High performance solar-blind UV detector with Mg0.472Zn0.528O/Mg0.447Zn0.553O double layer structure on MgO substrate.

Mg0.472Zn0.528O/Mg0.447Zn0.553O double layer structure UV detectors are made on single structure MgO substrate by PLD method, and the effect of different thickness top MgZnO layer on the UV response characteristics of the detector are studied. Compared with the single layer MgZnO detector that made by Mg0.3Zn0.7O target, the Mg0.472Zn0.528O/Mg0.447Zn0.553O double layer detector with 30 nm top layer, shows much higher deep UV response (21.3 A W-1at 265 nm), much smaller dark current(66.9 pA) and much higher signal-to-noise ratio (2.8 × 105) at 25 V bias voltage. And the device also shows relative high response (23.1 A W-1) at 235 nm deep UV light at 25 V bias voltage, which is mainly attributed by the bottom MgZnO layer with higher Mg composition. When the top layer is 66.7 nm thick, the response of the Mg0.472Zn0.528O/Mg0.447Zn0.553O detector reached 228.8 A W-1at 255 nm under 25 V bias voltage, the signal-to-noise ratio of which is 10573 under 20 V bias voltage, and the near UV response of the device is also big because of more h-MgZnO in top MgZnO layer. When the top layer reached 90.2 nm, there are much more h-MgZnO in the top MgZnO layer, the peak response of the Mg0.472Zn0.528O/Mg0.447Zn0.553O detector is just 6.65 A W-1at 320 nm under 25 V bias voltage, the signal-to-noise ratio of which is 1248. The high Mg composition bottom MgZnO decrease the dark current of the Mg0.472Zn0.528O/Mg0.447Zn0.553O detector, both the 2DEG effect of the double layer structure and the amplify effect of the mix-phase MgZnO top layer, increased theIuvand deep UV response of the Mg0.472Zn0.528O/Mg0.447Zn0.553O detector. Therefore, the double layer Mg0.472Zn0.528O/Mg0.447Zn0.553O detector is more sensitive at faint deep UV light compared with previous reported MgZnO detectors, and the MgxZn1-xO/MgyZn1-yO detector shows similarIuvand signal-noise-ratio at faint deep UV light as high-temperature fabricated AlxGa1-xN/AlyGa1-yN detectors.

GATCF: Graph Attention Collaborative Filtering for Reliable Blockchain Services Selection in BaaS.

Blockchain technology is a decentralized ledger that allows the development of applications without the need for a trusted third party. As service-oriented computing continues to evolve, the concept of Blockchain as a Service (BaaS) has emerged, providing a simplified approach to building blockchain-based applications. The growing demand for blockchain services has resulted in numerous options with overlapping functionalities, making it difficult to select the most reliable ones for users. Choosing the best-trusted blockchain peers is a challenging task due to the sparsity of data caused by the multitude of available options. To address the aforementioned issues, we propose a novel collaborative filtering-based matrix completion model called Graph Attention Collaborative Filtering (GATCF), which leverages both graph attention and collaborative filtering techniques to recover the missing values in the data matrix effectively. By incorporating graph attention into the matrix completion process, GATCF can effectively capture the underlying dependencies and interactions between users or peers, and thus mitigate the data sparsity scenarios. We conduct extensive experiments on a large-scale dataset to assess our performance. Results show that our proposed method achieves higher recovery accuracy.

Crystallization Engineering of CuNi2 S4 Ultra-Fine Nanocrystals with Optimized Band Structures for Efficient Photocatalytic Pollutant Degradation and Hydrogen Production.

