Proteolytic modification of rat prolactin by subcellular fractions of the lactating rat mammary gland

The current study explored prolactin proteolysis by rat lactating mammary gland. 125I-labelled rat prolactin was incubated with tissue fractions of lactating mammary gland and the extent of prolactin degradation and fragment formation was visualized and densitometrically quantitated from autoradiographs derived from SDS-polyacrylamide gel electrophoresis under reducing conditions. At pH 4.5, the 25 000 X g pellet of mammary gland converted intact prolactin (23 kDa band) to proteolytic fragments (8-16 kDa bands) in a time- and tissue concentration-dependent fashion similar to that reported previously for rat ventral prostate. The prolactin-degrading and -fragmenting activity in lactating mammary gland was 5-10-times that observed for ventral prostate, the most active male tissue. This activity at acid pH was also demonstrable in other fractions of mammary gland but appeared to predominate in the cytosol. The above activities in mammary gland virtually disappeared at pH 7.4, appeared sensitive to aspartate and sulfhydryl proteinase inhibitors, and insensitive to serine and metalloenzyme proteinase inhibitors. The distribution of this activity could not be correlated with a particular enzyme marker. These characteristics of mammary gland activity differed significantly from those reported previously for prostate. When electrophoresis was conducted under non-reducing conditions, prolactin proteolysis in prostate and mammary gland was primarily associated with the formation of a more slowly migrating product (24 kDa band) with little spontaneous 8-16 kDa fragment formation. Re-electrophoresis of the 24 kDa band under reducing conditions resulted in the appearance of the 8 and 16 kDa fragments. In conclusion, prolactin is proteolytically modified by prostate and lactating mammary gland to a variant of intact hormone (24 kDa band) with a cleavage site in its large loop, by two or more widely distributed, acid-dependent proteinases. Lactating mammary gland, the principal target for prolactin, has the capacity to cleave the hormone in its loop at rates higher than any other tissue examined to date.     

Characterization of the lectin from females of Phlebotomus duboscqi sand flies.

Lectin from females of the important sand fly vector, Phlebotomus duboscqi (Diptera: Psychodidae), was isolated by immunoaffinity chromatography using a minicolumn with immobilized anti-lectin immunoglobulins. Carbohydrate-binding specificity of active fractions corresponded to that of midgut and salivary gland lysates. Haemagglutination was inhibited by d-glucosamine, d-galactosamine and d-mannosamine. The homogeneity and molecular mass of the purified lectin was examined by SDS/PAGE in both reducing and nonreducing conditions. The active fractions showed one band strongly stained by Coomassie blue or silver nitrate; the molecular mass of the lectin was 42 kDa under nonreducing and 44 kDa under reducing conditions. SDS/PAGE of active fractions from the gel filtration revealed four to six protein bands, but the 42/44-kDa protein present in all active fractions was the only component reacting with specific antibodies in Western blots. Localization of the lectin in the gut of females was studied using indirect immunofluorescence on sections. The positive reaction of specific antibodies was localized in the lumen and along the microvillar surfaces of epithelial cells. The lectin was partially sequenced and characterized by MS. Peptide maps were obtained by MALDI-TOF MS, and several sequence tags were identified from tandem mass spectra on an ion trap. These sequences displayed high similarity to salivary protein precursors previously identified in a cDNA library of the sand flies Phlebotomus papatasi and Lutzomyia longipalpis. Two main hypotheses on the role of female lectin in Leishmania development are discussed.     

Dominant fungi in the rhizosphere of established tea bushes and their interaction with the dominant bacteria under in situ conditions.

