Plant resistance, plant traits, and host plant choice of the leaf-folding sawfly on the arroyo willow

Abstract. 1. The hypotheses that genetic variation in host plant resistance of the arroyo willow affected leaf folder ( Phyllocolpa sp.) (Hymenoptera: Tenthredinidae) density and that genetic variation in shoot length and leaf length was correlated with resistance were tested.
2. Willows grown in pots and exposed to ovipojsition by the leaf folding sawfly in cages had significantly different densities among clones, indicating variation in resistance caused by genetic differences among conspecific host plants.
3. There was a general correspondence between leaf folder density on potted cuttings and on the plants in the field that were the sources of cuttings.
4. In behavioural choice experiments, susceptible clones (with highest leaf fold densities) had the highest oviposition activity of female leaf folders compared to clones that were resistant to the leaf folder.
5. Clones differed significantly in shoot length and leaf length among clones grown in pots, among clones in the field, and between shoots with galls and shoots without galls on clones in the field.
6. Leaf folder density was significantly positively correlated with mean shoot length on field clones in 1985 and 1986, but was not correlated with leaf length, although leaf length and shoot length were correlated.
7. Leaf length variation among willow clones accounted for a significant portion of the variation in resistance of potted willows, but shoot length was unimportant.     

Vectors permitting visual monitoring of simple transposition events

The construction and use of two novel transposon(Tn)-delivery vectors is described. These vectors carry Inc.W or Inc.N broad-host-range transfer functions cloned next to the narrow-host-range replicon of pBR329. The host specificities of pSLX10 and pSLX23 both complement and extend the host specificities of existing Tn delivery vectors. Plasmids pSLX10 and pSLX23 were shown to transfer at high frequency in intergeneric matings. The lux genes which are present on each vector permit the visual monitoring of transconjugants which have retained a Tn element, but are devoid of plasmid molecules. pSLX10 and pLSX23 were efficiently used to generate a range of auxotrophic mutants in various strains of Pseudomonas as well as to clone genes from Serratia liquefaciens. These vectors may have general applicability to identify and clone genes in a wide range of Gram-negative bacteria.     

Freezing pattern in apple seeds as affected by the temperature of fruit storage

Storage of apple fruits ( Pyrus malus L. cv. Golden Delicious) at different temperatures (0, 12 and 35°C) markedly altered the pattern of water freezing in the seeds. Higher temperatures of storage brought about a shift from the sequential to the discontinuous type of freezing in seeds, the low temperature exotherm (LTE) being much more pronounced than the high temperature one (HTE). The occurrence of LTE was highly correlated with embryo death. Fruit storage at higher temperatures also caused a decrease in the threshold super cooling temperature of seeds and of naked embryos, removed from the seed coat and endosperm. The decrease was less pronounced in naked embryos than in intact seeds. The results presented show that the frost resistance of apple seeds relies mainly on the supercooling ability of the embryos and is increased by the presence of seed coat and endosperm. The broad peak of the LTE indicates that, in contrast with other seeds and many super cooling organs, massive ice nucleation in apple seeds occurs within the embryo tissues and that extra organ freezing seems to be of less importance. Therefore, the increased super cooling ability of apple seeds, isolated from fruits stored at higher temperatures, seems to rely on those seed properties that protect embryo cells against heterogeneous ice nucleation.     

Functional analysis of a complex oncogene arrangement in biotype III Agrobacterium tumefaciens strains

