Effect of relative humidity at chronic temperature on growth performance,glucose consumption,and mitochondrial ATP production of broilers

An experiment was conducted to investigate the effect of relative humidity(RH) at chronic temperature on growth performance, glucose consumption, and mitochondrial adenosine triphosphate(ATP) production of broilers. A total of 180 28-day-old Arbor Acres broilers(half males and half females) were randomly allocated to three treatments, each containing six replicates of 10 birds per treatment, using a completely randomized design. Birds were reared at 35, 60 or 85% RH at 32°C for 15 days(temperature increased by 3°C every 3 days from 20 to 32°C within 15 days: 20–23–26–29–32°C). RH affected(P0.05) average daily feed intake(ADFI), average daily gain(ADG), average daily water consumption(ADWC), blood glucose concentrations, muscle glycogen levels, avian uncoupling protein(av UCP) mRNA expression, and cytochrome c oxidase(CCO) activity in liver of broilers at 42 days of age. The 85% RH decreased(P0.05) ADFI, ADG and ADWC; 35% RH decreased(P0.02) ADG. Both 85 and 35% RH increased(P0.01) blood glucose and decreased(P0.05) muscle glycogen. Both 85 and 35% RH increased(P0.05) av UCP mRNA expression. 35% RH decreased(P0.05) CCO activity. In conclusion, both high and low RH inceased glucose consumption and reduced mitochondrial ATP poduction, leading to a decline in growth rate.     

Effect of relative humidity at either acute or chronic moderate temperature on growth performance and droppings' corticosterone metabolites of broilers

The present study aimed to investigate the effect of relative humidity(RH) at either acute or chronic moderate ambient temperature(Ta) on growth performance and droppings' corticosterone metabolites of broilers.Two experiments were conducted: effect of RH(35,60 or 85%) on average daily feed intake(ADFI) and droppings' corticosterone metabolites at acute(1 d: 20–26 or 31–20°C,26 or 31°C for 6 h d–1 at 10:00–16:00) moderate Ta(experiment 1) and effect of RH(35,60 or 85%) on growth performance and droppings' corticosterone metabolites at chronic(step-wisely increasing temperature by 3°C every 3 d from 20 to 32°C within 15 d: 20–23–26–29–32°C) moderate Ta(experiment 2).Droppings were collected at the 2,4,6,8,and 22 h after Ta-RH controlled in experiment 1 and at the 2,4,6,and 22 h after Ta controlled to 32°C in experiment 2.The results showed that: 1) In experiment 1,85% RH increased(P0.05) the droppings' corticosterone metabolites at the 2,6,8,and 22 h and 35% RH increased(P0.05) it at the 2 and 22 h compared to the 60% RH.Moreover,85% RH further increased(P0.05) it compared to the 35% RH,however,no difference(P0.05) was found in ADFI among the three RH groups at acute moderate 26°C; 35 and 85% RH increased(P0.05) droppings' corticosterone metabolites at the 2,6,8 and 22 h and decreased(P0.05) ADFI compared to the 60% RH,moreover,85% RH further increased(P0.05) droppings' corticosterone metabolites and further decreased(P0.05) ADFI compared to the 35% RH at acute moderate 31°C; and the average of droppings' corticosterone metabolites in the whole period had a negative correlation(P0.02) with the ADFI.2) In experiment 2,85% RH increased(P0.01) droppings' corticosterone metabolites only at the 2 h and decreased(P0.02) ADFI and average daily gain(ADG) compared to the 60% RH,no difference(P0.05) in droppings' corticosterone metabolites was found between the 35 and 60% RH,however,35% RH decreased(P0.01) ADG compared to the 60% RH,and the average of droppings' corticosterone metabolites in the whole period also had a negative correlation(P0.02) with ADFI and ADG.In conclusion,droppings' corticosterone metabolites could be used as a RH stress index and low and high RH,especially high RH,reduced growth performance possibly through inducing RH stress at moderate temperature.     

