冰核活性细菌(INA bacteria)对杏花器官ABA、IAA和可溶性蛋白质含量的影响

试验以2个杏品种花器官为试材,研究低温及INA细菌处理下,花瓣、雄蕊及雌蕊ABA、IAA、可溶性蛋白质含量变化。结果表明:随温度下降,未接菌杏花器官内ABA和可溶性蛋白质含量呈上升趋势,-5℃是花器官的受害温度。接种INA细菌后,ABA、可溶性蛋白质含量下降,杏花器官在-3~-4℃受到伤害。接种INA细菌与对照花器官间ABA与可溶性蛋白质含量差异达显著或极显著水平。在低温及INA细菌影响下,IAA在杏花器官间无规律变化。     

山东省植物上冰核活性细菌种类与分布研究

从山东省25种植物上分离到60株冰核活性细菌，鉴定结果为：假单胞菌属有37株，其中非荧光假单胞菌10株，占16.7%；丁香假单胞菌11株，占18.3%；荧光假单胞菌2株，占3.3%；菜豆荚斑假单胞菌14株，占23.3%。欧文氏菌属有23株，其中菠萝欧文氏菌21株，占355；草生欧文氏菌2株，占3.3%。INA细菌的种类和分布受季节、环境、地域和植物种类等多种因素的影响，这是山东省关于冰核细菌研究的首次报道。     

冰核细菌冰核基因多态性的研究

 根据冰核细菌基因中的多拷贝重复编码区设计并合成简并引物inaZI[5'-GCCGGTTATGGCAGC(T)ACGCTGACC-3'],通过聚合酶链式反应(Polymerase Chain Reaction,PCR)扩增20株不同种属的INA⁺和INA^-细菌菌株.结果表明:所有供试的冰核活性菌株均获得扩增产物,而非冰核活性菌株则无扩增产物.冰核基因的扩增产物呈多态性.     

冰核细菌对液体食品过冷却点的影响

于 2 2℃下在KB培养基上培养冰核活性细菌 (Xanthomonascampestris菌株XcIN 1) ,对数生长期离心获得的细胞冰核活性最强。该细胞在 - 3℃时能够起到冰核的作用使纯水结冰。把冰核细菌与液体食品 (如蔗糖、蛋清、牛奶、番茄汁、苹果汁、橘汁、梨汁、酱油、豆酱和食醋 )混合 ,观察其对过冷却点的影响。结果是 ,加入冰核菌使液体食品的过冷却点提高了 0 .3～ 3.7℃ ,表明在冷冻食品工业中应用细菌冰核可以节约能源并提高效率     

A Stably Transgenic INA Enterobacter cloacae for Control of Insect Pests

Using the minitransposon pMini-Tn5 and the ice-nucleation active (INA) gene of iceA, a suicide recombinant plasmid pTnice1 was constructed, which has the ability of broad-host-range conjugal mobilization and integration of iceA into chromosomal DNA of many gram-negative bacteria by Tn5 transposition.We used this plasmid to integrate the iceA into chromosomal DNA of Ent. cloacae and obtained the transgentic strain Enc1. 2022ina. In this transgenic Ent. cloacae, iceA would never be transferred elsewhere through transposition, and constantly expressed high ice nucleation activity even in the absence of antibiotic pressure.The transgenic strain was ingested by corn borer larvae. Over the 7 d after ingestion, the mean supercooling points (SCPs) of the larvae was about 10℃ higher than those of larvae treated with distilled water (control).The maintenance of these high SCPs was related to the stable gut colonization of transgenic strain. At 6th day post ingestion, the larva was exposed at - 5 or - 7℃ for 12 h, the percentages of larvae frozen to death were 85and 100%, respectively. In contrast, none or a small proportion of control larvae was frozen to death under the same conditions. Further studies demonstrated that this transgenic strain bore weak epiphytic ability.Therefore, this genetically engineered strain may be a promising candidate for control of insect pests in agricultural fields.     

