Role of Tocochromanols in Tolerance of Cereals to Biotic Stresses: Specific Focus on Pathogenic and Toxigenic Fungal Species

Fungal pathogens capable of producing mycotoxins are one of the main threats to the cultivation of cereals and the safety of the harvested kernels. Improving the resistance of crops to fungal disease and accumulation of mycotoxins is therefore a crucial issue. Achieving this goal requires a deep understanding of plant defense mechanisms, most of them involving specialized metabolites. However, while numerous studies have addressed the contribution of phenylpropanoids and carotenoids to plant chemical defense, very few have dealt with tocochromanols. Tocochromanols, which encompass tocopherols and tocotrienols and constitute the vitamin E family, are widely distributed in cereal kernels; their biosynthetic pathway has been extensively studied with the aim to enrich plant oils and combat vitamin E deficiency in humans. Here we provide strong assumptions arguing in favor of an involvement of tocochromanols in plant–fungal pathogen interactions. These assumptions are based on both direct effects resulting from their capacity to scavenge reactive oxygen species, including lipid peroxyl radicals, on their potential to inhibit fungal growth and mycotoxin yield, and on more indirect effects mainly based on their role in plant protection against abiotic stresses.     

Rhizopus and Fusarium are Selected as Dominant Fungal Genera in Rhizospheres of Brassicaceae

We isolated several strains of Rhizopus and Fusarium spp. as dominant fungi in the rhizospheres of Brassicaceae plants. The Fusarium isolates showed a higher tolerance of the antifungal constituents of "mustard oil," which originates from the glucosinolates that are characteristic secondary metabolites of the Brassicaceae, than other Fusarium isolates from non-Brassicaceae plants. In contrast, the Rhizopus isolates showed a high tolerance regardless of their source. Myrosinase activity was found in Bn-R-1-1 (Rhizopus sp.) isolated from the rhizoplane of Brassica napus and Ls-F-in-4-1 (Fusarium sp.) isolated from a surface-disinfected root of Lepidium sativum (Brassicaceae). Ls-F-in-4-1 was the Fusarium most tolerant of the Brassicaceae antifungal constituents. These results suggest that fungi in the rhizospheres of Brassicaceae plants may be selected because of secondary metabolites exuded from the roots of host plants.     

Whole-Genome Metalloproteases in the Wheat Sharp Eyespot Pathogen Rhizoctonia cerealis and a Role in Fungal Virulence

Rhizoctonia cerealis is the causal agent of sharp eyespot, a devastating disease of cereal crops including wheat. Several metalloproteases have been implicated in pathogenic virulence, but little is known about whole-genome metalloproteases in R. cerealis. In this study, a total of 116 metalloproteases-encoding genes were identified and characterized from the R. cerealis Rc207 genome. The gene expression profiles and phylogenetic relationship of 11 MEP36/fungalysin metalloproteases were examined during the fungal infection to wheat, and function of an upregulated secretory MEP36 named RcFL1 was validated. Of 11 MEP36 family metalloproteases, ten, except RcFL5, were predicted to be secreted proteins and nine encoding genes, but not RcFL5 and RcFL2, were expressed during the R. cerealis infection process. Phylogenetic analysis suggested that MEP36 metalloproteases in R. cerealis were closely related to those of Rhizoctonia solani but were remote to those of Bipolaris sorokiniana, Fusarium graminearum, F. pseudograminearum, and Pyricularia oryzae. Expression of RcFL1 was significantly upregulated during the infection process and induced plant cell death in wheat to promote the virulence of the pathogen. The MEP36 domain was necessary for the activities of RcFL1. Furthermore, RcFL1 could repress the expression of wheat genes coding for the chitin elicitor receptor kinase TaCERK1 and chitinases. These results suggest that this MEP36 metalloprotease RcFL1 may function as a virulence factor of R. cerealis through inhibiting host chitin-triggered immunity and chitinases. This study provides insights on pathogenic mechanisms of R. cerealis. RcFL1 likely is an important gene resource for improving resistance of wheat to R. cerealis through host-induced gene silencing strategy.     

