Table of Content

12 February 2017, Volume 43 Issue 02

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REVIEW

Characteristics of Genes Selected by Domestication and Intensive Breeding in Crop Plants

ZHANG Xue-Yong, MA Lin, ZHENG Jun

Acta Agron Sin. 2017, 43(02):  157-170.  doi:10.3724/SP.J.1006.2017.00157

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Crop genomics made great progress in last 15–20 years. Second generation sequencing technology has dramatically reduced the cost of genome sequencing, brought life science into the times of genomics,and strongly promoted development of system biology, genetics, breeding and genetic resources. Single nucleotide polymorphism (SNP) and haplotype block analysis are currently widely used forexploring animal and plant genetic resources and breeding. Successful isolation of many important genes help us elucidate the history of crop domestication and breeding, andpredict the future of breeding. It has been changing the breeding concepts and strategies. Most crop cultivars used today have experienced two major steps of harsh artificial selection, i.e., domestication and breeding. Despite so many similarities between domestication and breeding, they are different in some aspects. Domestication relatively affects small regions of plant genome. The dramatic reduction of diversity is usually caused by bottleneck effect.Although the breeding history is only about 100 years, it has brought tremendous alteration in most crop genomes.Breeding targets much more genes than domestication.It is very difficult for further selection of alleles at domestication targeted locus, usually only one alleleiskept, which referred as fixed. However, it is not in the case of selecting alleles at breeding targeted locus. Few alleles can be present at the same time in varient populations and rotate at the same locus in cultivars released in different periods or regions. Frequency of favored alleles in new cultivars has been increased dramatically because of positive selection. In addition,strong artificial selection usually reshapes the sub-genomes in polyploid species, which made them quite distinct from donor’s genomes. Therefore, it would be a good strategy to highlight future breeding through elucidating the basic rule of crop genome and gene in reaction to artificial selection at the targeted regions. Here, webriefly review the current major strategies for dissection of genes, haplotype blocks as well as the major genes targeted in crop domestication and breeding selection. We also give a brief introduction on the mission and strategies for “formation and evolution mechanism of funder genotypes and famous cultivars in major crops”, a newly initiated national key research and development program of China.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Fertility Alteration in Male Sterile Line BS210 of Wheat

SUN Hui**,ZHANG Feng-Ting**,WANG Yong-Bo,YE Zhi-Jie,QIN Zhi-Lie,BAI Xiu-Cheng,YANG Ji-Fang,GAO Jian-Gang,ZHAO Chang-Ping

Acta Agron Sin. 2017, 43(02):  171-178.  doi:10.3724/SP.J.1006.2017.00171

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Two-line hybrid wheat is an innovation in China and its critical technique is the application of thermo-photo-sensitive male sterile line. BS210 is a male sterile wheat line developed by our group. We studied the fertility transition characteristics of BS210 with differentially sowing tests at three ecological locations and contorlled experiments in growth chambers from 2012 to 2014. In the hybrid seed-produing locations, BS210 showed sterility of 95–100% under suitable sowing conditions with the safe sowing dates from September 30th to October 10th in Fuyang of Anhui and September 30th in Lijiang of Yunnan. In the self-reproducting locations, BS210 showed fertility of 70% under late sowing conditions with the safe sowing dates of November 10th in Haidian of Beijing and from September 30th to November 10th in Shunyi of Beijing. The fertility alteration of BS210 was induced mainly by temperature rather than photoperiod. The phase from pollen mother cell formation to mono-nucleate was sensitive to fertility alteration of BS210. The critical temperature of alteration was 10–12°C under the photoperiod of 10.0–12.5 h and 8–10°C under the photoperiod of 14 h. The pollen-staining observation indicated that the sterile pollen grains belonged to stained abortion type under short-day and low-temperature condition and the fertile pollen grains were round in shape and dark blue in color under long-day and high-temperature condition. Defining the fertility transition characteristics of BS210 will provide theoretical guidelines for selecting suitable ecological zone to ensure safe seed production.

QTL Mapping for Seedling Dry Weight and Fresh Weight under Salt Stress and Candidate Genes Analysis in Brassica napus L.

