三种外源植物激素对黄花风铃木幼苗生物量、叶绿素荧光参数及光合特性的影响

以黄花风铃木(Tabebuia chrysantha (Jacq.) Nichols)幼苗为材料,采用L16(45)正交实验方法,测定生根粉(GGR)、3-吲哚乙酸(IAA)、多效唑(PP333) 3种外源植物激素不同组合处理下黄花风铃木幼苗的生物量、叶绿素含量、叶绿素荧光参数以及光合特性,研究3种外源植物激素不同组合对黄花风铃木幼苗生长和光合作用的影响,筛选出适宜黄花风铃木幼苗生长的最佳浓度组合。结果显示:11号处理(GGR 400 mg/L、IAA 400 mg/L、PP333400 mg/L)幼苗鲜重、干重均大于其他组合处理。3种外源植物激素中,GGR对幼苗鲜重、幼苗干重增长起主导作用,IAA和PP333的作用不明显。11号处理下的幼苗净光合速率、气孔导度、蒸腾速率、叶绿素含量、叶绿素荧光参数均大于其他处理,胞间二氧化碳浓度值最低。分析得出IAA对黄花风铃木幼苗的净光合速率、气孔导度、蒸腾速率、光合系统潜在活性、最大光能转换效率和叶绿素含量起主导作用,GGR和PP333的作用不明显。综合分析各指标得出,适宜黄花风铃木幼苗生长的最佳外源激素浓度组合为11号处理,此浓度下黄花风铃木幼苗综合质量最佳。     

The role of the conversion of IBA into IAA on root regeneration in apple: introduction of a test system

A test system for root regeneration was developed that consists of stem slices of apple shoots (ca. 0.5 mm thick; fresh weight ca. 1 mg). Roots regenerated synchronously without intervening callus formation and without interference with compounds originating from other parts of the plant. Supply of indolebutyric acid (IBA) or indoleacetic acid (IAA) induced maximally an average of 8 or 4.5 roots per slice, respectively. After uptake of IBA, a high degree of conjugation resulted in a recovery of 2.5% as internal free IBA (ca. 2 times the medium concentration). Due to conversion of absorbed IBA into IAA a fraction of 0.4% was recovered as (physiologically active) free IAA. After incubation on medium with IAA, 0.5% of the absorbed hormone was recovered in the free acid form. No conversion of IAA into IBA was observed. Equimolar contents of internal free IAA after incubation on IBA or IAA resulted for IBA in a higher number of roots than for IAA. This means that IBA may also act via internal free IBA or may synergistically modify the action or endogenous synthesis of IAA.Abbreviations BHT butyl hydroxy toluene - EtOH ethanol - FW fresh weight - HAc acetic acid - HPLC high performance liquid chromatography - IAA indoleacetic acid - IAA^int free (internal) IAA in the tissue derived from IBA or IAA uptake - IBA indolebutyric acid - IBA^int free (internal) IBA in the tissue derived from IBA or IAA uptake - MeOH methanol - PAR photosynthetic active radiation - SEM standard error of the mean - TLC thin layer chromatography - UV ultra violet     

Effect of Endosperm Removal on 7 Normal NaOH-Labile Indole-3-acetic Acid Conjugates in Shoots and Roots of Zea mays Seedlings

The pool of amide-linked indole-3-acetic acid (amide IAA) in the shoot of growing etiolated seedlings of Zea mays increases between the 3rd and 5th day of germination to equal the amount of free IAA and two-thirds the amount of ester IAA. Deseeding the germinant changes the pool size of free and amide IAA in a manner suggestive of conversion of endogenous free IAA to amide IAA. Deseeding also caused an almost total disappearance of amide IAA from the root, demonstrating that the pool of amide IAA is not inert and can be actively metabolized in young Z. mays seedlings.     

多效唑对紫穗槐生长及生理特性的影响

采用盆栽试验的方法研究了土施不同浓度多效唑(1、5、10、15、20 mg/L)对紫穗槐(Amorpha fruticosa Linn.)生长及生理特性的影响,以探明多效唑对紫穗槐的作用机制和最佳处理方式。结果显示:随着多效唑处理浓度(1~20 mg/L)的增加,紫穗槐幼苗株高、单叶面积和主根长呈下降趋势,基径、叶片长宽比、根鲜重和根冠比呈上升趋势;多效唑各处理均使紫穗槐幼苗叶片的相对含水量、叶绿素、可溶性糖和可溶性蛋白含量显著升高,POD活性显著增加,MDA含量和相对电导率显著下降。采用隶属函数法对各项生长、生理指标进行综合评价,结果发现20 mg/L多效唑处理下紫穗槐幼苗的抗性最强。说明多效唑可通过调节紫穗槐幼苗的生物量分配、水分状况、细胞渗透性和抗氧化性等,有效改善其生长、生理特性及提高抗逆性。本研究结果为多效唑在边坡植被建成和恢复中的应用提供了理论依据。     