“激健”农药减量助剂防治小麦赤霉病的减施技术研究

"激健"是农药减量增产助剂,为验证农药与"激健"混用对小麦赤霉病的防效及施药剂量,2017年于安徽宿州开展田间药效试验。试验结果表明:在小麦始花期防治小麦赤霉病,"激健"与唑醚·戊唑醇减量30%处理防治效果和增产效果与常规用药处理相当。     

Comparative Mitogenomics of Fungal Species in Stachybotryaceae Provides Evolutionary Insights into Hypocreales

Stachybotrys chartarum is one of the world’s ten most feared fungi within the family Stachybotryaceae, although to date, not a single mitogenome has been documented for Stachybotryaceae. Herein, six mitogenomes of four different species in Stachybotryaceae are newly reported. The S. chartarum mitogenome was 30.7 kb in length and contained two introns (one each in rnl and cox1). A comparison of the mitogenomes of three different individuals of S. chartarum showed few nucleotide variations and conservation of gene content/order and intron insertion. A comparison of the mitogenomes of four different Stachybotryaceae species (Memnoniella echinata, Myrothecium inundatum, S. chartarum, and S. chlorohalonata), however, revealed variations in intron insertion, gene order/content, and nad2/nad3 joining pattern. Further investigations on all Hypocreales species with available mitogenomes showed greater variabilities in gene order (six patterns) and nad2/nad3 joining pattern (five patterns) although a dominant pattern always existed in each case. Ancestral state estimation showed that in each case the dominant pattern was always more ancestral than those rare patterns. Phylogenetic analyses based on mitochondrion-encoded genes supported the placement of Stachybotryaceae in Hypocreales. The crown age of Stachybotryaceae was estimated to be approximately the Early Cretaceous (141–142 Mya). This study greatly promotes our understanding of the evolution of fungal species in Hypocreales.     

受污染源水生物预处理挂膜过程研究

本文利用中试和生产性试验对受污染源水生物预处理的自然挂膜过程进行研究,讨论了挂膜过程污染物去除效果的变化、生物膜上细菌数量的增长、生物膜总的状况变化及动物组成的演化;分析了影响填料挂膜的各种因素,提出了判断生物膜成熟的依据、填料挂膜的适宜参数。     

二氯甲烷提取小麦中吡虫啉的可行性研究

对甲醇提取的关键步骤——分液进行了优化,比较了甲醇和二氯甲烷提取小麦中吡虫啉的添加回收率及提取效果的差异。结果表明,分液萃取静置时间影响甲醇对吡虫林的提取,以30 min最佳,此时添加回收率为99.22%～100.56%:二氯甲烷提取不需分液萃取静置,添加回收率为100.25%～101.93%,与甲醇提取优化后的添加回收率相当,可用于提取小麦中的吡虫啉。因二氯甲烷提取较甲醇提取操作步骤简便,提取杂质少,样品测定周期短,测定成本低,故二氯甲烷比甲醇更适合用于小麦样品大批量的测定。     

秸秆苯酚选择性液化研究

苯酚液化是生物质液化的重要手段,农作物秸秆是一种不均一的原料,而完全液化将其看作是 "单一"的原料,针对这一问题本研究采用选择性液化处理方式对小麦秸秆进行了苯酚液化,并对比了选择性液化与完全液化。结果表明:低温下适当的浓硫酸用量、较高的苯酚用量、适当的反应时间有利于保留纤维素而选择性液化半纤维素和木质素;与完全液化处理方式相比,选择性液化反应条件温和,保留了大量的纤维素,大大提高了原料利用价值。通过均匀试验和数据回归分析并实验验证得到选择性液化优化条件为:浓硫酸用量占总反应体系质量分数的 3.0%,反应温度 100℃,反应时间 30 min,苯酚与秸秆质量比 3:1,纤维素残留率达 70%,而液化产物结合酚质量分数可达 100%。     

Conservation Study of Imprinted Genes in Maize Triparental Heterozygotic Kernels

Genomic imprinting is a classic epigenetic phenomenon related to the uniparental expression of genes. Imprinting variability exists in seeds and can contribute to observed parent-of-origin effects on seed development. Here, we conducted allelic expression of the embryo and endosperm from four crosses at 11 days after pollination (DAP). First, the F1 progeny of B73(♀) × Mo17(♂) and the inducer line CAU5 were used as parents to obtain reciprocal crosses of BM-C/C-BM. Additionally, the F1 progeny of Mo17(♀) × B73(♂) and CAU5 were used as parents to obtain reciprocal crosses of MB-C/C-MB. In total, 192 and 181 imprinted genes were identified in the BM-C/C-BM and MB-C/C-MB crosses, respectively. Then, by comparing the allelic expression of these imprinted genes in the reciprocal crosses of B73 and CAU5 (BC/CB), fifty-one Mo17-added non-conserved genes were identified as exhibiting imprinting variability. Fifty-one B73-added non-conserved genes were also identified by comparing the allelic expression of imprinted genes identified in BM-C/C-BM, MB-C/C-MB and MC/CM crosses. Specific Gene Ontology (GO) terms were not enriched in B73-added/Mo17-added non-conserved genes. Interestingly, the imprinting status of these genes was less conserved across other species. The cis-element distribution, tissue expression and subcellular location were similar between the B73-added/Mo17-added conserved and B73-added/Mo17-added non-conserved imprinted genes. Finally, genotypic and phenotypic analysis of one non-conserved gene showed that the mutation and overexpression of this gene may affect embryo and kernel size, which indicates that these non-conserved genes may also play an important role in kernel development. The findings of this study will be helpful for elucidating the imprinting mechanism of genes involved in maize kernel development.     