Effects of Dietary Protein and Temperature on Growth and Flesh Quality of Songpu Mirror Carp

The study was conducted to demonstrate the effects of dietary protein and water temperature on growth and flesh quality of Songpu mirror carp （Cyprinus carpio） at an initial weight （165.24±5.08） g. Practical diets were formulated to contain five protein levels （29.12%, 31.46%, 34.49%, 38.17%, and 40.13%）, and each diet was randomly assigned triplicate groups of 15 fishes at three temperatures （18℃, 22℃, and 26℃） in the recirculation system. Fishes were fed twice daily to apparent satiation for 56 days. Results indicated that fishes had higher weight gain rate at 22℃ and 26℃ than that at 18℃ （P〈0.05）, but there were no significant differences between 22℃ and 26℃ （P〉0.05）. Based on the weight gain rate, dietary protein level 29.12% could meet the requirement of the body at 18℃, 22℃, or 26℃. Crude protein, crude lipid, moisture and ash of muscle had no significant differences among those treatments （P〉0.05）. pH （after 24 h） of muscle was the highest at 18℃ and the lowest at 22℃ （P〈0.05）, but no differences were observed among different protein level groups at each temperature （P〉0.05）. No significant differences on shear force, water holding capacity, collagen, glycogen and lactate among all the treatments were found （P〉0.05）. It was concluded that when C. carpio fed to apparent satiation, the growth mainly depended upon temperature. Dietary protein could not significantly affect flesh quality, but temperature significantly affected pH of muscles. A dietary protein level 29.12% could meet the requirement of the body at 18℃, 22℃, or 26℃.     

Comparing Immature Development and Life History Traits in Two Coexisting Host-Feeding Parasitoids,Diglyphus isaea and Neochrysocharis formosa (Hymenoptera: Eulophidae)

Coexisting natural enemies that share a common host resource in the same guild usually exhibit variation in their life history traits, due to their need to share a similar ecological niche. In this study, we compared the immature development times and adult life history traits of two coexisting, host-feeding parasitoids, Diglyphus isaea Walker and Neochrysocharis formosa Westwood (Hymenoptera: Eulophidae), of which both attack larvae of the same agromyzid leafminers. These two species are both synovigenic, idiobiont parasitoids, whose adults consume host fluids (“host feeding”) and lay anhydropic eggs. Of the two, D. isaea has a larger body but little or no initial egg load, and engages in similar lifetime host-feeding events. However, it achieves higher fecundity, longer adult longevity, and higher host suppression ability than N. formosa, which has a smaller body and higher initial egg load. Although D. isaea engages in similar lifetime host-feeding events with N. formosa, all of its gains in life history traits per host-feeding event of D. isaea were larger than those of N. formosa. The age-specific fecundity and host mortality curves of N. formosa were more skewed in early life than those of D. isaea. In addition, the ovigeny index of N. formosa was negatively correlated to body size. Our results confirmed that two coexisting parasitoids, which share the same host resource, show different immature development patterns and life history traits, suggesting that different resource allocation mode could be a general rule of coexisting species sharing the same habitat or host.     

Effects of Environmental Temperature on the Regeneration Frequency of the Immature Embryos of Wheat （Trificum aestivum L.）

The immature embryos （IEs） of wheat are the most widely used tissues for in vitro culture and genetic transformation due to its high regeneration competency. However, this explant can only be maintained in 4℃ daily cooler for a short period time for its use in plant tissue culture or transformation experiments. This study aimed to investigate the effects of environmental temperature, cryopreservation storage temperature, and heat shock culture （HSC） temperature on the regeneration frequency of wheat IEs. Results indicated that environmental temperature significantly affected the induction of embryonic calli. The optimum total accumulated temperature （TAT） during the time of anthesis and sampling for regeneration of these tissues was around 280℃ for spring wheat type cv. CB037 and approximately 300℃ for winter wheat type cv. Kenong 199. Regeneration ability obviously declined when the highest environmental temperature was over 35℃ for 1 d or a high temperature between 30 and 33℃ lasted for 5 d during anthesis and sampling. This finding was verified by culturing the freshly isolated IEs under different temperatures from 29 to 37℃ in different controlled growth incubators for 5 d; the IEs almost completely lost regeneration ability when the temperature rose to 37℃. Cryopreservation of-20℃ caused the wheat samples lost ability of producing callus or embryonic callus in a few days, and cryopreservation of-10℃ more than 10 d made the regeneration potential of the tissues dramatically declined. Comparatively, the temperature that best maintained high regeneration ability was -5℃, at which the materials can be maintained for around 1 mon. In addition, the preservation of the immature samples at -5 or -10℃ inhibited the direct germination of the IEs, avoiding the embryo axis removing process. Our results are useful for ensuring that field collection and cryopreservation of the wheat IEs are done correctly to enable tissue culture and genetic transformation.     