冰核活性细菌拮抗菌株的筛选

 从多种植物根际土壤中分离到300个细菌分离物,通过含菌平板培养筛选出F015,F023,F046等近20株对冰核细菌具有较强的拮抗力,室内测定对冰核细菌病原物抑菌圈达0.8～3.0 cm. 挑选出F015,F023,F046进一步进行室内抗菌机理、菌株鉴定和室外田间小区实验。实验结果表明,菌株初步鉴定为芽孢杆菌（Bacillus spp.）和假单胞杆菌（Pseudomonas spp.）。其代谢产物蛋白质粗提物对冰核细菌的生长有明显的抑制作用。室外防霜效果在19.5％～36.9％,可有效地控制霜冻害的发生与危害,具有广阔的应用前景。     

诱发枇杷霜冻害的冰核细菌拮抗菌分离与筛选

[目的]筛选出具有防除枇杷INA细菌的拮抗菌.[方法]从枇杷根际土壤中分离冰核细菌拮抗菌,对其进行抑菌圈、杀菌能力、破坏冰核活性蛋白能力测定.[结果]从不同海拔地区的根际土壤中共分离得到128个菌株,其中有拮抗效果的有55株,平皿拮抗效果强的有15株,再经拮抗系数比较得到9株强拮抗菌菌株,最后筛选出l株杀菌率达98％、破坏冰核蛋白能力达100％的拮抗菌BL-36.[结论] BL-36既有杀菌效果又有破坏冰核蛋白能力,是具有较好利用前景的防除诱发枇杷霜冻害冰核细菌、减轻枇杷霜冻害的生物防治材料.     

北方杨树上冰核活性细菌的研究

从辽宁省、黑龙江省及北京市的杨树不同部位及干部溃疡类病害的病斑上分离到大量细菌。约有６０％左右的菌株在－３．５～６℃具有冰核活性。其中，从树干冻伤部位分离的细菌数量最多，冰核活性细菌的比例也最高；由Ｄｏｔｈｅｏｒｅｌｌａ ｇｒｅｇａｒｉａＳａｃｃ，引起的大型溃疡病病斑上也分离到较多的冰核活性细菌。用干部大型溃疡斑上分离到的１个冰核活性较强菌株和叶部分离１个冰核活性强的菌株，在人工霜箱中测定，可使     

Evaluation of postharvest treatments with chemical resistance inducers to control green and blue molds on orange fruit

Preventive and curative activities of postharvest treatments with selected chemical resistance inducers to control postharvest green (GM) and blue (BM) molds on oranges (cvs. ‘Valencia’ or ‘Lanelate’) artificially inoculated with Penicillium digitatum and Penicillium italicum, respectively, were evaluated. In vivo primary screenings to select the most effective chemicals and concentrations were performed with benzothiadiazole (BTH), β-aminobutyric acid (BABA), 2,6-dichloroisonicotinic acid (INA), sodium silicate (SSi), salicylic acid (SA), acetylsalicylic acid (ASA) and harpin. INA at 0.03 mM, SA at 0.25 mM, BABA at 0.3 mM and BTH at 0.9 mM were selected and tested afterwards as dips at 20 °C for 60 or 150 s with oranges artificially inoculated before or after the treatment and incubated for 7 d at 20 °C. Although it was an effective treatment, SSi at 1000 mM was discarded because of potential phytotoxicity to the fruit rind. Preventive or curative postharvest dips at room temperature had no effect or only reduced the development of GM and BM very slightly. Therefore, these treatments cannot be recommended for inclusion in postharvest decay management programs for citrus packinghouses.     

Effects of INA on postharvest blue and green molds and anthracnose decay in citrus fruit

As a synthetic functional analog of salicylic acid, 2,6-dichloroisonicotinic acid(INA) is effective in inducing the host disease resistance of a plant against a pathogen. The effects of INA on controlling postharvest blue and green molds and anthracnose decay and defense-related enzymes on citrus fruits were investigated, and the ascorbic acid of naturally infected citrus flavedo was also measured. Results showed that 1.0 mmol L~(–1) INA treatments significantly reduced blue and green molds and anthracnose decay development on both wound-inoculated fruit and naturally-infected fruit compared with the control fruit. The treatment effectively enhanced the β-1,3-glucanase(GLU), chitinase(CHI), phenylalanine ammonia-lyase(PAL) and peroxidase(POD) activities and the polyphenol oxidase(PPO) in flavedo. The results presented here suggest that INA might be used as a chemical fungicide substitution to control postharvest diseases in citrus fruits.