黄瓜-酸黄瓜渐渗系霜霉病抗性及感病前后几种酶活性的变化

 Using resistant and susceptible cultivars as controls, the resistant evaluation to Pseudoperonospora cubensis was carried out in 12 introgression lines from wide cross between cucumber(Cucumis sativus L.) and sour cucumber(Cucumis hystrix Chakr.). Three enzyme activities including POD, SOD and PAL were analyzed before and 7 d after inoculation, and the POD isozyme was detected by polyacrylamide electrophoresis. The inoculation results showed that, of the 12 accessions, 3 were identified as high resistant, 5 were moderately resistant and 4 were moderately susceptible to downy mildew. The enzyme activities of POD, SOD and PAL were greatly increased in resistant accessions after inoculation. PAL enzyme activities showed close correlation with disease rating before or after inoculation, which implicated that PAL enzyme activity might be used to estimate the resistance to downy mildew. POD isozyme electrophoresis showed that the number and intensity for the bands of resistant lines were significantly increased more than those of susceptible lines after inoculation.     

西瓜感染黄瓜绿斑驳花叶病毒后糖的变化与倒瓤关系的研究

 By high performance liquid chromatography (HPLC), the contents of glucose, fructose and sucrose, and the sweetness were analyzed in watermelon inoculated with Cucumber green mottle mosaic virus (CGMMV).The relationship between sugar change and blood-flesh of watermelon was determined. The results indicated that the content of glucose was apparently increased compared to that of the control before maturity (within 28 days after pollination), but reduced to 24.8% of the control after maturity (at 35 days after pollination). The content of fructose was higher than that of the control within 14 days after pollination, and then decreased with a significant difference. In all cases, the content of sucrose increased with the growth of watermelon. However, compared with the control, the sucrose content of watermelon inoculated with CGMMV was lower. The ratios of glucose, fructose and sucrose in the total sugar were abnormal. Coincidence with the changes of the total sugar, the fruit sweetness before maturity was higher than that of the control, whereas decreased sharply after maturity (lower than that of the control). The inner pulp of the mature fruit appeared to be water-soaked and dirty red with no edibility. In a word, after inoculation with CGMMV, the changes of sugars and sweetness affected the watermelon quality.     

壳寡糖诱导烟草防御酶系活性变化及PR-1a基因表达研究

 The activity change of defensive enzymes and PR-1a gene expression of tobacco (Nicotiana tabacum) seedling induced by chito-oligosaccharides were studied. The results showed that high level systemic acquired resistance (SAR) was expressed in tobacco plants treated with chito-oligosaccharides solution at the concentration of 50 μg/mL. PAL activity increased greatly with 2 peaks, the activity of SOD decreased initially followed by an increase with higher increment, and the activity of POD peaked early followed by a gentle fall in chito-oligosaccharide treated plants. The PR-1a gene was strongly expressed in tobacco due to systemic acquired resistance induced by chito-oligosaccharides. At 168 h after inoculation the expression quantity (co-pies/2 μL) of PR-1a gene was increased to 2 469.6 in treated tobacco leaf, reached 392.6% than that at 0 h after inoculation, it was increased 3.05 times of that in untreated control.     

Effects of artificially cultivated biological soil crusts on soil nutrients and biological activities in the Loess Plateau