The mono-dispersed cubic siegenite CuNi2 S4 ultra-fine (≈5 nm) nanocrystals are fabricated through crystallization engineering under hot injection. The strong hydroxylation on mostly exposed CuNi2 S4 (220) surface leads to the formation of multi-valence (Cu+ , Cu2+ , Ni2+ , Ni3+ ) species with unsaturated hybridization and coordination micro-environments, which can induce rich redox reactions to optimize interfacial kinetics for the adsorbed reaction intermediates. The as-synthesized CuNi2 S4 nanocrystals with ultra-small particle size and the characteristics of being highly dispersed can increase specific surface area and hydroxylated active sites, which considerably contribute to the improvement of photocatalytic activities. Experimental and theoretical studies indicate that the CuNi2 S4 with unique surface condition can properly modulate the charge density distribution and the electronic band structure, thus achieving an optimal band gap for enhancing visible light absorption. Additionally, the strong hydroxylation on CuNi2 S4 (220) surface can not only make the photocatalytic process stable in alkaline environment but also bring about an impurity level between conduction and valence band, which facilitates the separation of photo-induced charge carriers by suppressing the rapid re-combination of exited electrons and holes. The optimization of band structure should be the intrinsic reason for the efficient photocatalytic pollutant degradation and hydrogen production under visible light illumination.

Complete Genomic Sequence of Xanthomonas oryzae pv. oryzae Strain, LA20, for Studying Resurgence of Rice Bacterial Blight in the Yangtze River Region, China.

Xanthomonas oryzae pv. oryzae (Xoo) is a causative agent of rice bacterial blight (BB). In 2020-2022, BB re-emerged, and there was a break out in the Yangtze River area, China. The pandemic Xoo strain, LA20, was isolated and identified from cultivar Quanyou1606 and demonstrated to be the Chinese R9 Xoo strain, which is able to override the widely adopted xa5-, Xa7- and xa13-mediated resistance in rice varieties in Yangtze River. Here, we report the complete genome of LA20 by PacBio and Illumina sequencing. The assembled genome consists of one circular chromosome of 4,960,087 bp, sharing 99.65% sequence identity with the traditional representative strain, YC11 (R5), in the Yangtze River. Comparative genome analysis of LA20 and YC11 revealed the obvious variability in Tal genes (the uppermost virulence determinants) in numbers and sequences. Particularly, six Tal genes were only found in LA20, but not in YC11, among which Tal1b (pthXo1)/Tal4 (pthXo6), along with the lost one, pthXo3 (avrXa7), might be the major factors for LA20 to overcome xa5-, Xa7- and xa13-mediated resistance, thus, leading to the resurgence of BB. This complete genome of the new pandemic Xoo strain will provide novel insights into pathogen evolution, the traits of pathogenicity on genomic level and the epidemic disease status in China.

Cytological observation and transcriptome analysis reveal dynamic changes of Rhizoctonia solani colonization on leaf sheath and different genes recruited between the resistant and susceptible genotypes in rice.

Sheath blight, caused by Rhizoctonia solani, is a big threat to the global rice production. To characterize the early development of R. solani on rice leaf and leaf sheath, two genotypes, GD66 (a resistant genotype) and Lemont (a susceptible genotype), were observed using four cytological techniques: the whole-mount eosin B-staining confocal laser scanning microscopy (WE-CLSM), stereoscopy, fluorescence microscopy, and plastic semi-thin sectioning after in vitro inoculation. WE-CLSM observation showed that, at 12 h post-inoculation (hpi), the amount of hyphae increased dramatically on leaf and sheath surface, the infection cushions occurred and maintained at a huge number from about 18 to 36 hpi, and then the infection cushions disappeared gradually from about 42 to 72 hpi. Interestingly, R. solani could not only colonize on the abaxial surfaces of leaf sheath but also invade the paraxial side of the leaf sheath, which shows a different behavior from that of leaf. RNA sequencing detected 6,234 differentially expressed genes (DEGs) for Lemont and 7,784 DEGs for GD66 at 24 hpi, and 2,523 DEGs for Lemont and 2,719 DEGs for GD66 at 48 hpi, suggesting that GD66 is recruiting more genes in fighting against the pathogen. Among DEGs, resistant genes, such as OsRLCK5, Xa21, and Pid2, displayed higher expression in the resistant genotype than the susceptible genotype at both 24 and 48 hpi, which were validated by quantitative reverse transcription-PCR. Our results indicated that the resistance phenotype of GD66 was the consequence of recruiting a series of resistance genes involved in different regulatory pathways. WE-CLSM is a powerful technique for uncovering the mechanism of R. solani invading rice and for detecting rice sheath blight-resistant germplasm.

