水稻根尖边缘细胞对铁胁迫的缓解效应

 从20个水稻品种中筛选出较耐亚铁的水稻品种协优9308和敏感品种IR64,采用静置培养（使边缘细胞附于根尖）和摇床培养（移除根尖边缘细胞）,测定根相对伸长率、含水量、根尖保护酶（POD、SOD、CAT）活性以及各根段铁含量,研究边缘细胞对水稻根尖铁胁迫的缓解效应。结果表明,铁毒处理抑制根的伸长、降低幼根的含水量,移除边缘细胞的根相对伸长率以及含水量都低于保留边缘细胞的根,且随着铁毒处理时间的增加,根相对伸长率和幼根的含水量总体呈现下降趋势。在200 mg/L铁毒处理下,根尖保护酶（POD、SOD、CAT）活性受到抑制（除静置培养下协优9308的POD活性外）,摇床培养对酶活性的抑制程度较大。铁毒处理使根段铁含量显著上升,静置培养下根段铁含量从0~2 mm到8~10 mm依次增大,摇床培养除8~10 mm根段外其余均无显著差异。说明边缘细胞在水稻根尖铁毒防御中起着一定的作用。     

乙烯利-缩节安复配剂对夏玉米根系伤流液的影响

研究结果表明:夏玉米根系伤流量在吐丝期前后达到高峰,其后随着植株的衰老成熟不断下降,伤流液中各种营养元素和内源激素流量基本与伤流量的变化趋势一致。在大喇叭口期叶面喷施乙烯利-缩节安复配剂后,根系伤流量有所减少,但差异不明显;在吐丝期或子粒形成初期前,复配剂处理的大量和微量元素流量要略高于对照,其后则明显低于对照;内源激素流量在吐丝期前高于对照,其后则略低于对照。上述结果表明,乙烯利-缩节安复配剂具有调控根系伤流量、营养元素和内源激素流量的作用。     

乙烯利和光强对水稻节间生长的协合效应

喷乙烯利或遮光处理后,水稻拔节期分别比对照提早19天和10天;喷乙烯利并加遮光的处理,拔节期比对照提早天数增加到23天。单喷乙烯利和单遮光的处理,其第一伸长节间长度和对照的对应节间相近,但喷乙烯利并加遮光的处理,其第一伸长节间长为10.0厘米.显著长于对照相应节间(2.3厘米)。因此,乙烯利与光强对水稻节间的伸长有显著的协合效应(synergistic effect).     

乙烯利浸种对甘蔗苗期生长及生理生化特性的影响

本试验采用3种不同浓度乙烯利溶液（0mg/L、100mg/L,400mg/L)分别对中熟品种桂糖15号（G15）和早熟品种新台糖20号（ROC20）在下种前进行24h浸种处理后进行砂培试验，结果表明：用乙烯利溶液浸种处理后的一个月内，内蔗糖幼苗 1叶中的生长素（IAA）、赤霉素（GA3）、玉米素（Zeatin)含量显著降低，应激内源乙烯含量上升，光合速率下降，并且提高了叶片含水量，细胞膜透性，过氧化物酶和中性转化酶的活性，降低了水溶性蛋白质含量和酸性转化酶的活性，从而使甘蔗苗期生长受到抑制，假茎高，叶面积、地上部干重和根系活力下降，且浓度越高，抑制越明显。     

菠萝SVP基因对乙烯利刺激的响应

SVP（short vegetative phase）是一类开花抑制基因,通过调节开花相关基因的表达,影响植物从营养生长阶段向生殖生长阶段的转变进程。根据公布的菠萝基因组信息,从‘台农4号’菠萝中克隆到2个AcSVP基因AcSVP1和AcSVP2。结果表明：AcSVP1和AcSVP2分别编码225和230个氨基酸,均含有MADS-box、K-box保守结构域,二者所编码蛋白均属MADS-box基因家族成员。定量PCR分析结果显示,2个AcSVP基因在菠萝茎尖、茎基和叶中均有不同程度的表达,乙烯利处理后主要表现为下调。乙烯利处理8 h内,AcSVP1在茎尖、叶中的表达显著下调,但在茎基组织中呈现先下调后上升的趋势;乙烯利处理后8 h,茎基组织中AcSVP1的相对表达量略高于对照。与AcSVP1不同,乙烯利处理8 h内AcSVP2在茎尖、茎基、叶3种组织中均明显下调;乙烯利处理后8 h,AcSVP2在茎尖、茎基、叶组织中的相对表达量只有对照的8%、44%和33%。SVP是目前已知的最重要的一类开花抑制基因,AcSVP在响应乙烯利的过程中表达显著下调,表明其在乙烯利诱导菠萝成花过程中可能发挥重要作用。     

