Overexpression of the peroxidase gene ZmPRX1 increases maize seedling drought tolerance by promoting root development and lignification

Drought is a main abiotic stress factor hindering plant growth,development,and crop productivity.Therefore,it is crucial to understand the mechanisms by which plants cope with drought stress.Here,the function of the maize peroxidase gene ZmPRX1 in drought stress tolerance was investigated by measurement of its expression in response to drought treatment both in a ZmPRX1 overexpression line and a mutant line.The higher root lignin accumulation and seedling survival rate of the overexpression line than that of the wild type or mutant support a role for ZmPRX1 in maize drought tolerance by regulating root development and lignification.Additionally,yeast one-hybrid,Dule luciferase and ChIP-qPCR assays showed that ZmPRX1 is negatively regulated by a nuclear-localized ZmWRKY86 transcription factor.The gene could potentially be used for breeding of drought-tolerant cultivars.

Hatching and development of maize cyst nematode Heterodera zeae infecting different plant hosts

The occurrence, distribution, and rapid molecular detection technology of Heterodera zeae Koshy et al. 1971, have been reported in China. We explored the biological characteristics of H. zeae sampled in Henan Province, China to understand its interaction with plants. Cysts and second-stage juveniles(J2s) were identified under an optical and scanning electron microscope, internal transcribed spacer(ITS) phylogenetic tree, and sequence characterized amplified region(SCAR)-PCR analyses. The optimum hatching temperatures of H. zeae were 30°C and 28°C, with cumulative hatching rates of 16.5 and 16.1%, respectively, at 30 days post-hatching(dph). The hatching rate of H. zeae eggs was improved by 20-and 50-time maize soil leachate and root juice, and 10-time root exudates. The hatching rate in 10-time root exudates was the highest(25.9%). The 10-time root exudates of maize and millet produced the highest hatching rate at 30 dph(25.9 and 22.9%, respectively), followed by wheat(19.9%), barley(18.3%), and rice(17.6%). Heterodera zeae developed faster in maize than in other crops. Fourth-stage juveniles(J4s) were detected in maize roots 8 days post-inoculation(dpi) at 28°C but not in other crops. Combined with hatching tests, the Huang–Huai–Hai summer maize region and the south and central-southwest mountainous maize areas are highly suitable for H. zeae in China. This is the first systematically study of the hatching and infection characteristics on different plant hosts of corn cyst nematode H. zeae in temperate regions. This study laid a theoretical foundation for the rapid spread and high environmental adaptability of corn cyst nematode.

Dek219 encodes the DICER-LIKE1 protein that affects chromatin accessibility and kernel development in maize

Chromatin accessibility plays a vital role in gene transcriptional regulation.However,the regulatory mechanism of chromatin accessibility,as well as its role in regulating crucial gene expression and kernel development in maize(Zea mays)are poorly understood.In this study,we isolated a maize kernel mutant designated as defective kernel219(dek219),which displays opaque endosperm and embryo abortion.Dek219 encodes the DICER-LIKE1(DCL1)protein,an essential enzyme in mi RNA biogenesis.Loss of function of Dek219 results in significant reductions in the expression levels of most mi RNAs and histone genes.Further research showed that the Heat shock transcription factor17(Hsf17)-Zm00001d016571 module may be one of the factors affecting the expression of histone genes.Assay results for transposase-accessible chromatin sequencing(ATAC-seq)indicated that the chromatin accessibility of dek219 is altered compared with that of wild type(WT),which may regulate the expression of crucial genes in kernel development.By analyzing differentially expressed genes(DEGs)and differentially accessible chromatin regions(ACRs)between WT and dek219,we identified 119 candidate genes that are regulated by chromatin accessibility,including some reported to be crucial genes for kernel development.Taken together,these results suggest that Dek219 affects chromatin accessibility and the expression of crucial genes that are required for maize kernel development.

