A Putative Calcium-Permeable Cyclic Nucleotide-Gated Channel, CNGC18, Regulates Polarized Pollen Tube Growth

A tip-focused Ca^2＋ gradient is tightly coupled to polarized pollen tube growth, and tip-localized influxes of extracellular Ca^2＋ are required for this process. However the molecular identity and regulation of the potential Ca^2＋ channels remains elusive. The present study has implicated CNGC18 （cyclic nucleotide-gated channel 18） in polarized pollen tube growth, because its overexpression induced wider and shorter pollen tubes. Moreover, CNGC18 overexpression induced depolarization of pollen tube growth was suppressed by lower extracellular calcium （[Ca^2＋]ex）. CNGC18-yellow fluorescence protein （YFP） was preferentially localized to the apparent post-Golgi vesicles and the plasma membrane （PM） in the apex of pollen tubes. The PM localization was affected by tip-localized ROP1 signaling. Expression of wild type ROP1 or an active form of ROP1 enhanced CNGC18-YFP localization to the apical region of the PM, whereas expression of RopGAP1 （a ROP1 deactivator） blocked the PM localization. These results support a role for PM-Iocalized CNGC18 in the regulation of polarized pollen tube growth through its potential function in the modulation of calcium influxes.     

Effects of peach branches returning on autotoxins and microbes in soil and tree growth of peaches

Aims This study aimed to investigate the effects of branch returning on the growth of peach (Amygdalus persica "Chunmei/Maotao") saplings, soil enzyme activity, and soil contents of phenolic acids and amygdalin, thereby providing scientific evidence against the application of branch returning for peach trees. Methods One-year-old potted peach tree (Amygdalus persica "Chunmei/Maotao") was used in this study with four agricultural treatments applied, including soil coverage by fragmented peach tree branches (fragment treatment;1.5 and 22.5 g·kg^-1) and applying leachate solutions of peach tree branches to soil (leachate treatment; 1.5 and 22.5 g·kg^-1). No branch addition was used as control (CK). Solid phase extraction, high performance liquid chromatography (HPLC), biological high-throughput sequencing was used to determine the content of autotoxic substances, and microbial community structure in soil. Soil coverage and leachate solution treatments of 30 g and 450 g branches applied to the peach trees were described as 1.5 and 22.5 g·kg^-1, respectively in this paper.Important findings Compared with CK, the phenolic acid and amygdalin contents significantly increased after both fragment and leachate treatments in high quantities (22.5 g·kg^-1). Soil microbial community structure altered in both treatments, with the proportion of fungi (particularly Agaricomycetes, Tubeufia and Cystofilobasidiaceae) increased significantly and bacteria decreased accordingly. Invertase activity in both high-quantity treatments exceeded that in the CK significantly. The activity of catalase and urease was higher at first and then decreased relative to CK under high-quantity fragment and leachate treatments. Specifically, the effect of leachate treatment on enzyme activity was higher than the fragment treatment in the short term. Chlorophyll content, ground diameter (diameter of 5 cm from the ground) growth and net photosynthesis rate of plants were lower in high-quantity fragment and leachate treatments than those in CK, with earlier retardation of new shoot growth. We observed an increase in soil phenolic acids and enzymes in treatments in normal pruning quantity, while no inhibition effect was found on the tree growth. In conclusion, autotoxins (such as phenolic acid and amygdalin) inhibited the growth of peach trees both directly and indirectly through changing soil enzyme activity and microbial community.     

预防疫情,我们一直在行动

在疫情爆发初期,卫生部和国家疾病预防控制中心立即密切跟踪疫情动态,分析疫情发展情况,就疫情对我国的影响进行评估。我国风险评估报告认为,疫情在我国流行的可能性较小,     

移栽基质对赤桉试管苗移栽成活和苗木生长的影响

赤桉(Eucalyptus camaldulensis Dehnh)试管苗由本校组培室提供.花盆以0.1%高锰酸钾消毒,用塑料薄膜保湿.用4种移栽基质移栽:(1)黄土:河砂=5:3,(2)黄土:珍珠岩=2:1,(3)黄土:火土灰:珍珠岩=1:1:1,(4)黄土:河砂:腐殖土=3:1:1.每花盆装半盆基质,重复4次.     

外源植物生长调节物质对烟草根中烟碱含量和烟碱合成酶活性变化的生理效应

水培法研究烟草打顶和喷施外源生长调节物质的结果表明:打顶的比不打顶的烟草根中鸟氨酸脱羧酶(ODC)、腐胺N-甲基转移酶(PMT)和N-甲基腐胺氧化酶(MPO)活性升高,烟叶中烟碱含量剧增;打顶喷施ABA和6-BA烟叶中烟碱含量升高,喷施IAA和GA3的下降,IAA的效果更明显.     