Characterization of the chemosensory protein EforCSP3 and its potential involvement in host location by Encarsia formosa

Chemosensory proteins (CSPs) perform several functions in insects. This study performed the gene expression, ligand-binding, and molecular docking assays on the EforCSP3 identified in the parasitoid wasp Encarsia formosa, to determine whether EforCSP3 functions in olfaction, especially in host location and host preference. The results showed that EforCSP3 was highly expressed in the female head, and its relative expression was much higher in adults than in other developmental stages. The fluorescence binding assays suggested that the EforCSP3 exhibited high binding affinities to a wide range of host-related volatiles, among which dibutyl phthalate, 1-octene, β-elemene, and tridecane had the strongest binding affinity with EforCSP3, besides α-humulene and β-myrcene, and should be assessed as potential attractants. Protein structure modeling and molecular docking predicted the amino acid residues of EforCSP3 possibly involved in volatile binding. α-Humulene and β-myrcene attracted E. formosa in a previous study and exhibited strong binding affinities with EforCSP3 in the current study. In conclusion, EforCSP3 may be involved in semiochemical reception by E. formosa.     

Role of TRP channels and HSPs in thermal stress response in the aphid parasitoid Aphelinus asychis(Hymenoptera:Aphelinidae)

Aphelinus asychis is an important aphid endoparasitoid. Under field and greenhouse conditions, high temperature is one of the factors limiting the application of A. asychis for biological pest control. To explore the potential role of transient receptor potential(TRP) channels and heat shock proteins(HSPs) in this process, we identified 11 genes encoding TRP channels and nine genes encoding HSPs. Three proteins(AasyTRPA5, AasyPyrexia, AasyPainless) that belong to transient receptor potential ankyrin(TRPA) subfamily and nine HSPs are involved in the response to high temperature. We also investigated the survival of A. asychis and the response of the identified TRP channels and HSPs to high temperature. The results showed that the maximum temperature that allowed A. asychis survival was approximately 41℃; females had higher survival rates than that of the males at 40 and 41℃. Short-term heat-shock resulted in increased expression of Aasyshsp in males, and Aasyhsp40, Aasyhsp68, Aasyhsp70-4, Aasyhsp70-5 and Aasyhsp90 were upregulated and then downregulated, whereas Aasyhsp70-3 was upregulated at 41℃. Moreover, Aasyhsp40 and Aasyhsp90 showed higher expression levels in females, while Aasyshsp and Aasyhsp70-3 presented opposite expression patterns. At temperature above 35℃, expression of AasyPyrexia in females was significant higher than that in males, whereas AasyPainless and AasyTRPA5 presented higher expression in males at 40 and 41℃, respectively. Altogether, these results indicate that protection against thermal stress in A. asychis is coordinated by TRP channels and HSPs. These findings provide a basis for understanding the potential mechanism of A. asychis in response to high temperatures.     