The pentatricopeptide repeat protein EMP601 functions in maize seed development by affecting RNA editing of mitochondrial transcript ccmC

Although several pentatricopeptide repeat(PPR) proteins are involved in post-transcriptional processing of mitochondrial RNA, it is unclear which specific protein is involved in the RNA editing of ccmC in maize(Zea mays). Here we report the identification of the maize empty pericarp 601(emp601) mutant and the map-based cloning of the Emp601 gene, which encodes an E2-type PPR protein that is targeted to mitochondria. A single-nucleotide deletion in the emp601 mutant caused a frameshift and introduced a premature stop codon into the predicted EMP601. This mutation was associated with reduced accumulation of mitochondrial complex Ⅲ as well as with inhibition of growth and differentiation of basal endosperm transfer layer cells, leading to final degeneration of the embryo and endosperm. We determine that loss of EMP601 function prevents the C-to-U RNA editing of the mitochondrial transcript ccmC at position 358.EMP601 binds to the ccmC transcript and directly interacts with Multiple organellar RNA editing factor 8and may be a component of the plant mitochondrial editosome. We conclude that EMP601 functions in RNA editing of mitochondrial ccmC transcripts and influences mitochondrial function and seed development.

In Vitro Development of Tobacco Primary Endosperm Cells in Microculture

用酶解_研磨法分离出烟草 (NicotianatabacumL .)受精后胚囊和初生胚乳细胞进行微室饲养培养。培养基为Km8p附加各种其他成分 ,饲养细胞为分裂旺盛的烟草叶肉原生质体 ,在 2 5℃下静止暗培养。培养 3d后 ,初生胚乳细胞开始第一次分裂 ,继续分裂至 14d时形成大的细胞团。首次报道了双子叶植物初生胚乳细胞的离体发育。

Regulation of Foliar Application DCPTA on Growth and Development of Maize Seedling Leaves in Heilongjiang Province

DCPTA （2-diethylaminoethyl-3, 4-dichlorophenylether） is a new plant regulator which can be used to regulate growth and development for crops. Experiments on maize seedlings were conducted in the growth chamber to study the effects of foliar applied DCPTA. The plant pots were placed in a completely randomized design with three replicates. The maize seedlings were treated with 0 mg·L-1 （control）, 20 mg·L-1 and 40 mg·L-1 DCPTA solution. The effects of DCPTA on the photosynthetic characteristics （photosynthesis, stomata conductance, intercellular CO2, and transpiration rate）, related physiological characteristics （contents of soluble sugar and starch）, chlorophyll fluorescence parameters （Fo, Fro, Fv/Fm, Fv/Fo, qP, and qN） and the weight of dry matter in maize seedling were studied. The results showed that DCPTA enhanced photosynthesis of maize seedling. In general, photosynthetic rate in leaves was significantly promoted through spraying DCPTA solution, and 40 rag＂ L~ DCPTA was found to be the best concentration for maize. The relationship between stomata conductance and transpiration rate in maize leaves could be described as linear. With regard to the chlorophyll fluorescence parameters, our fmdings showed that 40 mg·L-1 DCPTA in maize seedling caused an increase in Fm, Fv/Fm, Fm/Fo, qP and a decrease in Fo and qN at some time points checked. It is suggested that DCPTA increased photosynthetic rate by raising both the content of chlorophyll and activities of PSII and the contents of sugar and starch. Compared with the control, the treated maize seedling caused an increase in plant height, root length, shoot dry mass, root dry mass, or the total （root plus shoot） dry mass.