HOU Lin-Tao,WANG Teng-Yue,JIAN Hong-Ju,WANG Jia,LI Jia-Na,LIU Lie-Zhao

Acta Agron Sin. 2017, 43(02):  179-189.  doi:10.3724/SP.J.1006.2017.00179

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Salt stress is one of the main abiotic stresses affecting crop yield and it would be very important by using the salt tolerance related markers in rapeseed breeding to improve the oilseed production. In this research, the Brassica napus L high generation recombinant inbred lines (RIL) population derived from the cross of GH06 and P174 via single seed descent propagation was used for QTL mapping and candidate gene analysis. The fresh and dry weight of leaf and root were measured at 25 days after the seedlings were grown in Hoagland solution with 16 g L^–1 NaCl. Composite interval mapping (CIM) was used to identify the related QTLs according to the high density SNP genetic map, and the candidate gene expression in the extreme lines tested by qRT-PCR. A total of 19 QTLs were identified in the control and salt stress treatment, and six QTLs were mapped on chromosomes A02, A04 and C03 under salt stress, with contribution rate ranged from 7.16% to 16.15%. Eight genes were identified according to the BLAST of genes in the QTL confidence intervals and the salt stress related genes in Arabidopsis. The expression of four candidate genes in the extreme lines showed that BnaA02g14680D and BnaA02g14490D under salt stress treatment for 48 or 72 hours had higher expression than the control, which indicates that the expressions are induced by salt stress. The relative expressions of gene BnaC03g64030D in sensitive extreme lines were higher than those in tolerant extreme lines. There were no changed in expression for gene BnaC03g62830D in sensitive extreme lines but increased expression at 48 hours and reduced expression at 72 hours after salt treatment in tolerant extreme lines, showing the enhance of plant salt tolerance possibly. Our research laid a foundation for the function research of salt tolerant gene in rapeseed and the breeding of salt tolerant rapeseed.

Cloning of Na⁺ Transporter Protein SbSKC1 Gene from Sorghum and Identification of Its Salt-resistant Function in Tobacco

YAO Xin-Zhuan,LIU Yang,ZHAO De-Gang

Acta Agron Sin. 2017, 43(02):  190-200.  doi:10.3724/SP.J.1006.2017.00190

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Na⁺ transporter proteingene plays an important role in plant in response to abiotic stresses. In this research, SbSKC1, a Na⁺ transporter gene was cloned from Sorghum bicolor. The full-length open reading frame comprises 1497 bp and encodes 498 amino acids. Multiple sequence alignment and phylogenetic analysis showed that the Na⁺ transporter gene SbSKC1 in sorghum and maize had a high similarity. The SbSKC1gene was transferred into tobacco (Nicotiana tabacum cv. Xanthi) via Agrobacterium- mediated transformation. The salt tolerance of transgenic tobacco was screened by PCR. Under the 300mmol L^-1 NaCl treatment, the survival rate of transgenic tobacco was higher than that of wild type and the root length of transgenic tobacco was significantly higher than that of the wild type. At the same time, transgenic tobacco maintained a higher content of K⁺/Na⁺. Under salt stress treatment, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were significantly higher in transgenic tobacco than in the wild type. However, the content of hydrogen peroxide (H₂O₂) in transgenic tobacco was 37.7% lower than in the wild type tobacco. It’s suggests that overexpression of SbSKC1 gene can significantly improve the salt resistance of tobacco.

Cloning, Molecular Characterization, and Functional Analysis of Wheat TaVIP1 Genes