Characterization of T-complex polypeptide 1 (TCP-1) from the Chilo suppressalis HSP60 family and its expression in response to temperature stress

Many proteins require assistance from molecular chaperones at various stages to attain correctly folded states and functional conformations during protein synthesis. In this study, the gene encoding T-complex polypeptide 1(TCP-1), which belongs to the heat shock protein 60(HSP60) family, was isolated and characterized from the rice stem borer, Chilo suppressalis, by RACE and q PCR, respectively. The full-length c DNA of Tcp-1 was 2 144 bp and encoded a 1 635-bp ORF; the deduced translational product contained 545 amino acids with 5′-and 3′-UTRs and an isoelectric point of 5.29. Cluster analysis confirmed that the deduced amino acid sequence shared high identity(60–99%) with TCP-1 from other insects. To investigate Tcp-1 expression in response to abiotic stress, q PCR was used to analyze expression levels of Tcp-1 m RNA in C. suppressalis larvae exposed to temperatures ranging from –11 to 43°C. With respect to heat shock, Tcp-1 expression was higher than the control after a 2-h exposure to 30 and 36°C and declined at 39 and 43°C. Difference in Tcp-1 expression was observed at temperatures ranging from –11 to 27°C. q PCR analyses revealed that Tcp-1 expression was the highest in hindgut tissue as compared to heads, epidermis, fat body, foregut, midgut, and malpighian tubules. Our results indicated that Tcp-1 expression was differentially expressed in C. suppressalis tissues, and was impacted by temperature stress.     

中国梨木虱冬型成虫性信息素成分的提取和GC-MS鉴定

通过鉴定中国梨木虱性信息素的成分,为进一步开发其性引诱剂提供基础资料.本试验利用正己烷分别提取梨木虱冬型雌、雄成虫体表浸提物,用Y型嗅觉仪测试了浸提物对中国梨木虱冬型雌和雄成虫行为反应的影响,并运用气相色谱-质谱联用仪对浸提物进行了分析和鉴定.雌虫浸提物对雄性梨木虱有较强的引诱作用,雄虫浸提物对雄木虱,雌、雄浸提物对雌木虱均无引诱作用,说明雌虫浸提物中含有雌木虱释放的性信息素.气相色谱-质谱联用仪(GC-MS)分析结果表明,雌虫浸提物中13-甲基二十七烷和2-甲基二十七烷的含量多于雄虫浸提物中的含量.在保留时间为23.136 min时,雌虫浸提物出现色谱峰,而雄虫浸提物没有出峰.这3种化合物可能是中国梨木虱冬型雌成虫的性信息素成分.     

Characterization of two novel heat shock protein 70s and their transcriptional expression patterns in response to thermal stress in adult of Frankliniella occidentalis (Thysanoptera: Thripidae)

Heat shock protein 70(HSP70) is one of the most important members in the heat shock protein family, and plays important roles in the thermotolerance of insect. To explore the molecular mechanism of thermotolerance of Frankliniella occidentalis adults, the difference in the expression of HSP70s in F. occidentalis male or female adults under the thermal stress was studied under the laboratory conditions. Two full length c DNAs of HSP70s gene(Fohsc704 and Fohsc705) were cloned from F. occidentalis by using RT-PCR and RACE. The genomic sequence was demonstrated by genomic validation, and the position and size of the intron were analyzed by sequence analysis of c DNA. Real-time PCR was used to analyze the HSP70 expression patterns. The c DNA of Fohsc704 and Fohsc705 possessed 2 073 and 1 476 bp which encoded 690 and 491 amino acids(aa) with a calculated molecular weight of 75 and 54 k Da, respectively. Four introns in Fohsc704 and six introns in Fohsc705 protein were found. However, the HSP70 protein sequences in our study were ended with EKKN and GIFL, which were different from the reported Fo HSP70s. Various expression patterns of Fohsc704 and Fohsc705 were found in both genders of F. occidentalis under thermal stress. The expression of Fohsc704 and Fohsc705 reached to the highest level at –12 and –8°C in male adults, respectively, and Fohsc705 expressed the highest level at 33°C in female adults. In conclusion, HSP70s of F. occidentalis in our study are novel heat shock proteins. There were difference in expression patterns of the two hsc70s in genders of F. occidentalis, and the two HSP70s play important roles in the thermotolerance of F. occidentalis.     

