-wave infrared (LWIR) bands, with its responsivity demonstrating an order-of-magnitude improvement compared to the counterparts with planar silicon heterojunctions. Under 11 µm laser irradiation, the noise equivalent power (NEP) can reach 1.76 nW·Hz-1/2 (@1 kHz). These findings offer a strategic approach to the design and fabrication of high-performance broadband photodetectors based on Dirac semimetals.

Dissipation behaviours, residues, and health risk of six herbicides in sugar beets under field conditions.

This study established a residue detection method based on the QuEChERS pre-treatment method and combined it with high-performance liquid chromatography-tandem mass spectrometry to test six herbicides (metamitron, clopyralid, desmedipham, phenmedipham, ethofumesate, and haloxyfop-p-methyl) in sugar beet plants, soil, and roots. The degradation dynamics and terminal residues of each herbicide in sugar beets were analysed. Finally, the dietary risks of various herbicides in sugar beets were evaluated based on the dietary structure of Chinese people, and the risk quotient values were below 100%. Using this detection method, all reagents exhibited good linearity (0.9724 ≤ R2 ≤ 0.9998), The limit of quantification (LOQ) ranged from 0.01 to 0.05 mg/L, the matrix effect ranged from -1.2% to -50%, the addition recovery rate ranged from 77.00% to 103.48%, and the relative standard deviation ranged from 1.61% to 16.17%; therefore, all indicators of this method met the residue detection standards. Under field conditions, the half-lives (t1/2) ranged about 0.65 ∼ 2.96 d and 0.38 ∼ 27.59 d in sugar beet plants and soil, respectively. All herbicides were easily degraded in sugar beet plants and soil (t1/2 < 30 d). The terminal residue amounts in the beet plants, soil, and roots ranged from < LOQ to 0.243 mg/kg. The dietary risk assessment of each pesticide was conducted based on the residual median of the terminal residues and the highest residual values on the edible part of the beetroot. The chronic exposure risk quotient (RQc) and acute exposure risk quotient (RQa) values were < 100%, indicating that the residue of each pesticide in beetroot posed low risks to consumers in China at the recommended dosage.

Comparative genomic and functional analyses of Paenibacillus peoriae ZBSF16 with biocontrol potential against grapevine diseases, provide insights into its genes related to plant growth-promoting and biocontrol mechanisms.

Paenibacillus peoriae is a plant growth-promoting rhizobacteria (PGPR) widely distributed in various environments. P. peoriae ZBFS16 was isolated from the wheat rhizosphere and significantly suppressed grape white rot disease caused by Coniella vitis. Here, we present the complete genome sequence of P. peoriae ZBFS16, which consists of a 5.83 Mb circular chromosome with an average G + C content of 45.62%. Phylogenetic analyses showed that ZBFS16 belongs to the genus P. peoriae and was similar to P. peoriae ZF390, P. peoriae HS311 and P. peoriae HJ-2. Comparative analysis with three closely related sequenced strains of P. peoriae identified the conservation of genes involved in indole-3-acetic acid production, phosphate solubilization, nitrogen fixation, biofilm formation, flagella and chemotaxis, quorum-sensing systems, two-component systems, antimicrobial substances and resistance inducers. Meanwhile, in vitro experiments were also performed to confirm these functions. In addition, the strong colonization ability of P. peoriae ZBFS16 was observed in soil, which provides it with great potential for use in agriculture as a PGPR. This study will be helpful for further studies of P. peoriae on the mechanisms of plant growth promotion and biocontrol.

First report of Coniella vitis causing white rot on Virginia creeper (Parthenocissus quinquefolia [L.] Planch.) in China.