High Photoresponse Black Phosphorus TFTs Capping with Transparent Hexagonal Boron Nitride.

Black phosphorus (BP), a single elemental two-dimensional (2D) material with a sizable band gap, meets several critical material requirements in the development of future nanoelectronic applications. This work reports the ambipolar characteristics of few-layer BP, induced using 2D transparent hexagonal boron nitride (h-BN) capping. The 2D h-BN capping have several advantages over conventional Al2O3 capping in flexible and transparent 2D device applications. The h-BN capping technique was used to achieve an electron mobility in the BP devices of 73 cm2V-1s-1, thereby demonstrating n-type behavior. The ambipolar BP devices exhibited ultrafast photodetector behavior with a very high photoresponsivity of 1980 mA/W over the ultraviolet (UV), visible, and infrared (IR) spectral ranges. The h-BN capping process offers a feasible approach to fabricating n-type behavior BP semiconductors and high photoresponse BP photodetectors.

First Report of New Bacterial Leaf Blight of Rice Caused by Pantoea ananatis in Southeast China.

In autumn 2020, leaf blight was observed on rice (Oryza sativa L., variety Zhongzao39, Yongyou9, Yongyou12, Yongyou15, Yongyou18, Yongyou1540, Zhongzheyou8, Jiafengyou2, Xiangliangyou900 and Jiyou351) in the fields of 17 towns in Zhejiang and Jiangxi Provinces, China. The disease incidence was 45%-60%. Initially, water-soaked, linear, light brown lesions emerged in the upper blades of the leaves, and then spread down to leaf margins, which ultimately caused leaf curling and blight during the booting-harvest stage (Fig. S1). The disease symptoms were assumed to be caused by Xanthomonas oryzae pv. oryzae (Xoo), the pathogen of rice bacterial blight. 63 isolates were obtained from the collected diseased leaves as previously described (Hou et al. 2020). All isolates showed circular, smooth-margined, yellow colonies when cultured on peptone sugar agar (PSA) medium for 24h at 28℃. The cells were all gram-negative and rod-shaped with three to six peritrichous flagella; positive for catalase, indole, glucose fermentation and citrate utilization, while negative for oxidase, alkaline, phenylalanine deaminase, urease, and nitrate reductase reactions. 16S rRNA gene sequence analysis from the 6 isolates (FY43, JH31, JH99, TZ20, TZ39 and TZ68) revealed that the amplified fragments shared 98% similarity with Pantoea ananatis type strain LMG 2665T (GenBank JFZU01) (Table S3). To further verify P. ananatis identity of these isolates, fragments of three housekeeping genes including gyrB, leuS and rpoB from the 6 isolates were amplified and sequenced, which showed highest homology to LMG 2665T with a sequence similarity of 95%-100% (Table S3). Primers (Brady et al. 2008) and GenBank accession numbers of gene sequences from the 6 isolates are listed in Table S1 and Table S2. Phylogenetic analysis of gyrB, leuS and rpoB concatenated sequences indicated that the 6 isolates were clustered in a stable branch with P. ananatis (Fig. S2). Based on the above morphological, physiological, biochemical and molecular data, the isolates are identified as P. ananatis. For pathogenicity tests, bacterial suspension at 108 CFU/mL was inoculated into flag leaves of rice (cv. Zhongzao39) at the late booting stage using clipping method. Water was used as a negative control. The clipped leaves displayed water-soaked lesions at 3 to 5 days after inoculation (DAI); then the lesion spread downward and turned light brown. At about 14 DAI, blight was shown with similar symptoms to those samples collected from the rice field of Zhejiang and Jiangxi provinces (Fig. S1). In contrast, the control plants remained healthy and symptomless. The same P. ananatis was re-isolated in the inoculated rice plants, fulfilling Koch's postulates. In the past decade, P. ananatis has been reported to cause grain discoloration in Hangzhou, China (Yan et al. 2010) and induce leaf blight as a companion of Enterobacter asburiae in Sichuan province, China (Xue et al. 2020). Nevertheless, to the best of our knowledge, this is the first report of P. ananatis as the causative agent of rice leaf blight in southeast China. This study raises the alarm that the emerging rice bacterial leaf blight in southeast China might be caused by a new pathogen P. ananatis, instead of Xoo as traditionally assumed. Further, the differences of occurrence, spread and control between two rice bacterial leaf blight diseases caused by P. ananatis and Xoo, respectively need to be determined in the future.

