Functional characterization of an invertase inhibitor gene involved in sucrose metabolism in tomato fruit

In this study, we produced tomato plants overexpressing an invertase inhibitor gene (Sly-INH) from tomato, using a simple and efficient transient transformation system. Compared with control plants, the expression of Sly-INH was highly upregulated in Sly-INH overexpressing plants, as indicated by real-time polymerase chain reaction (PCR). Physiological analysis revealed that Sly-INH inhibited the activity of cell wall invertase (CWIN), which increased sugar accumulation in tomato fruit. Furthermore, Sly-INH mediated sucrose metabolism by regulating CWIN activity. Our results suggest that invertase activity is potentially regulated by the Sly-INH inhibitor at the post-translational level, and they demonstrate that the transient transformation system is an effective method for determining the functions of genes in tomato.     

Effect of ethylene on polygalacturonase, lipoxygenase and expansin in ripening of tomato fruits

Fruit ripening is a complex process and is regulated by many factors.Ethylene and polygalacturonase (PG),lipoxygenase (LOX),expansin (EXP) are all critical regulating factors in fruit ripening and softening process.With antisense,ACS tomato,Nr mutant tomato and cultivated tomato as materials,Northern blot hybridization showed that PG,LeEXP1 and LOX expressed differently in different parts of cultivated tomato fruit during ripening,which was related to fruit ripening.The ripening process of columella and radial pericarp was faster than pericarp.In both Nr mutant and antisense ACS transgenic tomato fruit,expression levels of PG,LeEXP1 and LOX were generally lower than those in cultivated fruit but still related to fruit ripening.The expression levels of PG,LeEXP1 and LOX increased in the mature green tomato fruits after 0.5 h treatment with ethylene ( 100 μL/L).These results indicate that gene expression of PG,LeEXP1 and LOXwere positively regulated by ethylene.The time and cumulative effect of the concentration exists in the expression of PG regulated by ethylene.The regulation of LOX expression mainly depended on the fruit development after great amount of ethylene was produced.PG played a major role in ripening and softening of tomato fruit,and cooperated with the regulation of EXP and LOX.     

微生物降解有机磷农药的研究进展

果蔬菜等农产品有机磷农药残留越来越严重,利用微生物降解有机磷农药,在改善环境和人们生活质量方面已显得经济而有效。本文就降解有机磷农药的微生物种类,降解机制及编码降解酶的相应基因,以及工程菌的构建作了综述。     

Alteration of <Emphasis Type="Italic">SlYABBY2b</Emphasis> gene expression impairs tomato ovary locule number and endogenous gibberellin content

Tomato is an ideal model species for fleshy fruit development research. SlYABBY2b regulates the ovary locule number, which is increased by gibberellins, in tomato. However, the relationship between SlYABBY2b and endogenous gibberellin is poorly understood. In this study, SlYABBY2b-overexpressing and RNA interference (RNAi) transgenic tomato plants were used to elucidate the mechanism by which SlYABBY2b regulates the ovary locule number and endogenous gibberellin content in tomato. SlYABBY2b-overexpressing plants showed fewer locules and lower gibberellin content than the control plants. Contrasting results were found in the RNAi lines. Therefore, the SlYABBY2b gene negatively regulates tomato ovary locule number and endogenous gibberellin content. Furthermore, the expression of SlYABBY2b gene was remarkably higher than that of the wild type in the apical shoots of gibberellindeficient mutants. This showed that the gibberellins can inhibit the expression of SlYABBY2b gene negative regulation. Further study revealed that SlYABBY2b suppressed the expression of SlGA20ox1 and SlGA3ox2, but increased that of SlGA2ox1 and SlGA2ox5 in the apical shoots of SlYABBY2b-overexpressing plants, thereby reducing gibberellin content. Contrasting results were found in the RNAi lines. Our results showed that the SlYABBY2b gene was located on gibberellin signal transduction pathways, fed back regulation of the synthesis of gibberellin, and felt exogenous gibberellin signal to further regulate the formation of tomato locule.     