Virginia creeper (Parthenocissus quinquefolia [L.] Planch.) belongs to the genus of Parthenocissus and Vitaceae family, which is very common in vineyards and where wild grape occurs (Bergh et al., 2011). In September of 2021, a severe white rot disease was observed on Virginia creeper around the vineyard of wine grapevine (Cabernet Sauvignon) located in Penglai city (37º 75'38" N, 120º 84'28" E), Shandong province of China. The disease incidence was about 75%, and infected leaf of Virginia creeper exhibited irregular necrotic lesion with brown center, and most lesion occurred on leaf margin, black pycnidia were also observed on the infected leaf at the late stage of infection. To determine the causal agent, symptomatic leaves with typical lesions were cut into small pieces (5 mm × 3 mm), surface sterilized with 75% ethanol for 1 min, followed by three times rinsed in sterile water. Leaf sections were plated onto potato dextrose agar (PDA) medium and incubated at 28°C for 3 days. Totally, five isolates (referred to as JD01, JD07, JD09, JD12 and JD16) were collected and transferred on to fresh PDA medium for incubation at 28°C. Seven days later, colonies on PDA plates had crenulated edges with concentric rings, the upper surface of colonies was mostly flat and white with many pycnidia. The conidia were hyaline at immature and became brown later, spherical or ellipsoid, aseptate, and 7.92 ± 1.20 µm × 5.18 ± 0.61 µm (n=50), length : width ratio is nearly 2. Morphologically, the isolates were identified as Coniella vitis (Chethana et al., 2017). Further to confirm the fungal species, the internal transcribed spacer region (ITS) of the ribosomal RNA gene, large subunit rRNA gene (LSU) and the translation elongation factor 1-alpaha gene (TEF1-α) were amplified using primers ITS1/ ITS4, LR7/ LROR, and TEF1- 728F/ TEF1- 986R (Chethana et al., 2017; Raudabaugh et al., 2018). The amplification products were sequenced and deposited in GenBank database. The sequences were compared to type sequences in GenBank. The results showed that ITS (GenBank accession numbers ON329769, ON329770, ON329771, ON329772 and ON329773), LSU (ON358423，ON358424, ON358425, ON358426 and ON358427) and TEF (ON297671, ON229071, ON229072, ON229073 and ON297672) sequences of the five isolates were 99.66%, 96.90% and 98.79% identical with the sequences data from C. vitis isolates in GeneBank (MFLUCC 18-0093, JZB3700020 and MFLUCC 18-0093, respectively). Furthermore, concatenated sequences of the three genes (ITS, LSU and TEF) were used to conduct a phylogenetic tree using maximum likehood MEGA-X (Raudabaugh et al., 2018). The phylogenetic analysis showed that the five isolates (JD01, JD07, JD09, JD12 and JD16) belong to C. vitis clade among the 41strains of Coniella spp. In the pathogenicity tests, detached leaves of Virginia creeper (1-year-old) were inoculated with mycelia plugs (5 mm diameter) (form 3-day-old of isolate JD07 culture), and control were inoculated with PDA plugs (5 mm diameter). Virginia creeper live plants (1-year-old) were inoculated with conidial suspension (2.5×106 spores/ml) of the isolate JD07 of one week old, and control plants were inoculated with sterile water. All treated Virginia creeper plants (detached leaves) were placed in a greenhouse maintained at 28°C and 95% relative humidity. Virginia creeper plants (detached leaves) inoculated with the conidial suspension (fungal mycelia) had brown lesion on leaves, the disease symptoms were similar to those observed in field. No such symptoms were observed on control plants (detached leaves). The pathogen was reisolated from inoculated Virginia creeper plants and re-identified, thus fulfilling Koch's postulates. C. vitis had been reported to cause grape white rot in China (Chethana et al., 2017). Virginia creeper, as an excellent host of C. vitis, will increase the transmission risk of the pathogens. To our knowledge, this is the first report of C. vitis causing white rot on Virginia creeper, and this finding will provide useful information for developing effective control strategies for white rot disease.

Suppression of Grape White Rot Caused by Coniella vitis Using the Potential Biocontrol Agent Bacillus velezensis GSBZ09.

Grape white rot caused by Coniella vitis is prevalent in almost all grapevines worldwide and results in a yield loss of 10-20% annually. Bacillus velezensis is a reputable plant growth-promoting bacterial. Strain GSBZ09 was isolated from grapevine cv. Red Globe (Vitis vinifera) and identified as B. velezensis according to morphological, physiological, biochemical characteristics and a multilocus gene sequence analysis (MLSA) based on six housekeeping genes (16S rRNA, gyrB, rpoD, atpD, rho and pgk). B. velezensis GSBZ09 was screened for antifungal activity against C. vitis under in vitro and in vivo conditions. GSBZ09 presented broad spectrum antifungal activity and produced many extracellular enzymes that remarkably inhibited the mycelial growth and spore germination of C. vitis. Furthermore, GSBZ09 had a high capacity for indole-3-acetic acid (IAA) production, siderophore production, and mineral phosphate solubilization. Pot experiments showed that the application of GSBZ09 significantly decreased the disease index of the grape white rot, directly promoted the growth of grapes, and upregulated defense-related enzymes. Overall, the features of B. velezensis GSBZ09 make it a potential strain for application as a biological control agent against C. vitis.

