The BUD2 mutation affects plant architecture through altering cytokinin and auxin responses in Arabidopsis

The ratio of auxin and cytokinin plays a crucial role in regulating aerial architecture by promoting or repressing axillary bud outgrowth. We have previously identified an Arabidopsis mutant bud2 that displays altered root and shoot architecture, which results from the loss-of-function of S-adenosylmethionine decarboxylase 4 （SAMDC4）. In this study, we demonstrate that BUD2 could be induced by auxin, and the induction is dependent on auxin signaling. The mutation of BUD2 results in hyposensitivity to auxin and hypersensitivity to cytokinin, which is confirmed by callus induction assays. Our study suggests that polyamines may play their roles in regulating the plant architecture through affecting the homeostasis of cytokinins and sensitivities to auxin and cytokinin.

Cytokinin induced shoot regeneration and flowering of Scoparia dulcis L.(Scrophulariaceae)-an ethnomedicinal herb

Objective:To develop an improved protocol for micropropagation of ethnomedicinally important Scoparia dulcis(S.dulcis) L.Methods:Explants were inoculated on MS basal medium supplemented with kinelin and 6-benzylaminopurine for shoot bud induction.To enhance the shoot induction,various auxins like 3-indoleacetic acid or 3-indolebutyric acid or a-naphthylacetic acid were tested along with 2.32 M KI and 4.44 μ M BAP.The regenerated shoots were rooted in half strength MS medium supplemented with various concentrations of IAA,IBA or NAA.After roots were developed,the plantlets were transplanted to pots filled with vermiculate and sand and kept in growth chamber with 70%-80%humidity under 16 h photoperiod.After acclimatization,the plantlets were transferred to the garden and survival percentage was calculated.Data were statistically analyzed and means were compared using Duncan's multiple range test(P<0.05).Results:An in vitro method was developed to induce high frequency shoots regeneration from stem,mature leaf and young leaf explants of S.dulcis.Shoot induction on young leaf explants was most successful in MS medium supplemented with combination of two cytokinins(2.32 μ M KI and 4.44 μ M BAP) 2.85 μ M IAA,10%CM and 1 483.79 μM adenine sulfate.A single young leaf explant was capable of producing 59 shoots after 13 days of culture. Flower was induced in medium supplemented with combination of KI and BAP.Conclusions: Cytokinins are the key factor to induce the direct shoot regeneration and flowering of S.dulcis.

Effect of Macronutrients, Cytokinins and Auxins, on <i>in Vitro</i>Organogenesis of <i>Thymus vulgaris</i>L.

The present study reports an efficient protocol for in vitro propagation of Thymus vulgaris L., an aromatic and medicinal plant in Morocco. Initially, we performed in vitro multiplication of Thymus vulgaris explants existing in the laboratory and obtained from micropropagation by shoot tip culture. Afterwards, we have evaluated the effect of six macronutrients. After that, seven cytokinins (Kin, BAP, 2iP, DPU, Adenine, Zeatine and TDZ) in three different concentrations (0.46, 0.93, 2.32 μM) have been evaluated to optimize cultures multiplication and elongation. Moreover, the effect of three auxins (IAA, IBA and NAA) at 0.57 μM, combined to 4 cytokinins (Kin, BAP, DPU and Ad.) at 0.46 μM, on shoot rooting has been studied. Thereby, MS medium has been proved the most favorable for plantlets growing. Also, we found that the addition of certain cytokinins, specifically 0.46 Kin, 0.46 and 0.93 BAP, 0.46 2iP, 0.46 DPU, 0.46 Ad. and 0.46 Zeat., ensures better multiplication and growth of vitroplants. In addition, multiplication and rooting of cultures were well optimized after addition 0.46 Kin + 0.57 IAA or NAA, 0.46 DPU + 0.57 IBA and 0.46 Ad. + 0.57 IBA combinations to the culture medium. Lastly, plantlets with roots were successfully acclimatized to ex-vitro conditions and these latter served as a source to establish in vitro culture again.