乙烯利对夏玉米子粒干物质积累的影响及生理机制探究

以郑单958为试验材料,于玉米第9展叶期喷施200、400、800 mg/L乙烯利,喷施清水作对照,测定子粒发育过程中灌浆速率及可溶性糖、淀粉和激素含量,考种计产。结果表明,400 mg/L和800 mg/L乙烯利处理显著降低郑单958的单穗重和千粒重,同时降低灌浆后期生长素(IAA)、脱落酸(ABA)和赤霉素(GA3)的含量及平均灌浆速率和最大灌浆速率,降低子粒中淀粉含量;200 mg/L乙烯利处理单穗重及灌浆速率与对照差异不显著。结合产量、干物质积累和激素含量变化分析,喷施高浓度乙烯利导致子粒中激素含量变化是子粒灌浆速率下降、干物质积累速率减慢和千粒重下降。建议生产中用200 mg/L乙烯利为主要喷施浓度。     

乙烯利和赤霉素对高山羊齿孢子生长的影响

采用不同浓度的乙烯利、赤霉素喷施高山羊齿,浓度设定为:10 mg/L,50 mg/L,100 mg/L,150 mg/L,喷施清水为对照,探讨乙烯利、赤霉素对高山羊齿生长量及孢子生长的影响;结果表明:分别喷施了不同浓度的乙烯利和赤霉素,高山羊齿的生长量都低于对照,而在对照中高山羊齿均无孢子出现,而喷施了不同浓度的乙烯利和赤霉素的高山羊齿的叶背均出现了孢子,且随着乙烯利和赤霉素浓度的增加,产孢率不断上升;乙烯利和赤霉素对于高山羊齿而言,会抑制其营养生长而促进其生殖生长。     

一氧化氮对甘蔗锰积累的影响

近年来在广西主要的甘蔗种植区出现了土壤中锰含量过高所导致的甘蔗宿根蔗幼苗黄化问题,这严重降低了甘蔗的产量和品质,制约了甘蔗产业发展。一氧化氮（NO）是植物体内介导植物响应重金属胁迫的信号分子,在缓解重金属毒害方面起着重要作用。采用水培试验方法研究了锰胁迫下NO积累与甘蔗植株锰含量及细胞壁多糖组分的关系,旨在为揭示甘蔗锰毒耐受机制提供科学依据。结果表明,锰处理后植株锰含量显著增加,并且植株中的锰主要积累在细胞壁及其果胶组分中;0.5、1.0 mmol/L锰处理24 h,后根尖中NO的积累量显著增加。在0.5 mmol/L锰溶液中添加NO供体硝普钠（SNP,0.2 mmol/L）增加植株NO积累后,根系锰含量为1215.4 mg/kg,叶片锰含量为525.5 mg/kg,相对于对照增加了37.1%,根及叶片中的锰含量、根细胞壁及其果胶组分中的锰含量均显著增加;一氧化氮清除剂（cPTIO,0.1 mmol/L）处理后,有效减少植株NO积累,并降低了根系、根系细胞壁及细胞壁果胶组分中的锰含量,根系锰含量相较于对照降低了78.2%,根系细胞壁和细胞壁果胶的锰含量相对于对照分别降低57.4%、40.6%;与此相同,硝酸还原酶抑制剂钨酸钠（0.3 mmol/L）处理抑制了硝酸还原酶（NR）活性并降低了植株NO积累,甘蔗植株、根系细胞壁及其果胶组分中的锰含量均显著下降。虽然钨酸钠处理后根系细胞壁中的半纤维素I和半纤维素II组分含量变化不显著,但细胞壁果胶组含量、果胶甲酯酶活性以及果胶去甲酯程度显著降低,从而减少了细胞壁的锰吸附。可见,锰胁迫引起甘蔗细胞积累NO,而NO通过调控细胞壁的多糖组分及果胶甲酯化程度介导植株锰积累与分布。     

乙烯利对离体培养的玉米子粒发育及酸性蔗糖酶的影响

采用玉米子粒离体培养的方法,研究不同浓度乙烯利处理对子粒的生长发育及酸性蔗糖酶(SAI)的影响。结果表明,玉米子粒败育率随乙烯利浓度的提高呈上升趋势,乙烯利浓度在50～1 200mg/L时,子粒的鲜粒重、干物重高于对照;乙烯利浓度小于50mg/L时,对SAI活性起抑制作用;浓度在100～1 200mg/L时,SAI活性远高于对照;浓度为400mg/L时,子粒的鲜粒重、干物重和SAI活性分别达最高值。在玉米子粒发育中期,用适当浓度(400mg/L)乙烯利处理有利提高产量。     