Biological soil crusts （BSCs） play an important role in the early succession of vegetation restoration in the Loess Plateau, China. To evaluate the effects of artificially cultivated BSCs on the soil surface micro-envir- onment, we obtained natural moss crusts and moss-lichen crusts from the Loess Plateau of Shaanxi province, and subsequently inoculated and cultivated on horizontal and sloping surfaces of loess soil in a greenhouse. The chemical and biological properties of the subsoil under cultivated BSCs were determined after 10 weeks of cul- tivation. The results indicated that BSCs coverage was more than 65% after 10 weeks of cultivation. Moss crust coverage reached 40% after 5 weeks of cultivation. Compared with the control, soil organic matter and available nitrogen contents in moss crust with the horizontal treatments increased by 100.87% and 48.23%, respectively; increased by 67.56% and 52.17% with the sloping treatments, respectively; they also increased in moss-lichen crust with horizontal and sloping treatments, but there was no significant difference. Available phosphorus in cultivated BSCs was reduced, soil pH was lower and cationic exchange capacity was higher in cultivated BSCs than in the control. Alkaline phosphatase, urease and invertase activities were increased in artificially cultivated BSCs, and alkaline phosphatase activity in all cultivated BSCs was obviously higher than that in the control. Numbers of soil bacteria, fungi and actinomycetes were increased in the formation process of cultivated BSCs. These results indicate that BSCs could be formed rapidly in short-term cultivation and improve the mi- cro-environment of soil surface, which provides a scientific reference for vegetation restoration and ecological reconstruction in the Loess Plateau. China.     

Comparison of photosynthesis and antioxidative protection in Sophora moorcroftiana and Caragana maximovicziana under water stress

This study aims to investigate the protective roles of photosynthetic characteristics and antioxidative systems in the desiccation tolerance of Sophora moorcroftiana and Caragana maximovicziana as they adapt to arid environments. A variety of physiological and biochemical parameters in the leaves of two Leguminosae species were monitored for 1, 7, 14, 21 and 28 d of drought stress. Soil water content decreased from 38.58% to 7.33% after exposure to 28 d of water stress. The photosynthetic carbon-assimilation rates of the two Leguminosae plants decreased for non-stomatal limitation with processing water stress. The malondialdehyde content and cell membrane relative conductivity of the two species increased significantly from 1 to 21 d and then decreased. S. moorcroftiana showed higher superoxide dismutase and peroxidase activities than C. maximovicziana during the 28 d treatment period. However, the catalase activities and proline content of C. maximovicziana were higher than those of S. moorcroftiana before the water stress treatment reached 21 d. Nine physiological and biochemical parameters were selected to comprehensively evaluate the two species’ drought-resistance by the membership function values(MFV). The mean MFV indicated that S. moorcroftiana has a relatively stronger drought defense capability than C. maximovicziana. S. moorcroftiana mainly uses carbon-assimilation rate and osmotic adjustment to combat water deficiency.     

Responses of microbial activities and soil physical-chemical properties to the successional process of biological soil crusts in the Gurbantunggut Desert,Xinjiang

Biological soil crusts(BSCs) are capable of modifying nutrient availability to favor the establishment of biogeochemical cycles. Microbial activities serve as critical roles for both carbon and nutrient transformation in BSCs. However, little is known about microbial activities and physical-chemical properties of BSCs in the Gurbantunggut Desert, Xinjiang, China. In the present research, a sampling line with 1-m wide and 20-m long was set up in each of five typical interdune areas selected randomly in the Gurbantunggut Desert. Within each sampling line, samples of bare sand sheet, algal crusts, lichen crusts and moss crusts were randomly collected at the depth of 0–2 cm. Variations of microalgal biomass, microbial biomass, enzyme activities and soil physical-chemical properties in different succession of BSCs were analyzed. The relationships between microalgal biomass, microbial biomass, enzymatic activities and soil physical-chemical properties were explored by stepwise regression. Our results indicate that microalgal biomass, microbial biomass and most of enzyme activities increased as the BSCs developed and their highest values occurred in lichen or moss crusts. Except for total K, the contents of most soil nutrients(organic C, total N, total P, available N, available P and available K) were the lowest in the bare sand sheet and significantly increased with the BSCs development, reaching their highest values in moss crusts. However, pH values significantly decreased as the BSCs developed. Significant and positive correlations were observed between chlorophyll a and microbial biomass C. Total P and N were positively associated with chlorophyll a and microbial biomass C, whereas there was a significant and negative correlation between microbial biomass and available P. The growth of cyanobacteria and microorganism contributed C and N in the soil, which offered substrates for enzyme activities thus increasing enzyme activities. Probably, improvement in enzyme activities increased soil fertility and promoted the growth of cyanobacteria, eukaryotic algae and heterotrophic microorganism, with the accelerating succession of BSCs. The present research found that microalgal-microbial biomass and enzyme activities played important roles on the contents of nutrients in the successional stages of BSCs and helped us to understand developmental mechanism in the succession of BSCs.     