Effects of temperatures on the development and reproduction of the armyworm,Mythimna roseilinea: Analysis using an age-stage,two-sex life table

The armyworm Mythimna roseilinea(Walker) is a major pest of grain crops in South China. So far little is known about its basic biology and ecology, making prediction of population dynamics difficult. This study examined the relationships of individual development and population growth with temperature based on an age-stage, two-sex life table of M. roseilinea reared on maize in the laboratory at 18, 21, 24, 27 and 30°C. The highest values of net reproductive rate(R_0) and fecundity were observed at 21 and 24°C, respectively. Both the intrinsic rate of increase(r) and finite rate of increase(λ) increased significantly and mean generation time(T) decreased significantly with increasing temperature. M. roseilinea was able to develop, survive and lay eggs at all temperature regimes tested. Development rates of the egg, larval, pupal, as well as the whole pre-oviposition stages had a positive linear relationship with temperature. The calculated development threshold temperatures of egg, larval, pupal, pre-oviposition and total pre-oviposition stages were 13.29, 8.39, 14.35, 7.42, and 12.24°C, respectively, and their effective accumulated temperatures were 63.59, 445.00, 211.11, 89.02, and 698.95 degree-days, respectively. These results provide insight into temperature-based phenology and population ecology of this insect pest and will allow population prediction and management available in the field.     

Effects of constant and stage-specific-alternating temperature on the survival,development and reproduction of the oriental armyworm,Mythimna separata (Walker) (Lepidoptera: Noctuidae)

Migratory insects make diverse adaptive strategies in response to changes in external environment. Temperature has an impact on the survival, development, reproduction, and migration initiation of insects. Previous research has primarily been focused on the effects of constant temperature on populations, but changing temperature has received less attention. Three constant temperature treatments(20, 25 and 30°C) and three pupal-alternating temperature treatments(20–25, 25–20 and 25–30°C) were set up to study the relationship between temperature and population development by age-stage, two-sex life table analysis in the oriental armyworm, Mythimna separata Walker, a notorious migratory pest in grain crops. The 25°C treatment was considered optimal with 20 and 30°C as low suitable temperature and high temperatures, respectively. The survival rate was relatively low before third instar larvae at 20°C(63.0%) and 20–25°C(70.1%), and extreme low after pupal stage at 30°C(20.6%). Developmental duration of each stage was negatively correlated with temperature. The adult preoviposition period, when most migratory insects initiate migration, was the shortest at 25°C(2.69d) but was lengthened at both low suitable(7.48d for 20°C, 6.91d for 25–20°C and 4.57d for 20–25°C) and high temperatures(3.74d for 25–30°C and 5.00d for 30°C). Both low suitable and high temperature decreased lifetime fecundity, net reproductive rate and the intrinsic rate of increase, with variability observed across developmental duration and stage during non-optimal temperature. The results expand knowledge of the relationship between changing temperature and armyworm population development, and adaptive strategies in complex ambient environment.     

Characterization of wheat monogenic lines with known Sr genes and wheat cultivars for resistance to three new races of Puccinia graminis f. sp. tritici in China

Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a potentially devastating fungal disease of wheat worldwide. The present study was to evaluate the resistance of 42 wheat monogenic lines with known stem rust resistance (Sr) genes and 69 wheat cultivars to three new Pgt races (34C0MRGQM, 34C3MKGQM, and 34C6MTGSM) identified from aeciospores at the seedling and adult-plant stages. The phenotyping results revealed that monogenic lines harboring resistance genes Sr9e, Sr17, Sr21, Sr22, Sr26, Sr30, Sr31, Sr33, Sr35, Sr36, Sr37, Sr38, Sr47, SrTmp, and SrTt3 were effectively resistant to all three Pgt races at the seedling and adult-plant stages. In contrast, monogenic lines containing Sr5, Sr6, Sr7b, Sr9a, Sr9d, Sr9f, Sr9g, Sr9b, Sr16, Sr24, Sr28, and Sr39 were highly susceptible to these races at both seedling and adult-plant stages. The other lines with Sr8a, Sr10, Sr11, Sr13, Sr14, Sr15, Sr18, Sr20, Sr19, Sr23, Sr25, Sr27, Sr29, Sr32, and Sr34, displayed variable levels of resistance to one or two of the tested races. Seedling infection types (ITs) and adult-plant infection responses (IRs) indicated that 41 (59.4%) of the wheat cultivars showed high resistance to all the three races. Molecular marker analysis showed that four wheat culitvars likely carried Sr2, 20 wheat culitvars likely carried Sr31, 9 wheat culitvars likely carried Sr38, and none of the cultivars carried Sr24, Sr25, and Sr26. Our results provide a scientific basis for rational utilization of the tested Sr genes and wheat cultivars against these novel Pgt races.     