Studies on the Programmed Cell Death in Rice During Starchy Endosperm Development

Morphological variations of the nucleus in starchy endosperm cell were observed by theelectron-transmisson microscope during endosperm development in rice. Along with thedevelopment of the starchy endosperm, the nuclei of the cells showed chromatin condensation,the typical feature of programmed cell death (PCD). The nuclei also showed nucleusdeformation, disruption of nuclear envelope, nucleoplasm leaking into the cytoplasm andnucleus disintegration resulting in nuclear residue formation. From the nucleus deformationto the nucleus disintegration, the morphological changes of the nucleus were orderlyprogressive. This indicated that the cell death of starchy endosperm in rice wasprogrammed cell death. Evans Blue staining observation showed that the cell death wasinitially detected in the central part of starchy endosperm in rice, then expandedoutward. The activities of superoxide dismutase (SOD) and catalase (CAT) in rice starchyendosperm both descended continuously as development progressed. The analysis of DNA ofrice starchy endosperm did not show the presence of DNA laddering. The above resultsshowed that the cell death of starchy endosperm in rice was a special form of PCD.

SWOT Analysis and Development Strategies of Maize Industry in Heilongjiang Province

With the development of China＇s market economy, the international grain supply situation is increasingly tense, and the grain has been regarded as an important international strategic resource in the international market. Due to the reduction of international grain output and expected inflation, the gap between maize supply shortage and increasing demand is apparent in China, so that China is described as a worrying importer country. By using SWOT analysis belonging to the field of enterprise strategic management, this paper analyzed the current maize industry development in Heilongjiang Province as an entry point, the strength, weakness and opportunity and threat were put forward. Thereby, the developing principles and strategies were proposed to stimulate the maize industry development in Heilongjiang Province, which would lay a good foundation of 50 billion kilograms grain production capacity by 2015 in China, as well as the economic development and local farmers＇ income increase.

Effects of Planting Date on Development and Field of Forage Maize

[ Objective] To investigate the effects of planting date on development and yield of forage maize and to determine the appropriate plant- ing date for forage maize. [ Method] Using forage maize 50 as experimental material, the development of forage maize was observed, and the yield of forage in the later grain filling period and mature stage was measured, after the maize were planted at different dates, r Remltl With the delaying planting date, phenological period was delayed, and the duration of the same growing stage was shortened among different treatments. The shor- test duration days of anthesis maturity period appeared in the treatment of planting in June 15, and the duration days of anthesis maturity period was increased in the treatment of planting in June 30. With the delaying planting date, the height of maize plant in the five leaf stage was increased. The highest plant in the jointing stage appeared in the treatment of planting in June 15. However, the highest plant appeared in the treatment of planting in May 30 after the jointing stage. The number of green leaves per plant was reduced with the delaying planting date in the tasseling stage, and it was increased with the delaying planting date from later grain filling period to mature stage. With the delaying planting date, the fresh matter yield, forage yield and grain yield were reduced. [ Conclusion] The study provides theoretical and practical reference for high-yield cultivation of forage maize.

Recent Development in Maize Research at Institute for Agricultural Research, Samaru, Nigeria

Maize research at Institute for Agricultural Research, Samaru, Nigeria resulted in sustained growth in yields in the last two decades. Maize is grown throughout the country with guinea savanna as the most important maize growing zone. In the last five years, four new open pollinating varieties developed in collaboration with the International Institute of Tropical Agriculture （IITA, Ibadan） had been released for production. Hybrid varieties are also marketed by seed companies. The research was focused on variety improvement, improved management practices, integrated pests and disease control, soil fertility management, on-farm testing of improved production packages and socio-economics of production as well as adoption studies. The recently released quality protein maize has improved the nutritional status of vulnerable groups. Drought tolerant maize for Africa research project has contributed to sustainable maize production, poverty reduction and food security in the continent.

Effect of three insect-resistant maizes expressing Cry1le,Cry1Ab/Cry2Aj and Cry1Ab on the growth and development of armyworm Mythimna separata(Walker)