Tolerance to Zn deficiency and P-Zn interaction in wheat seedlings cultured in chelator-buffered solutions

Zinc deficiency is a common constraint for wheat production in the regions with limited precipitation,particularly in the regions with high levels of available phosphate (P) in soil.Two experiments were conducted using chelator-buffered nutrient solutions to characterize differences in tolerance to Zn deficiency among three winter wheat (Triticum aestivum L).genotypes and to investigate the relationship between P and Zn nutrition in wheat species.Four indices,Zn efficiency,relative shoot-to-root ratio,total Zn uptake in shoot,and shoot dry weight were used to compare the tolerance to Zn deficiency among three wheat genotypes.The results indicated that the four indices could be used in breeding selection for Zn uptake-efficient genotypes.The genotype H6712 was the most tolerant to Zn deficient,followed by M19,and then X13.Specifically,H6712 had the highest Zn uptake efficiency among the three genotypes.The addition of P to the growth medium increased Zn uptake and translocation from roots to shoots.Total Zn content of the wheat plant was 43% higher with 0.6 mmol/L P treatment than that of control with 0 mmol /L P treatment.The Zn translocation ratios from roots to shoots were increased by 16% and 26% with 0.6 mmol/L P treatment and 3 mmol/L P treatment,respectively,compared with 0 mmol/L P treatment.In contrast,high Zn concentrations in the growth medium inhibited P translocation from roots to shoots,but the inhibitive effects were not strong.Sixty-six percent of P taken up by wheat plants was translocated to the wheat shoots at 0 μmol/L Zn treatment,while the percent was 60% at 3 μmol/L Zn treatment.The result may be due to the fact that the wheat plants need more P than Zn.     

Saline soil enzyme activities of four plant communities in Sangong River basin of Xinjiang,China

Soil enzyme activity plays an important role in the conversion of soil organic carbon into inorganic carbon,which is significant for the global carbon cycle.In this study,we investigated the soil enzyme activities of two ligninolytic enzymes(peroxidase and polyphenol oxidase)and five non-ligninolytic enzymes(α-1,4-glucosidase(AG);β-1,4-glucosidase(BG);N-acetyl-β-glucosaminidase(NAG);β-D-cellobiosidase(CBH);andβ-xylosidase(BXYL))in four plant communities of the Sangong River basin in Fukang,North Xinjiang,China.The four typical plant communities were dominated by Haloxylon ammodendron,Reaumuria soongonica,Salsola passerina,and Tamarix rarmosissima,respectively,with saline soils of varied alkalinity.The results showed that the soil peroxidase activity decreased seasonally.The activities of the five non-ligninolytic enzymes decreased with increasing soil depths,while those of the two ligninolytic enzymes did not show such a trend.In the four plant communities,BG had the highest activity among the five non-ligninolytic enzymes,and the activities of the two ligninolytic enzymes were higher than those of the four non-ligninolytic ones(AG,NAG,CBH,and BXYL).The community of H.ammodendron displayed the highest activity with respect to the two ligninolytic enzymes in most cases,but no significant differences were found among the four plant communities.The geometric mean of soil enzyme activities of the four plant communities was validated through an independently performed principal component analysis(PCA),which indicated that different plant communities had different soil enzyme activities.The correlation analysis showed that soil polyphenol oxidase activity was significantly positively correlated with the activities of the five non-ligninolytic enzymes.The soil pH value was positively correlated with the activities of all soil enzymes except peroxidase.Soil microbial carbon content also showed a significant positive correlation(P0.01)with the activities of all soil enzymes except polyphenol oxidase.The results suggested that the H.ammodendron community has the highest ability to utilize soil organic carbon,and glucoside could be the most extensively utilized non-ligninolytic carbon source in the saline soil of arid areas in Xinjiang.     

