Construction of DNA Fingerprint Using SSR Marker for Hybrid Rice Cultivars Approved by Hunan Province

[Objective] This study aimed to construct DNA fingerprint for hybrid rice cultivars those have been approved by Hunan Province. [Method] The primers which produced polymorphic and bright DNA bands were selected to construct the DNA molecular fingerprint map for 77 major hybrid rice cultivars approved by Hunan Province. [ Result] A total of 48 SSR primers were selected. Every cultivar had its unique fingerprint map so that the obtained data could identify differ- ent hybrid rice cultivars. [ Conclusion] This study made great contributions to the perfection of hybrid rice germplasm identification.

CRISPR–Cas9-mediated promoter editing of FERONIA-Like receptor 13 increases plant growth and disease resistance in rice

Receptor kinases play a pivotal role in detecting environmental signals,and consequently,gene pleiotropy is frequently observed within this family.However,the trade-off in trait expression resulting from gene pleiotropy poses a constraint on the utilization of such genes in agricultural breeding.In this study,we identified the receptor kinase gene FERONIA-Like Receptor 13(FLR13)as a pleiotropic gene influencing plant height,tillering,grain yield,and disease resistance.Using promoter editing,we generated novel alleles(FLR13T5T6-1,FLR13T5T6-2)that confer resistance to rice blast and increase per-plant yield.The knockout of the T5T6 segment alleviates the inhibitory effects of two transcription factors,OsGBP1 and OsWRKY53,on FLR13 expression.In summary,our study presents a promising avenue for enhancing the pivotal attributes of receptor-like kinases through a promoter-editing strategy.

Single-cell transcriptome sequencing reveals the mechanism regulating rice plumule development

Seed plumules comprise multiple developing tissues and are key sites for above-ground plant organ morphogenesis.Here,the spatial expression of genes in developing rice seed plumules was characterized by single-cell transcriptome sequencing in Zhongjiazao 17,a popular Chinese indica rice cultivar.Of 15 cell clusters,13 were assigned to cell types using marker genes and cluster-specific genes.Marker genes of multiple cell types were expressed in several clusters,suggesting a complex developmental system.Some genes for signaling by phytohormones such as abscisic acid were highly expressed in specific clusters.Various cis-elements in the promoters of genes specifically expressed in cell clusters were calculated,and some key hormone-related motifs were frequent in certain clusters.Spatial expression patterns of genes involved in rapid seed germination,seedling growth,and development were identified.These findings enhanced our understanding of cellular diversity and specialization within plumules of rice,a monocotyledonous model crop.

Treatments of Pollen with Different Solvents Affect the Seed Setting Rate of Rice(Oryza sativa L.)

This study aimed to investigate the effects of treatments of rice pollen with different solvents on the seed setting rate.Rice pollen was treated with ultrapure water,0.5%dimethyl sulfoxide,ethanol(1%,5%,and 8%),and 0.5%dimethyl sulfoxide+8%ethanol,and the pollen without treatment was taken as the control.Then,crossing was conducted with the treated rice plants as the male parents and plants subjected to emasculation by warm water as the female parents.The seed setting rates of the male and female parents were then recorded.The results showed that the treatments with different solvents significantly decreased the seed setting rates of both male and female parents.The treatment with 1%ethanol resulted in the highest seed setting rates for both male and female parents,while the treatment with 0.5%dimethyl sulfoxide resulted in the lowest seed setting rates for both parents.Although these solvents affected the seed setting rate of rice,they served as intermediate solvents to dissolve chemicals used in the induction of rice haploids.This study layed a technical foundation for subsequent chemical induction of rice haploids.