Three transgenic maize events(IE09S034,Shuangkang 12--5 and C0030.3.5)produced Cry1le,Cry1Ab/Cry2Aj and G10-EPSPS,Cry1Ab and EPSPS,respectively,all of which target the Asian corn borer.The oriental armyworm Mythimna separata(Walker)is the secondary target.In this study,the effects of the three Bt maizes on the development and survival of armyworm were studied.The results showed that IE09S034 had insecticidal activity against 1st instar larvae,and the survival rate of armyworm fed with Bt maize for 10 days was 462%,significantly lower than that of the control.The larvae at 3rd--6th instar were more tolerant of the Bt toxin than the early instar larvae.However,Shuangkang 12-5 had good insecticidal activity against 1st-5th instar larvae.The mortality was nearly 100%when the larvae were fed with Shuangkang 12-5 before 3rd instar,and the toxin had quick acting eficacy.This event significantly ihibited the development of armyworm;that is,the larval duration of the 3rd and 4th instar larvae fed with Shuangkang 12-5 was prolonged by 4.5 and 3.0 days,respectively.The pupal weight and egg number were also significantly lower than those of the control.For C0030.3.5,it could control 1st--5th instar larvae effectively.The mortality rates were all over 50%if 1st-3rd larvae were fed with this event.The pupal weight of 4th-6th instar larvae fed with Bt maize were only 53.9,56.8 and 54.6%,respectively,compared to that of the control.The number of eggs laid was significantly less than the control.The results indicate that all three transgenic maize events exhibit the potential to provide effective control of early instar larvae of armyworm.which can be commercialized in future to control lepidoptera pests such as Asian corn borer and armyworm.

Identification and Genetic Analysis of a Novel Allelic Variation of Brittle-1 with Endosperm Mutant in Maize

Endosperm mutants are critical to the studies on both starch synthesis and metabolism and genetic improvement of starch quality in maize.In the present study,a novel maize endosperm mutant A0178 of natural variation was used as the experimental material and identified and then characterized.Through phenotypic identification,genetic analysis,main ingredients measurement and embryo rescue,development of genetic mapping population from A0178,the endosperm mutant gene was located.The results showed that the mutant exhibited extremely low germination ability as attributed to the inhibited embryo development,and amounts of sugars were accumulated in the mutant seeds and more sugars content was detected at 23 days after pollination(DAP)in A0178 than B73.Employing genetic linkage analysis,the mutant trait was mapped in the bin 5.04 on chromosome 5.Sequence analysis showed that two sites of base transversion and insertion presented in the protein coding region and non-coding region of the mutant brittle-1(bt1),the adenylate translocator encoding gene involved in the starch synthesis.The single base insertion in the coding region cause frameshift mutation,early termination and lose of function of Brittle-1(BT1).All results suggested that bt1 is a novel allelic gene and the causal gene of this endosperm mutant,providing insights on the mechanism of endosperm formation in maize.

Ultracytochemical Localization and Functional Analysis of ATPase During the Endosperm Development in Oryza sativa L.

Ultracytochemical localization of ATPase during development of rice endosperm was performed using a lead phosphate precipitation technique. The results indicated that, at the coenocyte and cellularization stages, active ATPase was mainly distributed in an embryo sac wall, nucleus, and plasma membrane. At the early stage of development and differentiation, active ATPase was observed in the plasma membrane. At the grain filling stage, ATPase was highly active in the plasma membrane, intercellular space, and plasmodesmata in aleurone, moderately active on the plasma membrane in subaleurone. In starchy endosperm, ATPase was localized in the plasma membrane and degenerated nucleus. ATPase activity also appeared around vacuole and protein body in endosperm cell. The relationships between the ultracytochemical localization of ATPase and its function during the development of rice endosperm were discussed. Overall, ATPase was involved in the process of nutrition absorption and protein synthesis.