Differential responses of root growth to nutrition with different ammonium/nitrate ratios involve auxin distribution in two tobacco cultivars

Nitrogen(N), the major forms of which are nitrate(NO3–) and ammonium(NH4+), plays an important role in plant growth and mediation of root development. However, the role of auxin in root growth in response to different NH4+/NO3– ratios remains unclear. Two tobacco cultivars(Nicotiana tabacum L.) were adopted in this study, which displayed variant growth features under the situations with sole NO3– nutrition ratio(NH4+/NO3– ratio: 0/100), low NO3– nutrition ratio(NH4+/NO3– ratio: 97/3), and optimal NH4+/NO3– ratio(50/50). We investigated the effects of the different NH4+/NO3– ratios on the formation and elongation of lateral roots(LRs), auxin concentration, DR5::GUS expression, 3 H-labeled indole acetic acid([3 H]IAA) transport, and the expression of six PIN genes in tobacco roots. We also examined the effects of exogenous auxin and a transport inhibitor on LRs growth. The results are shown as follows, compared to optimal N nutrition conditions, the biomass and nitrogen(N) accumulation were largely reduced by sole and low NO3– nutrition treatment in NC89, but no difference was observed in Zhongyan 100. In most cases, sole and low NO3– nutrition impaired the elongation and formation of firstorder lateral roots(1° LRs), only in NC89, thus reducing the root growth. IAA concentration and DR5::GUS expression levels decreased in roots when NC89 was subjected to sole and low NO3– nutrition media, suggesting that different NH4+/NO3– ratios affect the transport of auxin from leaves to roots. Results were similar following exogenous NAA application to low NO3– nutrition treated seedlings. Based on direct [3 H]IAA transport measurement, the transport of polar auxin from shoots to roots decreased due to low NO3– nutrition. PIN4 expression levels were markedly decreased in roots of NC89by sole and low NO3– nutrition, while they were unaffected in Zhongyan 100 roots. Overall, our findings suggest that LRs formation in tobacco seedlings is regulated by NH4+/NO3– ratios via modifying polar transport of auxin.

EFFECT OF CYTOKININS AND AUXINS ON THE GROWTH OF FREE-LIVING CONCHOCELIS OF PORPHYRA YEZOENSIS

1AA 3-Indolylacetic acid, NAA a-Naphthylacetic acid and cytokinins in PESI culture medium were used in a study on the effects of plant hormones on the growth of free-living conchocelis of Porphyra yezoensis which showed that its growth in medium with cytokinins, 1AA and NAA was more rapid than that in medium with non-phytohormones; that the optimal concentrations for promoting growth were 10μg/L for IAA and ZA (Zeatin), and 0.1 μg/L for BA 6-Benzyl amino purine and KIN 6-Furfurylamino- purine. Mix use of NAA, 1AA and cytokinins, NAA/ZA 1-1000/1μg/L, NAA/BA 10/1-1000 μg/L, NAA/KIN 1/1-1000 μg/L promoted growth. 1AA/ZA 0.1-1/0.1-1μg/L; 1AA/BA 0.1-1/0.1-10 μg/L IAA/KIN 1/0.1-1000μg/L also promoted growth.

ARR5 and ARR6 Mediate Tissue Specific Cross-talk between Auxin and Cytokinin in <i>Arabidopsis</i>

Auxin and cytokinin interaction plays an essential role in a wide range of plant growth and developmental processes. The interaction consequence of the two hormones is highly tissue specific. The molecular mechanisms underlying the tissue specificity are largely unknown. Here we show that the cytokinin signaling pathway key components ARR5 and ARR6 respond to auxin with a highly tissue specific and contrasted pattern in Arabidopsis seedlings and calli in the presence of cytokinin. Our results suggest that the two highly homologous but functionally distinct genes, ARR5 and ARR6, play a critical role in mediating tissue specific interaction between auxin and cytokinin.

Efficient Plant Regeneration from Explants of Compact Oregano (Origanum compactum Bentham)