Characterization and fine mapping of RTMS10, a semi-dominant reverse thermo-sensitive genic male sterile locus in rice

The discovery and application of environment-sensitive genic male sterile(EGMS) rice germplasm provide an easy method for hybrid rice breeding and have made great contributions to hybrid rice production. Typically, the photoperiod-and thermosensitive GMS(P/TGMS) lines utilized in two-line hybrid systems are male sterile under long day or/and high temperature but fertile under short day or/and low temperature conditions. However, Yannong S(Yn S), a reverse TGMS(rTGMS) line, is sterile under low t...     

Attraction of bruchid beetles Callosobruchus chinensis (L.) (Coleoptera: Bruchidae) to host plant volatiles

Host-plant volatiles play an important role as cues for herbivores in search of resources, mates and oviposition sites in complex environments. Plant volatile-based attractants can be developed for pest monitoring and control. Previously, we indicated that mated female adults of Callosobruchus chinensis showed choice preference behavior toward 2-hexenal and benzaldehyde. Our objective here was to investigate the synergistic effect of host-derived attractive volatiles in attracting C. chinensis under laboratory and field conditions in Shanxi Province, China. We hypothesized that the ratio and concentration of volatiles derived from Vigna radiata play critical roles for C. chinensis in locating this host. Therefore, we collected and identified the volatiles of mungbean by using headspace collection and GC-MS. The effectiveness of different ratios and concentrations of two compounds (2-hexenal and benzaldehyde) that elicit C. chinensis searching behavior were examined in Y-tube olfactometer assays. The combination of 300 μg μL⁻¹ 2-hexenal and 180 μg μL⁻¹ benzaldehyde loadings exhibited a synergistic effect on attracting C. chinensis (82.35%). Compared to control traps, the adults were significantly attracted to traps baited with blends, and more attraction to females than males was found for blend traps in the field experiments. Our results suggest that blends of this specific concentration and ratio of benzaldehyde and 2-hexenal can be used in traps as attractants for C. chinensis monitoring and control in the field.     

Gene bank scheduling of seed regeneration: Interim report on a long term storage study

A major challenge for the management of gene banks is the maintenance of good seed health in the collections. Large germplasm collections 10 000 accessions often have been acquired from different sources over a range of dates, may differ in germination at time of deposition in the gene bank, and may have genetic differences in seed longevity. The major storage variables affecting seed longevity are temperature and seed moisture content. Two varieties of each pea(Pisum sativus L.), lentil(Lens culinaris Medikus subsp. culinaris), and chickpea(Cicer arietinum L.), were stored at three temperatures; 40, 20, and 2°C, each with three seed moisture levels of 10.9–13.8%(high), 7.9–10.3%(medium), and 7–7.8%(low), in the Australian Temperate Field Crops Collection gene bank. Seed longevity at a given storage period was estimated by the corresponding germination percentage for each treatment. This paper is an interim report on seed viability decline in the first seven years of this seed longevity study, in which viability decline towards zero was almost completed in the three seed moisture treatments at 40°C and the 20°C high seed moisture treatment, but had not declined in the other treatments. Seed longevity positively responded to a reduction in temperature and then to a reduction in seed moisture. The number of days in storage for seed germination decline to 85%(p85), and to 50%(p50) for mean seed viability, are reported by storage/varietal treatment. Both p85 and p50 showed significant inverse linear responses with seed moisture at 40°C for pea and lentil varieties, with intra-specific variation for pea. This long term trial aims to provide informed timing of seed regeneration for accessions in a gene bank.     