甲辛酮乳油用于小麦拌种的应用研究

甲辛酮乳油是由甲拌醇，辛硫磷和三唑酮及其有关助剂加工而成的三元混剂。经室内毒力测定证明，对暗黑金龟甲幼虫毒力较强，增效共毒系数为２８１．４。从１９９２年开始，经安徽，河南，等地大田小区试验和生产示范推广，每化顷应用５％乳油１５００毫升拦麦种１５０公手，能很好地控制冬前蛴螬，金针虫等地下害虫的然害，同时控制前期小麦白粉病和叶锈病的发生。     

叶菌唑在小麦中的最终残留研究

为了评价叶菌唑在小麦上使用的安全性,开展了叶菌唑在小麦中的最终残留量研究。建立了分散固相萃取前处理方法,并采用液质联用测定叶菌唑在小麦中的残留量。结果表明,该测定方法具有较高的准确度和精密度,方法的相关系数为0.999。有效成分用量为540~810 g/hm~2,施药2~3次,末次药后14,21,28 d,叶菌唑在小麦麦粒和植株中的最终残留分别为未检出至0.16 mg/kg,未检出至1.1 mg/kg。     

A Focus on Natural Variation for Abiotic Constraints Response in the Model Species Arabidopsis thaliana

Plants are particularly subject to environmental stress, as they cannot move from unfavourable surroundings. As a consequence they have to react in situ. In any case, plants have to sense the stress, then the signal has to be transduced to engage the appropriate response. Stress response is effected by regulating genes, by turning on molecular mechanisms to protect the whole organism and its components and/or to repair damage. Reactions vary depending on the type of stress and its intensity, but some are commonly turned on because some responses to different abiotic stresses are shared. In addition, there are multiple ways for plants to respond to environmental stress, depending on the species and life strategy, but also multiple ways within a species depending on plant variety or ecotype. It is regularly accepted that populations of a single species originating from diverse geographic origins and/or that have been subjected to different selective pressure, have evolved retaining the best alleles for completing their life cycle. Therefore, the study of natural variation in response to abiotic stress, can help unravel key genes and alleles for plants to cope with their unfavourable physical and chemical surroundings. This review is focusing on Arabidopsis thaliana which has been largely adopted by the global scientific community as a model organism. Also, tools and data that facilitate investigation of natural variation and abiotic stress encountered in the wild are set out. Characterization of accessions, QTLs detection and cloning of alleles responsible for variation are presented.     

Molecular Identification of Fusarium Species in Gibberella fujikuroi Species Complex from Rice, Sugarcane and Maize from Peninsular Malaysia

The objective of this study was to identify Fusarium species in the Gibberella fujikuroi species complex from rice, sugarcane and maize as most of the Fusarium species in the species complex are found on the three crops. Isolates used were collected from the field and obtained from culture collection. The Fusarium isolates were initially sorted based on morphology and identifications confirmed based on the DNA sequence of the translation elongation factor 1-α (TEF-1α) gene. Based on the closest match of BLAST analysis, five species were recovered, namely, F. sacchari, F. fujikuroi, F. proliferatum, F. andiyazi and F. verticillioides. This is the first report regarding F. andiyazi from rice in Malaysia and Southeast Asia. The phylogenetic tree generated by using the neighbor joining method showed that isolates from the same species were grouped in the same clade. The present study indicated that Fusarium species in the G. fujikuroi species complex are widespread in rice, sugarcane and maize in Peninsular Malaysia. The findings also suggest that the use of morphological characters for identification of Fusarium species in the G. fujikuroi species complex from the three crops will lead to incorrect species designation.     