A Linear Regression Model for the Prediction of Rice Sheath Blight Field Resistance.

Rice sheath blight (SB) disease is a global issue that causes great yield losses each year. To explore whether SB field resistance can be predicted, 273 rice genotypes were inoculated and evaluated for SB field resistance across nine environments from 2012 to 2019 to identify loci associated with SB resistance by association mapping. A total of 80 significant marker-trait associations were detected in nine environments, among which six loci (D130B, D230A, D304B, D309, D427A, and RM409) were repeatedly detected in at least two environments. A linear regression model for predicting SB lesion length was developed using genotypic data of these six loci and SB field resistance data of the 273 rice genotypes: y = 34.44 - 0.56x, where y is the predicted value of lesion length, and x is the total genotypic value of the six loci. A recombinant inbred line (RIL) population consisting of 219 lines that was grown in six environments (from 2013 to 2018) for evaluation of SB field resistance was used to check the prediction accuracy of the prediction model. The average absolute error between the predicted lesion length and real lesion length for the RIL population was 6.67 cm. The absolute errors between predicted and real lesion lengths were <6 cm for 51.22% of the lines and <9 cm for 71.22% of the lines. An SB visual rating prediction model was also developed, and the average absolute error between the predicted visual rating and real visual rating for the RIL population was 0.94. These results indicated that the rice SB lesion length can be predicted by the development of a linear regression model using both genotypic and phenotypic data.

Solar-Blind Photodetector with Lower Dark Current and Higher Ilight/Idark Ratio Based on Mg0.38Zn0.62O Film Deposited by Pulsed Laser Deposition Method.

In this study, pulsed laser deposition method (PLD) was employed to grow MgxZn1-xO films on quartz substrates. The optimal deposition temperature of 300 °C for MgxZn1-xO film was decided and Mg0.38Zn0.62O, Mg0.56Zn0.44O and Mg0.69Zn0.31O films were grown respectively using MgxZn1-xO targets with different Mg contents (x = 0.3, 0.5 and 0.7). As-deposited Mg0.38Zn0.62O film possessed the mixed-phase (hexagonal and cubic phase) structure, appropriate band gap of 4.68 eV and smaller surface roughness of 1.72 nm, and the solar-blind photodetector (PD) based on it was fabricated. The key features of our PD are the cutoff wavelength of 265 nm lying in solar-blind band, lower dark current (Idark) of 88 pA, higher peak responsivity of 0.10 A/W and bigger Ilight/Idark ratio of 1688, which provide the new idea for the application of solar-blind PDs based on MgxZn1-xO films.

Electric field modulation in the auxetic effect of BP-analog monolayer As and Sb by first-principles calculations.

In this paper, we have introduced the auxetic effect in black phosphorus (BP) analog Sb and achieved auxetic modulations in monolayer As and Sb via first-principles calculations. Compared with monolayer As, the monolayer Sb is phonon unstable. By applying uniaxial strain along each direction, we discovered zigzag-vertical reversibility on out-of-plane auxeticity, and the negative Poisson's ratios for monolayer As and Sb were simulated to be -0.125/-0.172 and -0.036/-0.063, respectively, by applying the strain along zigzag/vertical directions. The negative Poisson's ratio could be significantly manipulated by applying a vertical electric field as it can be increased up to 70.3% for monolayer As and decreased up to 55.6% for monolayer Sb. Such an intrinsic negative Poisson's ratio and electric field modulation could endow these monolayers with potential applications in auxetic optoelectronic devices, electrodes and sensors, leading to novel multi-functionalities.

Solar-Blind Photodetector with Lower Dark Current and Higher Ilight/Idark Ratio Based on Mg0.38Zn0.62O Film Deposited by Pulsed Laser Deposition Method.