Identification of QTLs and Validation of qCd-2 Associated with Grain Cadmium Concentrations in Rice

Cadmium(Cd) is one of heavy metals harmful to human health. As rice is the main staple food in Asia and Cd is easily contaminated in rice, the molecular regulation of Cd accumulation should be explored. In this study, a recombinant inbred population derived from Xiang 743/Katy was grown in Cd-polluted fields and used to map the quantitative trait loci(QTLs) for Cd accumulation in rice grains. We identified seven QTLs distributed on chromosomes 2, 3, 6, 7, 8 and 10. These QTLs displayed phenotypic variances of 58.50% and 40.59% in 2014 and 2015, respectively. Two QTLs, qCd-2 and qCd-7, were identified in both the two years. qCd-2 was detected on the interval of RM250–RM207 on chromosome 2, with an LOD of 2.51 and a phenotypic contribution of 13.75% in 2014, and an LOD of 3.35 and a phenotypic contribution of 14.16% in 2015. qCd-7 co-localized with the cloned qCdT7 on chromosome 7 and may represent the correct candidate. The other five QTLs were detected only in one year. To further confirm the effects of qCd-2, a residual heterozygous line designated as RHL945, with a heterozygous interval of RM263–RM207 on chromosome 2, was selected from the recombinant inbred population and used to develop an F2 population consisting of 155 individual plants. By incorporating further simple sequence repeat markers into the segmental linkage map of the target region, qCd-2 was delimited in the interval of RM5404–RM3774, with an LOD value of 4.38 and a phenotypic contribution of 15.52%. These results reflected the genetic regulation of grain Cd in rice and paved the way for the future cloning of qCd-2.

Effects of Mulching Mode on Canopy Physiological, Ecological Characteristics and Yield of Upland Rice

The effects of mulching mode on population physiology and ecology of rice were studied using a combination P88S/1128 as the material under three mulching cultivation modes including plastic film mulching, straw mulching and liquid film mulching, as well as bare cultivation (control). The results indicated that mulching mode had significant effects on micro-meteorological factors and individual growth of rice, as shown by an increase of relative humidity, a better internal micro-meteorological environment of rice population, a significant reduction under the rice canopy temperature, especially during high-temperature periods. Rice plants under mulching cultivation conditions displayed a stronger transpiration and lower leaf temperature, thereby improving the ability of anti-high temperature stress and markedly increasing the photosynthetic rate. Furthermore, the yield components of rice were significantly optimized under mulching cultivation, of which with plastic film mulching displayed the highest grain number per panicle and seed-setting rate, and a yield increase of 16.81% compared with the control; and with straw mulching displayed an increase of effective panicle number and a 9.59% increase of total yield compared to the control.

Screening and Verification of Rice Varieties with Low Cadmium Accumulation

In order to improve the utilization efficiency of heavy metal pollution of farmland,the revitalization of Hunan rice brand,this research worked on 20142016 oriented social extensive collection of 285 varieties of rice,including 98 early rice varieties and 187 late rice varieties.Screening and veri fication of rice varieties with low Cadmium accumulation were studied in Changsha-Zhuzhou-Xiangtan of Hunan Province,and in other typical cadmium polluted area in Hunan Province.12 early rice varieties and 13 late rice varieties were selected as low Cadmium accumulation varieties.Field test showed that,through the screening of varieties(V),irrigation(I)and acidity adjustment(P),the content of cadmium in early rice is 0.064~0.233 mg/kg,and 0.143~0.246 mg/kg in late rice,basically to ensure the content of cadmium in rice to reach the national standard,and to ensure good food security.

Effects of Cadmium Stress on the Growth of Rice Seedlings

The seedlings of 6 rice varieties were treated with Cd concentrations of 25,50 and 100μmol/L for 5 d.The results showed that the longest root length,seedling height,fresh weight per plant and dry weight per plant of 6 rice varieties were significantly inhibited.The inhibiting effects showed a trend as the following:the longest root length>fresh weight per plant>dry weight per plant>seedling height,and the inhibiting effect increased with the increase of Cd stress concentration.It is more economical and reasonable to use 50μmol/L Cd stress concentration to identify Cd tolerance of rice seedlings.And it is more scienti fic to evaluate the Cd tolerance of rice seedling comprehensively by using the 4 indexes of longest root length,fresh weight per plant,dry weight per plant and seedling height.

Breeding High-Grain Quality and Blast Resistant Rice Variety Using Combination of Traditional Breeding and Marker-Assisted Selection

We reported a novel rice variety developed by integrating the advantages of high eating quality from Xiangwanxiaa 17(XWX17)and rice blast resistance from Gumei 4(GM4)using a combination of traditional breeding and marker-assisted selection(MAS).Using molecular markers for QTLs/genes responsible for amylose content(AC),fragrance and blast resistance,three inbred lines were selected.