植物抗旱性中的补偿效应及其在农业节水中的应用

在论述植物补偿效应存在类型和研究范畴的基础上,详细评述了植物抗旱性中根系形态结构功能及地上部干物质积累、产量和水分利用效率方面的补偿效应及其影响因素,并对植物抗旱作用中补偿生长的可能生理学机制作了探讨。同时,对补偿效应在提高农业水分利用效率中的应用进行了讨论     

草地早熟禾草坪土壤水分动态与根系生长分布

对草地早熟禾草坪土壤水分动态和根系生长发育状况进行研究,结果发现不同土壤层次水分变化有所不同,0～15cm变化最大,15～30cm次之,30cm以下土层水分变化不大;草地早熟禾的根系生长呈现双峰曲线模式,5月中旬和8月中下旬总根量处于峰值;其主体根系主要分布在0～30cm土层内,占总根量的85%以上;根重密度随土层深度呈指数衰减关系,0～30cm土层下降幅度较大,30cm以下土层根重密度相差不大;在0～30cm土层内不同层次根量占总根量的比例在不同时期亦有差异,春秋季节10～20cm和20～30cm土层内根量比例较大,说明此时期主体根系分布在较深的土层;综合分析认为草地早熟禾草坪主要利用土壤浅层水分,在降雨较少的春秋季节,根系较深,适宜深层灌溉,在降雨频繁的夏季,根系较浅,适宜浅层灌溉。     

不同来源和粒径的胶体对光合细菌生长的效应

天然胶体是近岸海域细菌和浮游植物可利用氮的一个重要来源 ,其含量的增加可促进藻类的繁殖和生长 ,有时甚至引发赤潮。研究显示 ,细菌在高分子量胶体存在下的生长和代谢速率比在低分子量中的提高 3～ 6倍 ,暴露在阳光下的胶体有机物可释放生物可利用的富氮组分 ,进而提高细菌对胶体的分解。利用错流超滤技术从河流、河口、海洋水体和微藻培养液中提取胶体 ,研究了胶体来源和粒径对光合细菌 (PSB,沼泽红假单胞菌 Rhodopseudomonaspalustris)生长的影响。结果表明 ,在一定的胶体有机碳浓度范围 ,河流胶体 (0～ 2 81.0μmol/ L )、河口胶体 (0～ 12 1.2μmol/ L )、海洋胶体 (0～ 88.8μmol/ L )和生源胶体 (7.7～5 4 8.6μmol/ L )都能促进 PSB的生长 ,分别使其相对增长率平均提高了 4 7.3%～ 196 .2 % ,3.6 %～ 9.3% ,8.1%～ 10 .4 %和2 .4 %～ 6 .9%。其中 ,PSB在河流胶体中的相对增长率的平均值 (Y)与有机碳浓度 (CDOC)呈对数相关 (Y (% ) =- 193.7 70 .7ln CDOC) ,表明高浓度的河流胶体 ,对 PSB生长的促进效果更显著。两种生源胶体中 ,海水小球藻胶体 (0～ 5 4 8.6μmol/ L )对PSB生长的促进作用大于球等鞭金藻胶体 (7.7～ 384 .4 μmol/ L) ;PSB在粒径为 10 k D～ 0 .2 2 μm的海洋胶体中的生长大于     

鲤科鲴亚科鱼类的系统发育及动物地理学

以雅罗鱼亚科为外群,采用分支系统学的原理和方法对鲐亚科17个属(须鳊属除外)进行了系统发育和动物地理学的分析。结果表明,(1)鲴亚科这17个属为一个单系群,并由4个较小的单系群组成;(2)鲴亚科现在的地理分布格局除源自离散事件外,主要源于扩散事件。鲐亚科的特征演化还表明,东亚地区地质历史的反转演化和平行演化可能在鲴亚科系统发育过程中起了重要的作用。     

CO_2对牟氏角毛藻高密度培养的影响

以牟氏角毛藻为材料,通过对比实验研究了CO2和CO2通入方式对光合生物反应器中高密度培养的牟氏角毛藻的生长速度和细胞密度的影响;并以水体pH值为指标,控制CO2的通入数量,进而研究了牟氏角毛藻在我们自行研制的卧式光合生物反应器中的生长情况。结果表明细胞悬浮培养达到一定密度之后,CO2的供应,可以有效地提高生长速度和细胞密度。对CO2通入方式的实验结果表明,不同的CO2通入方式,产生的效果不同,其中以空气和纯CO2混合后通入,效果最好。