Species of Penicillium and Trichoderma were found to dominate the rhizosphere of established tea bushes in a detailed study conducted from various tea growing locations in India. Penicillium erythromellis, P. janthinellum, P. raistrickii, Trichoderma pseudokoningii and T. koningii were found to be closely associated with tea roots. While seasonal fluctuation was observed in the case of Penicillium spp., the population of Trichoderma spp. showed less variation during the year. Both species were sensitive to low temperatures. In general, fungi associated with the tea rhizosphere were found to prefer a mesophillic temperature range (15 °C to 35 °C). The dominant species of Penicillium and Trichoderma also exhibited tolerance to lower temperatures, i.e., 5 to 10 °C on agar plates. Most fungi were able to grow in a wide range of pH (4 to 12). Lowering of soil pH in the rhizosphere of tea bushes was positively correlated with the age of the bush and may have affected the development of a specific microbial community in the rhizosphere.

The populations of Penicillium and Trichoderma species were inversely correlated with the populations of two most dominant rhizosphere bacteria, Bacillus subtilis and B. mycoides. Both Bacillus species have been shown to have antagonistic activity against these two fungi under in vitro conditions. The present study demonstrates the existence of a similar antagonism under in situ conditions in the rhizosphere of established tea bushes.     

The salivary adenosine deaminase from the sand fly Lutzomyia longipalpis

In the process of sequencing a subtracted cDNA library from the salivary glands of the sand fly Lutzomyia longipalpis, we identified a cDNA with similarities to gene products of the adenosine deaminase family. Prompted by this cDNA finding, we detected adenosine deaminase activity at levels of 1 U/mg protein in salivary gland homogenates. The activity was significantly reduced following a blood meal indicating its apparent secretory fate. The native enzyme has a K(m) of approximately 10 microM, an isoelectric pH between 4.5 and 5.5, and an apparent molecular weight of 52 kDa by size exclusion chromatography. The possible role of this enzyme, which converts adenosine to inosine, in the feeding physiology of L. longipalpis is discussed.     

Drought stress induced changes in some organic substances in nodules and other plant parts of two potential legumes differing in salt tolerance

A greenhouse experiment was conducted to assess the effect of water stress on growth and metabolic changes in nodules and other plant parts of two leguminous species, Phaseolus vulgaris and Sesbania aculeata, with the major objective that nodules play a vital role in drought tolerance. Imposition of water deficit conditions for 45 days to 15-day-old plants of P. vulgaris and S. aculeata reduced shoot mass and nodule mass of both species, but the reduction was more pronounced in P. vulgaris than in S. aculeata. Nitrate reductase (NR) activity was reduced more in the leaves and nodules of P. vulgaris than in S. aculeata. Soluble proteins in the nodules of S. aculeata were more decreased as compared to that in P. vulgaris. Free amino acids increased in all parts of both species due to water deficit, but a higher increase was observed in leaf and nodules of P. vulgaris than in S. aculeata. Osmoprotectants such as proline and glycine betaine increased more in the nodules and other parts of S. aculeata under drought stress. In conclusion, S. aculeata (salt tolerant) showed a higher degree of drought tolerance than P. vulgaris (salt sensitive). Drought tolerance of S. aculeata was found to be associated with a smaller reduction in number and mass of root nodules, a high activity of nitrate reductase in leaves and nodules, high accumulation of free proline in roots and nodules, and high glycine betaine content in nodules.     

Acidophilic tannase from marine Aspergillus awamori BTMFW032

Aspergillus awamori BTMFW032, isolated from sea water, produced tannase as extracellular enzyme under submerged culture conditions. Enzyme with a specific activity of 2761.89 IU/mg protein, a final yield of 0.51 %, and a purification fold of 6.32 was obtained after purification to homogeneity by ultrafiltration and gel filtration. SDS-PAGE analyses under non- reducing and reducing conditions yielded a single band of 230 kDa and 37.8 kDa, respectively, indicating presence of six identical monomers. pI of 4.4 and 8.02 % carbohydrate content in the enzyme were observed. Optimal temperature was 30oC, although the enzyme was active at 5-80 oC. Two pH optima, pH 2 and pH 8, were recorded and the enzyme was stable only at pH 2.0 for 24 h. Methylgallate recorded maximal affinity and K(m) and V(max) were recorded, respectively, as 1.9 X 10?3 M and 830 micronmol/min. Impact of several metal salts, solvents, surfactants, and typical enzyme inhibitors on tannase activity were determined to establish the novelty of the enzyme. Gene encoding tannase isolated from A. awamori is 1.232 kb and nucleic acid sequence analysis revealed an open reading frame consisting of 1122 bp (374 amino acids) of one stretch in -1 strand. In-silico analyses of gene sequences and comparison with reported sequences of other species of Aspergillus indicated that the acidophilic tannase from marine A. awamori is differs from that of other reported species.     