ZHAO Pei,TENG Li-Jie,WANG Ke,DU Li-Pu,REN Xian,SHE Mao-Yun,YE Xing-Guo

Acta Agron Sin. 2017, 43(02):  201-209.  doi:10.3724/SP.J.1006.2017.00201

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Plant VIP1 (VirE2 interacting protein 1) is involved in the transportation of T-DNA in plant cells after Agrobacterium infection, affecting plant transformation efficiency. However, the function of TaVIP1 is unknown. Using in silico technique, a family of TaVIP1 genes were successfully cloned from common wheat in this study. The gene family encompasses four exons and shares high similarity among its members while only 50.7%–51.4% similarity to the AtVIP1 in Arabidopsis. Southern blotting assay showed that the TaVIP1 had three allelic copies in wheat genome. The three copies of TaVIP1 were further assigned to wheat chromosomes 4AL, 4BS, and 4DS according to Blastn in the IWGSC (International Wheat Genome Sequencing Consortium) database, and experimentally confirmed by PCR using specific primers to each TaVIP1 allele based on their DNA sequences and Langdon durum disomic substitution lines. Subcellular localization analysis showed that TaVIP1 proteins were located in cell membrane, cytoplasm and nucleus. Over-expression of TaVIP1 in tobacco obviously reduced Agrobacterium-mediated transformation efficiency. The amino acid sequence encoded by TaVIP1 only had less similarity to the corresponding amino acid sequence encoded by AtVIP1 in Arabidopsis or NtVIP1 in tobacco. This might be a reason of the low transformation efficiency of wheat mediated by Agrobacterium.

Exploring Sterility Gene from Tea Plant Flower Based on Digital Gene Expression Profiling

CHEN Lin-Bo,XIA Li-Fei,TIAN Yi-Ping,LI Mei,SONG Wei-Xi,LIANG Ming-Zhi,JIANG Chang-Jun

Acta Agron Sin. 2017, 43(02):  210-217.  doi:10.3724/SP.J.1006.2017.00210

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Tea tree (Camellia sinensis) blossoms every year and a lot of nutrients are consumed by itself during blooming and fruiting, resulting in decreased yield and quality of fresh tea leaf. In the present study, the flowers of Fuding Dabaicha (male parent), Foxiang 2 (female parent) and their hybrid (sterile flowers) were used to construct cDNA libraries and the gene expression profiles were analyzed by Solexa sequencing technology. A total of 1219 candidate sterility genes were identified according to their differential expression between the male/female parent and the hybrid but identical between the two parents. These sterility gene were subject to GO analysis, and metabolic process, hydrolase activity and catalytic activity were enriched. KEGG pathway analysis showed that the sterility genes were involved in biosynthesis of amino acids and carbohydrate, second any metabolism, plant hormone signal transduction, and energy metabolism. In the function group of plant hormone signal transduction, 16 annotated genes were involved in the auxin signal transduction pathway, including five up-regulated AFR genes in the hybrid and 11 down-regulated genes. Thus, we speculate that auxin signal transduction might regulate the flower sterility in tea tree. Five sterility genes were selected randomly for qRT-PCR assay and the result was consistent with that of Solexa sequencing. The candidate sterility genes found in this study are worthy of sterile mechanism research in tea plant and sterility gene screening.

Screening of AhHDA1 Interacting-Protein AhGLK and Characterization in Peanut (Arachis hypogaea L.)

LI Mei-Juan,SU Liang-Chen,LIU Shuai,LI Xiao-Yun*,LI Ling*

Acta Agron Sin. 2017, 43(02):  218-225.  doi: 10.3724/SP.J.1006.2017.00218

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With AhHDA1 as bait, the peanut (Arachis hypogaea L.) cDNA library was screened and characteristics of the interacting-protein was analysed, getting a protein of Golden 2-like (AhGLK) interacted with AhHDA1 which was proved by yeast two-hybrid experiments, and further confirmed by bimolecular fluorescence complementation (BiFC) assay. Bioinformatics software analysis indicated that AhGLK contained a MYB conserved domain having high homology with GsGLK (Glyine soja) and AtGLK (Arabidopsis thaliana). AhGLK was found to be located in nucleus and testified as a transcriptional activation factor. Tissue specific analysis showed that AhGLK accumulated in leaves mainly, and the expression was down-regulated by 30% PEG treatment. The results lay a foundation for further study on AhGLK, which might be involved in drought stress resistance of peanut.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effect of Root-shoot Interaction on Cotton Leaf Senescence