三种植物生长调节剂对除虫菊酯含量与产量相关性状的影响

以从云南田间筛选的优良除虫菊无性系为试材,比较研究营养生长期和花蕾期喷施不同浓度的乙烯利、多效唑和比久对花序中除虫菊酯含量及产量相关性状的影响。结果表明,3种植物生长调节剂均能显著提高花序的除虫菊酯含量,以1 000 mg/L比久和50 mg/L乙烯利处理较好,增幅分别达17.9%和15.2%。喷施乙烯利、多效唑和比久也均能提高鲜花产量和干花产量,从而增加除虫菊酯产量,以150 mg/L多效唑处理效果最佳,除虫菊酯产量比对照显著提高了770 mg/株,其次为50 mg/L乙烯利处理,比对照显著提高了514 mg/株。     

Effects of Ethephon on Aerenchyma Formation in Rice Roots

The effects of ethephon on the constitutive aerenchyma formation in roots were studied with a rice variety Yangdao 6 as material. The number of air spaces formed by disintegrated cells in mediopellis increased significantly with the rising ethephon concentrations, whereas superoxide dismutase (SOD) activity showed downward trends. Compared with the control, the expression levels of xyloglucan endotransglycosylase (XET) gene were markedly higher both at the apical 10 mm and distal parts of roots in 100 mg/L ethephon treated plants. The accumulation of XET was supposed to be associated with the aerenchyma development. Furthermore, earlier cortical cell death was observed under the ethephon treatments, and most of nuclei of cells at 4 mm from the root apex disintegrated with many Golgi apparatus, mitochondria and membrane- bound vesicles around the cell wall.     

Improved waterlogging tolerance of barley (Hordeum vulgare) by pretreatment with ethephon

ABSTRACT

Root growth into hypoxic or anoxic waterlogged soil relies on internal aeration in plants. The plant hormone ethylene helps adapt to waterlogging by inducing the formation of aerenchyma, which provides a low-resistance pathway for the transport of oxygen from the shoot to the root apex. Waterlogging-susceptible crops including barley start to form aerenchyma after suffering waterlogging stress. But waterlogging can be fatal if aerenchyma formation is not fast enough. Here, we investigated whether pre-treating barley with ethephon, an ethylene-releasing agrochemical, could improve its tolerance to mimicked waterlogging conditions (using stagnant deoxygenated agar nutrient solution). In barley growing in aerated nutrient solution, ethephon treatment enhanced aerenchyma formation at the root tips and induced the development of shorter and shallower roots. Pre-treating barley leaves also delayed waterlogging-caused whiting and increased the percentages of viable root-tips under waterlogging conditions. However, the pretreatment did not noticeably increase fresh weight or shoot length. Further studies are needed to optimize ethephon treatment conditions to improve barley production under waterlogged conditions.     

淹水胁迫下小麦根通气组织形成的PCD特征及活性氧作用初探

为了解淹水条件下小麦根通气组织形成的细胞学特点和活性氧(Reactive oxygen species, ROS)在通气组织形成中的作用,以高度耐湿的华麦8号幼苗为材料进行淹水处理,在显微水平上系统地观察了通气组织的形成过程,在分子水平上检测了细胞核DNA的断裂情况,并对ROS的动态变化进行了荧光观察.结果表明:(1)通气组织最先起源于根皮层中部,然后逐渐扩展,到淹水8 d时基本形成,淹水60 d时更为发达;(2)淹水1.5～48 h根皮层出现大量细胞核DNA断裂,且细胞核DNA降解为180～200 bp的片段,证明小麦根通气组织的形成过程是根皮层细胞发生细胞程序化死亡(Programmed cell death, PCD)的过程,而且淹水1.5～48 h是根皮层细胞死亡高峰期;(3)ROS在细胞核DNA发生断裂前开始积累,在通气组织形成中呈现动态变化.上述结果表明, 淹水胁迫下小麦根通气组织形成是一个皮层细胞PCD的过程,并且ROS可能参与介导了PCD的进程.另外,淹水胁迫在前期抑制了次生根的产生,随后又促进了次生根的产生.     

渍涝对不同耐性花生品种根系形态特征及解剖结构的影响

为解析渍涝对花生根系形态特征的影响，以耐性品种湘花2008与敏感品种中花4号根系为研究材料，在自制根架系统内进行盆栽培养，于幼苗期分别进行0、3、6、9、12 d渍涝胁迫处理，通过根系的鲜（干）重以及显微和超微结构研究不同耐性花生品种根系形态特征的差异。结果表明，渍涝胁迫下中花4号根系受影响较大，随着淹水天数延长，根系颜色加深，臭味加重，而湘花2008仅根系中、上部根色变黄，臭味较轻，湘花2008根系鲜重耐渍系数高于中花4号。湘花2008出现了通气组织，且随着淹水时间增加，通气组织数量增加、横截面积加大；主根中段木质部基本保持正常，导管大体呈射线状分布。而中花4号未形成明显的通气组织，木质部和导管呈不规则分布。湘花2008主根细胞内的细胞核、线粒体虽受到影响，但仍能维持细胞活动，保持根系生长状态。中花4号细胞器受渍涝胁迫较敏感，加速衰老死亡。综上认为，渍涝胁迫下湘花2008根色和根味受影响较小，主根出现了通气组织，主根中段木质部与细胞中的细胞核、线粒体基本正常。而中花4号根色和根味受影响较重，未形成明显的通气组织，主根中段木质部和导管呈不规则分布，主根中段细胞中的细胞质溶解，线粒体异常。本研究可为解析花生耐渍涝机理提供依据。     