Characteristics of fruit ripening in tomato mutant epi

INTRODUCTION As a gaseous phytohormone, ethylene plays an important role in plant growth and development. Eth-ylene can alter plant physiology and morphology due to its effect of regulating gene expression (Moc-tezuma et al., 2003). Such regulation apparently de-pends on the effect of the normal ability of the plant tissues on ethylene perception and signal transduction.Impairment of the perception and signal transduction pathway(s) would thus ultimately lead to alterations in the plant…     

Nitric oxide induced by polyamines involves antioxidant systems against chilling stress in tomato (<Emphasis Type="Italic">Lycopersicon esculentum</Emphasis> Mill.) seedling

Polyamines (PAs) and nitric oxide (NO) are vital signals in modulating plant response to abiotic stress. However, to our knowledge, studies on the relationship between NO and PAs in response to cold stress in tomato are limited. Accordingly, in this study, we investigated the effects of putrescine (Put) and spermidine (Spd) on NO generation and the function of Spd-induced NO in the tolerance of tomato seedling under chilling stress. Spd increased NO release via the nitric oxide synthase (NOS)-like and nitrate reductase (NR) enzymatic pathways in the seedlings, whereas Put had no such effect. Moreover, H₂O₂ might act as an upstream signal to stimulate NO production. Both exogenous NO donor (sodium nitroprusside (SNP)) and Spd enhanced chilling tolerance in tomato, thereby protecting the photosynthetic system from damage. Compared to chilling treatment alone, Spd enhanced the gene expressions of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), and their enzyme activities in tomato leaves. However, a scavenger or inhibitor of NO abolished Spd-induced chilling tolerance and blocked the increased expression and activity due to Spd of these antioxidant enzymes in tomato leaves under chilling stress. The results showed that NO induced by Spd plays a crucial role in tomato’s response to chilling stress.     

溶菌酶降解壳聚糖的实验研究

[目的]探讨溶菌酶对壳聚糖有水解活性并对水解后的产物进行初步分析.[方法]在37℃条件下,将溶菌酶作用于壳聚糖,测定作用后溶液的粘度和还原糖量的变化;用纸层析法分析溶菌酶作用壳聚糖后的产物.[结果]溶菌酶具有一定的水解壳聚糖活性,且水解后壳聚糖的粘度随水解时间延长而下降,还原糖量随时间延长而增加,10 h后趋于平稳,水解产物的相对迁移率小于棉子糖.[结论]溶菌酶可以水解壳聚糖,水解产物为大于三糖的多糖.     

NaCl胁迫对不同番茄品种幼苗及果实的影响

研究了NaCl胁迫对5个不同番茄品种的幼苗生长、果实可溶性糖含量及产量的影响.结果表明,盐胁迫抑制了番茄幼苗植株的生长,降低了幼苗的单株鲜重,减少了果实产量,但可以提高果实可溶性糖含量.同一盐胁迫条件下,不同番茄品种性状存在显著差异.     

番茄ACC合成酶反义基因在转基因猕猴桃中表达的初步研究

利用从番茄(Lycopersicum esculentumMill.)果实中分离到的ACC合成酶cDNA基因，反向置于CaMV35S启动子的控制之下(所用根癌杆农菌中合有改建后分别携带嵌合NPT Ⅱ基因和番茄的ACC合成酶反义基因的质粒)，并转入美味猕猴桃(Actinidiadeliciosa cv.Hayward)的愈伤组织中。通过分化，2周后获得了能在附加羧苄青霉素(Carbenicillin,500mg/l)和卡那霉素(Kanamycin,50mg/l)的MSA(MS盐类，3．0mg/lBA，0．2mg/l IAA)培养基上生长的抗性愈伤组织。经过半年多的继代培养并筛选，获得了大量的抗卡那霉素(50mg/l)的丛芽以及由抗性芽发育形成的抗性试管苗。探讨了在用卡那霉素进行筛选的条件下影响愈伤组织诱导率的一些因素。     

Expression of Drosophila melanogaster acetylcholinesterase (DmAChE) gene splice variants in Pichia pastoris and evaluation of its sensitivity to organophosphorus pesticides