土壤处理对西洋参根际线虫数量动态的影响及对防治茎线虫根腐病的效果

 Root rot of American ginseng (Panax quinquefolium) caused by Ditylenchus destructor is a novel disease found recently in Beijing area. The effects of three soil treatments (fumigating with chloropicrin, chloropicrin + lvfeng organic manure and nematicide fosthiazate) on the number of rhizospheric nematodes, survived plants, root yield and root rot of 3-year ginseng plant were compared. The effects were also investigated at the second year after treatment. The results indicated that the number of parasitic nematodes in rhizosphere of treated soil reached the peak value in late June to early July as the soil temperature raised in the growing season. Compared with the regular treatment, the number of plant parasitic nematodes was reduced while non-plant parasitic nematodes increased. The number of non-plant parasitic nematodes in the soil treated with chloropicrin + lvfeng organic manure was 2 times than that treated with chloropicrin only. The ratio of non-parasitic to parasitic nematodes of three treatments was higher than the control. Percent of survived plants was 94.8%-96.4% and diseased root was decreased obviously. The control efficacy was more than 89% at the first year after treatment. The survived plants and plot yield of ginseng increased significantly and the control efficacy was around 40% at the second year. The best of the three treatments was by chloropicrin + organic manure.     

Vegetation cover change and the driving factors over northwest China

In this paper the spatio-temporal variation of vegetation cover in northwest China during the period of 1982-2006 and its driving factors were analyzed using GIMMS/NDVI data. The annual average NDVI was increased with a rate of 0.0005/a in northwest China and there was an obvious difference between regions. The trend line slopes of NDVI were higher than 0.0005 in the Tianshan Moutains and Altay Mountains of Xinjiang,the Qilian Mountains of Gansu and the eastern part of Qinghai,which indicated the vegetation cover was significantly increased in these areas. The trend line slopes of NDVI were lower than 0.0005 in the southern region of Qinghai,the border regions of Shaanxi and Ningxia,the parts of Gansu and Tarim Basin,Turpan and Tuoli in Xinjiang,which indicated the vegetation cover was declined in these areas. The NDVI of woodland,grassland and cultivated land had an ascending tendency during the study period. The study shows that the vegetation cover change was caused by both natural factors and human activities in northwest China. The natural vegetation change,such as forests was influenced by climate change,while human activities were the main reason to the change of planting vegetation. The changes of vegetation covers for different elevations,slopes and slope aspects were quite different. When the elevation is exceeded to 4,000 m,the NDVI increasing trend was very low;the NDVI at the slope of less than 25° was increased by the ecological construction;the variation of NDVI on sunny slope was stronger than that on shady slope. The temperature rose significantly in recent 25 years in northwest China by an average rate of 0.67oC/10a,and precipitation increased by an average rate of 8.15 mm/10a after 1986. There was positive correlation between vegetation cover and temperature and annual precipitation changes. Rising temperature increased the evaporation and drought of soils,which is not conducive to plant growth,and the irrigation in agricultural areas reduced the correlation between agricultural vegetation NDVI and precipitation. The improvement of agricultural production level and the projects of ecological construction are very important causes for the NDVI increase in northwest China,and the ecological effect of large-scale ecological construction projects has appeared.     