太湖两种大型沉水植物无机碳利用效率差异及其机理

该文通过pH值漂移实验比较了太湖常见的两种沉水植物菹草(Potamogeton crispus)和马来眼子菜(P. malaianus)对无机碳利用效率的差异,并测定两者无机碳吸收关键酶——碳酸酐酶的活性,探讨了两者无机碳吸收效率差异的原因。根据太湖自然水体的无机碳条件设定了3种不同碱度条件,测定起点pH值和无机碳条件。不同碱度下pH值漂移变化和总无机碳/碱度比值的结果表明,两个种均能利用${HCO_{3}}^{-}$,适应低无机碳条件。两者对${HCO_{3}}^{-}$的吸收速率决定于其浓度大小,该离子浓度越大,光合速率越高。但是对${HCO_{3}}^{-}$的吸收速率存在差异:马来眼子菜在各碱度下终点pH值显著高于菹草,整体光合速率较高。CO₂-光合速率响应曲线表明,在高pH值(CO₂受到限制)时,马来眼子菜对CO₂亲和力较大。尽管菹草在pH值较低(6.5~7.0)时有相对较高的光合速率,但是基于太湖自然水体夏季高pH值(>8.5)条件,马来眼子菜具有更大的生长优势,成为优势种群。两者无机碳吸收速率的差异是造成它们生活史差异和时间生态位的一重要原因。同时,马来眼子菜碳酸酐酶活性明显高于菹草,表明在相同无机碳条件下,前者催化${HCO_{3}}^{-}$与CO₂之间的转化效率更高,这可能是造成两者无机碳吸收速率差异的原因。     

刺芹侧耳产漆酶条件优化及对偶氮染料甲基橙的脱色

漆酶是一种含铜的单电子多酚氧化酶,能够催化氧化各种酚类及多种染料,在处理染料废水方面具有巨大的潜力。刺芹侧耳Pleurotus eryngii具有较强的产漆酶能力,但漆酶产量在较大程度上受环境条件限制。本文研究了氮源含量、pH、温度、金属离子等环境条件对刺芹侧耳产漆酶能力的影响,优化了其产漆酶条件,并用其粗酶液对典型偶氮类染料甲基橙进行脱色,结果表明,在氮源0.5%（W/W）、pH 5.5、温度28℃、添加5.0mmol/L Mg ²⁺的培养条件下,刺芹侧耳产漆酶能力最强,培养6d时,漆酶酶活可达78.0U/L。用优化培养的刺芹侧耳粗酶液对偶氮染料甲基橙进行脱色,28h后脱色率可达90%,脱色反应为准一级动力学反应,甲基橙并未完全矿化,而是生成小分子中间产物。     

Selected cultural and environmental parameters influence disease severity of dandelion caused by the potential bioherbicidal fungi, Phoma herbarum and Phoma exigua