Origanum compactum Benth., a species endemic to Morocco characterized by its biological activities, is overexploited because of its commercial value and threatened with extinction. Accordingly, measures for its conservation are needed. Micropropagation serves as a solution for the protection and the domestication of this species. In this investigation, we established a protocol for vegetative multiplication in vitro of Origanum compactum by the axillary bud technique. Six culture media (SH, SD, N30K, MS, MSm, B5) were tested to determine the most suitable mineral medium for growth and development of explants. Four cytokinins: Kinetin, Zeatin, BAP (6-Benzylaminopurine), 2ip (2-Isopentenyladenine) and three compounds with cytokinin activity: Adénine, 1,3-Diphenylurea (DPU) and Thidiazuron (TDZ) at five concentrations (0.44, 1.33, 2.22, 3.11, 4.44 μM) were tested on budding, growth, hyperhydria and rooting. Then three auxins, Indole-3-acetic acid (IAA), Naphthalene acetic acid (NAA) and Indole butyric acid (IBA) at four concentrations (1.14, 2.85, 4.56, 6.27 μM) in presence of 2.22 μM BAP were evaluated. The combination of Gibberellic acid (0.29, 1.5, 2.60, 2.89 μM GA3) and three polyamines (Putrescine, Spermidine, Spermine) at five concentrations (1.134, 3.402, 5.67, 7.938, 11.34 μM) with cytokinins and auxins were considered. Our results show that Margara medium is the most efficient and BAP at 2.22 μM is the best cytokinin for development of the aerial parts, with a regeneration rate of 88, 90%;rhizogenesis is successful with the combination of 6.27 μM IAA and 2.22 μM BAP. Moreover, the integration of 2.89 μM GA3 with 2.22 μM BAP and 6.27 μM IAA promotes vitroplant growth, bud and shoot multiplication and elongation of the aerial part. The addition of polyamines with 2.22 μM BAP and 6.27 μM IAA does not improve the root part, but Spermine at 5.67 μM promotes bud and shoot multiplication with a high percentage of regeneration, and spermidine at the same concentration gives long explants. Finally, plantlets with good root development were successfully acclimatized to natural conditions and served as a source to establish in vitro culture again.

Combination of 6-Benzylaminopurine and Thidiazuron Promotes Highly Efficient Shoot Regeneration from Cotyledonary Node of Mature Peanut (Arachis hypogaea L.) Cultivars

Efficient in vitro plantlet regeneration is an important step to successfully transform genes for the improvement of agronomic traits.A combination of 6-benzylaminopurine(BAP)and thidiazuron(TDZ)plant growth regulators was applied to evaluate shoot regeneration capacity whereasα-naphthalene acetic acid(NAA)combination with 6-benzylaminopurine(BAP),and 2,4-dichlorophenoxyacetic acid(2,4-D)with 6-benzylaminopurine were tested to optimize root induction for two peanut cultivars.The result showed combination(BAP with TDZ)was found to be effective in promoting shoot.The highest shoot regeneration frequency(93%)was obtained on a medium supplemented with 4 mg/L BAP and 0.5 mg/L TDZ while an average regeneration frequency(87%)was achieved in a medium containing combinations of 2 mg/L BAP with 1 mg/L TDZ.The shooting rate increased for both cultivars as the concentrations of BAP increased and TDZ decreased.The highest rooting rate(93%)was obtained on a medium supplemented with 3.5 mg/L NAA with 2.5 mg/L BAP for both cultivars.The rooting rate increased as the concentration of auxin to cytokinin ratio increased.The maximum rooting rate(83%)was obtained on MS medium supplemented with 0.3 mg/L 2,4-D with 0.2 mg/L BAP for the cultivar N3.The result indicated that BAP with NAA was much better than BAP with 2,4-D in rooting rate.Thus,the protocol developed was genotype independent and effective for peanut tissue culture.

生长素和细胞分裂素诱导植物胚性愈伤组织研究进展

植物胚性愈伤组织在植物研究与应用中是一种重要的试材,有很多关于植物胚性愈伤组织诱导方法研究的报道。生长素和细胞分裂素被广泛应用于胚性愈伤组织的诱导,是胚性愈伤组织诱导的关键因子。阐述了生长素和细胞分裂素在植物胚性愈伤组织诱导及体细胞胚胎发生过程中的作用,讨论了其在植物胚性愈伤组织诱导中的作用、使用方法与原则,为愈伤组织诱导、愈伤组织胚性化诱导等研究中植物生长调节剂的使用提供依据。