Acetylcholinesterase(AChE) is a key enzyme used to detect organophosphorus pesticide residues by the enzyme inhibition method.An accidental discovery of a mutant strain with AChE activity was made in our laboratory during the process of AChE expression by Pichia pastoris.The pPIC9 K-Drosophila melanogaster acetylcholinesterase(DmAChE)-like expression vector was constructed by codon optimization of this mutant strain,which was transformed into P.pastoris GS115,and positive clones were selected on yeast peptone dextrose(YPD) plate with G418 at 4.0 mg/mL.The GS115-pPIC9 K-DmAChE-like strain was subjected to 0.5% methanol induction expression for 120 h,with a protein band at 4.3 kDa found by the tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) pattern of the fermentation supernatant.After preliminary purification by ammonium sulfate precipitation,the enzyme activity was detected to be 76.9 U/(mL·min).In addition,the pesticide sensitivity test proved that DmAChE-like is selective and sensitive to organophosphorus pesticides.     

Genetic analysis of fruit shape traits at different maturation stages in sponge gourd

The fruit shape is important quantitative trait closely related to the fruit quality. However, the genetic model of fruit shapes has not been proposed. Therefore, in the present study, analysis of genetic effects for fruit shape traits （fruit length and fruit perimeter） in sponge gourd was conducted by employing a developmental genetic model including fruit direct effects and maternal effects. Analysis approaches of unconditional and conditional variances were applied to evaluate the genetic behavior of fruit shape traits at economical and physiological maturation times. The results of variance analysis indicated that fruit length and fruit perimeter were simultaneously affected by fruit direct genetic effects and maternal effects. Fruit direct genetic effects were relatively more important for fruit shape traits at whole developmental period. The gene expression was most active at the economical maturation stage （1-12 d after flowering） for two shape traits, and the activation of gene was mostly due to direct dominance effects at physiological maturation stage （13-60 datter flowering）. The coefficients due to different genetic effects, as well as the phenotypic correlation coefficients, varied significantly between fruit shape traits themselves at various maturation stages. The results showed that it was relatively easy to improve fruit shape traits for industrial purpose by carefully selecting the parents at economical maturation stage instead of that at physiological maturation stage.     

Microarray-based identification of tomato microRNAs and time course analysis of their response to Cucumber mosaic virus infection

A large number of plant microRNAs (miRNAs) are now documented in the miRBase, among which only 30 are for Solanum lycopersicum (tomato). Clearly, there is a far-reaching need to identify and profile the expression of miRNAs in this important crop under various physiological and pathological conditions. In this study, we used an in situ synthesized custom microarray of plant miRNAs to examine the expression and temporal presence of miRNAs in the leaves of tomato plants infected with Cucumber mosaic virus (CMV). Following computational sequence homology search and hairpin structure prediction, we identified three novel tomato miRNA precursor genes. Our results also show that, in accordance with the phenotype of the developing leaves, the tomato miRNAs are differentially expressed at different stages of plant development and that CMV infection can induce or suppress the expression of miRNAs as well as up-regulate some star miRNAs (miRNA*s) which are normally present at much lower levels. The results indicate that developmental anomalies elicited by virus infection may be caused by more complex biological processes.     

Construction of recombinant industrial Saccharomyces cerevisiae strain with bglS gene insertion into PEP4 locus by homologous recombination

