石臼湖原生动物种群分布及其同质化

石臼湖地处长江中下游,是国内为数不多的通江淡水湖。为探讨湖泊与入湖支流不同生境中原生动物种群结构及其相似性,于2012年平水期和枯水期分别对石臼湖及其周边入湖支流进行原生动物调查,研究河流和湖泊区域原生动物的种类组成及其季节变化,同时与同一地区的相邻湖泊固城湖作对比,通过计算相似性指数,探讨原生动物对生境同质化的响应。结果表明:调查共采集到原生动物57种,平水期种类多于枯水期;石臼湖河流区各站点原生动物相似性指数在Ⅰ~Ⅲ级之间,为完全不同-轻度相似;湖区站点相似性指数在Ⅱ~Ⅳ之间,为极不相似-中度相似;河流区种类季节之间的相似度极低(0.050~0.267),而湖泊区种类季节之间处于中等相似水平(0.250~0.375),说明河流区原生动物种类的季节变化较湖泊区明显,生物组成的异质性也高于湖泊;原生动物分布对水质有很好的响应关系,氮磷元素在影响原生动物种类组成和分布中起了主要作用;通过石臼湖与固城湖及长江中下游其他湖泊的对比分析,表明在一定范围内,随着生境尺度的增加,生境的同质化会提高生物同质化水平,但超过景观尺度,原生动物地域性特征逐渐显现,即使生境同质,其生物也未必同质;且随着距离的增加,不同区域的生物相似性呈降低的趋势。     

水分对有机基质栽培番茄生理特性、品质及产量的影响

以"齐粉"番茄品种为试材,研究了不同相对含水量对有机基质栽培番茄生长、生理特性、产量、品质和水分利用率的影响.结果表明:随着有机基质相对含水量的升高,番茄株高、茎粗、节间长和单株叶面积极显著增加,叶片色素含量、水势、渗透势及根系活力和果实产量显著增加,而番茄果实品质和水分利用率显著降低.从果实产量、品质和水分利用率方面综合考虑,80%基质相对含水量处理的果实产量达26 kg.m-2以上,可作为番茄有机基质栽培水分管理的量化指标;如果仅考虑果实品质,则50%基质相对含水量可以作为水分管理指标.     

Cre recombinase expression can result in phenotypic aberrations in plants

The cre recombinase gene was stably introduced and expressed in tomato, petunia and Nicotiana tabacum. Some plants expressing the cre gene driven by a CaMV 35S promoter displayed growth retardation and a distinct pattern of chlorosis in their leaves. Although no direct relation can be proven between the phenotype and cre expression, aberrant phenotypes always co-segregate with the transgene, which strongly suggests a correlation. The severity of the phenotype does not correlate with the level of steady-state mRNA in mature leaves, but with the timing of cre expression during organogenesis. The early onset of cre expression in tomato is correlated with a more severe phenotype and with higher germinal transmission frequencies of site-specific deletions. No aberrant phenotype was observed when a tissue-specific phaseolin promoter was used to drive the cre gene. The data suggest that for the application of recombinases in plants, expression is best limited to specific tissues and a short time frame.[12pt] Abbreviations: bar, the phosphinotricin acetyltransferase gene; CAM, chloramphenicol resistance gene; Ds 5 & Ds 3, borders of the Ds transposable element from maize forming a functional transposable element that embodies the interjacent DNA; gus, the -glucoronidase gene; gus-int, the gus gene interrupted by a plant intron; hpt, the hygromycin phosphotransferase gene; nptII, the neomycin phosphotransferase gene; ORI, bacterial origin for plasmid replication in Escherichia coli of plasmid p15A     

昼夜温差对番茄生长发育、产量及果实品质的影响

在3间人工气候室精密受控环境中,保持日平均温度为22 ℃,设置昼夜温差分别为6 ℃(25 ℃/19 ℃)、8 ℃(26 ℃/18 ℃)、10 ℃(27 ℃/17 ℃),研究昼夜温差对番茄生长的影响.结果表明: 番茄不同品种、不同生长时期适宜的昼夜温差条件不同.番茄开花前,与6 ℃温差相比,8 ℃温差可显著加快野生种醋栗番茄LA1781生长发育,使幼苗株高增加23.1%,出叶加快1～2片,开花提前7 d;10 ℃温差对LA1781苗期的促进作用与8 ℃温差相似.对栽培种普通番茄LA2397和LA0490来说,6 ℃温差使幼苗生长良好,8 ℃温差对幼苗无显著促进作用;与6 ℃温差相比,10 ℃温差对苗期生长及开花有抑制作用,使株高降低12.0%～18.3%,出叶慢2～3片,开花推迟2～4 d.10 ℃温差使3个品种番茄地上部分干质量增加25.2%～44.2%.番茄开花后,与6 ℃温差相比,10 ℃温差可显著提高LA1781的产量和果实品质,使果实数增加34.7%,单株产量增加92.1%,平均单果质量增加40.0%,果实可溶性糖含量增加16.3%,番茄红素含量增加95.6%.与6 ℃温差相比,LA2397和LA0490在8 ℃温差下产量和果实品质提高,番茄红素含量增加超过2倍;在10 ℃温差下产量略有降低(5.0%),果实含糖量降低,但果实尺寸和番茄红素含量增加.表明番茄苗期生长温差不宜过大,花果期适当增大昼夜温差可提高产量和果实品质,但温差过大易造成生长不良和减产.     