绿色木霉菌T23对黄瓜枯萎病防治效果及其几种防御酶活性的影响

 本文通过生物测定的方法初步研究了绿色木霉菌T23分生孢子和厚垣孢子对黄瓜枯萎病防治效果及黄瓜幼苗几种防御酶活性的影响。结果表明:黄瓜幼苗经木霉菌处理后,病情指数由33.69分别降至13.12和10.28,经木霉菌处理的黄瓜体内与抗性反应相关的苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、多酚氧化酶(PPO)及过氧化氢酶(CAT)活性有明显增加,其峰值分别为对照的2.75、2.49、2.42及15.84倍,说明生物防治过程中可能有木质素、植保素等抗性物质的参与。与分生孢子处理相比,木霉菌厚垣孢子处理的酶活高峰出现得晚,但酶活峰值高。     

枯萎病菌对不同抗性黄瓜品种几种酶活性的影响

用枯萎病菌接种不同抗性黄瓜品种,研究不同抗性黄瓜品种的过氧化物酶（POD）、多酚氧化酶（PPO）和几丁质酶的活性变化。结果表明,接种后抗感品种POD、PPO和几丁质酶活性基本都呈现先升后降再升（再降）的趋势。抗感品种均在接种后12 h时出现第1次POD活性峰值,抗病品种中农13号、津优3号分别在接种后60、72 h、感病品种在84 h出现第2次POD活性峰值;接种后24 h时抗感品种均达到第1次PPO活性峰值,抗病品种在48 h、感病品种在60 h时达到第2次PPO活性峰值;接种后抗病品种在48 h时达到第1次几丁质酶活性峰值,72 h时达到第2次峰值,而感病品种只在60 h时出现1次几丁质酶活性峰值。抗感品种的POD、PPO、几丁质酶活性的2次峰值都显著或极显著地高于各自的对照,在接种后的早期阶段,感病品种的POD、几丁质酶活性的第1次峰值都显著或极显著地高于抗病品种,PPO活性的第1次峰值极显著地低于抗病品种。     

Defense enzymes induced in cucumber roots by treatment with plant growth-promoting rhizobacteria (PGPR) and Pythium aphanidermatum

Root and crown rot of cucumber caused by Pythium aphanidermatum can be suppressed by various rhizobacteria or PGPR (plant growth-promoting rhizobacteria). When cucumber roots were treated with Pseudomonas corrugata 13 or Pseudomonas aureofaciens 63–28, phenylalanine ammonia-lyase (PAL) activity was stimulated in root tissues in 2 days and this activated accumulation lasted for 16 days after bacterization. Peroxidase (PO) and polyphenol oxidase (PPO) activities were increased in roots 2–5 days after bacterization with P. corrugata strain 13. After bacterized cucumber roots were challenged with P. aphanidermatum, the enzyme activities of PAL, PO and PPO increased as the disease developed on the roots. These accumulations peaked 4–6 days after pathogen inoculation. A split root system demonstrated that the three enzymes could be systemically induced by the Pseudomonas strains 63–28 and 13, as well as P. aphanidermatum. Furthermore, isoperoxidase native PAGE (polyacrylamide gel electrophoresis) analysis indicated that the peroxidase isomer forms in cucumber roots induced by rhizobacteria were different from that in roots infected with P. aphanidermatum. These results suggest that the plant defense enzymes could be stimulated in cucumber roots which have been colonized by non-pathogenic rhizobacteria or in a compatible interaction between cucumber and P. aphanidermatum. The mechanisms of PO activation by the rhizobacteria may be different from those of pathogen infection.     

真菌Sr18代谢产物对根结线虫胁迫下黄瓜叶片保护酶的影响

为探究根结线虫胁迫下丝状真菌Sr18代谢产物对黄瓜的作用机理,采用温室盆栽及人工接种试验,研究了不同浓度的Sr18代谢产物对南方根结线虫胁迫下黄瓜叶片保护酶的影响。结果表明,线虫侵染黄瓜根部以后,黄瓜叶片SOD、POD和CAT活性减弱,PPO和PAL浓度降低。施加不同浓度的Sr18代谢产物,能够使线虫胁迫下的黄瓜叶片SOD、POD和CAT活性增强,使PPO和PAL的含量增加,说明Sr18代谢产物能够提高黄瓜的保护酶活性与含量,增强黄瓜对南方根结线虫的抗性。     

