Studies on Amylase and Degradation of Starch and Pigment of Tobacco Leaf During Process of Flue-Curing

The changes in the activity of amylase and amylase-isoenzyme and the degradation of starch and pigment of tobacco leaf during flue-curing were studied by using the electric- heated flue-curing barn designed and made by the Henan Agricultural University. The temperature and humidity of the barn were controlled automatically. The results indicated that starch in tobacco leaf decreased rapidly and leveled off after 48 h of curring, in the meantime, the content of soluble sugar increased accordingly and reached a peak at the stage of color-fixing. Both of them had a rapid-changing stage in the first 36 hours of yellowing. The changes of starch and soluble sugar contents had highly significant negative-correlation at 1 % level (rNC89 = -0.8962**, rYY85 = -0.9704**). The activity of amylase increased with the proceeding of curing and reached a peak after 36 hours of curing, then decreased. But the activity of amylase kept at a high level when the humidity of curing-environment was very low, even if the tobacco leaf had been dried. The rapid degradation of starch showed a significantly negative correlation with the increase of activity of amylase at 5 % level (rNC89 = -0.8495*, rYY85 = -0.7839*). The degradation of starch and pigment had the same regulation and had highly significant correlation at 1 % level (rNC89= 0.9649**, rYY85= 0.9428**). There were mainly three amylase-isoenzyme bands -A, B, C respectively, in tobacco leaf during flue curing. They were identified as α-AMY, β-AMY, R-AMY, and the activity of β-AMY was the highest. The changes in amylase activity and contents of starch and pigment were affected by the tobacco leaf moisture and environmental humidity during curing.

Dynamics of Microbial Communities in Bulk and Developing CucumberRhizosphere Soil

The microbial population dynamics in bulk and developing cucumber rhizospheres were studiedby cultivation and cultivation-independent approach based on directly extracted DNA toprovide baseline data. Soil and rhizosphere samples were taken from tested field 2, 4, 7 and10 weeks after the seeds were planted, which was positively related to the corresponding dateof cucumber growth stages. The plate culture amount showed that total number of bacteria,fungi and actinomyces began to rise when cucumber planted and quickly reached peak at seedlingor blossom period, but decreased slightly later. Bacterial population in rhizosphere washigher by comparison with that of counterpart except for seedling and flowering stages, butthe shift trend of them were quite similar all the time. Nitrogen fixating, nitrobacter andammonifying bacteria showed the same change tendency in population as bacteria and actinomycesdid, however, cellulose-decomposing bacteria had the contrary rhizosphere effect as cucumberdeveloped. Data revealed that positive relevance existed between the dominant rhizospheremicrobe population and cucumber development. PCR was employed to amplify the V3 region of 16SrDNA, then the products were subjected to denaturing gradient gel electrophoresis(DGGE). DGGEprofile indicated that a few microbe species lived stable in farmland soil, but some wereinfluenced by population due to cucumber roots growth. Significant difference was observed inbulk and rhizosphere soils especially for the seedling and flowering samples. Few prominentbands in DGGE patterns, which displayed stronger or less illumination, means the representativebacteria had great population variation in that period. These phenomena indicated thatflowering cucumber heavily affected rhizosphere bacteria, or the bacteria, most probably theuncultured bacteria, functioned specially to cucumber blossom. Most detected bands with noillumination change in DGGE quite possibly represent the indigenous microbes that wereessential for constructing and stabilizing farmland microecological environment.

Changes in the Activities of Enzymes Involved in Starch Synthesis in the Kernel During Grain Filling in Winter Wheat Cultivars of Different Spike Types

Two winter wheat(Triticum aestivum L.)cultivars, large-spike type Yumai66 and small-spike type Yumai49, were used to study the activities of enzymes involved in starch synthesis in the kernel during grain filling. Starch accumulated faster in the kernel of Yumai49 than Yumai66 up to 25 d after anthesis, thereafter starch accumulated faster in the kernel of Yumai66. Starch accumulation in Yumai66 peaked at 20 -25 d after anthesis, while in Yumai49 starch accumulation peaked at 15 -20 d after anthesis and 25 -30 d after anthesis. The first peak was much higher than that of the second. Sucrose content and sucrose synthase activity peaked at 20 and 15 d after anthesis in Yumai66 and Yumai49, respectively. The sucrose content and sucrose synthase activity in Yumai66 were higher than that in Yumai49 during grain filling. ADP-glucose pyro-phosphorylase and starch branching enzyme activity in the kernel of Yumai66 peaked at 20 d after anthesis. while soluble starch synthase activity peaked at 10 and 20 d after anthesis. The second peak was much higher than that of the first.