5种不同的植物激素对白花前胡种子萌发的影响

目的 研究生长素(IAA)、细胞分裂素(6-BA)、赤霉素(GA3)、脱落酸(ABA)和乙烯(ET)5种植物激素对白花前胡种子萌发的影响。方法 以宁国产并在室温放置12个月的白花前胡种子为材料,把5种不同的植物激素均配制成4个梯度浓度(1×10^(-1)、1×10^(-2)、1×10^(-3)、1×10^(-4)mg·mL^(-1)),对白花前胡种子进行浸种处理。通过培养皿萌发试验,分析种子的发芽率、根长和鲜重的变化情况。结果 在4个梯度范围内,6-BA对白花前胡种子的生长状态整体起抑制作用。把1×10^(-1)mg·mL^(-1)和1×10^(-2)mg·mL^(-1)设置为高浓度,1×10^(-3)mg·mL^(-1)和1×10^(-4)mg·mL^(-1)设置为低浓度。其中6-BA无论是高浓度还是低浓度均对白花前胡种子的生长状态整体起抑制作用。而GA3和ET在高浓度(1×10^(-1)mg·mL^(-1)和 1×10^(-2)mg·mL^(-1))及ABA和IAA在低浓度(1×10^(-3)mg·mL^(-1)和1×10^(-4)mg·mL^(-1))下均对白花前胡种子的萌发率、根长和鲜重都表达出明显的促进作用。结论 植物激素对白花前胡种子的生长发育均有不同程度的影响,其中ET在1×10^(-2)mg·mL^(-1)时,对白花前胡种子的生长发育影响最为显著,白花前胡种子的萌发率,最大根长和最大鲜重均高于其他组。

不同铵硝配比对茶树生长及生长素含量的影响

【目的】明确不同茶树品种最适生长铵硝比,为实现“因种施肥”、茶园氮肥营养管理提供借鉴与参考。【方法】采用营养液水培试验分析5种铵硝配比(NH_(4)^(+)∶NO_(3)-=4∶0、3∶1、2∶2、1∶3、0∶4)条件下1 a生茶树扦插苗‘信阳10号’和‘中茶108’的生长表型及游离生长素IAA和IBA含量。【结果】5种铵硝配比条件下,信阳10号在铵硝比3∶1时长势最好,表现为叶片数和单株芽头数最多,根系和芽叶干重最高,平均不定根最长,根系游离生长素IAA和IBA含量均最高;中茶108则在铵硝比4∶0时长势最好,具有较高的株高、茎粗、单株芽头数和发芽率,根、茎、芽叶干重最高,氮素积累量最多,侧根数目和侧根密度最高,根系IAA以及IAA、IBA的总量最高。相关性分析结果表明,信阳10号根系参数与生长素含量相关性较强,而中茶108根系参数则与氮含量相关性较强。【结论】信阳10号和中茶108最适生长铵硝比分别为3∶1和4∶0,前者耐硝,后者对硝敏感。

A predictive model for ethylene-mediated auxin and cytokinin patterning in the Arabidopsis root

The interaction between auxin and cytokinin is important in many aspects of plant development.Experimental measurements of both auxin and cytokinin concentration and reporter gene expression clearly show the coexistence of auxin and cytokinin concentration patterning in Arabidopsis root development.However,in the context of crosstalk among auxin,cytokinin,and ethylene,little is known about how auxin and cytokinin concentration patterns simultaneously emerge and how they regulate each other in the Arabidopsis root.This work utilizes a wide range of experimental observations to propose a mechanism for simultaneous patterning of auxin and cytokinin concentrations.In addition to revealing the regulatory relationships between auxin and cytokinin,this mechanism shows that ethylene signaling is an important factor in achieving simultaneous auxin and cytokinin patterning,while also predicting other experimental observations.Combining the mechanism with a realistic in silico root model reproduces experimental observations of both auxin and cytokinin patterning.Predictions made by the mechanism can be compared with a variety of experimental observations,including those obtained by our group and other independent experiments reported by other groups.Examples of these predictions include patterning of auxin biosynthesis rate,changes in PIN1 and PIN2 patterns in pin3,4,7 mutants,changes in cytokinin patterning in the pls mutant,PLS patterning,and various trends in different mutants.This research reveals a plausible mechanism for simultaneous patterning of auxin and cytokinin concentrations in Arabidopsis root development and suggests a key role for ethylene pattern integration.