ZHANG Qiao-Yu,WANG Yi-Ru,AN Jing,WANG Bao-Min,TIAN Xiao-Li

Acta Agron Sin. 2017, 43(02):  226-237.  doi: 10.3724/SP.J.1006.2017.00226

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Researches and practices associated with grafting indicate that the diversity of root-shoot interaction is universal in different physiological processes of plant. Our previous grafting study with CCRI41, an early senescence cotton cultivar, and SCRC22, a late senescence cultivar as materials found that shoot played a major role in mediating leaf senescence of cotton. In the present study, CCRI41 and another late senescence cotton cultivar CCRI49 were used to do standard grafting (I-grafting, one scion grafted onto one rootstock) and Y-grafting (two scions grafted onto one rootstock). Leaf senescence of grafts was induced by low potassium (K; 0.03 mmol L^–1). Contrary to the grafting combination of CCRI41 and SCRC22, the combination of CCRI41 and CCRI49 showed that the role of root was more important than that of shoot for leaf senescence, as characterized by SPAD reading. Accordingly, the concentration of ZR+Z or iPA+iP in roots and the youngest fully expanded leaf and their delivery rate in xylem sap regarding I-grafting combinations with CCRI41 as rootstock were significantly lower than those with CCRI49 as rootstock in most of situations. However, the results of free ABA level were exactly opposite. With respect to the Y-grafting of CCRI41 and CCRI49, the results were similar to those of I-grafting, whereas the role of root was not absolutely predominant any more. The mechanism for different root-shoot interactions in cotton leaf senescence was discussed from the perspective of root-shoot-root distance communication.

Effects of Spikelet and Grain Positions on Grain Weight and Protein Content of Different Wheat Varieties

LI Hao-Sheng,CAO Xin-You,SONG Jian-Min,LIU Peng,CHEN Dun-Gong,LIU Ai-Feng,WANG Can-Guo,LIU Jian-Jun,SUN Zheng-Juan

Acta Agron Sin. 2017, 43(02):  238-252.  doi:10.3724/SP.J.1006.2017.00238

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Wheat seeds are developed in a spatial-temporal order resulting in different grain weights and protein contents in different positions of spike. Dissecting the position effect of grain weight and protein content is helpful to go into the mechanism of yield and quality formation. This study was carried out in the 2009–2010 and 2010–2011 winter wheat seasons with four varieties in three quality types. The dynamic changes of grain weight, protein accumulation and protein content were measured according to spikelet–grain position. Variations of grain weight and protein accumulation affected by spikelet–grain position were greater than those by environment (year) or genotype. Variation of protein content affected by environment was larger than that by genotype or spikelet–grain position, however, the spikelet–grain position was the first affecting factor at maturity stage. Large-grain variety was more sensitive to environment, whereas, small-grain variety was relatively stable. During grain filling, the protein content of strong-gluten wheat was higher than that of medium-gluten wheat, and influenced greatly by filling stage and environment. The single grain weight, protein content, and protein accumulation of superior grains were significantly higher than those of inferior grains during the grain-filling period, and the mid-position grains were significantly superior to the upper- and lower-position grains. However, the difference between mid- and lower-position grains became smaller with the filling process, until no significant difference in protein content at maturity stage (36 days after flowering). The dynamics of single grain weight and protein accumulation showed an “S” curve of slow–fast-slow changing trend and the dynamics of protein content showed a “V” curve, in spite of genotype or spikelet–grain position. During late filling stage, the supervisor grains in mid- and lower-positions, as well as inferior grains in lower-position had faster increase of protein content than grains in other positions. For grain weight, the maximum growth rate appeared at 18–21 days after flowering, and the rapid growth period appeared at 12–26 days after flowering. For grain protein, the maximum accumulation rate appeared at 21–24 days after flowering, and the fast accumulation period was from 13 to 32 days after flowering. It is concluded that moderate grain size and floret number are important for high-yield and high-quality wheat breeding, and an appropriate increase of the mid- and lower-position grains may accelerate grain-filling speed at 13–26 days after flowering.