Maize endosperm development

Recent breakthroughs in transcriptome analysis and gene characterization have provided valuable resources and information about the maize endosperm developmental program.The high temporal-resolution transcriptome analysis has yielded unprecedented access to information about the genetic control of seed development.Detailed spatial transcriptome analysis using laser-capture microdissection has revealed the expression patterns of specific populations of genes in the four major endosperm compartments:the basal endosperm transfer layer(BETL),aleurone layer(AL),starchy endosperm(SE),and embryo-surrounding region(ESR).Although the overall picture of the transcriptional regulatory network of endosperm development remains fragmentary,there have been some exciting advances,such as the identification of OPAQUE11(O11)as a central hub of the maize endosperm regulatory network connecting endosperm development,nutrient metabolism,and stress responses,and the discovery that the endosperm adjacent to scutellum(EAS)serves as a dynamic interface for endosperm-embryo crosstalk.In addition,several genes that function in BETL development,AL differentiation,and the endosperm cell cycle have been identified,such as ZmSWEET4c,Thk1,and Dek15,respectively.Here,we focus on current advances in understanding the molecular factors involved in BETL,AL,SE,ESR,and EAS development,including the specific transcriptional regulatory networks that function in each compartment during endosperm development.

Striking a growth–defense balance:Stress regulators that function in maize development

Maize(Zea mays)cultivation is strongly affected by both abiotic and biotic stress,leading to reduced growth and productivity.It has recently become clear that regulators of plant stress responses,including the phytohormones abscisic acid(ABA),ethylene(ET),and jasmonic acid(JA),together with reactive oxygen species(ROS),shape plant growth and development.Beyond their well established functions in stress responses,these molecules play crucial roles in balancing growth and defense,which must be finely tuned to achieve high yields in crops while maintaining some level of defense.In this review,we provide an in-depth analysis of recent research on the developmental functions of stress regulators,focusing specifically on maize.By unraveling the contributions of these regulators to maize development,we present new avenues for enhancing maize cultivation and growth while highlighting the potential risks associated with manipulating stress regulators to enhance grain yields in the face of environmental challenges.

Business Model,Current Situation and Development Countermeas-ures of Maize in Shiyan City,Hubei Province

In order to understand the status of business model and scale business of maize in Shiyan City,Hubei Province,the situation of maize production in 314 households of 6 counties and cities of Shiyan City was investigated in terms of rural basic situation,business models,economic benefits and scale business. Targeting at the actual problems in business models and scale business,corresponding countermeasures of actively promoting the construction of industrialized business mechanism,improving the construction of agricultural infrastructure,strengthening land transfer management and promoting scientific and technological progress and innovation were put forward to provide reference for the future scale development of maize in Shiyan City.

Sucrose-associated SnRK1a1-mediated phosphorylation of Opaque2 modulates endosperm filling in maize

During maize endosperm filling,sucrose not only serves as a source of carbon skeletons for storage-reserve synthesis but also acts as a stimulus to promote this process.However,the molecular mechanisms underlying sucrose and endosperm filling are poorly understood.In this study,we found that sucrose promotes the expression of endosperm-filling hub gene Opaque2(O2),coordinating with storage-reserve accumulation.We showed that the protein kinase SnRK1a1 can attenuate O2-mediated transactivation,but sucrose can release this suppression.Biochemical assays revealed that SnRK1a1 phosphorylates O2 at serine 41(S41),negatively affecting its protein stability and transactivation ability.We observed that mutation of SnRK1a1 results in larger seeds with increased kernel weight and storage reserves,while overexpression of SnRK1a1 causes the opposite effect.Overexpression of the native O2(O2-OE),phospho-dead(O2-SA),and phospho-mimetic(O2-SD)variants all increased 100-kernel weight.Although O2-SA seeds exhibit smaller kernel size,they have higher accumulation of starch and proteins,resulting in larger vitreous endosperm and increased test weight.O2-SD seeds display larger kernel size but unchanged levels of storage reserves and test weight.O2-OE seeds show elevated kernel dimensions and nutrient storage,like a mixture of O2-SA and O2-SD seeds.Collectively,our study discovers a novel regulatory mechanism of maize endosperm filling.Identification of S41 as a SnRK1-mediated phosphorylation site in O2 offers a potential engineering target for enhancing storage-reserve accumulation and yield in maize.