In this study, pulsed laser deposition method (PLD) was employed to grow MgxZn1-xO films on quartz substrates. The optimal deposition temperature of 300 °C for MgxZn1-xO film was decided and Mg0.38Zn0.62O, Mg0.56Zn0.44O and Mg0.69Zn0.31O films were grown respectively using MgxZn1-xO targets with different Mg contents (x = 0.3, 0.5 and 0.7). As-deposited Mg0.38Zn0.62O film possessed the mixed-phase (hexagonal and cubic phase) structure, appropriate band gap of 4.68 eV and smaller surface roughness of 1.72 nm, and the solar-blind photodetector (PD) based on it was fabricated. The key features of our PD are the cutoff wavelength of 265 nm lying in solar-blind band, lower dark current (Idark) of 88 pA, higher peak responsivity of 0.10 A/W and bigger Ilight/Idark ratio of 1688, which provide the new idea for the application of solar-blind PDs based on MgxZn1-xO films.

High Sensitivity NO2 Gas Sensor Based on 3D WO3 Microflowers Assembled by Numerous Nanoplates.

Tungsten oxide microflowers (WO3 MFs) were fabricated by a simple hydrothermal process through adjusting the pH of the solution by HCl. These MFs possess the outer diameters of about 2 µm and are composed of numerous nanoplates with the average pore size of 10.9 nm. Chemiresistive activity of as-fabricated WO3 MFs sensor was attempted towards oxidizing and reducing target gases, revealing a superior selectivity to NO2 with a maximum response of 22.95 (2 ppm NO2) @105 °C compared to other target gases. One of the key features of as-fabricatedWO3 MFs sensor is the lower detection limit of 125 ppb and operating temperature of 105 °C to NO2 with better reproducibility, signifying commercial prospective of the developed sensor materials. Finally, the gas sensing mechanism of WO3 MFs sensor has been proposed.

The effective photocatalysis and antibacterial properties of AgBr/Ag2MoO4@ZnO composites under visible light irradiation.

A novel Z-scheme AgBr/Ag2MoO4@ZnO photocatalyst was fabricated via a hydrothermal process and in situ growth method. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy were used to determine the structure of the photocatalyst. The results showed that the composites were tightly connected by the (101) lattice plane of ZnO, the (222) plane of Ag2MoO4 and the (200) lattice plane of AgBr. Because of the strong redox activity and good separability of photoelectrons and holes induced by the Z-scheme structure, the photodegradation rate for ciprofloxacin (CIP) solution was 80.5% by the photocatalysis of 0.5 AgBr/Ag2MoO4@ZnO. In addition, more than 99.999% of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa cells were killed within 60 min. These results demonstrate that AgBr/Ag2MoO4@ZnO is a promising photocatalyst, which can be used in organic pollutant degradation and the photocatalytic antibacterial area.

Field Emission Properties of Molybdenum Nanoparticles Decorated ZnO Nanorod Arrays.

Precisely controlled dimensions of heterostructured ZnO nanorod arrays were grown on micropatterned Au films supported by Si substrate using chemical vapor deposition (CVD). The field emission properties were attributed to pointed nanorods, thickness of catalyst, preferential growth, density, morphology of ZnO and Molybdenum (Mo) decorated ZnO nanorod arrays (Mo/ZnO). The selective restrained heterostructure approach resulted in excellent control over periodicity, location and density of ZnO nanorod arrays. Overall, field emission properties of bare ZnO nanorod arrays showed a low turn-on field of ~4.7 V/µm and a high field enhancement factor (ß) ~1686 to 7.3 V/µm and (ß) ~807 for Mo/ZnO. It was also found that the field emission properties were significantly influenced by densely decorated Mo nanoparticles on as-grown ZnO nanorod arrays.

Proteomic dissection of the rice-Fusarium fujikuroi interaction and the correlation between the proteome and transcriptome under disease stress.

