Inheritance pattern of mungbean yellow mosaic disease resistance and gene action for different traits in mungbean (Vigna radiata (L.) Wilczek) under protected and unprotected field conditions

Understanding of mungbean yellow mosaic disease resistance is crucial to develop resistant varieties to combat worldwide threat of the disease epidemics. This study was aimed to determine nature of disease resistance in terms of number of genes governing it and genetics of related traits. Experimental site was located on 31.43°N and 73.06°E with an elevation of 186 m, and evaluation trials were conducted during spring season due to high disease epidemics in this season. Two contrasting genotypes, that is, NM 6‐68‐2 (resistant) and NM 1‐32‐1 (highly susceptible), were crossed to raise six populations, that is, P₁, P₂, F₁, F₂, BC₁ and BC₂ for evaluation under protected and unprotected field conditions using chi‐square test and generation mean and variance analysis. It was discovered that disease resistance was governed by two major genes with additive effects. Disease resistance can easily be incorporated through backcrossing and direct selection following hybridization. Direct selection should be practised at earlier generation for plant height, chlorophyll contents and number of seeds per pod due to preponderance of additive effects whereas at later generations for seed yield per plant, 100 seed weight, harvest index, number of pods per plant and pod length due to involvement of duplicate epistasis.     

Control of Fusarium wilt disease of cucumber plants with the application of a bioorganic fertilizer

Two field experiments were conducted to evaluate the effect of organic fertilizer application either with or without antagonistic bacteria (Bacillus subtilis SQR-5 and Paenibacillus polymyxa SQR-21) on the control of Fusarium oxysporum f. sp. Cucumerinum J. H. Owen wilt disease in cucumber. The incidence of Fusarium wilt disease was 5.3–13.5% for cucumber plants treated with bioorganic fertilizer, while it was 30.3–51% in controls (only with organic fertilizer). Higher yields and lower disease incidences were observed in the dry season when compared with the wet season for both types of organic fertilizer treatments. Biolog analysis showed a significant change in soil bacterial composition and activity after bioorganic fertilizer application. The numbers of colony-forming units of F. oxysporum f. sp. Cucumerinum J. H. Owen for bioorganic-fertilizer-treated soils were significantly decreased compared with control. Scanning electron micrographs of cucumber basal stems showed a presence of mycelia-like mini strands accompanied by an amorphous substance within the xylem vessels. This amorphous substance and mini strands were richer in calcium and phosphorus but had low carbon and oxygen than the living mycelia. Reverse-phase high-pressure liquid chromatography and mass spectroscopic analysis showed that the antagonistic bacteria produced the antifungal compounds fusaricidin A, B, C, and D with molecular weights of 883.5, 897.5, 947.5, and 961.5 Da, respectively. The application of bioorganic fertilizer has a great potential for the control of F. oxysporum wilt disease in cucumber plants.     

Retraction Note to: “Hassan W,David J (2014) Effect of lead pollution on soil microbiological index under spinach (Spinacia oleracea L.) cultivation. J Soils Sediments 14: 44–59

Journal of Soils and Sediments - This article has been retracted by the Editors-in-Chief.     

mVOCs在根际免疫中的研究进展及思考

由土传病原菌引起的作物病害频发制约着世界农业的可持续发展。以根际微生物群落这一生物屏障为核心的根际免疫在抵御土传病原菌入侵中发挥着至关重要的作用。除竞争营养、产生抗生物质等外,根际微生物还通过分泌易挥发性有机物（Microbial volatile organic compounds,mVOCs）与病原菌、其他土著微生物以及宿主植物互作,以更好地适应根际环境和发挥抑病功能。由于具有作用浓度低、可在水-土-气等多界面自由迁移和长距离传播等优势,mVOCs日益成为根际免疫领域机理研究和产品开发的热点。本文首先介绍mVOCs参与土壤抑菌性的发现过程,系统梳理抑制土传病原菌的mVOCs及分泌源——有益微生物。其次,从抑制土传病原菌生长和致病、调控微生物群落互作以及激发植物抗性3个方面阐述mVOCs提升根际免疫的作用机理。随后,总结mVOCs在防控土传病害中的应用现状,并分析影响mVOCs产生和作用效果的土壤生物和非生物因素。最后,提出与根际免疫相关的mVOCs研究思考,呼吁关注mVOCs在根际免疫领域的理论和实践价值。关键词：微生物易挥发性有机物;土传病害;根际免疫;微生物生态     

Isolation and characterisation of fusaricidin-type compound-producing strain of <Emphasis Type="Italic">Paenibacillus polymyxa</Emphasis> SQR-21 active against <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f.sp. <Emphasis Type="Italic">nevium</Emphasis>

A bacterial strain was isolated from the rhizosphere of healthy watermelon plants in a heavily wilt-diseased field. This isolate was tentatively identified as Paenibacillus polymyxa (SQR-21) based on biochemical tests and partial 16S rRNA sequence similarity. The purified antifungal compounds were members of the fusaricidin group of cyclic depsipeptides having molecular masses of 883, 897, 947, and 961 Da with an unusual 15-guanidino-3-hydroxypentadecanoic acid moiety, bound to a free amino group. The strain SQR-21 was not able to produce antifungal volatile compounds but was able to produce cellulase, mannase, pectinase, protease, β-1,3-glucanase and lipase enzymes. However, the strain did not show any chitinase activity. Biocontrol potential of this strain was evaluated against Fusarium oxysporum cause of Fusarium wilt disease of watermelon in a greenhouse experiment. This strain combined with organic fertiliser decreased the disease incidence by 70% and increased the dry plant weight by 113% over the control.     