Fusarium graminearum Infection Strategy in Wheat Involves a Highly Conserved Genetic Program That Controls the Expression of a Core Effectome

Fusarium graminearum, the main causal agent of Fusarium Head Blight (FHB), is one of the most damaging pathogens in wheat. Because of the complex organization of wheat resistance to FHB, this pathosystem represents a relevant model to elucidate the molecular mechanisms underlying plant susceptibility and to identify their main drivers, the pathogen’s effectors. Although the F. graminearum catalog of effectors has been well characterized at the genome scale, in planta studies are needed to confirm their effective accumulation in host tissues and to identify their role during the infection process. Taking advantage of the genetic variability from both species, a RNAseq-based profiling of gene expression was performed during an infection time course using an aggressive F. graminearum strain facing five wheat cultivars of contrasting susceptibility as well as using three strains of contrasting aggressiveness infecting a single susceptible host. Genes coding for secreted proteins and exhibiting significant expression changes along infection progress were selected to identify the effector gene candidates. During its interaction with the five wheat cultivars, 476 effector genes were expressed by the aggressive strain, among which 91% were found in all the infected hosts. Considering three different strains infecting a single susceptible host, 761 effector genes were identified, among which 90% were systematically expressed in the three strains. We revealed a robust F. graminearum core effectome of 357 genes expressed in all the hosts and by all the strains that exhibited conserved expression patterns over time. Several wheat compartments were predicted to be targeted by these putative effectors including apoplast, nucleus, chloroplast and mitochondria. Taken together, our results shed light on a highly conserved parasite strategy. They led to the identification of reliable key fungal genes putatively involved in wheat susceptibility to F. graminearum, and provided valuable information about their putative targets.     

稻茬免（少）耕小麦田除草技术试验研究

1995～1996年在稻茬免耕小麦田,进行了播前和播后药剂除草试验.结果表明,播前用41%草甘膦75ml/667m~2或20%百草枯100ml/667m~2防除杂草效果分别为96、94.1%.播后4天用10%甲黄隆4g/667m~2、10%甲黄隆4g/667m~2+25%异丙隆100g/667m~2.对总草株防效分别61.4、80.3%,明显优于50%丁草胺100ml/667m~2防效(44.2%).而在小麦苗2叶1心期用10%甲黄隆4g/667m~2、10%甲黄隆4g/667m~2+25%异丙隆100g/667m~2、10%甲·绿5g/667m~2、25%异丙隆250g/667m~2,对总草株防效分别达82.6、97.3、90.0、88.3%.且比播后土壤处理防效好,并对小麦较安全.示范推广应用中,将播前和播后药剂除草技术相结合,可有效控制稻茬免(少)耕小麦田草害.     

吡虫啉防治小麦丛矮病试验

吡虫啉适用于水田、旱田蚜虫、飞虱等害虫，而小麦丛矮病系由灰飞虱传播的病毒病害，试验表明１０％吡虫啉可湿性超微粉以３００克／公顷拌种。可有效地防治小麦丛矮病，其防效与甲拌磷无显著区别，而对小麦的安全性好于甲拌磷，产量高于甲拌磷处理区。     

麦秸快速热解的试验研究

介绍了喷动流化床(喷动床)快速热解试验装置及方法,研究了主要影响因素———热解温度对麦秸热解气、液、固三种产品的产率和热解气成分的影响,采用色-质谱联用仪(GC-MS)分析了热解液成分。结果表明,热解温度为460~520℃时热解油产率最大,主要有醋酸、羟基乙醛、羟基丙酮、左旋葡聚糖、糠醛,油热值为17.0MJ.kg-1;热解气主要为CO2和CO,还含有少量H2、CH4和C2~C4的烯烃。     

Role of Selenium in Viral Infections with a Major Focus on SARS-CoV-2

Viral infections have afflicted human health and despite great advancements in scientific knowledge and technologies, continue to affect our society today. The current coronavirus (COVID-19) pandemic has put a spotlight on the need to review the evidence on the impact of nutritional strategies to maintain a healthy immune system, particularly in instances where there are limited therapeutic treatments. Selenium, an essential trace element in humans, has a long history of lowering the occurrence and severity of viral infections. Much of the benefits derived from selenium are due to its incorporation into selenocysteine, an important component of proteins known as selenoproteins. Viral infections are associated with an increase in reactive oxygen species and may result in oxidative stress. Studies suggest that selenium deficiency alters immune response and viral infection by increasing oxidative stress and the rate of mutations in the viral genome, leading to an increase in pathogenicity and damage to the host. This review examines viral infections, including the novel SARS-CoV-2, in the context of selenium, in order to inform potential nutritional strategies to maintain a healthy immune system.