Cotton CC-NBS-LRR Gene GbCNL130 Confers Resistance to Verticillium Wilt Across Different Species.

Verticillium wilt (VW) is a destructive disease in cotton caused by Verticillium dahliae and has a significant impact on yield and quality. In the absence of safe and effective chemical control, VW is difficult to manage. Thus, at present, developing resistant varieties is the most economical and effective method of controlling Verticillium wilt of cotton. The CC-NBS-LRR (CNL) gene family is an important class of plant genes involved in disease resistance. This study identified 141 GbCNLs in Gossypium barbadense genome, with 37.5% (53 genes) GbCNLs enriched in 12 gene clusters (GC01-GC12) based on gene distribution in the chromosomes. Especially, seven GbCNLs from two largest clusters (GC11 and GC12) were significantly upregulated in the resistant cultivar (Hai No. 7124) and the susceptible (Giza No. 57). Virus-induced gene silencing of GbCNL130 in G. barbadense, one typical gene in the gene cluster 12 (GC12), significantly altered the response to VW, compromising plant resistance to V. dahliae. In contrast, GbCNL130 overexpression significantly increased the resistance to VW in the wild-type Arabidopsis thaliana. Based on our research findings presented here, we conclude that GbCNL130 promotes resistance to VW by activating the salicylic acid (SA)-dependent defense response pathway resulting in strong accumulation of reactive oxygen species and upregulation of pathogenesis-related (PR) genes. In conclusion, our study resulted in the discovery of a new CNL resistance gene in cotton, GbCNL130, that confers resistance to VW across different hosts.

Source-Sink Manipulation Affects Accumulation of Zinc and Other Nutrient Elements in Wheat Grains.

To better understand the source-sink flow and its relationships with zinc (Zn) and other nutrients in wheat (Triticum aestivum L.) plants for biofortification and improving grain nutritional quality, the effects of reducing the photoassimilate source (through the flag leaf removal and spike shading) or sink (through the removal of all spikelets from one side of the spike, i.e., 50% spikelets removal) in the field of the accumulation of Zn and other nutrients in grains of two wheat cultivars (Jimai 22 and Jimai 44) were investigated at two soil Zn application levels. The kernel number per spike (KNPS), single panicle weight (SPW), thousand kernel weight (TKW), total grain weight (TGW) sampled, concentrations and yields of various nutrient elements including Zn, iron (Fe), manganese (Mn), copper (Cu), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg), phytate phosphorus (phytate-P), phytic acid (PA) and phytohormones (ABA: abscisic acid, and the ethylene precursor ACC: 1-aminocylopropane-1-carboxylic acid), and carbon/N ratios were determined. Soil Zn application significantly increased the concentrations of grain Zn, N and K. Cultivars showing higher grain yields had lower grain protein and micronutrient nutritional quality. SPW, KNPS, TKW (with the exception of TKW in the removal of half of the spikelets), TGW, and nutrient yields in wheat grains were most severely reduced by half spikelet removal, secondly by spike shading, and slightly by flag leaf removal. Grain concentrations of Zn, N and Mg consistently showed negative correlations with SPW, KNPS and TGW, but positive correlations with TKW. There were general positive correlations among grain concentrations of Zn, Fe, Mn, Cu, N and Mg, and the bioavailability of Zn and Fe (estimated by molar ratios of PA/Zn, PA/Fe, PA × Ca/Zn, or PA × Ca/Fe). Although Zn and Fe concentrations were increased and Ca was decreased in treatments of half spikelet removal and spike shading, the treatments simultaneously increased PA and limited the increase in bioavailability of Zn and Fe. In general, different nutrient elements interact with each other and are affected to different degrees by source-sink manipulation. Elevated endogenous ABA levels and ABA/ACC ratios were associated with increased TKW and grain-filling of Zn, Mn, Ca and Mg, and inhibited K in wheat grains. However, the effects of ACC were diametrically opposite. These results provide a basis for wheat grain biofortification to alleviate human malnutrition.

