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.     

施肥对台湾桤木根系生长及结瘤的影响

为阐明施肥对台湾桤木根系生长及结瘤的影响,对广西引种的台湾桤木进行1年生苗施肥试验,研究了4种土壤类型(T_1:酸性黑壤土、T_2:酸性黄心土、T_3:酸性红壤土、T_4:碱性红壤土)下的3种施氮水平(N_1:0 g,N_2:3 g,N_3:6 g)对台湾桤木根系生长及根系结瘤的影响。结果表明:相同土壤类型下,N1(0 g)处理的台湾桤木苗木总根长、根系表面积、总体积、根系干重、根瘤鲜重、根瘤干重、根瘤数量、根瘤最大直径、根瘤平均直径以及根瘤固氮酶活等指标均明显高于N_2(3 g)和N_3(6 g)的相应值。4种土壤类型中以土壤pH值为4.77~5.00的酸性红壤或者黄壤更为适合台湾桤木生长。综合来看,1年生台湾桤木在不添加氮肥的情况下,可通过自身生物固氮满足其生长需求,有利于根系生长和根系结瘤;在施加氮肥3~6 g时,反而抑制其根系生长及根系结瘤,并且使其根瘤固氮酶活性下降。     

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.     

不同施肥处理下大豆品种辽豆15根系性状的比较

以大豆品种辽豆15作为试材,设置不施肥、复合肥和复合益生菌3个处理,比较不同施肥条件下大豆根系形态、根瘤数量、根瘤干重和根冠比的差异,结果表明,在大豆分枝期、开花期或鼓粒期,与不施肥相比,施用复合肥条件降低了辽豆15的根长、根系表面积、根毛数量、根瘤数量、根瘤干重和根冠比;施用复合益生菌则提高了辽豆15的根长、根系表面...     

过湿条件下大豆不定根的发生及其生理作用研究

大豆是实行水旱轮作的重要作物之一,在缺乏良好排水条件的水田中实行水旱轮作时,长期涝渍所致的伤害成为大豆生长不良及产量低的重要原因.通过盆栽和大田试验在大豆生育初期进行过湿处理,调查培土或无培土条件下不定根的发生情况,揭示不定根对伤流速度,氮素的吸收运转等的影响,讨论了不定根与大豆耐湿性的关系.淹水条件下培土对不定根及根瘤的发生产生较大的影响,淹水条件下发生的不定根的量占总根重的43.1%,这些不定根提供了81.4%的伤流速度.不定根的呼吸速度为2.61 mg CO2g-1h-1,是初生根的近3倍.淹水导致全叶位叶片的叶色变淡,不定根的发生改变了伤流液中不同形态氮素的组成和全氮含量,可使下位叶的叶色维持较高水平.淹水条件下大豆的冠根比比对照小.不定根取代了受涝渍伤害而失去功能的初生根的作用,积极地进行养分和水的吸收,确保了涝渍逆境下物质生产的顺利进行.     

植物生长调节剂BR和SHK-6对大豆生物产量和根瘤固氮活性的激素调控研究

应用快生根瘤菌(S inorhizobium xinjiangensis,CCBAU110T)和慢生根瘤菌(Bradyrhizobium japonicumT,USDA6T)接种大豆,在无菌沙培条件下叶面喷施植物生长调节剂BR和SHK-6研究调节剂对大豆植株及根瘤固氮的激素调控效应.结果表明:1)不同根瘤菌接种条件下,BR和SHK-6处理大豆根干重和茎干重得到显著增加,提高了根瘤数、根瘤重和根瘤固氮活性.2)BR和SHK-6处理提高了根瘤固氮能力,根瘤、根和茎的含氮量得到明显提高.3)BR和SHK-6处理通过改变激素平衡来调控根瘤固氮,其中CTK/GA、CTK/IAA对根瘤固氮有正调控作用,IAA/ABA和GA/ABA有负调控作用.     