The ubiquitous grapevine-associated octopine/cucumopine Ti plasmids of biotype III Agrobacterium tumefaciens strains carry two T regions, TA and TB, with a complex oncogene arrangement. Within the octopine/cucumopine group, two main strain types were identified: large TA strains with a TA region resembling the TL region of the biotype I octopine strain Ach5 and small TA strains with a similar T region organization as the large TA strains but with a large internal TA deletion. Structural and functional studies of the representative large TA strain Tm4 revealed six oncogenes. Each oncogene was inserted in a disarmed vector and tested for biological activity using the corresponding oncogenes of Ach5 as standards. Five Tm4 oncogenes, TA-iaaM, T-ipt, T-6b, TB-iaaH and TB-iaaM, were shown to be active, the IS-interrupted TA-iaaH gene was inactive. To study the role of each gene in the pTiTm4 context, several single and multiple pTiTm4 mutations were constructed. It was shown that whereas TA-iaaM and TB-iaaH are essential for tumour formation on grapevine, T-ipt, T-6b and TB-iaaM are not. The avirulence of the TA-iaaM ^- mutant was shown to be due to an inhibitory effect of the T-ipt gene, since a TA-iaaM ^- /T-ipt ^- double mutant was fully virulent. We conclude that the TA-iaaM gene of large TA strains is specifically required to counteract the tumour growth inhibiting activity of the T-ipt gene. Both TA-iaaM and T-ipt are absent from the small TA strains. A model on the roles and interactions of the different oncogenes in large TA and small TA strains is presented.     

Direct analysis of root zone data in a microculture system

Disks were isolated from young leaves of winter rape plants and grown in vitro at ambient (15°C) or low (2°C) temperatures for two weeks. In the control disks the growth cessation and beginning of chlorophyll degradation were observed after 1 week of culture. In the low-temperature treated disks the expansion of cells was slower than that in the control material but it continued for two weeks and was accompanied by a marked accumulation of dry matter. Practically, no chlorophyll degradation was observed. The low temperature treatment brought about the decrease in the frost killing temperature of the tissue which was associated with its increased capacity to subcool water. A short (18 h) exposure of the cold-grown leaf disks to slight frost (–5°C) increased further their resistance to freezing, despite the fact that the subcooling capacity of disks decreased in result of the treatment. Therefore, the two stages of hardening, observed previously for the whole plants, can also be detected in the isolated material. In the cold-grown disks, a transient accumulation of reducing sugars but a steady decrease in ATP and water-soluble protein contents were observed. These observations indicate that tissue isolation might affect processes involved in the functional adaptation of cells to cold.Abbreviations DTA differential thermal analysis - T_k50 frost killing temperature - T_in ice nucleation temperature     

Nuclear magnetic resonance and thermal studies of drug doped dipalmitoyl phosphatidyl choline-H2O systems

The influence of the sulfone drugs, diamino diphenyl sulfone and diamino monophenyl sulfone on the phase transitions and dynamics of dipalmitoyl phosphatidyl choline-H₂O/D₂O vesicles have been investigated using differential scanning calorimetry and nuclear magnetic resonance. Our results show that diamino diphenyl sulfone interacts quite strongly with the headgroups of dipalmitoyl phosphatidyl choline whereas the diamino monophenyl sulfone-dipalmitoyl phosphatidyl choline interaction is quite weak. This is attributed to the difference in the structure and hydrophobic character of the two drugs.     

黄连木五倍子的生态研究与利用

一、产地自然概况黄连木五倍子最早发现于河南省南部信阳市郊贤山脚下(东经114°0′,,北纬32°10′)。该地为低山丘陵,海拔90一320m,南部紧连鸡公山厂傍依南湾水库和狮河。     

吉林省寄螨亚科三新种(啤螨目:寄螨科)

本文记述寄螨亚科(Parasitinae)三新种。模式标本保存于吉林省地方病第一防治研究所。文内测量单位为微米,括号内为测量平均值。     

Host specificity ofAcanthoscelides quadridentatus andA. Puniceus [Col.: Bruchidae] for biological control ofMimosa pigra (with preliminary data on their biology)

The biology and host specificity of the seed-feeding bruchids,Acanthoscelides quadridentatus (Schaeffer) andA. puniceus Johnson, from Mexico were studied in quarantine facilities in Australia. Distinguishing characters in the genitalia of each species are illustrated. Oviposition was recorded on 16 of 73 species of plants tested but larvae died without entering pods or seeds, except onMimosa invisa K. F. P. von Martius andM. pigra L. Larvae entering seeds ofM. invisa died in the first instar. The bruchids were clearly specific toM. pigra and were subsequently released as part of a program for biological control of this weed in the Northern Territory, Australia in April 1983 and thailand in July 1984.