Induction of systemic resistance in tomato against broomrape (Phelipanche aegyptiaca)

Rhizosphere dwelling bacteria can increase plant resistance to biotic and abiotic stresses, and they promote plant growth through various mechanisms. In this study, three bioassays were conducted including the following: (a) screening for effective bacterial isolates in the suppression of broomrape, (b) evaluating induced systemic resistance against broomrape and (c) comparing the selected bacterium isolate with plant chemical inducers. Fifteen plant growth‐promoting rhizobacteria (PGPR) were examined to assess their biocontrol potential against Egyptian broomrape (Phelipanche aegyptiaca). Ten isolates significantly reduced the broomrape biomass compared to the control. The Lysinibacillus boronitolerans B124 reduced the dry weight of broomrape plants from 2.15 g in control to 0.45 g. Bacillus megaterium B6 was the best isolate in reducing the number of broomrape tubercles. In addition, the activity of three selected bacterial isolates was investigated in induced systemic resistance to broomrape by split‐root method. The Bacillus pumilus INR7 reduced the number of visible broomrape tubercles by 90%, and B. megaterium B71 and L. boronitolerans B124 were the next two in rank. Compared with the control, L. boronitolerans B124 reduced the dry weight of broomrape from 1.49 g in control to 0.39 g. In a subsequent experiment, L. boronitolerans B124 was evaluated along with some resistance‐inducing volatile compounds. Lysinibacillus boronitolerans B124 decreased the number of broomrapes by 87% on average, while the lowest dry weight of broomrape was observed in methyl jasmonate treatment. In conclusion, PGPR have considerable potential to be used in the integrated management of broomrape. It is also possible to use a mixture of rhizobacteria and defence inducers, such as biogenic volatiles as a promising approach in the management of this noxious parasitic weed.     

不同生长阶段遮荫对番茄光合作用、干物质分配与叶N、P、K的影响

对番茄植株做了两种不同程度的遮荫处理,观测了夏季午间遮荫对光合速率,干物质积累量及其在根,茎,叶之间的分配,和叶N,P,K的含量以及经济产量的影响,发现不同时期遮荫影响不同。（1）遮荫增加三个阶段（开花早期,盛花期和开花后期）的气孔导度和胞间CO2浓度,显著降低开花早期中午的净化合速率,但盛花期中度遮荫（40%遮荫）使净光合速率随着时间的增加逐渐上升,在开花后期表现更加明显,平均净光合速率比对照高20%以上,蒸腾速率也增加较多。（2）开花早期和盛花期重度遮荫（如本实验中的75%遮荫）显著降低根,茎的干重,而开花后期中度遮荫的根,茎干重高于对照,但遮荫对叶干重的影响不明显。（3）开花早期和盛花期遮荫不明显影响叶片中N,P,K的含量,但开花后期中度遮荫使N,P,K含量增加,（4）开花早期两种遮荫对果实产量影响较小,但盛花期重度遮荫使产量降低,全部产量中无效部分所占的比例上升,开花后期中度遮荫的总产量和有效产量增加,单果重也增加,这些结果表明,在某些时期中度遮荫可以克服夏天辐射过强,气温过高对番茄的不良影响,对番茄生长,干物质积累和提高产量等有利,在生产上有意义。     

Detection and Investigation of Soil Biological Activity against Meloidogyne incognita

Greenhouse experiments with two susceptible hosts of Meloidogyne incognita, a dwarf tomato and wheat, led to the identification of a soil in which the root-knot nematode population was reduced 5- to 16-fold compared to identical but pasteurized soil two months after infestation with 280 M. incognita J2/100 cm³ soil. This suppressive soil was subjected to various temperature, fumigation and dilution treatments, planted with tomato, and infested with 1,000 eggs of M. incognita/100 cm³ soil. Eight weeks after nematode infestation, distinct differences in nematode population densities were observed among the soil treatments, suggesting the suppressiveness had a biological nature. A fungal rRNA gene analysis (OFRG) performed on M. incognita egg masses collected at the end of the greenhouse experiments identified 11 fungal phylotypes, several of which exhibited associations with one or more of the nematode population density measurements (egg masses, eggs or J2). The phylotype containing rRNA genes with high sequence identity to Pochonia chlamydosporia exhibited the strongest negative associations. The negative correlation between the densities of the P. chlamydosporia genes and the nematodes was corroborated by an analysis using a P. chlamydosporia-selective qPCR assay.