接种根瘤菌对西南地区大豆光合性能和固氮能力的影响

为探讨接种根瘤菌对西南地区大豆固氮能力的有效性,在大田试验条件下,以根瘤菌株 Bradyrhizobium japonicum5038和B. japonicum 5136侵染南黑豆20和南夏豆25,比较两个大豆品种接种后植株的光合特性和叶绿素 含量,考察根瘤数量并测定分析其蔗糖含量、豆血红蛋白含量和固氮酶活性。结果表明：接种后两大豆品种叶片 chla/b值显著下降,叶绿素含量、净光合速率和气孔导度显著增加;根瘤数、单株瘤重、植株地上部和地下部生物量 均显著增加,单个瘤重和根冠比则无显著变化;根瘤内蔗糖含量和豆血红蛋白含量均显著增加,固氮酶活性提高。 不同大豆品种对不同菌株的响应不同,南夏豆25与根瘤菌B.japonicum5136的适配性最好,接种后大豆光合性能和 固氮能力的改善效果明显优于南黑豆20。     

淹水对大豆生长的影响

研究了两种不同的淹水方式－苗全被淹没（全淹）和基部淹没（半淹）对大豆苗生长的影响,在全淹下,苗完全停止生长,直至死亡。但是,只要露出顶芽在空气中,苗就不被淹死。大豆苗的耐涝性随苗龄增大而提高。半淹处理明显抑制苗根的生长和降低苗的根冠比,却大大刺不定根的生长。试验结果还显示,大豆能在长时期半淹条件下生长发育,但其营养器官和结实器官的发育无显著差于对照。淹水对根瘤的生长有抑制作用。     

诱发油菜结瘤固氮的研究

用果胶细菌处理油菜幼根,使花生根瘤菌侵入油菜根部并结瘤。试验结果表明:根瘤菌侵入油菜根细胞,形成含根瘤菌的根瘤,结瘤率为31.25％。从这些根瘤中分离出的菌株能回接到原寄主。血清学方法测定,油菜根瘤分离物与原接种的根瘤菌起凝集反应。根瘤石蜡包埋切片观察,根瘤细胞内充满了细菌。根瘤固氮酶活性为0.17—3.43nMC_2H_4/株小时,酰脲丰度为0.10％—3.58％。     

Nitrogen-Fixing Activity of Root Nodules in Relation to Their Size in Peanut (Arachis hypogaea L.)

Abstract

The nitrogen-fixing activity of root nodules was examined with reference to the nodule size in peanut. Root nodules of field-grown peanut were collected at flowering through harvesting stages and classified into five groups of size using a circle template. Then acetylene reduction activity was measured to evaluate nitrogen-fixing activity for respective size groups. In addition, the diameter of the cross-section of each root nodule and rhizobium-infected areas on the cross-section were measured. The results showed that the nitrogen-fixing activity of root nodules is closely related with their size. In the root nodules in the medium size group (1.5? 2.0 mm in diameter), nitrogen-fixing activity per unit fresh weight of nodule was highest at the flowering stage and rapidly decreased thereafter. The nitrogen-fixing activity of root nodules larger than 2.0 mm in diameter did not vary significantly with their size. Colors of rhizobium-infected zones varied with their size: white in small nodules; red in medium-sized nodules; and greenish in larger nodules, which suggests that the concentration of leghemoglobin is highest in the medium-sized nodules. Nitrogen-fixing activities of the medium-sized nodules might determine the amount of nitrogen fixation in the whole root system during pod-filling because medium-sized nodules had high activity and were large in number. Classification of root-nodule size based on the circle template is a simple, rapid, and useful method to evaluate nitrogen-fixing activity of root nodules.     

Nodulation Status and Nitrogenase Activity of Some Legume Tree Species in Bangladesh

Summary

A study was conducted to observe the nodulation status and measure nitrogenase activity of some important legume tree species in nursery. Of the thirteen species surveyed eight belong to Mimoceae, two Papilionaceae and three Caesalpiniaceae. All the species in Mimo-ceae and Papilionaceae were found nodulated whereas all the members of Caesalpiniaceae were non-nodulated. Among nodulated seedlings, highest number of nodules per seedling was recorded in Leucaena leucocephala (82) followed by Acacia auriculiformis (55), Acacia mangium (52), Albizia lebbeck (46), A. procera (41), Dalbergia sissoo (32) and Acacia catechu (29). Nitrogenase activity was highest in L. leucocephla (4913.59 nmole C₂H₄ h^?1) followed by Albizia procera (2080 nmole C₂H₄ h^?1). Seedling height, nodule fresh weight, root fresh weight and nitrogenase activity (per nodule per h, per gram nodule fresh weight per h, per gram root fresh weight per h and per gram root dry weight per h) were also highest in L. leucocephala.     