DDT降解菌株Chryseobacterium sp. PYR2对小麦的促生作用及其机理

【背景】前期结果表明,DDT降解菌株Chryseobacterium sp. PYR2可高效去除土壤中的DDT等污染物,具有潜在的应用价值,但该菌对植物的影响尚不清楚。【目的】探讨菌株Chryseobacterium sp. PYR2对植物的促生作用及其机理,为后续开发DDT降解及植物促生双效功能菌剂提供理论依据。【方法】配制该菌株的不同梯度稀释菌悬液,用纸卷发芽法和盆栽法研究菌悬液对小麦种子萌发和植株生长的影响;Salkowski法测定PYR2合成吲哚-3-乙酸(Indole-3-acetic acid,IAA)量;单因素实验研究不同培养条件对菌株生长及IAA合成的影响;液相色谱-串联质谱-多反应监测(LC-MS/MS-MRM)方法分析IAA在PYR2菌体内的生物合成途径。【结果】PYR2菌悬液可明显提高小麦种子萌发率并促进小麦植株的生长,小麦的侧根数、株高、鲜重、干重等指标均明显提高。该作用是由于菌株PYR2可以合成植物生长激素IAA。最适IAA合成条件:温度30°C,pH 7.0-8.0,盐浓度0.5%,L-色氨酸50mg/L。代谢液中检测到色醇、色胺和吲哚-3-乙酰胺3种中间代谢产物,推测PYR2体内存在3条IAA合成途径,分别为吲哚-3-丙酮酸(IPy A)、TAM和IAM途径。【结论】菌株PYR2对小麦具有明显的促生效果,是由于其具有多条高效合成IAA的代谢途径,表明其在农药污染土壤的生物修复及作物种植中具有潜在的应用前景。     

Influence of paclobutrazol in the soil on growth,nutrient elements in the leaves,and flood/freeze tolerance of citrus rootstock seedlings

Paclobutrazol [(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3ol] was applied to soil at 0, 100, or 250 mg/3.78-liter pot containing seedlings of Swingle citrumelo, Carrizo citrange, Cleopatra mandarin, sour orange, rough lemon, and Sun Chu Sha. All cultivars were sensitive to paclobutrazol, which caused a proliferation of shorter/thicker roots, and top growth showed shorter internodes and lower dry weight. Induced changes resulted in greater root/shoot ratios, and paclobutrazol treatments showed higher concentrations of nitrogen, calcium, boron, iron, and manganese in the leaves of different cultivars. Paclobutrazol-treated seedlings did not show a greater ability to tolerate flooded soil for 60 continuous days under greenhouse conditions nor survive-6.7°C controlled freeze tests. Paclobutrazol is a potentially useful plant growth regulator to dwarf citrus, but it apparently is not a strong candidate for increasing flooding and freezing tolerance in citrus rootstock seedlings.Abbreviations PPFD photosynthetic photon flux density - ANOVA analysis of variance     

多效唑和脱落酸对白兰花内源激素及光合速率的影响

以白兰花为试材,采用土施、喷施多效唑和脱落酸的方式对其植株进行处理,观察株高和开花情况,同时结合主要内源激素含量及光合特性进行分析。结果表明：经处理后,白兰花内源激素IAA、GA3、Z、ZR和ABA含量呈现不同的变化规律,且光合速率也出现明显的变化;经处理后的植株明显矮化,盛花期提前,开花数量大幅度增加,且开花次数也显著增多。其中以土施和喷施多效唑与脱落酸的效果最好,处理后的植株只有正常株高的40%～50%,开花数却达到正常植株的2.3倍。     

The Movement and Physiological Effect of Indoleacetic Acid Following Point Applications to Root Tips of Zea mays

Pinpoint applications of labeled and non-labeled indoleacetic acid (IAA) on resin beads were made, without injury, to vertical roots of intact seedlings of Zea mays. Points of application were at the extreme tip of the root, 0.5, 2 and 5 mm from the root tip. The movement of label and bending of the roots was recorded. Radiolabel was found to move basipetally from the extreme tip and 0.5 mm applications to a similar extent, reaching 8 mm from the tip. The level of label in the growing zone after 4 h was 10% of that found in the extreme tip. Movement from 2 and 5 mm applications was equal in both directions. Higher amounts of non-labeled IAA caused bending towards the point of application if applied at 0.5 or 2 mm but not at 5 mm from the tip. It is proposed that any endogenous IAA in the root cap could move to the growing zone and cause a unilateral inhibition of growth, provided that it was in the same transport pool as the exogenously applied IAA.     

Plant regeneration from long term suspension culture-derived protoplasts of hexaploid wheat (Triticum aestivum L.)