Short-term daily or weekly administration of micronutrient Sprinkles has high compliance and does not cause iron overload in Chinese schoolchildren: a cluster-randomised trial

ObJECTIVES: To examine consumption rates and serum ferritin (SF) concentrations (as a marker of safety) among schoolchildren (3-6 years) provided with daily and weekly micronutrients.DESIGN AND METHODS: Micronutrients were provided for one school term (13 weeks) to a kindergarten in northern China as single-dose Sprinkles sachets containing 30 mg of iron as encapsulated ferrous fumarate, 5 mg zinc gluconate, 50 mg vitamin C, 300 microg vitamin A, 7.5 microg vitamin D3 and 150 microg folic acid. Sixteen classrooms were randomly assigned to: (1) daily supplements for 5 days a week (daily group); (2) weekly supplements (weekly group); or (3) no supplements (control group). Consumption of sachets was monitored for each child and SF concentrations were measured at the end of study. Random effects general linear models and graphs were used to compare the groups.RESULTS: A total of 415 children from 16 classrooms entered the study. At the end of the study, mean consumption rates per child were 86% (daily group; standard deviation (SD) 12%) and 87% (weekly group; SD 16%). Median SF concentrations were 71 microg l(-1) (range 27-292 microg l(-1); daily group), 55 microg l(-1) (range 11-299 microg l(-1); weekly group) and 54 microg l(-1) (range 7-327 microg l(-1); control group); the overall difference was not significant (P=0.06). However, the daily group was significantly different from the control (P=0.02); daily and weekly groups had higher SF at lower percentiles and similar SF at higher percentiles compared with the control group.CONCLUSION: The high consumption rates and appropriate SF concentrations in the supplemented groups suggest that a short-term school programme with Sprinkles is an efficient and safe way to provide micronutrients (including iron).     

Long-term fertilisation regimes affect the composition of the alkaline phosphomonoesterase encoding microbial community of a vertisol and its derivative soil fractions

Alkaline phosphomonoesterase (ALP) mainly originates from soil microbial secretion and plays a crucial role in the turnover of soil phosphorus (P). To examine the response of ALP-encoding microbial communities (analysed for the biomarker of the ALP gene, phoD) of soils and derivative soil fractions to different fertilisation regimes, soil samples were collected from a long-term experimental field (over 35 years). The different organic P (Po) pools of soil fractions and the ALP activity of soil were also determined. Compared with chemical-only fertilised soils, the ALP activity was 232–815% higher in organic-amended soils, and the highest enzyme activity was observed in the organic-only fertilised treatment. The abundance of the phoD gene harbouring in soil fractions, determined by quantitative PCR (qPCR), was affected by different fertilisations. The highest abundance of the phoD gene was generally detected in the 2–63-μm-sized fraction (silt), but most phoD-encoding microbial species were associated to the 0.1–2-μm-sized fraction (clay) in the chemical-only fertilised soil. The contents of labile Po (LPo), moderately labile Po (MLPo) and fulvic acid-associated Po (FAPo) were significantly correlated with the phoD gene abundance, whereas only LPo content was significantly correlated with the ALP activity. The dominant phoD-encoding phylas were Actinobacteria and Proteobacteria, according to a high-throughput sequencing. Bradyrhizobium, a N₂-fixer identified as a phoD-encoding genus, showed the highest abundance in fertilised soils. The abundance of Bradyrhizobium, Streptomyces, Modestobacter, Lysobacter, Frankia and Burkholderia increased with the organic-only amendment and was significantly correlated with the ALP activity. According to structure equation models (SEM), pH and LPo content significantly and directly affected the ALP activity; the soil organic C (C_org) content was related to composition and abundances of phoD-harbouring microbial communities; since both microbial properties were correlated to the ALP activity, the C_org content was indirectly related to the ALP activity. In conclusion, soil management practices can be used to optimise the contents of soil available P and the organic P with regulation of soil ALP activity and the community composition of corresponding microbes.     

Effect of dry and wet storage at cool temperatures on the post-harvest performance of Ranunculus asiaticus L. flowers

A study was undertaken to assess the effect of different storage temperatures on senescence and postharvest performance of isolated flowers of Ranunculus asiaticus L.. The main aim of the work was to develop a cost-effective storage protocol to reduce the postharvest losses and to bring out the transportation of cut flowers of R. Asiaticus. The flowers were subjected to two different storage treatments, dry storage and wet storage, and their postharvest performance was compared under laboratory conditions. For this purpose, the buds were harvested at 8:00 AM at loose bud stage (Stage II of flower development). The harvested buds were cut to a uniform size of 15 cm and processed for dry or wet storage. For dry storage, the buds were packed after wrapping them in moistened filter papers and kept at 5°C and 10°C. For wet storage, the buds were held in distilled water in separate glass beakers kept at 5°C and 10°C, respectively. A separate set of buds each for dry and wet storage was kept at room temperature (15±2)°C. After 72 h storage, the buds were kept at room temperature in distilled water. The average life of an individual flower that opened fully was about 4–5 days. The buds kept under wet storage at 5°C and 10°C for 72 h maintained their premature status, while the buds held at room temperature for 72 h generally bloomed. All the buds stored dry maintained their premature status irrespective of storage temperature. Storage of buds for 72 h at 5°C, followed by transferring to distilled water improved the longevity by about 5 to 6 days. Cold storage treatment before transferring to holding solution improved floral diameter, membrane integrity besides maintaining higher fresh and dry mass of flowers, sugar content, soluble proteins, and phenols. Our results suggested that wet and dry storage of premature buds of R. asiaticus for 72 h at 5°C, followed by placing them in distilled water, improved the cut flower longevity and can be used as effective postharvest storage treatments for this beautiful cut flower.