Relationship Between LOX Activity, SA and JA Accumulation in Tobacco Leaves Under Water Stress

The relationship between LOX(lipoxygenase)activity, SA(salicylic acid)and JA(jasmonic acid)accumulation was studied in the tobacco leaf under water stress. The result showed that LOX activity and JA content increased simutaneously with losing of water . NDGA(nordihydroguaiaretic),an inhibitor of LOX, inhibited simultaneously both the activity of LOX and the enhancement of JA level under the stress. Likewise, adding LOX to tobacco cell-free system led to the increase of JA content. It suggested that LOX could be a key enzyme in JA biosynthesis under water stress. SA inhibited the enhancement of JA level under the stress.

Dynamics of Environmental Humidity and Water Content in Tobacco Leaf and Metabolism of Starch During Curing

Effect of environmental humidity and water content in tobacco leaf on starch metabolism was studied by using the electric-heated auto-controlled flue-curing barn supplied by Henan Agricultural University, China. The results indicated that the degradation of starch and decrease of water content in tobacco leaf during early yellowing at low humidity was the most rapid, and the water loss was the highest while the lowest under high humidity. The duration for starch degradation under low humidity was longer than that of CK. So the starch residue in cured leaf of different treatment took the order of high humidity yellowing treatment> low humidity yellowing treatment > CK. When the leaf water content was decreased to around 50 %, the starch degradation became slow and the content of starch was stable. Starch degradation and decrease of leaf water content was not synchronous. Starch in tobacco leaf during yellowing degraded more rapidly when humidity was decreased at a high speed, but the degradation stopped earlier at late stage. There was a quicker and higher degradation of starch under high environmental humidity. When the humidity decreased to 70 %, the content of starch was stable. The activity of amylase began to decrease when relative humidity was below 75 %, but it kept a high level of activity when the environmental humidity was below 70 %.

Biodegradation of imazapyr in typical soils in Zhejiang Province,China

The degradation of imazapyr in non-sterile and sterile soils from four sampling sites in Zhejiang, China was studied. The results showed that the half-lives of imazapyr in non-sterile soils were in the range of 30 to 45 d, while 81 to 133 d in sterile(by autoclaving) soils. It means the rate constants of imazapyr under non-sterile conditions were 2 3—4 4 times faster than that under sterile(by autoclaving) conditions, evidently indicating that the indigenous microorganisms in soil play an important role in the degradation of imazapyr. The different sterilization methods could result in different degradation rates of imazapyr. The heat of sterilization of soil largely decreased the degradation. However, the sterile treatment of soil by sodium azide had a different effect from that by autoclaving. Further more, the mechanism was also discussed. Biodegradation in four non-sterile soils accounted for 62% to 78% of imazapyr degradation. In contrast, less than 39% of imazapyr degradation was associated with chemical mechanisms. Therefore, the degradation mechanism was predominantly involved in biology including organisms and microorganisms in soil. Two imazapyr-degrading bacterial strains were isolated in enrichment culture technique and they were identified as Pseudomonas fluorescenes biotypeⅡ(ZJX-5) and Bacillus cereus(ZJX-9), respectively. When added at a concentration of 50 μg/g in mineral salts medium(MSM), ZJX-5 and ZJX-9 could degrade 81% and 87% imazapyr after 48 h of incubation. For the treatment of incorporation of ZJX-5 or ZJX-9 into soil, the degradation rate enhanced 3—4 fold faster than that for control samples, which showed an important value in quick decontamination of imazapyr in soil.

一类高维半线性热传导方程解的唯一性与稳定性

Abstract: This paper deals with the uniqueness of solution to a class of semi-linear heatconductmn equation in higher dimension on the basis of references [1] and [2]. The main results in this paper are as follows: the solution of problem (A) is unique and stable if it exists.

Asymptotic Behavior of Global Solution for Nonlinear Generalized Euler-Possion-Darboux Equation

J. L Lions and W. A. Stranss [1] have proved the existence of a global solution of the initial boundary value problem for nonlinear generalized Euler-Possion-Darboux equation. In this paper we are going to investigate the asymptotic behavior of the global solution by a difference inequality.