Selected cultural and environmental variables were investigated for their influence on the efficacy of Phoma herbarum and Phoma exigua to cause disease on dandelion (Taraxacum officinale) under growth room conditions. In both species, mycelial fragments caused significantly greater disease severity on dandelion than spore suspensions. Mycelial age was not an important factor in disease severity caused by P. herbarum, with all cultures causing high disease ratings. However, younger cultures of P. exigua caused the greatest disease severity on dandelion, but significantly less than that caused by P. herbarum. The initial pH of the growth medium (potato dextrose broth) did not affect disease severity caused by either Phoma species. Increasing concentrations of mycelia of P. herbarum were applied to dandelions that were then exposed to various leaf wetness durations. Disease severity increased with increasing leaf wetness duration. For dandelions exposed to no leaf wetness duration, the greater the mycelial concentration, the greater the disease rating. However, for dandelions exposed to all leaf wetness durations, all concentrations of mycelia caused similar disease ratings. As P. herbarum caused high disease ratings on dandelion, it therefore warrants further investigation as a potential bioherbicide for the control of this weed.     

Interaction between a fungal endophyte and root herbivores of Ammophila arenaria

The effect of an endophytic fungus (Acremonium strictum) on plant-growth related parameters of marram grass (Ammophila arenaria), and its potential as a protective agent against root herbivores (Pratylenchus dunensis and Pratylenchus penetrans, root-lesion nematodes) was investigated in two inoculation experiments under different conditions. Acremonium strictum-inoculated plants showed increased plant development in terms of root biomass in the first experiment and increased number of tillers in the second experiment and biomass was less suppressed by nematodes than the Acremonium strictum-free plants. In neither experiment did Acremonium strictum reduce multiplication of root herbivores. On the contrary, Acremonium strictum-inoculated plants seemed to increase herbivore multiplication. Plants infected with P. penetrans benefitted more from the endophytic fungus than those with P. dunensis in terms of total biomass. The effect of Acremonium strictum on interspecific competition was also analyzed by plant inoculation with both nematode species. In Acremonium strictum-free plants with mixed nematode inoculum, the total number of nematodes, compared to numbers observed in one-species inoculation, was less than expected, suggesting that interspecific competition took place. In Acremonium strictum-inoculated plants no interspecific competition was observed. Plants inoculated with P. dunensis, P. penetrans and Acremonium strictum showed decreased total biomass compared to Acremonium strictum-free plants inoculated with the same nematodes. The implications of increased tillering and root growth of plants with Acremonium endophytes are discussed in relation to the sand stabilizing role of Ammophila arenaria in coastal dunes.     

Expression of a Bacillus subtilis pectate lyase gene in Pichia pastoris

The methylotrophic yeast Pichia pastoris is an attractive heterologous protein expression host, mainly for genes from higher eukaryotes. However, no successful examples for the expression of bacterial gene encoding pectate lyase in P. pastoris have been reported. The present study reports for the first time the cloning and functional expression of the bacterial Bacillus subtilis gene encoding alkaline pectate lyase in P. pastoris. A molecular weight of 43,644 Da was calculated from the deduced amino acid sequence. A pectate lyase activity as high as 100 U/ml was attained in the fermentation broth of P. pastoris GS 115, which was about 10 times higher than when the gene is expressed in Escherichia coli. The recombinant pectate lyase was purified to homogeneity and maximal activity of the enzyme was observed at 65 °C, and pH 9.4. The recombinant enzyme showed a wider pH and thermal stability spectrum than the purified pectate lyase from B. subtilis WSHB04-02. Pectate lyase activity slightly increased in the presence of Mg²⁺ (ion) but decreased in the presence of other metal ions. Analysis of polygalacturonic acid degradation products by electrospray ionization-mass spectrometry revealed that the degradation products were unsaturated trigalacturonic acid and unsaturated bigalacturonic acid, which confirms that the enzyme catalyzes a trans-elimination reaction.     

