Expression of ROP/RAC GTPase genes in postharvest loquat fruit in association with senescence and cold regulated lignification

ROP/RAC GTPases regulate various development processes and play important roles in plant defense responses. Recently, lignification or secondary cell wall formation related ROP members were reported in rice, zinnia, cotton and Eucalyptus. The present study aimed to investigate the possible association of loquat ROPs with flesh lignification under different temperatures. Four ROP cDNA fragments, EjROP1.1, EjROP1.2, EjROP2 and EjROP3, were isolated from ‘Luoyangqing’ (LYQ) loquat fruit, and all of them shared over 80% nucleotide identity with known ROPs from other plants. Sequence analysis revealed that EjROP1.1, EjROP2 and EjROP3 might be functional while EjROP1.2, with mutated C-terminal resulted from a 65 bp deletion in the corresponding nucleotide sequence as compared with EjROP1.1, might be dominant-negative and consequently act as a negative regulator of ROP signal transduction. Increase in expression of EjROP1.1, EjROP2 and EjROP3 was observed during first 4 or 6 d of storage at 20 °C and was positively correlated with the increase in flesh firmness. Expression of EjROP1.2 was constantly low under 20 °C but was quickly, within 6 h, induced under 0 °C, and it increased by about 20 times within 24 h. The expression was induced under 5 °C as well but not so strong as that under 0 °C, and transfer of fruit from 5 °C to 0 °C re-stimulated the expression. The possible roles of EjROPs played during senescence and cold regulated lignification was discussed, and the simultaneous increase in the expression of three functional EjROPs and the negative regulator EjROP1.2 was suggested to be important for maintaining a ROP rheostat to protect cells from excessive lignification. To our knowledge, this is the first study on a dominant-negative ROP resulted from a deletion mutation, and a ROP responded to low temperature.     

短低温早花观赏桃新品种——探春的选育

探春是用迎春为母本,白山碧桃为父本、进行人工杂交培育成的观赏桃新品种。该品种为重瓣花,蔷薇型,花粉红色,花径4.6cm,花瓣4～6轮,花瓣数20～25枚,雌蕊常退化。花有淡香味。节间较长,节长2.3cm。果实小,果肉薄,有苦味,不宜食用。郑州地区3月初开花,需冷量短,400h。开花早,能弥补早春桃花的空缺,通过保护地促早栽培,能顺利在春节前开放,满足中国传统节日对桃花的需求。     

谈冬季树木防寒

受气候因素的影响,丹东市近年来连续出现倒春寒现象,部分不耐寒树种及早期放叶,开花的树木,在早春经常遭受冻害或出现"生理干旱"现象。本文从生产实践出发,论述了受害树木的部位及受害原因,并提出具体的保护措施。     

白毛茶树早春受低温冻害的原因与防御补救措施

茶树原属亚热带植物,抗寒能力较弱,其能承受的最低温度在-7～-15℃,各品种间差异显著。白毛茶树是叶用作物,其1～2月份新梢萌发期极易受"倒春寒"的影响,轻则幼嫩芽叶卷曲、变褐、变焦,茶叶减产;重则茶树生长势衰落,枝枯叶落,甚至死亡。通过对白毛茶冻害研究,提出了相应的对策,供生产参考。     

2008年初黔西南州甘蔗冻害调查与分析

调查了2008年初黔西南州甘蔗冻害情况,分析冻害机理、分布情况及环境因素,提出了预防甘蔗冻害的具体措施。     

猕猴桃根提取物抗氧化及保肝作用的研究

[目的]研究猕猴桃根不同极性溶剂的提取物在体外抗氧化活性及对CCl4肝损伤小鼠血浆转氨酶活性的影响。[方法]采用FTC法进行体外抗氧化试验,并用CCl4建立小鼠急性肝损伤模型,以不同的提取物和阳性对照药甘草酸二铵灌胃治疗,测定小鼠血浆中丙氨酸转氨酶(ALT)、天冬氨酸转氨酶(AST)活性。[结果]猕猴桃根经乙酸乙酯萃取部分的抗氧化活性较强,其用量为60 mg/kg时,对CCl4造成的小鼠急性肝损伤ALT、AST活性升高具有显著的降低作用。[结论]乙酸乙酯萃取部分对肝脏损伤有保护作用。     

库尔勒香梨历年冬季低温评价及严重冻害成因分析

通过评价1958-2008年库尔勒香梨越冬期间及早春低温资料,分析了历年冻害发生情况及冻害成因.结果表明:1958-2008年,气温异常偏低年份有9年,香梨发生了6次严重冻害,其中5次严重冻害发生在越冬期间,早春冻害1次(2005),剩余3年气温在临界线附近,没有造成严重冻害;1958-1986年极端最低气温变化趋势基本正常,之后有升高趋势;2007-2008年冬季气温异常偏低,导致了大面积冻害;香梨冻害发生临界温度大致为-20 ℃;香梨冻害与极端低温、低温持续日数、降温幅度、降雪厚度及持续时间、立地条件及管理水平等因素有关.     

A Preliminary Analysis of the Relationship between Longan Canopy Temperature and Air Temperature during Overwintering Period

[Objective] The study aimed to provide supports for developing chilling and freezing injury monitoring and disaster damage assessment of longan(Dimocarpus Longan Lour.).[Method] Based on field observation data,the relationships between longan canopy temperature and air temperature under different weather types(sunny,cloudy to sunny,cloudy,rainy,radiation chilling injury and advection chilling injury)in 2007-2008 winter were analyzed.[Result] Diurnal variations of longan canopy temperature under sunny and radiation chilling injury weather conditions were most dramatic,followed with those under cloudy to sunny condition,while variations under cloudy,rainy and advection chilling injury conditions were mild.Diurnal variations of orchard air temperature were also closely related to weather types.By using linear and curvilinear regression methods,the relationship models between longan canopy temperature and observation station air temperature were established.The models for cloudy,rainy and advection chilling injury had better effects than those for sunny,cloudy to sunny and radiation chilling injury;the models for night were better than those for daytime and the whole day.[Conclusion] To some extent,applying the relationship models between longan canopy temperature and observation station air temperature could make up the shortcoming of meteorological data which were higher than the real values.     

茶多糖对四氯化碳致小鼠肝损伤的保护作用

从六安炒青水提物中分离纯化得到茶多糖TPS-II,对其纯度和分子量进行检测,通过测定小鼠血清超氧化物歧化酶(SOD)活性、天冬氨酸转氨酶(AST)活性、丙二醛(MDA)含量及肝脏指数,研究其对四氯化碳(CCl4)引起的急性肝损伤的保护作用。结果表明TPS-II相对分子量约为1.01×105,总糖含量为85.30%,蛋白含量为2.80%,并对CCl4引起的小鼠急性肝损伤有明显的保护作用。     

低温与赤霉素处理对‘凤丹’种子萌发和幼苗生长的影响

研究了在容器栽培条件下,赤霉素(GA₃)与低温处理对促进‘凤丹’牡丹种子生根、萌芽和幼苗生长的效果,结果表明：GA₃能够促进种子生根,100～200 mg﹒L-1低浓度处理有利于提高生根率与生根质量;在一定范围内,延长低温处理时间促进种子萌发和幼苗生长;在低温足以打破上胚轴休眠时,较高浓度的GA₃对幼苗生长发育不利。综合分析不同处理对发芽率、发芽指数、苗高、叶片数、第1叶叶宽、茎长以及地上和地下部干质量等指标的影响,发现21 d和28 d低温分别结合100或200 mg﹒L-1 GA₃处理,最有利于种子萌发和幼苗生长。