Effects of Different Irrigation and Nitrogen Application Regimes on Cook-ing Quality of Chinese Noodle in Winter Wheat

Two wheat cultivars, strong-gluten Yumai66 and medium-strong-gluten Yumai49, were usedto test the effects of irrigation and nitrogen application regimes on cooking quality ofChinese noodle in 2001-2002. The results showed that both in Yumai49 and Yumai66, valueof total organic matter (TOM) of noodle and noodle cooking loss rate ranked the firstwhile noodle score (NS) ranked the lowest in treatments without any nitrogen application.As nitrogen application rate increased, TOM value decreased but NS increased. The lowestTOM and the highest NS existed for treatments with 225 and 150 kg N ha-1 in Yumai49 andYumai66, respectively. Increasing irrigation resulted in greater TOM and NS, but lessbroken noodles. However, no significant difference was found in NS among differentirrigation treatments. Significant difference was found in TOM, NS, breaking rate andwater absorption rate of noodle between these two cultivars. Yumai49, with an average TOMvalue of 1.19 g and NS of 88.5, was better than Yumai66, with an average TOM value of1.55 and NS of 85.7. Interaction in TOM value was found between irrigation and nitrogenapplication. Effects of nitrogen fertilization were greater than that of irrigation inYumai49, while in Yumai66 the other way round. It is suggested, therefore, thosedifferent irrigation and nitrogen application regimes be chosen in production practicebased upon cultivar quality traits.

Effects of Exogenous Amino Acids on the Contents of Amino Acids in Tobacco Leaves

The effect of three amino acids on the growth of flue-cured tobacco was studied with water culture. The results showed that the three amino acids improved the growth of flue-cured tobacco and increased the contents of chlorophyll a, chlorophyll b and carotenoid in tobacco. At the same time, the activities of NR (nitrate reductase), INV(invertase) and root growth activity were also significantly enhanced. The exogenous glutamic, aspartate and phenylalanine all increased the amino acid contents of tobacco leaves. Of these three amino acids, glutamic had the greatest effect, the next was aspartate, and phenylalanine had the least effect. These three amino acids all had significantly increased the accumulation of amino acids in the leaves of individual plants of tobacco; and the magnitude of accumulation indicated aspartate > glutamic > phenylalanine.

Evaluation and characterization of an endosperm-specific sbeⅡa promoter in wheat

Starch, the main component of the wheat grain, is the product of a complex biochemical pathway. The sbeⅡa gene plays a key role in controlling the synthesis of starch, in particular, the biosynthesis of amylopectin, in maturing wheat grain. To investigate its regulatory mechanisms and endosperm-specific expression pattern, the sbeⅡa promoter (3094 bp in length) was cloned using APCR and sequenced. The effect of a series of deletions was studied using a GUS transient assay system. Results showed that the 3094 bp se-quence (sbe.g construct) exhibited full stable promoting ac-tivity and that the activities of 5′ or 3′ deletions reduced levels of GUS expression. Some constructs with internal dele-tions showed only weak activity, however, sbe.e, with a dele-tion from -1579—-1210 bp resulted in higher levels of ex-pression than the full-length promoter sequence, sbe.g. This indicates that motifs such as the -300 bp element, G-box and/or P-box act as positive elements and are necessary in determining the promoters endosperm-specific pattern and that negative repressor elements or motifs may also be pre-sent within the -1579—-1210 bp sequence. The age of wheat endosperm tissue used in the GUS-transient assay system is shown to be of significant importance.

GLOBAL SOLUTIONS OF NONLINEAR SCHRODINGER EQUATIONS

In this paper we study the existence of global solutions to the Cauchy problem of nonlinear SchrSdinger equation by establishing time weight function spaces and using the contraction mapping principle.

Cloning, Physical Mapping and Expression Analysis of a Wheat Mlo-like Gene

Reverse transcription-polymerase chain reaction (RT-PCR) was performed to isolate a cDNA clone using specific primers designed based on the barley (Hordeum vulgare L.) Mlo gene cDNA sequence.A full-length cDNA encoding an Mlo-like protein was isolated and characterized in a Triticum aestivum L.-Haynaldia villosa L. 6VS/6AL translocation line. The putative protein consists of 534 amino acid residues,which contain a nuclear localization motif (NLS), nine casein kinase Ⅱ motifs (S/T-X-X-D/E) and seven protein kinase C motifs (S/T-X-R/K). It is highly homologous to other plant Mlo proteins. Thus, this clone was designated as Ta-Mlo (GenBank accession No. AF384144). Northern blotting analysis showed that the transcription of Ta-Mlo was enhanced slightly by Blumeria graminis (DC) EO Speer f. sp. tritici. Western blotting analysis showed that the protein expression product of the Ta-Mlo gene in wheat seedling leaves is a membrane-bound protein. The protein could be induced by B. graminis. Southern blotting analysis indicated that there is one copy of the Ta-Mlo gene in each wheat genome. Ta-Mlo was localized on specific chromosomal regions of 2AL, 2BL, and 2DL in wheat.