Effect of Soil Depth with Supplemental Irrigation on Canopy Photosynthetically Active Radiation Interception andChlorophyll Fluorescence Parameters in Jimai 22

YANG Chuan-Bang,YU Zhen-Wen,ZHANG Yong-Li*,SHI Yu

Acta Agron Sin. 2017, 43(02):  253-262.  doi:10.3724/SP.J.1006.2017.00253

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Supplemental irrigation based on moisture measurement of soil is a water-saving technology newly developed in wheat cultivation,in which soil depth is one of the key factors. In this study, we conducted a field experiment with the high-yield variety Jimai 22 in Yanzhou, Shandong province in 2013–2014 and 2014–2015 winter wheat seasons to unravel the photosynthetic basis of high yield by supplemental irrigation in the proper soil layer. Four supplemental irrigation treatments (relative soil water content of 70% and 75% at jointing and anthesis stage, respectively) were designed with the target soil depths of 20 (T20, 40 (T40), 60 (T60), and 80 cm (T80), and no irrigation and traditionally fixed irrigation (60 mm at jointing and anthesis each) were used as the controls. The indices measured were canopy photosynthetically active radiation(PAR) interception, canopy apparent photosynthesis(CAP), and chlorophyll fluorescence parametersof flag leaves from 0 to 30 days after anthesis, as well as grain yield and water use efficiency(WUE). The leaf area index, PAR interception, canopy light interception rate, CAP of treatment T40 were 6.0–42.4%, 8.5–27.9%, 6.7–14.5%, and 11.0–14.6% higher than those of treatment T20,respectively.At the same time, the maximal quantum yield of PSII (F_v/F_m), actual efficiency of PSII (Φ_PSII) of flag leaves also improved significantly. When making supplemental irrigation to 60cm and 80cm soil layers, the above parameters had no significant increase. The grain yield of treatment T40 was not significantly different from that of T60,T80 andfixed irrigation control. However, irrigation amount significantly decreased by 26.9–46.9mm, water use efficiency and irrigation benefit significantly increased by 16.2–16.7% and 34.0–68.1% respectively during both wheat growing seasons as compared with those of fixed irrigation control. Supplemental irrigation based on soil moisture measurement in 0–40 cm soil layer is the most appropriate treatment in similar ecological conditions to this study for Jimai 22wheat cultivar.

Effects of Nitrogen Application Rates on Dry Matter Productivity and Nitrogen Utilization of Different Type Maize Hybrids

ZHOU Pei-Lu,REN Hong,QI Hua,ZHAO Ming,LI Cong-Feng

Acta Agron Sin. 2017, 43(02):  263-276.  doi:10.3724/SP.J.1006.2017.00263

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To understand the relationship between dry matter productivity, nitrogen utilization and grain yield of spring maize hybrids in Northeast China, we conducted a field experiment in 2014 and 2015. Using two maize hybrids (Xianyu 335 and Zhangdan 958), under two planting densities (90 000 plants ha^-1 and 67 500 plants ha^-1) and five N application rates [0 kg ha^-1 (N0); 100 kg ha^-1 (N1); 200 kg ha^-1 (N2); 300 kg ha^-1 (N3); and 400 kg ha^-1 (N4)]. The average maximum grain yield in two years was higher in Xianyu 335 (XY335), while, the optimum N application rate was 4.8%-10.6% lower than that in Zhengdan 958 (ZD958). Compared with ZD958, total dry matter accumulation, dry matter accumulation after flowering, and dry matter translocation efficiency of XY335 were higher in nitrogen treatments, but lower in treatments without nitrogen application. At the same time, dry matter accumulation and dry matter translocation efficiency were increased gradually with increasing N application in XY335, especially under high density plantation. N concentration in leaf and stem of XY335 was different, showing higher at silking (P<0.05) and lower at harvest, which was due to better translocation efficiency in XY335 than in ZD958 after silking. The grain N content had small difference between two cultivars under high plant density, and significantly increased in XY335 under lower plant density (P < 0.05). In nitrogen treatments, XY335 had higher N accumulation at pre-silking and post-silking and significantly higher (P < 0.05) contribution of leaf N translocation to grain yield was than ZD958. At optimal nitrogen application rate, N use efficiency(NUE) and N recovery efficiency(NRE) were significantly higher (P < 0.05) in XY335 under both planting densities, while agronomic nitrogen efficiency (ANUE) and partial factor productivity from applied N (PFPN) were not significantly different between XY335 and ZD958. In XY335, NUE was significantly higher under high planting density due to higher dry matter production and better translocation efficiency during filling stage. Our results suggest that XY335 is a high nitrogen efficient (HNE) spring maize variety in the northeast of China, and can be better used to obtain high yield and high efficiency in intensive farming.