Flight behavior of the sycamore lace bug,Corythucha ciliata,in relation to temperature,age, and sex

The flight capacity of different ages and sexes of the sycamore lace bug, Corythucha ciliata, was studied at different temperatures using a flight mill system. The results of regression analysis showed a significant effect of temperature on flight distance(P=0.0082). Temperature did not influence flight duration(P=0.212) or flight speed(P=0.175). The mean flight distance(1 024 m) and mean flight duration were the greatest at 25.2°C. The age of C. ciliata had a significant influence on flight distance(P=0.0005), flight duration(P=0.0005) and flight speed(P=0.026). The 12-d-old adult had the greatest flight distance(887 m), duration(3 875 s) and speed(0.22 m s–1). Flight distances and flight duration of females were significantly longer than that of males. However, the male had significantly greater flight speed than the female. The insect appears to be capable of long distance flights. The understanding of the optimal age and temperature for the flight of this insect through this study provides a foundation for better management of the insect in China.     

Physiological mechanisms of resistance to cold stress associated with 10 elite apple rootstocks

A study was conducted in attempting to identify the cold-resistant apple rootstocks and to establish a comprehensive evaluation system. In this study, 10 elite apple dwarfing rootstocks(GM256, JM7, M26, M7, SC1, SH1, SH38, SH6, M9, and T337) were employed for the experiment and the following parameters were investigated under different low temperature stress conditions(0, –15, –20, –25, –30, and –35°C): the changes of the relative electrical conductivity(REC), anthocyanin content, protein content, soluble sugar content, soluble starch content, proline content, malondialdehyde(MDA) content, superoxide dismutase(SOD) activity, and peroxidase(POD) activity of the dormant branches. The inflection temperature that could represent the plant tissue semi-lethal temperature(LT_(50)) was obtained by the measurements of REC. The LT_(50) was used to evaluate eight other indices. The results showed that there was no significant correlation between LT_(50) and POD activity as well as between the soluble sugar, protein and proline contents at 0 and –15°C. Soluble starch content at 0 and –15°C and anthocyanin content at –15–(–30)°C were significantly but negatively correlated to the LT50 and the MDA content at 0–(–20)°C was significantly positively correlated to the LT_(50). Statistical analysis based on principal component analysis and LT50 showed that cold resistant apple rootstocks in the decreasing order from high to low as GM256, SH6, SH38, SH1, SC1, M26, M7, JM7, T337, and M9.     

Isolated pea anther culture

Callus tissues and green globular embryoids are obtained in a pea anther culture on a medium with 2,4-D after cold (4°C) treatment of buds. In experiments with the use of treating buds with cold (4°C) and anther culture with heat (32 and 35°C), green embryogenic and morphogenetic calli are induced and regenerant plants are obtained. The origin of the regenerants is established by genetic markers.     

Biological characteristics of strain F603 of Epicoccom sp., an antagonistic fungus for controlling Phytophthora infestans

Factors influencing vegetative growth and spore germination of strain F603 of Epicoccom sp., an antagonistic fungus for Phytophthora infestans (Mont) de Bary, were studied. Among the different growth media tested, Rye agar was the best medium for its vegetative growth. The range of temperature and pH value for mycelial growth was 5–35°C and 2–12, respectively, with the optimum 25°C and 6–9, respectively. The fungus grew better in Czapek medium with maltose and dextrose as carbon sources and peptone, KNO₃, and NaNO₃ as nitrogen sources. The range of temperature for spore germination of strain F603 was 5–35°C, the optimum was 20°C. The range of temperature for sporulation was 10–30°C, and the optimum was 15–18°C.