C/A值与甘薯丛枝病症状发生的关系

采用高效液相色谱（ＨＰＬＣ），对比测定了由植物类菌原体（ＭＬＯ）引起的甘薯丛枝病病株和甘薯健株中细胞分裂素和生长素含量在整个生长周期内的变化。结果显示：甘薯中细胞分裂素以玉米素为主。病株中玉米素含量一直处于较高水平，而吲哚乙酸含量仅在芽萌发时期病、健材料间存在明显差异，随着甘薯的生长，这种差异逐渐消失。结合甘薯丛枝病发病特点，讨论了植物激素Ｃ／Ａ值的改变对病状发生的作用。

N-5-四唑基-N′-芳甲酰基脲的合成及其生物活性

合成了 15个新的含四唑基的芳甲酰基脲类化合物 ,用IR ,1HNMR和元素分析证实了它们的结构 ,并进行了初步的生物活性试验 ,生测结果证明一些目标化合物具有优良的植物生长调节活性 ,其中N 5 四唑基 N′ 对甲氧基苯基甲酰基脲(2h)和N 5 四唑基 N′ 对溴苯基甲酰基脲 (2j)具有很好的生长素活性 ,2h ,2j和N 5 四唑基 N′ 对甲基苯基甲酰基脲 (2m )

文心兰组织培养的研究

以文心兰不同发育时期的花蕾为外植体,研究了影响丛芽诱导、增殖、生根壮苗的主要因素。结果表明,处于原芽期的花蕾是诱导丛芽的较好材料;适合花原芽诱导丛芽的培养基是MS+6-BA 4.0 mg/L+NAA 0.5 mg/L+3％蔗糖,适合丛芽增殖成苗的培养基是MS+6-BA 2.0-4.0 mg/L+NAA 0.5 mg/L+3％蔗糖,适合生根壮苗的培养基为1/2 MS+IBA 0.5 mg/L+2％蔗糖。

具有植物激素活性的Schiff碱化合物的研究(Ⅲ)——噻二唑类Schiff碱的合成及其生物活性

Twelve new Schiff bases of thiadiazole have been synthesized for the first time. Their physical constants, UV, IR, 1H NMR and elementary analysis were originally characterized, biological activity were originally studied. It is found from the results of biological activity tests that some compounds have a remarkable activity on plant growth hormone. Compounds Ⅲa and Ⅲk have a good activity on cytokinin, compounds Ⅲe and Ⅲj and Ⅲl have an excellent activity on auxin.

大花蕙兰组培快繁影响因素分析

在大花蕙兰组培快繁过程中 ,细胞分裂素BA和KT对类原球茎诱导有极显著影响 ,ZT的作用不明显 ;BA和生长素NAA均对类原球茎的诱导和增殖起明显的促进作用 ,且BA对大花蕙兰幼苗的增殖效果更为显著。类原球茎诱导分化过程中所需的蔗糖浓度相对较低。GA和香蕉泥的合理组配是大花蕙兰生根壮苗的关键。

2-氨基-5-(4-吡啶基)-1,3,4-噻二唑Schiff碱的合成及其生物活性

含杂环的Schiff碱具有优良的生物活性,有的已被研究开发作为植物生长调节物质[1～4].1,3,4-噻二唑的某些衍生物也因为具有良好的杀菌、除草和植物生长调节等功能倍受关注[5～9].

云南烟草丛枝症病害研究 Ⅶ 激素的变化

采用植物激素ＥＬＩＳＡ测定试剂盒，对比测定了烟草感染丛枝症的病株与健株体内细胞分裂素（ｉＰＡ和ＺＲ）与生长素（ＩＡＡ）含量的变化．结果表明：生长素含量在整个发病期间健株都较高于病株，细胞分裂素含量在发病初期明显高于健株，随后呈下降趋势并趋于稳定，Ｃ／Ａ值在病程中相对处于较高水平．

核桃砧穗生理状态对微枝嫁接成活的影响

核桃微枝嫁接是以子苗为砧木，以无根试管苗为接穗进行无性繁殖的一项新技术。子苗及试管苗生理状态对嫁接成活影响很大。真叶展开之前子苗内源细胞分裂素、生长素、含水量、葡萄糖、果糖均处于较高水平，嫁接易于成活（成活率为９０％）；真叶展开后，上述生理指标急剧下降，随之嫁接成活率也降低（成活率由８２．５％降至２５％）。上述生理指标较高、生理活性较强的试管苗有较高成活率（９１．４％），而干瘦细长、老态、叶卷曲的试管苗上述生理指标低，嫁接难以成活（成活率３７．１％）。