Effects of Shading on Leaf Structure and Photosynthetic Fluorescence Characteristics of Soybean seedlings in Maize-Soybean Relay Intercropping System

FAN Yuan-Fang,YANG Feng*,LIU Qin-Lin,CHEN Jun-Xu,WANG Rui,LUO Shi-Ling,YANG Wen-Yu*

Acta Agron Sin. 2017, 43(02):  277-285.  doi:10.3724/SP.J.1006.2017.00277

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Shading in relay intercropping system is a major factor affecting the low growing of crop growth and development. This study attempted to compare leaf structure and photosynthetic characteristics of cultivar Nandou 12 under maize-soybean relay intercropping systems. Three treatments were designed including one row maize to one row soybean with 50 cm of row space between maize and soybean (A1); two rows maize to two rows soybean with 40 cm of row space for maize or soybean and 60 cm of row space between maize and soybean (A2), sole cropping of soybean. The result indicated that shading caused the changes of both anatomical structure of leaf and photosynthetic characteristics in maize/soybean relay strip intercropping systems. During the V5 stage of soybean, the PAR density in treatments (A1 and A2) were lower than that in CK by 91.2% and 66.8%, respectively. The content of Chl a of treatments (A1 and A2) was lower than that in CK by 50.24% and 27.9%. The P_n of treatments (A1 and A2) was lower than that in CK by 63.2% and 37.8%. The F_v/F_m, q_P, NPQ in leaf of treatments (A1 and A2) were lower than there in CK significantly, F_v'/F_m' and F_q'/F_m' of treatments (A1 and A2) were higher than that in CK. Under light microscope, compared with CK, A1 and A2 treatments decreased palisade tissue thickness and spongy tissue thickness of leaf. The leaf of treatment CK was 2.15 and 1.69 times as thick as that of treatments A1 and A2. In A1 and A2 treatments leaf chloroplast morphology was normal, the number of chloroplasts, granule lamella and osmophilic globule in chloroplast increased; the structure of chloroplast was not damaged; There were few starch grains in chloroplasts; and the structure of cell organelles was normal. Therefore, the different spatial patterns of maize-soybean intercropping system result in different light environments above the soybean canopy, and directly affect soybean leaf structure and photosynthetic fluorescence characteristics.

Influence of Long-term Fertilizations on Nutrients and Fungal Communities in Typical Paddy Soil of South China

CHEN Dan-Mei,YUAN Ling,HUANG Jian-Guo,JI Jian-Hua,HOU Hong-Qian,LIU Yi-Ren

Acta Agron Sin. 2017, 43(02):  286-295.  doi:10.3724/SP.J.1006.2017.00286

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A long-term field experiment was carried out for 31 years in Jiangxi Academy of Agricultural Sciences with a typical paddy soil in South China to study the influence of fertilizer application on changes of soil nutrients and fungal communities by rational analysis and 454 high-throughput sequencing technology. The fertilization treatments included control (without fertilizer), sole chemical fertilizer, 70% chemical fertilizer in combination with 30% organic fertilizer, 50% chemical fertilizer in combination with 50% organic fertilizer and 30% chemical fertilizer in combination with 70% organic fertilizer. The soil pH decreased in the treatment of sole chemical fertilizer, but increased obviously with the proportion of organic fertilizer increased. Organic-inorganic fertilizations significantly increased organic matter, available nitrogen and phosphorus, and microbial biomass carbon and nitrogen in the soil. The number of soil fungal 18S rDNA sequences was doubled while the species number of fungi decreased by 11-40 when received chemical fertilizer only, compared with the treatment of organic-inorganic fertilization. The top 20 predominant fungi ranged from 78.82% to 91.51% of the total in soil, and among them 7-13 species attributed to Ascomycetes which was the largest soil fungal group and accounted for 23.13%-75.09% of the top 20 predominant fungi. Compared with the control, 14-15 of the same species of dominant fungi were found in the treatment of organic-inorganic fertilizers but only nine in the treatment of sole chemical fertilizer. Principal component analysis showed the significant difference in soil fungal community compositions between treatment of sole chemical fertilizer and others. In general, sole application of chemical fertilizer results in soil acidification, and exponential increment of soil fungi, but significant reduction in their species, richness and diversity indexes, suggesting the great changes in fungal community composition and the risk of over production of pathogen fungi in the soil. On the contrary, organic-inorganic fertilization treatment is beneficial to maintain the healthy ecological environment of paddy soil and the diversity of soil fungal communities.