Effects of Different Soil Preparation and Fertilizer Application Methods on the Growth and Yield of the Rice-Crayfish Rotation Direct Seeding Rice Nongxiang 32

In order to improve the yield and fertilizer utilization of the ricecrayfish rotation and direct seeding rice Nongxiang 32,the effects of different soil preparation and fertilizer application methods on the growth,yield and fertilizer utilization of the variety were studied.The results showed that,under the rice-crayfish rotation and direct seeding farming mode,the contributions of seed setting rate,1000-grain weight,yield,and fertilizer contribution rate to yield of Nongxiang 32 in the treatments with rotary tillage with base fertilizer,rotary tillage without base fertilizer and no-tillage with base fertilizer were relatively higher than those in the treatments with rotary tillage without fertilizer,no-tillage without fertilizer and no-tillage without base fertilizer,and there were no significant differences between the three treatments.Rotary tillage with base fertilizer and rotary tillage without base fertilizer significantly increased the total number of stems and tillers,total number of ears,and number of effective ears.Rotary tillage and application of base fertilizer also significantly increased the number of tillers,plant weight and weed suppression ability in the early stage of rice growth.Therefore,in the different soil preparation and fertilizer application methods,the application of base fertilizer with rotary tillage was the best,followed by rotary tillage without base fertilizer and no-tillage with base fertilizer.

Screening of New Rice Lines with Low CadmiumAccumulation

In order to screen new rice lines with low cadmium accumulation,20 rice materials/lines bred by Hunan Rice Research Institute were planted in three cadmium-contaminated areas for three consecutive years.The contents of cadmium in rice were detected and compared with those of emergency varieties Xiangwanxian 13 and Yangdao 6,which had low cadmium accumulation and high cadmium accumulation respectively.The results showed that the cadmium contents of 20 materials were lower than that of Yangdao 6,and 16 materials were lower than that of Xiangwanxian 13.Among them,10 materials such as R1195 were significantly lower than that of Xiangwanxian 13 and 8 materials such as BG130 were most significantly lower than that of Xiangwanxian 13.The low cadmium accumulation male sterile lines W115S and restorer lines R1195 and R1514 were screened out.

Verification of Glyphosate Resistance, Lepidopteran Resistance and Wide Compatibility of Male Sterile Line E1C4008S in Rice

Weeds and insect pests are two important biotic stresses resulting in yield loss in rice, and wide compatibility is the essential characteristic of breeding inter-subspecific hybrid rice. This study focused on glyphosate resistance, lepidopteran resistance and wide compatibility as well as identification of molecular and some agronomic characteristics of transgenic male sterile line E1 C4008 S. The results indicated that glyphosate resistance gene Epsps^# and lepidopteran resistance gene Cry1 ca^# were transferred into japonica wide compatibility male sterile line 4008 S by Agrobacterium-mediated method, and four independent transformation events named E1 C4008 S-1, E1 C4008 S-2, E1 C4008 S-3 and E1 C4008 S-4 were obtained, in which E1 C4008 S-3 and E1 C4008 S-4 were of single copy insertion. The EPSPS protein contents of E1 C4008 S-3 and E1 C4008 S-4 in different organs were significantly different both in descending order of leaf > stem > root, and ranged from 300.58 to 1410.69 μg/g at the tillering stage. The glyphosate tolerable concentration(dosage) of E1 C4008 S-3 and E1 C4008 S-4 reached at least 16 g/L(54.42 kg/hm^2), and the seeds of E1 C4008 S-4 can germinate normally on the medium containing 1 g/L glyphosate. The CRY1 C protein contents of E1 C4008 S-3 and E1 C4008 S-4 in different organs were significantly different both in descending order of leaf > stem > root, and ranged from 0.62 to 2.43 μg/g at the tillering stage. The larvae mortalities of rice leaf rollers fed on leaves of E1 C4008 S-3 and E1 C4008 S-4 for 5 d were 95.35% and 97.77%, respectively, while the average mortalities of silkworms fed with protein extracts from leaves of E1 C4008 S-3 and E1 C4008 S-4 reached 94.55% and 83.64%, respectively. The results suggested that wide compatibility and evaluated agronomic traits of E1 C4008 S-4 were not significantly changed by insertion of the exogenous genes. Overall, a novel male sterile germplasm with glyphosate resistance, lepidopteran resistance and wide compatibility was verified to be developed in rice.