菌核多孔菌培养特性及驯化栽培

为了充分开发利用菌核多孔菌Polyporus tuberaster资源,对采自吉林省露水河东升林场的野生菌核多孔菌进行分离纯化获取纯菌株作为实验材料,采用十字划线法研究固体培养条件下不同碳源、氮源、pH和温度对其菌丝生长的影响,从以上4个单因素实验中选出3个最优水平进行正交实验。结果表明,菌核多孔菌P. tuberaster的最适培养条件为：碳源糊精粉（20mg/mL）、氮源酵母浸粉（2mg/mL）、pH 5.0、温度25℃。在最适培养条件下采用试剂盒测定液体培养条件下菌株的产酶活力,结果表明,菌核多孔菌产漆酶能力较强,酶活力最高可达386.96U/L;木质素过氧化物酶活力仅为5.23U/L;未检测到锰过氧化物酶。出菇实验中,二级种选用麦粒菌种,500mL罐头瓶装干料160g,每瓶接种蚕豆大小菌块3-4块,25℃培养,菌丝满瓶时间为20d;栽培种配方为阔叶树木屑78%、麦麸20%、石灰粉1%、石膏1%、含水量65%左右,17cm×33cm×0.05cm栽培袋装干料520g,每袋接种蚕豆大小二级种3-4块,菌丝发菌时间为26d;在92%-95%空气湿度、一定散射光和20-21℃低温刺激下培养13d后原基分化形成菇蕾,此后加大空气湿度至97%-98%并保持温度24-25℃培养32d后子实体成熟。     

Use of Pseudomonas fluorescens-based formulations for management of tomato spotted wilt virus (TSWV) and enhanced yield in tomato

Strains of Pseudomonas fluorescens were investigated for biocontrol efficacy against tomato spotted wilt virus (TSWV) in tomato both alone and in mixtures. P. fluorescens strains applied to seed, soil and foliage or as a seedling dip significantly reduced TSWV, with a concomitant increase in growth promotion in both the glasshouse and field. Two native strains (CoP-1 and CoT-1) and one foreign strain (CHAO) reduced TSWV. In P. fluorescens-treated tomato plants, increased activity of polyphenol oxidase, β-1,3-glucanase and chitinase was observed, and induction of chitinase was confirmed by western blot analysis. Induction of new protein (18 kDa) detected by SDS-PAGE in P. fluorescens-treated tomato plants was not found in healthy and P. fluorescens-untreated virus inoculated control plants. Indirect ELISA clearly showed a reduction in viral antigen concentration in P. fluorescens-treated tomato plants corresponding to reduced disease ratings. All the P. fluorescens-treated tomato plants also showed enhanced growth and yield compared to control plants. Hence, plant growth promoting rhizobacteria (PGPR) could play a major role in reducing TSWV and increasing yield in tomato plants.     

Enzymatic properties of a novel highly active and chelator resistant protease from a Pseudomonas aeruginosa PD100

Pseudomonas aeruginosa PD100 capable of producing an extracellular protease was isolated from the soil collected from local area (garbage site) from Shivage market in Pune, India. The purified protease showed a single band on native and SDS-PAGE with a molecular weight of 36 kDa on SDS-PAGE. The optimum pH value and temperature range were found to be 8 and 55–60 °C, respectively. The enzyme exhibited broad range of substrate specificity with higher activity for collagen. The enzyme was inhibited with low concentration of Ag²⁺, Ni²⁺, and Cu²⁺. β-Mercaptoethanol was able to inactivate the enzyme at 2.5 mM, suggesting that disulfide bond(s) play a critical role in the enzyme activity. Studies with inhibitors showed that different classes of protease inhibitors, known to inhibit specific proteases, could not inhibit the activity of this protease. Amino acid modification studies data and pK_a values showed that Cys, His and Trp were involved in the protease activity. P. aeruginosa PD100 produces one form of protease with some different properties as compared to other reported proteases from P. aeruginosa strains. With respect to properties of the purified protease such as pH optimum, temperature stability with capability to degrade different proteins, high stability in the presences of detergents and chemicals, and metal ions independency, suggesting that it has great potential for different applications.     