Dilemma and solution of land scarcity, agro-production, and environmental risk for typical grain-producing areas in rapid urbanizing process in China.

How to satisfy food production sustainably in the rapid urbanizing process is a vital problem for major grain-producing areas. Taking two national grain-producing regions in China, Shandong and Dongting Lake Region as examples, this study uses step-by-step prediction and a double-objective linear programming model to analyze the dilemma of land scarcity, food demand, and environmental load. It is found that food demand by 2030 will induce partial regional cropland deficiency and heterogeneous agro-environmental risk among cities. The double-objective linear programming model finds possible solutions in different scenarios: on the premise of keeping the current cropland area unchanged, the upper threshold of crop yield by 2030 will be 2539.06 × 104 t in Dongting and 7175.13 × 104 t in Shandong, respectively. On the condition of guaranteeing food self-sufficiency and minimizing the environmental load, the lower threshold of arable land area should be 99.47 × 104 ha in Dongting and 436.85 × 104 ha in Shandong. Pollutant reduction will be realized by reallocation of agro-production task and optimized practices. The food carbon impact can be reduced by up to 1.27 kg CO2 eq/kg. This study contributes to feasible pathways towards adequate agro-production, lessened land scarcity, and minimal environmental risk for rapid urbanizing cities in a sustainable way.

Diversity and spoilage potential of microbial communities associated with grape sour rot in eastern coastal areas of China.

As a polymicrobial disease, sour rot decreases grape berry yield and wine quality. The diversity of microbial communities in sour rot-affected grapes depends on the cultivation site, but the microbes responsible for this disease in eastern coastal China, has not been reported. To identify the microbes that cause sour grape rot in this important grape-producing region, the diversity and abundance of bacteria and fungi were assessed by metagenomic analysis and cultivation-dependent techniques. A total of 15 bacteria and 10 fungi were isolated from sour rot-affected grapes. High-throughput sequencing of PCR-amplicons generated from diseased grapes revealed 1343 OTUs of bacteria and 1038 OTUs of fungi. Proteobacteria and Firmicutes were dominant phyla among the 19 bacterial phyla identified. Ascomycota was the dominant fungal phylum and the fungi Issatchenkia terricola, Colletotrichum viniferum, Hanseniaspora vineae, Saprochaete gigas, and Candida diversa represented the vast majority ofmicrobial species associated with sour rot-affected grapes. An in vitro spoilage assay confirmed that four of the isolated bacteria strains (two Cronobacter species, Serratia marcescens and Lysinibacillus fusiformis) and five of the isolated fungi strains (three Aspergillus species, Alternaria tenuissima, and Fusarium proliferatum) spoiled grapes. These microorganisms, which appear responsible for spoiling grapes in eastern China, appear closely related to microbes that cause this plant disease around the world.

Discussing the regional-scale arable land use intensity and environmental risk triggered by the micro-scale rural households' differentiation based on step-by-step evaluation-a case study of Shandong Province, China.

Under the rapid social-economic development process, the income structure and arable land size among rural households are facing with increasing differentiation in China. How the regional-scale arable land use intensity and environmental risk triggered by the rural households' differentiation would be is a question that has not been widely discussed. To fill this research gap, this study established three step-by-step indexes, rural households' ER index, arable land use intensity (LUI), and environmental risk index (RI), to measure rural households' differentiation, regional arable land use intensity, and environmental risk, respectively. By gathering data from questionnaire investigation of 950 rural households in Shandong Province, China, the result showed a wide range of ER index (0.006-0.056), LUI (2748.90-6361.54), and RI (0.0966-0.5032). ER index based on farm income, nonfarm income, and arable land size among rural households showed different distributions among cities. Though huge differences of arable land use existed in different rural households, including land area, crop species, use of production materials (agro-machinery, fertilizer, pesticide), and attitude towards land transferring, the farmers' sense of belonging to farmland and their dependence on agriculture did not disappear in the process of rural households' differentiation. Moreover, as aggregated effects of rural households' behavior, differentiation of regional arable land use intensity and environmental risk appeared later and lower than the level of rural households' differentiation in the same city. Among this process, Laiwu, Weihai, and Yantai became "hotspots" with higher level of rural households' differentiation, arable land use intensity, and agro-environmental risk, respectively. This study pointed out a possibility of policy designation that prior controlling environmental risk of arable land use could be realized by identifying the rural households' differentiation on arable land use.