BACKGROUND: Bakanae disease, caused by the fungus Fusarium fujikuroi, occurs widely throughout Asia and Europe and sporadically in other rice production areas. Recent changes in climate and cropping patterns have aggravated this disease. To gain a better understanding of the molecular mechanisms of rice bakanae disease resistance, we employed a 6-plex tandem mass tag approach for relative quantitative proteomic comparison of infected and uninfected rice seedlings 7 days post-inoculation with two genotypes: the resistant genotype 93-11 and the susceptible genotype Nipponbare. RESULTS: In total, 123 (77.2% up-regulated, 22.8% down-regulated) and 91 (94.5% up-regulated, 5.5% down-regulated) differentially expressed proteins (DEPs) accumulated in 93-11 and Nipponbare, respectively. Only 11 DEPs were both shared by the two genotypes. Clustering results showed that the protein regulation trends for the two genotypes were highly contrasting, which suggested obviously different interaction mechanisms of the host and the pathogen between 93 and 11 and Nipponbare. Further analysis showed that a noticeable aquaporin, PIP2-2, was sharply upregulated with a fold change (FC) of 109.2 in 93-11, which might be related to pathogen defense and the execution of bakanae disease resistance. Certain antifungal proteins were regulated in both 93-11 and Nipponbare with moderate FCs. These proteins might participate in protecting the cellular integrity required for basic growth of the susceptible genotype. Correlation analysis between the transcriptome and proteome revealed that Pearson correlation coefficients of R = 0.677 (P = 0.0005) and R = - 0.097 (P = 0.702) were obtained for 93-11 and Nipponbare, respectively. Our findings raised an intriguing result that a significant positive correlation only in the resistant genotype, while no correlation was found in the susceptible genotype. The differences in codon usage was hypothesized for the cause of the result. CONCLUSIONS: Quantitative proteomic analysis of the rice genotypes 93-11and Nipponbare after F. fujikuroi infection revealed that the aquaporin protein PIP2-2 might execute bakanae disease resistance. The difference in the correlation between the transcriptome and proteome might be due to the differences in codon usage between 93-11and Nipponbare. Overall, the protein regulation trends observed under bakanae disease stress are highly contrasting, and the molecular mechanisms of disease defense are obviously different between 93 and 11 and Nipponbare. In summary, these findings deepen our understanding of the functions of proteins induced by bakanae disease and the mechanisms of rice bakanae disease resistance.

The effective photocatalysis and antibacterial properties of AgBr/AgVO3 composites under visible-light.

With the discharge of large amount of organic pollutants and antibiotics into the water environment, the water cycle has been seriously polluted, and at the same time, various drug-resistant bacteria have emerged in succession, which poses a serious threat to human health. In recent years, photocatalytic nanomaterials have become a research hotspot in the antimicrobial area. In this study, AgBr/AgVO3 photocatalysts were prepared by a hydrothermal process and an in situ growth method. The composites were tightly connected by the (501) plane of AgVO3 and the (200) lattice plane of AgBr. The photocatalytic activity was tested by degrading Rhodamine B (RhB) solution under visible-light, and the result indicated that the photodegradation rate for RhB solution was 92.3% by the photocatalysis with 0.5AgBr/AgVO3 and the photocatalytic performance of 0.5AgBr/AgVO3 was improved compared to pure AgVO3 and AgBr. In addition, more than 99.997% of E. coli, S. aureus, and P. aeruginosa cells were killed by the photocatalysis with 0.5AgBr/AgVO3 within 30 min. These results demonstrated that the 0.5AgBr/AgVO3 heterojunction photocatalyst could be widely used in the treatment of environmental pollution and in the antibacterial field.

Combination of twelve alleles at six quantitative trait loci determines grain weight in rice.

Grain weight, which is controlled by quantitative trait loci (QTLs), is one of the most important determinants of rice yield. Although many QTLs for grain weight have been identified, little is known about how different alleles in different QTLs coordinate to determine grain weight. In the present study, six grain-weight-QTLs were detected in seven mapping populations (two F2, one F3, and four recombinant inbred lines) developed by crossing 'Lemont', a United States japonica variety, with 'Yangdao 4', a Chinese indica variety. In each of the six loci, one allele from one parent increased grain weight and one allele from another parent decreased it. Thus, the 12 alleles at the six QTLs were subjected to regression analysis to examine whether they acted additively across loci leading to a linear relationship between the predicted breeding value of QTL and phenotype. Results suggested that a combination of the 12 alleles determined grain weight. In addition, plants carrying more grain-weight-increasing alleles had heavier grains than those carrying more grain-weight-decreasing alleles. This trend was consistent in the seven mapping populations. Thus, these six QTLs might be used in marker-assisted selection of grain weight, by stacking different grain-weight-increasing or -decreasing alleles.