Main Rice Pests Control with Trichogramma japonicum

This study used Trichogramma japonicumto to control Chilo suppressalis （Walker） and Cnaphalocrocis medinalis（Guenée）, and tested the effects of different control methods on main rice pests, natural enemies and rice yield. The results revealed that the parasitism of Trichogramma japonicum in the eggs of Chilo suppressalis （Walker） and Cnaphalocrocis medinalis （Guenée） reached 60.3% and 57.1%, and the control efficacy was up to 70.8 % and 91.99%, respectively. The control efficacy for Cnaphalocrocis medinalis （Guenée） was much better. This biological control method could be equivalent to chemical control method in the control effects on main pests in rice. The yield under the biological control was 26.5% higher than that of the control group, and the biological control had a signifcant increase in the number of natural enemies such as spider, up to 400 per 100 plants. Therefore, the sustainable prevention and control were achieved in the presentence with natural enemy organism.

Breeding of High Quality Conventional Japonica Type Glutinous Rice Bancangjingnuo

Bangcangjingnuo is a new, mid-maturing conventional Japonica type glutinous rice variety bred by Hunan Rice Research Institute and Hunan Wucai Agricultural Science and Technology Development Co., Ltd. In 2017, the Hunan Crop Variety Examination and Approval Committee approved Bangcangjingnuo. The breeding process of this cultivar was expounded in this study. This cultivar is highly glutinous and waxy, it produces a stable high yield, and it possesses the quality of low temperature resistance. The theoretical yield of Bangcangjingnuo is 8 731.5 kg/hm^2, and the actual output is about 7 422.0 kg/hm^2 according to the 85% discount.Finally, we described the main points of cultivation technique from the perspectives of timely planting and strict seed sterilization.

Heat Resistance of Rice Landrace D43 at Anthesis

Rice is extremely sensitive to high temperature, especially at the fowering stage. Identifying new germplasm and breeding heat-resistant rice varieties are therefore essential. After multi-year evaluations, a heat-resistant rice landrace D43 was identifed in our previous research. In this study, the relationship between heat resistance and flower opening time （FOT） was analyzed both in the field and in phytotron. The results showed that high temperature could accelerate fower opening of a range of rice varieties. The D43 showed early morning fowering （EMF） habit in different conditions, and the FOT of which was mainly concentrated in the period of 8：30~10：00 AM under high temperature. The spikelet fertility of D43 was relatively low after exposure to invariably high temperature during fower opening. However, the EMF habit of D43 was conducive to avoiding mid-day high temperature, and therefore increased the spikelet fertility under rising high temperature conditions in the feld and in phytotron. In addition, morphological traits including the anther dehiscence rate, the total number and germinated number of pollens on the stigma were signifcantly correlated with the spikelet fertility, and therefore they could be used to evaluate rice heat resistance at anthesis.

Genome-Wide Association Study for Milled Grain Appearance Traits Using Multi-Parent Advanced Generation Intercross Population in Rice

The identification of loci and markers associated with milled grain appearance traits is essential for breeding high-yielding and good-quality rice variety.To detect stable loci for these characteristics,grain length(GL),grain width(GW),grain length/width(GLW),chalkiness degree(CD),chalky-grain rate(CR)and translucency degree(TD)of 378 rice lines were evaluated in three seasons.These lines were derived from a multi-parent advanced generation intercross(MAGIC)population.

Genotype Analysis of Yuzhenxiang, a Long Grain, High Quality Aromatic Rice Cultivar

In China,the market share of a rice cultivar is mainly determined by its yield and quality.Yuzhenxiang is a high-quality variety with extra-slender grain shape,good quality and unique aroma.In order to investigate its genetic background,12 pairs of functional markers were used to detect the genotype distribution of eight major grain shape genes including GS3,GW5,GS6,GW6a,GL7/GW7,GLW7,GW8,GS9,one amylase gene Wx and one aroma gene BADH2 in Yuzhenxiang by using Nipponbare,9311,Huazhan,Zhonghui 8015 and Zhonghui 9308 as controls.The results indicated that the slender grain type of Yuzhenxiang was probably affected by GS3 and GL7/GW7 with the positive co-regulation of multiple grain shape genes,and its outstanding rice quality may be resulted from the cumulative effects of GLW7,GW8 and Wx genotypes,while its unique aroma may be mainly regulated by BADH2-E7 deletion.