密云水库上游油松人工水源涵养林林下植物多样性与土壤理化特性

以密云水库上游丰宁县4种油松人工水源涵养林(油松×落叶松混交林、油松×蒙古栎混交林、油松×山杏混交林、油松纯林)为对象,研究林下植物多样性与土壤理化性质特征,分析林下植物多样性与土壤因子的相关关系。结果表明: 4种人工水源涵养林林下植物群落组成结构差异显著,油松×山杏混交林林下植物群落物种组成最为丰富,绣线菊、虎榛子和披针薹草为主要优势种。从物种丰富度指数、Simpson优势度指数、Shannon多样性指数、Pielou均匀度指数来看,油松×山杏混交林林下整体植物多样性水平最高,灌木层和草本层植物多样性分别以油松×蒙古栎混交林和油松×山杏混交林最高。4种人工水源涵养林之间除全磷外其他各理化指标均差异显著,油松×山杏混交林土壤理化性质总体最优,油松×蒙古栎混交林最差。土壤毛管孔隙度、pH、有机质为灌木层植物多样性的主要影响因子,土壤pH、毛管持水量为草本层植物多样性的主要影响因子。营造油松×山杏混交林更有利于提高林下植物多样性并促进土壤改良,土壤pH、有机质、毛管孔隙度、毛管持水量为影响研究区林下植物多样性的主导土壤因子。     

不同栽培基质对糙皮侧耳不同发酵方式下产漆酶活性的影响

为了比较糙皮侧耳栽培种在不同常规栽培基质上的漆酶活性,分析更适合糙皮侧耳生长的栽培基质,以1株糙皮侧耳Pleurotus ostreatus栽培菌株为研究材料,研究在固态和液态发酵条件下添加木屑、玉米芯和棉籽壳这3种栽培基质后,对其产漆酶活性的影响。结果表明,不同栽培基质对糙皮侧耳漆酶活性具有极显著的影响（P<0.001）;不同发酵方法对糙皮侧耳漆酶活性也具有极显著的影响（P<0.001）,仅第2天差异不显著。固体发酵与液体发酵条件下,糙皮侧耳在棉籽壳培养基上所检测到的漆酶活性均高于在木屑或者玉米芯培养基上,表明棉籽壳对提高糙皮侧耳漆酶活性的诱导能力更强。此外,糙皮侧耳在棉籽壳培养基上能够快速分泌漆酶,表明棉籽壳对缩短糙皮侧耳漆酶分泌时间的诱导能力更强。     

西南亚高山针叶林主要树种互作及增温对根区土壤微生物群落的影响

温度与植物种类是生态系统土壤微生物群落组成与结构的重要影响因子。气候变暖背景下, 不同树种及树种互作对土壤微生物群落产生的影响仍不清楚。该文以西南亚高山针叶林主要建群种粗枝云杉(Picea asperata)和岷江冷杉(Abies faxoniana)为研究对象, 采用红外加热器模拟增温, 通过不同种植方式(云杉、冷杉单种和二者混种, 以及裸地对照), 研究不同物种及增温对土壤微生物磷脂脂肪酸(PLFAs)含量与群落结构的影响。结果表明: (1)无论增温与否, 与裸地相比, 云杉与冷杉单种均显著增加了土壤微生物群落主要类群及总PLFAs含量, 而混种仅在非增温条件下增加了微生物群落PLFAs含量; 另一方面, 增温显著促进了裸地真菌(F)和云杉根区革兰氏阴性菌(GN)的生长, 但对冷杉与冷杉-云杉混种小区微生物群落具有显著的抑制作用。(2)主成分分析(PCA)表明, 非增温条件下, 植物种植对土壤微生物群落组成的影响更为明显。非增温情况下云杉、冷杉单种和混种均对微生物群落结构有显著影响, 显著降低了土壤革兰氏阳性菌/阴性菌(GP/GN), 增加了土壤真菌细菌比(F/B)(64.29%-35.71%), 而增温时, 仅冷杉单种对GP/GN和F/B有显著影响。(3) PLFAs含量与土壤碳含量显著正相关, 微生物群落结构(F/B)则与土壤pH及无机氮含量有显著相关关系。以上结果说明, 在非增温情况下, 无论单种还是混种均有利于土壤微生物生长, 但在增温情况下混种对微生物群落PLFAs含量无显著影响, 两个物种对微生物群落结构的影响在增温条件下也有减弱的趋势。     