施氮水平对7S亚基缺失大豆根系形态和结瘤固氮的影响

为有效推广功能型大豆7S亚基缺失品种,以7S亚基缺失大豆品系东富2号为研究对象,设置4种施氮水平(纯N),N0(0 mg·kg~(-1))、N1(25 mg·kg~(-1))、N2(50 mg·kg~(-1))、N3(75 mg·kg~(-1)),采用桶栽法研究大豆根系形态和结瘤固氮对不同施氮水平的响应。结果表明:N1(25 mg·kg~(-1))水平下根系干重加大,根冠比增大,根瘤固氮潜力高,单株产量较高。N2(50 mg·kg~(-1))水平下根长、根表面积、根体积在生育后期增长较快,根系干重较大,根冠比低,固氮酶活性最高,单株籽粒产量最高。N3(75 mg·kg~(-1))水平下植株干重较大,无效生长较多,根瘤数少,固氮潜力和根冠比低,单株产量不高。综合籽粒产量和根系特性指标,功能型大豆7S亚基缺失品系东富2号的适宜施肥量为25~50 mg·kg~(-1)。     

玉米苗期氮素吸收利用效率差异及聚类分析

采用循环营养液培养法,研究安徽省23个玉米主推品种苗期吸收与积累氮素的差异.结果表明,在常氮(5 mmol/L)和高氮(45 mmol/L)水平下,玉米茎叶干重、总干重、叶面积、茎叶氮累积量和整株氮累积量的变异系数分别在0.34～0.58和0.35～0.51;其中,常氮和高氮条件下茎叶干重、总干重、叶面积、茎叶氮累积量和整株氮累积量呈极显著正相关(P<0.01),其相关系数分别在0.529～0.998和0.821～0.995.以玉米茎叶干重、总干重、叶面积、茎叶氮累积量和整株氮累积量为玉米苗期氮高效评价指标,玉米苗期氮效率综合值在常氮和高氮水平下分别在0.199～1.113和0.216～1.128,其中,浚单20在常氮和高氮条件下的氮效率综合值均大于0.90,且聚类分析中均在第一类群,为氮高效品种.     

黄曲霉毒素阻控与花生超级结瘤耦合效应研究初报

花生、大豆是我国重要的油料和经济作物,因易受黄曲霉毒素污染,严重威胁食品安全,制约产业发展,因此,黄曲霉毒素防控一直是国内外研究的热点难题。本团队首次提出将黄曲霉毒素绿色阻控与促进根瘤固氮耦合的研究思路,研发了生物菌剂ARC-BBBE,本文报道生物菌剂ARC-BBBE对黄曲霉毒素及其产毒菌阻控的大田应用效果,调查其对花生生物学性状及经济性状的影响,探索ARC-BBBE对花生、大豆根系结瘤及根瘤固氮的影响,为从田间源头阻控黄曲霉毒素及促进根瘤固氮、实现减肥减药提供理论依据和科学指导。连续2年在我国花生主产省开展田间防控试验,将绿色阻控生物菌剂ARC-BBBE于花生播种期以30 kg/hm²用量与基肥一起撒施于土壤中。同时开展室内花生、大豆盆栽试验。使用涂布法调查土壤中黄曲霉毒素产毒菌丰度,使用高效液相色谱法检测花生样品中黄曲霉毒素,使用乙炔还原法测定根瘤固氮活性,采用5点取样法调查统计根瘤数、根瘤重。结果表明,应用ARC-BBBE显著降低了土壤中黄曲霉毒素产毒菌的丰度（平均降低66.5%）和花生中黄曲霉毒素的含量（平均降低83.5%）。应用ARC-BBBE后,花生根系普遍出现超级结瘤现象,实验验证表明其根瘤具有固氮活性,平均结瘤数增加10倍以上（土壤贫瘠地区50倍以上）,瘤重增加8.8倍,每克根瘤固氮酶活性提高5倍以上。饱果率、产量均明显提高,叶色浓绿。花生室内盆栽结果表明,ARC-BBBE处理组根系结瘤数是对照组的2.2倍,固氮酶活性是对照组的4倍,叶绿素含量较对照组增加21.3%。大豆室内盆栽苗期实验结果表明,ARC-BBBE同样可诱发大豆结瘤及固氮效应：播种后第26天,处理组瘤数增加13.5倍、瘤重增加19.8倍;而且处理组有固氮活性,而对照组无固氮活性;苗期处理组的根长、根重、鲜重、叶绿素等生物学指标显著提升。ARC-BBBE对花生黄曲霉毒素及其产毒菌污染阻控效果极为明显,既可从生产源头有效阻控花生黄曲霉毒素产毒菌,降低黄曲霉毒素污染风险,同时大幅增加了花生根瘤数量和固氮酶活性,具有显著的促生长、增产量、控病害、保安全作用,具有显著的经济、社会、生态效益。对未来减施农药、化肥,保护农田生态,推动花生、大豆产业高质量绿色发展具有重要意义,在花生、大豆等豆科作物生产中应用前景广阔。     