Genome-Wide Characterization of bHLH Genes in Grape and Analysis of their Potential Relevance to Abiotic Stress Tolerance and Secondary Metabolite Biosynthesis.

Basic helix-loop-helix (bHLH) transcription factors are involved in many abiotic stress responses as well as flavonol and anthocyanin biosynthesis. In grapes (Vitis vinifera L.), flavonols including anthocyanins and condensed tannins are most abundant in the skins of the berries. Flavonols are important phytochemicals for viticulture and enology, but grape bHLH genes have rarely been examined. We identified 94 grape bHLH genes in a genome-wide analysis and performed Nr and GO function analyses for these genes. Phylogenetic analyses placed the genes into 15 clades, with some remaining orphans. 41 duplicate gene pairs were found in the grape bHLH gene family, and all of these duplicate gene pairs underwent purifying selection. Nine triplicate gene groups were found in the grape bHLH gene family and all of these triplicate gene groups underwent purifying selection. Twenty-two grape bHLH genes could be induced by PEG treatment and 17 grape bHLH genes could be induced by cold stress treatment including a homologous form of MYC2, VvbHLH007. Based on the GO or Nr function annotations, we found three other genes that are potentially related to anthocyanin or flavonol biosynthesis: VvbHLH003, VvbHLH007, and VvbHLH010. We also performed a cis-acting regulatory element analysis on some genes involved in flavonoid or anthocyanin biosynthesis and our results showed that most of these gene promoters contained G-box or E-box elements that could be recognized by bHLH family members.

The sustainable arable land use pattern under the tradeoff of agricultural production, economic development, and ecological protection-an analysis of Dongting Lake basin, China.

To find a solution regarding sustainable arable land use pattern in the important grain-producing area during the rapid urbanization process, this study combined agricultural production, locational condition, and ecological protection to determine optimal arable land use. Dongting Lake basin, one of the major grain producing areas in China, was chosen as the study area. The analysis of land use transition, the calculation of arable land barycenter, the landscape indices of arable land patches, and the comprehensive evaluation of arable land quality(productivity, economic location, and ecological condition) were adopted in this study. The results showed that (1) in 1990-2000, the arable land increased by 11.77%, and the transformation between arable land and other land use types actively occurred; in 2000-2010, the arable land decreased by 0.71%, and more ecological area (forestland, grassland, and water area) were disturbed and transferred into arable land; (2) urban expansion of the Changsha-Zhuzhou-Xiangtan city cluster (the major economy center of this area) induced the northward movement of the arable land barycenter; (3) the landscape fragmentation and decentralization degree of arable land patches increased during 1990-2010; (4) potential high-quality arable land is located in the zonal area around Dongting Lake, which contains the Li County, Linli County, Jinshi County, Taoyuan County, Taojiang County, Ningxiang County, Xiangxiang County, Shaoshan County, Miluo County, and Zhuzhou County. The inferior low-quality arable land is located in the northwestern Wuling mountainous area, the southeastern hilly area, and the densely populated big cities and their surrounding area. In the optimized arable land use pattern, the high-quality land should be intensively used, and the low-quality arable land should be reduced used or prohibitively used. What is more, it is necessary to quit the arable land away from the surrounding area of cities appropriately, in order to allow more space for urban expansion. This study could provide guidance for sustainable arable land use by both satisfying the future agricultural production and the local economic development, which can be used for the other major grain-producing areas in this rapid developing country.

Characterization of a novel type of HMW subunit of glutenin from Australopyrum retrofractum.

The Triticeae species Australopyrum retrofractum (genome WW) produces a single high molecular weight glutenin subunit (HMW-GS) in its endosperm. However, degenerate PCR amplification of its genome DNA revealed the presence of two related HMW-GS sequences, each consisting of an open reading frame. One of these (Glu-W1-2) has not previously been reported. Here, we sequenced Glu-W1-2 and showed that it encodes the same type of HMW-GS as Glu-W1-1, although its overall product length was much shorter, because the number of certain repetitive motifs was lower in its central region. Both A. retrofractum HMW-GSs have a unique repetitive motif, which differentiates them from other known x- and y-type subunits present in Triticeae species. We suggest that A. retrofractum must have diverged from the main Triticeae lineage prior to the Glu-1 duplication event which led to the evolution of the x- and y-type genes.