乙烯利-甜菜碱复配剂对玉米生长发育的影响

以宁玉614为试验材料,在玉米10叶展开时通过叶面喷施乙烯利和乙烯利-甜菜碱复配剂,研究甜菜碱（GB）对乙烯利喷施玉米效应的影响。结果表明,甜菜碱可缓解乙烯利对株高、穗位高以及节间伸长的抑制效应,也能抑制乙烯利对叶绿素的降解;甜菜碱增强乙烯利对节间粗度的促进效应,可诱导玉米产生更多气生根,对玉米增产起到一定的促进效应。     

乙烯利对花生农艺和生理性状的影响

以六种浓度的乙烯利对初花期花生进行叶面喷施,定期观测其主要农艺、生理生化及产量指标。结果表明,喷施适宜浓度的乙烯利可抑制地上部分的生长,提高叶片和植株物质积累量;100 mg/L和150 mg/L乙烯利处理能优化花生植株的生理生化特性,表现为显著提高花生叶片的蛋白质含量和叶绿素含量及SOD和POD活性,增强花生叶片的光合速率和蒸腾速率,增强了主根活力,降低花生叶片丙二醛和可溶性糖含量;200 mg/L乙烯利处理能提高植株的单株结荚数、饱果率和产量,但百果重和百仁重有所下降。     

Aerenchyma Formation in the Seminal Roots of Japanese Wheat Cultivars in Relation to Growth under Waterlogged Conditions

Abstract

Morphological adaptation of roots is critical for plants to survive under waterlogging. In this study, we evaluated the capacity of wheat to form aerenchyma in seminal roots in combination with the growth angle of the roots. We used five Japanese cultivars from the waterlogging-prone Kanto-Kyushu region in Japan, and a non-Japanese cultivar, Bobwhite for comparison. Seedlings in pot culture were waterlogged at a 3-cm depth for 7 days. The first adverse effect of waterlogging on plant growth was a significant reduction of root dry mass. The reduction rate varied with the cultivar, and it was 19.2% in cv. Shiroganekomugi and 40.0% in cv. Norin 61. Root aerenchyma was initially observed on the 2nd day of waterlogging and developed until the 7th day, in all 6 cultivars. Quantitative analysis of the aerenchyma development revealed no significant difference in radial distribution among the cultivars, whereas a slight difference was found in the axial distribution. As a consequence, the heavier root weight of Shiroganekomugi was not related to either the radial or axial developing capacity of aerenchyma but might be due to the effect of its shallow root angle in the soil. These results suggest that the capacity to form aerenchyma in the seminal root is not sufficient for expression of waterlogging tolerance in the Japanese wheat cultivars.     

乙烯利对香蕉抗寒性的影响

用乙烯利喷洒香蕉幼苗叶片1 d后,于6℃低温胁迫1 d,研究乙烯利对香蕉幼苗抗寒性的影响.结果显示:乙烯利预处理可以保护低温胁迫后香蕉叶片细胞结构的完整性,降低低温胁迫后叶片的萎蔫程度和相对电导率,提高低温胁迫后叶片的光合速率.表明乙烯利可以提高香蕉幼苗抗寒性,其中浓度为200mg/L时效果最佳.     

Effects of anti-auxins on secondary aerenchyma formation in flooded soybean hypocotyls

In flooded hypocotyl of soybean (Glycine max), cell division in phellogen and the elongation of these cells are enhanced, and thereby a secondary aerenchyma with high porosity is produced. Auxin controls cell division and cell elongation in many plants, so we studied its role in secondary aerenchyma development. Soybean plants with fully expanded unifoliolate leaves were flooded for 6 d with solutions (100 μM each) of seven anti-auxins. TIBA, NPA, HFCA, 1-NOA, or CHPAA did not restrict the secondary aerenchyma formation, while MH moderately suppressed the aerenchyma development, and PCIB strongly inhibited the development of phellogen and secondary aerenchyma. However, the endogenous IAA concentrations in the flooded hypocotyls did not increase or decrease relative to the controls until 72 h, when a secondary aerenchyma was observed. From these results, it is unclear whether auxin plays an important role in the process of secondary aerenchyma formation under flooding.