Effects of plant interspecific interaction and warming on soil microbial community in root zone soil of two dominant tree species in the subalpine coniferous forest in southwestern China

温度与植物种类是生态系统土壤微生物群落组成与结构的重要影响因子。气候变暖背景下, 不同树种及树种互作对土壤微生物群落产生的影响仍不清楚。该文以西南亚高山针叶林主要建群种粗枝云杉(Picea asperata)和岷江冷杉(Abies faxoniana)为研究对象, 采用红外加热器模拟增温, 通过不同种植方式(云杉、冷杉单种和二者混种, 以及裸地对照), 研究不同物种及增温对土壤微生物磷脂脂肪酸(PLFAs)含量与群落结构的影响。结果表明: (1)无论增温与否, 与裸地相比, 云杉与冷杉单种均显著增加了土壤微生物群落主要类群及总PLFAs含量, 而混种仅在非增温条件下增加了微生物群落PLFAs含量; 另一方面, 增温显著促进了裸地真菌(F)和云杉根区革兰氏阴性菌(GN)的生长, 但对冷杉与冷杉-云杉混种小区微生物群落具有显著的抑制作用。(2)主成分分析(PCA)表明, 非增温条件下, 植物种植对土壤微生物群落组成的影响更为明显。非增温情况下云杉、冷杉单种和混种均对微生物群落结构有显著影响, 显著降低了土壤革兰氏阳性菌/阴性菌(GP/GN), 增加了土壤真菌细菌比(F/B)(64.29%-35.71%), 而增温时, 仅冷杉单种对GP/GN和F/B有显著影响。(3) PLFAs含量与土壤碳含量显著正相关, 微生物群落结构(F/B)则与土壤pH及无机氮含量有显著相关关系。以上结果说明, 在非增温情况下, 无论单种还是混种均有利于土壤微生物生长, 但在增温情况下混种对微生物群落PLFAs含量无显著影响, 两个物种对微生物群落结构的影响在增温条件下也有减弱的趋势。     

遮荫条件下黄檗生长和生理响应的性别差异研究

分析遮荫条件下黄檗幼苗形态指标、生理指标和代谢物质性别间差异，探讨其对遮荫的响应策略，为黄檗野生资源保护及造林抚育提供理论依据。以2年生黄檗雌雄株幼苗为试验材料，采用控制实验，设置3个遮荫梯度，自然光为对照，对比研究遮荫条件下黄檗幼苗雌雄植株形态特征、生物量分配、抗氧化防御酶活性、代谢物质的差异，以揭示其遮荫条件下的生存策略。结果表明：遮荫处理更有利于黄檗的生长，轻度遮荫雌株生物量积累大于雄株，重度遮荫后雄株大于雌株；遮荫处理对叶绿素a、总叶绿素含量均有显著影响（P<0.01），性别间差异不显著，遮荫条件有利于促进黄檗幼苗叶绿素积累；遮荫处理对酶活性和MDA含量均有显著影响，性别间差异不显著，SOD酶活性均随遮荫强度的增强而增大，POD和CAT酶活性随遮荫强度的增强而减小，MDA含量在对照处理时最高；遮荫条件下可溶性糖和可溶性淀粉含量下降，性别间差异不显著。黄檗幼苗通过改变构件性状、生物量、抗氧化酶活性及代谢物质含量，适应遮荫环境。研究遮荫对黄檗生长和生理响应的性别差异，以期为遮荫环境下黄檗个体发育、种群形成、适应机制及种群繁衍等研究奠定基础，为雌雄异株植物资源的保护利用提供科学借鉴。