Roles of Root Aerenchyma Development and Its Associated QTL in Dry Matter Production under Transient Moisture Stress in Rice

Abstract

Enhanced aerenchyma development in rice under transient drought-to-waterlogged (TD-W) stress promotes root system development by promoting lateral root production. This study analyzed the quantitative trait loci (QTLs) associated with the plasticity in aerenchyma development under TD-W stress. A mapping population of 60 F₂ genotypes of chromosome segment substituted lines (CSSL) derived from CSSL47 and Nipponbare crosses were grown in rootboxes and evaluated for shoot and root growth, and aerenchyma development (expressed as root porosity). The TD-W stress was imposed starting with water saturated soil condition at sowing and then to progressive drought from 0 to 21 days after sowing (DAS) prior to exposure to sudden waterlogging for another 17 days (21 to 38 DAS). We performed simple and composite interval mapping to identify QTLs for aerenchyma development. QTL associated with aerenchyma development was mapped on the short-arm of chromosome 12 and designated as qAER-12. The effect of qAER-12 on the plasticity in aerenchyma development under TD-W was significantly associated with the increase in lateral root elongation and branching. This resulted in greater root system development as expressed in total root length and consequently contributed to higher dry matter production. This qAER-12 is probably the first reported QTL associated with aerenchyma development in rice under TD-W and is a useful trait for the improvement of the adaptive capability under fluctuating soil moisture conditions.     

野生大豆结瘤固氮与叶片和籽粒含氮量的关系

17份野生大豆的盆栽试验结果指出,野生大豆在结瘤固氮方面存在着明显的基因型差异。花期根瘤数、根瘤鲜重和固氮酶活性与单株叶片含氮量呈显著或极显著的正相关,固氮酶活性与单株籽粒氮产量呈正相关,分枝期、花期、结荚鼓粒期的相关系数分别为0.401,0.478和0.512。     

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...     

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.     

大豆根瘤菌接种效应及竞争结瘤能力分析

为了筛选获得竞争结瘤能力强且对大豆生长发育、产量有积极影响的大豆根瘤菌菌株,以前期分离、鉴定、纯化的10株根瘤菌菌株为材料,对高匹配性大豆品种进行了田间接种试验。于大豆盛花期测定根瘤菌的结瘤数量及固氮酶性能。同时,对接种供试菌株及分离获得的根瘤菌菌株进行BOX-PCR并比较不同菌株之间的BOX分子指纹图谱,以此获得供试菌株的田间占瘤率。于成熟期测定大豆的主要生育特征、产量构成因子。结果表明:大豆接种根瘤菌后在整个生长期,叶片表现为颜色深绿,质地鲜嫩;根瘤菌可以显著促进大豆根系结瘤,增加单株根瘤数目。接种处理I4(即接种菌株112-1)的单株根瘤数最多,比不接种对照处理I0多32.95%,差异显著。接种根瘤菌处理的根瘤干重均显著低于不接种对照处理。其中,接种处理I4的根瘤干重最高。接种处理I6的固氮酶活性最高,与接种处理I4之间差异不显著;接种菌株的占瘤率为10%~90%,占瘤率变化幅度较大,平均占瘤率为50%。I4处理占瘤率最高为90%,I6处理(即接种菌株113-1)的占瘤率次之,为75%;菌株占瘤率与单株根瘤数呈极显著的正相关(r=0.82**),单株瘤干重与菌株占瘤率、单株根瘤数、固氮酶活性均呈现负相关(r=-0.387,r=-0.50,r=-0.13);I6处理株高最高,I4处理次之,两处理之间差异并不显著;I2、I4、I6处理的单株荚数、单株粒数相对较高,3处理之间差异并不显著;I4处理的大豆百粒重均显著高于其它菌液处理。根据接种根瘤菌对大豆结瘤固氮性能、产量等方面的影响,结合各根瘤菌株的竞争结瘤能力,筛选获得适于黑龙江哈尔滨地区大豆生产有广阔利用价值的高效大豆根瘤菌株112-1和113-1。     

花生根瘤固氮酶活性与氮素种肥和籽粒蛋白质含量的关系

花生品种间根瘤量的变化有明显的差异,大粒种大于小粒种。特异固氮酶活性,品种间差异不显著,小粒种略高于大粒种,全生育期固氮酶活性出现两次高峰,与单株根瘤量的增长相一致。氮素种肥能抑制根瘤数和固氮酶活性,其抑制程度与氮肥量呈正相关,抑制时间发生在生育前期。固氮活性与籽粒蛋白质含量呈显著的正相关。