Genotype by Environment Interaction: The Greatest Obstacle in Precise Determination of Rice Sheath Blight Resistance in the Field.

Rice sheath blight (SB) is the most serious rice disease in China. Resistance of rice to SB is a quantitative trait that is easily influenced by the environment; however, the extent of environmental influence on SB field resistance is still poorly understood. To identify rice genotype by environment interactions for SB resistance, 211 rice genotypes originating from 15 countries were planted and evaluated for SB field resistance in six different environments between 2012 and 2016 after inoculation with the SB pathogen isolate ZJ03. In addition, 65 rice genotypes were evaluated for SB field resistance in another four environments between 2013 and 2016 using ZJ03. Variations in SB field resistance were observed in different genotypes in different environments using objective and subjective rating methods. Two-way analysis of variance indicated that the interaction between the genotype and environment had a highly significant effect on SB field resistance. This analysis indicated that the environment had more of an influence than the genotype itself on SB field resistance, and the genotype by environment interaction was the greatest obstacle in obtaining a precise determination of SB field resistance in rice. The most resistant genotype, GD66, is a good candidate for genetic studies and breeding.

Combination of Eight Alleles at Four Quantitative Trait Loci Determines Grain Length in Rice.

Grain length is an important quantitative trait in rice (Oryza sativa L.) that influences both grain yield and exterior quality. Although many quantitative trait loci (QTLs) for grain length have been identified, it is still unclear how different alleles from different QTLs regulate grain length coordinately. To explore the mechanisms of QTL combination in the determination of grain length, five mapping populations, including two F2 populations, an F3 population, an F7 recombinant inbred line (RIL) population, and an F8 RIL population, were developed from the cross between the U.S. tropical japonica variety 'Lemont' and the Chinese indica variety 'Yangdao 4' and grown under different environmental conditions. Four QTLs (qGL-3-1, qGL-3-2, qGL-4, and qGL-7) for grain length were detected using both composite interval mapping and multiple interval mapping methods in the mapping populations. In each locus, there was an allele from one parent that increased grain length and another allele from another parent that decreased it. The eight alleles in the four QTLs were analyzed to determine whether these alleles act additively across loci, and lead to a linear relationship between the predicted breeding value of QTLs and phenotype. Linear regression analysis suggested that the combination of eight alleles determined grain length. Plants carrying more grain length-increasing alleles had longer grain length than those carrying more grain length-decreasing alleles. This trend was consistent in all five mapping populations and demonstrated the regulation of grain length by the four QTLs. Thus, these QTLs are ideal resources for modifying grain length in rice.

Analysis on genetic diversification and heterosis in autotetraploid rice.

Polyploidization has played an important role in plant evolution and is a pathway for plants to increase genetic diversification and to get higher heterosis comparing with that of diploid does. This study was undertaken to assess the genetic variation and relationships among 40 autotetraploid rice genotypes and their counterpart diploid cultivars with 99 SSR markers screened from published rice genome. The 99 SSR markers detected polymorphism among autotetraploid genotypes and revealed a total of 291 alleles with an average of 2.949 alleles per locus. Autotetraploid lines showed higher genetic diversity and significant variation in agronomic traits than diploid cultivars. Phylogenetic analysis revealed that most of autotetraploid lines were genetically different from their diploid parents, and inter-subspecific hybrids were prepared on the basis of genetic distance between parents. Inter-subspecific autotetraploid hybrids showed a higher and positive heterobeltiosis and competitive heterosis than diploid hybrids, especially for grain yield. Genetic distance appeared not to predict heterosis in diploid rice for all traits; however, it showed a significant correlation with grain yield, grain length and grain length to width ratio in autotetraploid rice. This extensive research on autotetraploid heterosis and genetic diversity will be useful for the development of autotetraploid rice hybrids.