The metal tolerance protein OsMTP11 facilitates cadmium sequestration in the vacuoles of leaf vascular cells for restricting its translocation into rice grains

Rice(Oryza sativa)provides>20%of the consumed calories in the human diet.However,rice is also a leading source of dietary cadmium(Cd)that seriously threatens human health.Deciphering the genetic network that underlies the grain-Cd accumulation will benefit the development of low-Cd rice and mitigate the effects of Cd accumulation in the rice grain.In this study,we identified a QTL gene,OsCS1,which is allelic to OsMTP11 and encodes a protein sequestering Cd in the leaf during vegetative growth and preventing Cd from being translocated to the grain after heading in rice.OsCS1 is predominantly expressed in leaf vascular parenchyma cells,where it binds to a vacuole-sorting receptor protein OsVSR2 and is translocated intracellularly from the trans-Golgi network to pre-vacuolar compartments and then to the vacuole.In this trafficking process,OsCS1 actively transports Cd into the endomembrane system and sequesters it in the vacuoles.There are natural variations in the promoter of OsCS1 between the indica and japonica rice subspecies.Duplication of a G-box-like motif in the promoter region of the superior allele of OsCS1 from indica rice enhances the binding of the transcription factor OsIRO2 to the OsCS1 promoter,thereby promoting OsCS1 expression.Introgression of this allele into commercial rice varieties could significantly lower grain-Cd levels compared to the inferior allele present in japonica rice.Collectively,our findings offer new insights into the genetic control of leaf-to-grain Cd translocation and provide a novel gene and its superior allele for the genetic improvement of low-Cd variety in rice.

Weed biology andmanagement in the multi-omics era:Progress and perspectives

Weeds pose a significant threat to crop production,resulting in substantial yield reduction.In addition,they possess robust weedy traits that enable them to survive in extreme environments and evade human con-trol.In recent years,the application of multi-omics biotechnologies has helped to reveal the molecular mechanisms underlying these weedy traits.In this review,we systematically describe diverse applications of multi-omics platforms for characterizing key aspects of weed biology,including the origins of weed spe-cies,weed classification,and the underlying genetic and molecular bases of important weedy traits such as crop–weed interactions,adaptability to different environments,photoperiodicflowering responses,and herbicide resistance.In addition,we discuss limitations to the application of multi-omics techniques in weed science,particularly compared with their extensive use in model plants and crops.In this regard,we provide a forward-looking perspective on the future application of multi-omics technologies to weed science research.These powerful tools hold great promise for comprehensively and efficiently unraveling the intricate molecular genetic mechanisms that underlie weedy traits.The resulting advances will facilitate the development of sustainable and highly effective weed management strategies,promoting greener practices in agriculture.

Rapid CO_(2)-laser scribing fabrication of an electrochemical sensor for the direct detection of Pb^(2+) and Cd^(2+)

Laser-induced graphene(LIG)is a highly promising preparation material for electrochemical sensors;however,its preparation speed and nanomaterial modification steps significantly limit its mass production.Herein,this study proposed a new laser printing strategy that considerably improved the preparation speed of LIG with excellent electrochemical performance.Using the optimal parameters(laser power of 1%,scribing spacing of 0.12 mm,scribing speed of 100 mm·s^(−1)),it took only 14.2 s to complete the preparation of the detection electrode.Thus,we successfully detected Cd^(2+)and Pb^(2+)without any toxic reagents or electrode modification steps.The limits of detection of the sensor were 0.914 and 0.916μg·L^(−1)for Cd^(2+)and Pb^(2+),respectively,which are significantly lower than the required values for drinking-water quality,according to the World Health Organization guidelines.This study provides a novel approach for the rapid detection of heavy-metal ions.