The bglS gene encoding endo-1,3-1,4-β-glucanase from Bacillus subtilis was cloned and sequenced in this study. The bglS expression cassette, including PGK1 promoter, bglS gene fused to the signal sequence of the yeast mating pheromone α-factor (MFals), and ADH1 terminator with G418-resistance as the selected marker, was constructed. Then one of the PEP4 allele of Saccharomyces cerevisiae WZ65 strain was replaced by bglS expression cassette using chromosomal integration of polymerase chain reaction (PCR)-mediated homologous recombination, and the bglS gene was expressed simultaneously. The recombinant strain S. cerevisiae (SC-βG) was preliminarily screened by the clearing hydrolysis zone formed after the barley β-glucan was hydrolyzed in the plate and no proteinase A (PrA) activity was measured in fermenting liquor. The results of PCR analysis ofgenome DNA showed that one of the PEP4 allele had been replaced and bglS gene had been inserted into the locus of PEP4 gene in recombinant strains. Different endo-1,3-1,4-β-glucanase assay methods showed that the recombinant strain SC-βG had high endo-1,3-1,4-β-glucanase expression level with the maximum of 69.3 U/(h-ml) after 60 h of incubation. Meanwhile, the Congo Red method was suitable for the determination of endo-1,3-1,4-β-glucanase activity during the actual brewing process. The current research implies that the constructed yeast strain could be utilized to improve the industrial brewing property of beer.     

日光温室番茄品种比较试验

通过几个番茄品种的比较试验,研究了几个番茄品种在日光温室中的植物学、抗病性和产量等性状。试验结果表明：几个番茄品种的植物学性状、抗病性和产量都有一定程度的差异;其中中杂九号早熟优势明显,果实商品性状好,产量居首位,具有日光温室栽培的优势,是适合集宁地区日光温室栽培的优良番茄品种。     

稳恒磁场对多酚氧化酶活性影响的研究

多酚氧化酶是一种氧化还原酶,主要与植物色素的生成及其产品的色变有关,有利于水果或作物营养价值的保持．本论文以绿豆嫩叶多酚氧化酶粗提液为研究对象,采用不同条件下的磁感应强度的稳恒磁场处理,研究其对多酚氧化酶活性的影响．实验过程分别选用不同的磁感应强度以及时间处理,结果表明：在测酶活性过程中,酶与底物反映很快,1min时底物已全部反应,吸光度也不再增加．在反应初,对照组吸光度为0．8822．处理条件为1．6T15min时,磁场处理对PPO活性促进作用最明显,吸光度为1．0023．反应初始阶段完成以后,对照组酶活力为0．668U．处理条件为0．8T10min时,磁场处理对PPO活性促进作用最明显,酶活力为0．781U．     

农药残留状况研究

对蔬菜、粮食、水果、中药材以及环境中的有机氯、有机磷等农药残留现状进行了综述。     

Enhancing rice resistance to fungal pathogens by transformation with cell wall degrading enzyme genes from Trichoderma atroviride

INTRODUCTION Rice sheath blight (Rhizoctonia solani) and rice blast (Magnaporthe grisea) are two serious plantdiseases in China. Rice cultivars with high level and durable resistance to these two pathogens are noteasy to obtain by traditional breeding methods due to the lack of germplasm resistant to R. solani and the high genetic diversity of M. grisea. Cell wall degrading enzyme (CWDE) genes from biocontrol fungi belonging to the genus Trichoderma have been demonstrated to encode …     

Enhancing rice resistance to fungal pathogens by transformation with cell wall degrading enzyme genes from Trichoderma atroviride

Three genes encoding for fungal cell wall degrading enzymes (CWDEs), ech42, nag70 and gluc78 from the biocontrol fungus Trichoderma atroviride were inserted into the binary vector pCAMBIA1305.2 singly and in all possible combinations and transformed to rice plants. More than 1800 independently regenerated plantlets in seven different populations (for each of the three genes and each of the four gene combinations) were obtained. The ech42 gene encoding for an endochitinase increased resistance to sheath blight caused by Rhizoctonia solani, while the exochitinase-encoding gene, nag70, had lesser effect. The expression level of endochitinase but exochitinase was correlated with disease resistance. Nevertheless, exochitinase enhanced the effect of endochitinase on disease resistance when the two genes co-expressed in transgenics. Resistance to Magnaporthe grisea was found in all kinds of regenerated plants including that with single gluc78. A few lines expressing either ech42 or nag70 gene were immune to the disease. Transgenic plants are being tested to further evaluate disease resistance at field level. This is the first report of multiple of expression of genes encoding CWDEs from Trichoderma atroviride that result in resistance to blast and sheath blight in rice.