Increase in root density induced by coronatine improves maize drought resistance in North China

Drought stress caused by insufficient irrigation or precipitation impairs agricultural production worldwide.In this study,a two-year field experiment was conducted to investigate the effect of coronatine(COR),a functional analog of jasmonic acid(JA),on maize drought resistance.The experiment included two water treatments(rainfed and irrigation),four COR concentrations(mock,0μmol L^(-1);A1,0.1μmol L^(-1);A2,1μmol L^(-1);A3,10μmol L^(-1))and two maize genotypes(Fumin 985(FM985),a drought-resistant cultivar and Xianyu 335(XY335),a drought-sensitive cultivar).Spraying 1μmol L^(-1)COR at seedling stage increased surface root density and size,including root dry matter by 12.6%,projected root area by 19.0%,average root density by 51.9%,and thus root bleeding sap by 28.2%under drought conditions.COR application also increased leaf area and SPAD values,a result attributed to improvement of the root system and increases in abscisic acid(ABA),JA,and salicylic acid(SA)contents.The improvement of leaves and roots laid the foundation for increasing plant height and dry matter accumulation.COR application reduced anthesis and silking interval,increasing kernel number per ear.COR treatment at 1μmol L^(-1)increased the yield of XY335 and FM985 by 7.9%and 11.0%,respectively.Correlation and path analysis showed that grain yields were correlated with root dry weight and projected root area,increasing maize drought resistance mainly via leaf area index and dry matter accumulation.Overall,COR increased maize drought resistance mainly by increasing root dry weight and root area,with 1μmol L-^(-1)COR as an optimal concentration.

The DEAD-box RNA helicase ZmRH48 is required for the splicing of multiple mitochondrial introns,mitochondrial complex biosynthesis,and seed development in maize

RNA helicases participate in nearly all aspects of RNA metabolism by rearranging RNAs or RNA–protein complexes in an adenosine triphosphatedependent manner.Due to the large RNA helicase families in plants,the precise roles of many RNA helicases in plant physiology and development remain to be clarified.Here,we show that mutations in maize(Zea mays)DEAD-box RNA helicase48(Zm RH48)impair the splicing of mitochondrial introns,mitochondrial complex biosynthesis,and seed development.Loss of Zm RH48 function severely arrested embryogenesis and endosperm development,leading to defective kernel formation.Zm RH48 is targeted to mitochondria,where its deficiency dramatically reduced the splicing efficiency of five cis-introns(nad5 intron 1;nad7 introns 1,2,and 3;and ccm Fc intron 1)and one trans-intron(nad2 intron 2),leading to lower levels of mitochondrial complexes I andⅢ.Zm RH48 interacts with two unique pentatricopeptide repeat(PPR)proteins,PPR-SMR1 and SPR2,which are required for the splicing of over half of all mitochondrial introns.PPR-SMR1 interacts with SPR2,and both proteins interact with P-type PPR proteins and Zm-m CSF1 to facilitate intron splicing.These results suggest that Zm RH48 is likely a component of a splicing complex and is critical for mitochondrial complex biosynthesis and seed development.

ZmMS39 encodes a callose synthase essential for male fertility in maize(Zea mays L.)

Callose contributes to many biological processes of higher plants including pollen development,cell plate and vascular tissue formation,as well as regulating the transport function of plasmodesmata.The functions of callose synthase genes in maize have been little studied.We describe a maize male-sterile mutant 39(ms39)characterized by reduced plant height.In this study,we confirmed using CRISPR/Cas9 technology that a mutation in Zm00001d043909(ZmCals12),encoding a callose synthase,is responsible for the male sterility of the ms39 mutant.Compared with male-fertile plants,callose deposition around the dyads and tetrads in ms39 anthers was significantly reduced.Increased cell autophagy observed in ms39 anthers may have been due to the premature programmed cell death of tapetal cells,leading to collapse of the anther wall structure.Disordered glucose metabolism in ms39 may have intensified autophagy in anthers.Evaluation of the ms39 gene on maize heterosis by paired-crossed experiment with 11 maize inbred lines indicated that ms39 can be used for maize hybrid seed production.