新疆棉花品种次生代谢酶活性与诱导抗蚜性的关系

为了明确不同棉花品种次生代谢酶活性与诱导抗蚜性的关系,研究了不同类型棉花品种在棉蚜为害胁迫下,苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和多酚氧化酶(PPO)活性的变化及其对抗蚜性的影响。结果表明,未受蚜害时不同品种同一酶活性存在显著差异;受蚜害诱导后,抗蚜品种和感蚜品种3种酶活性均有不同程度的上升,抗蚜品种酶活性显著高于感蚜品种,诱导抗蚜性的强弱在不同品种间差异显著。     

壳聚糖诱导黄瓜幼苗抗灰霉病

为了明确壳聚糖(chitosan,CTS)对黄瓜幼苗抗灰霉病的诱导作用,采用根际注射结合叶面喷洒的方法,测定了灰霉病菌侵染下幼苗植株病情指数、防御酶活性和抗病相关物质含量等生理指标。结果表明:CTS降低了黄瓜幼苗的病情指数,最高幅度达39.4%,提高了苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和多酚氧化酶(PPO)活性,增加了总酚、类黄酮和木质素含量。说明CTS能诱导黄瓜幼苗对灰霉病的抗性,且最佳处理浓度为200mg·L-1。     

不同品种香蕉抗枯萎病效果及抗性生理研究

通过盆栽试验研究了向土壤中接种尖孢镰刀菌古巴专化型4号生理小种(FocTR4)后不同抗枯萎病香蕉品种发病率、根际可培养微生物及防御酶活性的变化。结果表明:试验处理中香蕉枯萎病发病率随着FocTR4接种浓度的增加而上升,但在相同浓度处理下,抗病品种发病率显著低于感病品种;各品种香蕉发病率与根际土壤可培养镰刀菌数量均呈显著正相关关系。抗病品种过氧化物酶(POD)、几丁质酶和β-1,3-葡聚糖酶活性高于感病品种,而与多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)活性存在一定的相关性。说明香蕉抗病性与香蕉根际土壤微生物群落结构及香蕉本身防御酶活性有关。     

硅对瓠瓜酚类物质代谢的影响及与抗白粉病的关系

研究了硅酸盐和诱导接种白粉菌对瓠瓜叶片苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)、过氧化物酶(POD)活性的动态变化和木质素含量的影响.结果表明,诱导接种提高了瓠瓜叶片的PAL、PPO、POD活性,加硅后接种处理植株叶片酶活性更明显增加;接种后瓠瓜叶片中木质素含量增加,加硅处理植株叶片木质素含量是不加硅处理的1.43倍.说明酚类物质代谢在植物抗病机制中起着重要作用,硅能提高酚类代谢的酶活性.1.7mmol/L的硅能显著降低瓠瓜白粉病的病情指数,提高其对白粉病的抗病能力.     

拮抗细菌诱导番茄植株抗灰霉病机理研究

 拮抗细菌多粘类芽孢杆菌(Paenibacillus polymyxa) W3菌株悬浮液及其滤液可以诱导番茄叶片对灰霉病(Botrytis cinerea)的系统抗性。W3及其滤液诱导处理后,植株叶内苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、多酚氧化酶(PPO)和超氧化物歧化酶(SOD)活性明显增强。诱导后1 d,PAL活性最大,是对照的3.8~3.9倍,6 d后仍为对照的2.5倍;POD和PPO诱导后3 d活性最高,分别比对照增加34.7%~54.1%和78.5%~78.7%,6 d后仍比对照高;SOD活性诱导后2d达高峰,6 d后稍高于对照。活性氧(O₂^-)产生速率诱导后1 d最大,比对照增加85.6%~88.6%,以后急剧下降,6 d后接近对照。此外,W3诱导后1 d或2 d,处理叶和上一叶位叶片水杨酸含量明显上升,分别是对照的2.6倍和1.6倍,这表明该拮抗细菌诱导的系统抗性可能与水杨酸介导有关。