RESEARCH NOTES

Effect of Variety and Application Amount of Stalk Strengthening Agent on Yield and Lodging Resistance in Rice

XIA Min,HU Qun,LIANG Jian,ZHANG Hong-Cheng,GUO Bao-Wei,CAO Li-Qiang,CHEN Hou-Cun

Acta Agron Sin. 2017, 43(02):  296-306.  doi:10.3724/SP.J.1006.2017.00296

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A field experiment was conducted using indica-japonica hybrid rice Yongyou 2640 and super rice cultivar Nanjing 9108, with five treatments (A-1: 18.75 kg ha^–1, A-2: 37.5 kg ha^–1, A-3: 56.25 kg ha^–1, A-4: 75.00 kg ha^–1, A-5: 93.75 kg ha^–1) of stalk strengthening agent A (seedling strengthening agent : quick acting silicon : biochar = 1.0 : 0.5 : 1.0), and five treatments (B-1: 7.5 kg ha^–1, B-2: 15 kg ha^–1, B-3: 22.5 kg ha^–1, B-4: 30 kg ha^–1, B-5: 37.5 kg ha^–1) of stalk strengthening agent B (Jiewei growth regulators of rice). In the thirtieth days after full heading, the lodging resistance of the first basal internode (N₁), the second basal internode (N₂), the third basal internode (N₃), the fourth basal internode (N₄), and main physical characteristics were studied. The effect of stalk strengthening agent A on yield and lodging resistance was better than that of stalk strengthening agent B. With the increase of application amount of stalk strengthening agent, the yield increased firstly and decreased then, with the highest yield in A-3, resulting from the increase of spikelets per panicle, seed-setting rate and 1000-grain weight, and in B-3 resulting from the increase of 1000-grain weight. In contrary, lodging index decreased firstly and increased then, with the significant decrease of the second basal internode and the third basal internode of A-3 and A-4. The reason lodging resistance increased was the increase of breaking resistance, through the increase of culm diameter, culm wall thickness and plumpness in N₁, N₂, and N₃ by stalk strengthening agent A, and of culm wall thickness in N₁, N₂, and N₃ by stalk strengthening agent B, showing advantage effect of agent A than agent B.

Development of Markers Closely Linked with Wheat Powdery Mildew Resistance Gene Pm48

FU Bi-Sheng,LIU Ying,ZHANG Qiao-Feng,WU Xiao-You,GAO Hai-Dong,CAI Shi-Bin,DAI Ting-Bo,WU Ji-Zhong

Acta Agron Sin. 2017, 43(02):  307-312.  doi:10.3724/SP.J.1006.2017.00307

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Pm48 is a novel powdery mildew resistance gene identified previously in our laboratory. This study aimed at developing close molecular markers for fine mapping of the gene. The ddRAD-sequencing assay revealed 81 SNPs associated with the target gene, in which one converted into the STS marker Xmp931 and three converted into the CAPS markers Xmp928, Xmp930, and Xmp936. We also developed 71 genomic SSR markers according to the genome sequence of Aegilops tauschii. And mapped two of them, Xmp1089 and Xmp1112. Using the 115 F_2:3 families derived from the cross of Ningnuomai 1 ´ Tabasco, the target gene was found to be co-segregated with Xmp928 and distal to Xmp1112 with the genetic distance of 3.1 cM towards centromere. In the 671 homozygous susceptible families, Xmp928 also showed co-segregated with the target gene. We also physically mapped Pm48 to the bin of 5DS 0.63–0.67 by using three Chinese Spring 5DS deletion lines.