Highly regenerable callus cultures have been obtained from immature embryos of hexaploid wheat cv. Oderzo. Friable fast growing calli were induced at high frequency. Suspensions were initiated from the most friable callus lines: they became established in about two months. Suspensions consisted of cell aggregates of 30 to 1000 um in diameter. Upon plating on MS hormone-free medium, suspensions regenerated green plantlets, and their regenerative capability was maintained for at least 10 months. Protoplasts were isolated from 7–8 day old suspension cultures with a yield of 4–6×10⁶ protoplasts/g fresh weight cells. Protoplast culture was either in liquid medium or in a bead-type system with agarose beads. First divisions were detected at day 5. At day 14 visible colonies were detected and the plating efficiency was evaluated between 2 and 8% over the initial number of protoplasts plated. Protoplast-derived calli were cultured in the presence of 1 mg/l IAA and 0.5 mg/l zeatin and were used for reinitiating new suspension cultures. Upon plating onto MS hormone-free medium, with or without the addition of 0.1 mg/l GA3, calliclones were induced to differentiate. Regeneration of complete plantlets, with shoot and roots took about two months. Plantlets were grown in sterile conditions until 12–15 cm height, and were subsequently transplanted in soil.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - MS Murashige and Skoog (1962) medium - PCV packed cell volume - MES morpholinoethanesulfonic acid     

Growth-Promoting Ability of Rhodopseudomonas palustris G5 and Its Effect on Induced Resistance in Cucumber Against Salt Stress

The objective of this study was to investigate the potential of Rhodopseudomonas palustris G5 in promoting growth and inducing salt resistance in cucumber (Cucumis sativus L.). In this study, the growth-promoting potential of the bacteria was studied by measuring the ability to produce indole-3-acetic acid (IAA) and 5-aminolevulinic acid (ALA), fix nitrogen, and solubilize potassium and phosphate. The greenhouse pot experiments were set up to study how strain G5 affected growth and salt resistance of cucumber seedlings. The results showed that strain G5 exhibited plant growth-promoting attributes such as the production of IAA and ALA, as well as nitrogen-fixing, potassium-solubilizing, and phosphorus-solubilizing ability. In pot trials, strain G5 increased shoot height, root length, fresh weight, dry weight, total chlorophyll content, and soluble sugar content of cucumber seedlings under salt stress, compared to the seedlings that were exposed to salt stress in the absence of the strain G5. Furthermore, antioxidant enzyme activity analysis showed that strain G5 strongly increased the activity of superoxide dismutase, peroxidase, and polyphenol oxidase in cucumber seedlings under salt stress. In addition, strain G5 treatment decreased H₂O₂ and malondialdehyde contents of salt-stressed seedling. In sum, these results showed that strain G5 enhanced growth and induced systemic resistance in cucumber seedlings under salt stress by the production of IAA, ALA, and soluble sugars, the induction of antioxidant enzymes as well as nutrient adjustment of nitrogen, phosphorus, and potassium.

     

Transport of benzyl-8-14C-adenine in pea seedlings in relation to stem apical dominance

In intact, decapitated and decapitated indole-3-acetic acid (IAA) treated pea seedlings the translocation of benzyl-8-^l4C-adenin (¹⁴C-BA) from the roots was studied with regard to the release of lateral buds from apex-induced inhibition. In intact plants (controls) a substantial part of the activity was found in the apical part of the epicotyl. Decapitation resulted in the initiation of growth of lateral buds. As early as 24 h after decapitation and application of¹⁴C-BA a significantly higher activity was found in growing lateral buds (cotylars) of decapitated plants than in inhibited ones of intact or IAA-treated decapitated plants. The accumulation of¹⁴C-activity in stump tops of decapitated plants treated with IAA was associated with the thickening growth.     

Regulation of organogenesis and somatic embryogenesis by auxin in melon,Cucumis melo L.

Various tissues of seeds and seedlings of melon were cultured in vitro to study the effects of auxin concentration on organogenesis and embryogenesis. Adventitious shoots and somatic embryos were formed from explants of cotyledons of mature seeds, hypocotyls of seedlings, and leaves and petioles of young plantlets. Expanded cotyledons of seedlings formed only adventitious shoots. All tissues responded similarly to the 2,4-D concentration in the media, that is, adventitious shoots were formed at low concentration, callus proliferated without differentiation at intermediate concentration and somatic embryos were induced at high concentration. Cotyledons of mature seeds formed both adventitious shoots and somatic embryos more efficiently than any other tissues cultured.Effects of three auxins, 2,4-D, NAA and IAA, on organogenesis and embryogenesis were compared using cotyledons of mature seeds. Adventitious shoots were formed at low level of auxins (0 to 0.01 mg/l 2,4-D; 0 to 0.1 mg/l NAA; 0 to 1.0 mg/l IAA), and embryos were formed at high level of auxins (1.0 to 2.0 mg/l 2,4-D; 3.0 to 10.0 mg/l NAA; 20.0 to 100.0 mg/l IAA). IAA gave more efficient shoot formation and embryogenesis than the other auxins.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - NAA -naphthaleneacetic acid - IAA 3indoleacetic acid - BA 6-benzylaminopurine - MS Murashige and Skoog     

An efficient in vitro plant regeneration system for the medicinal plant Teucrium stocksianum Boiss.

An efficient and rapid plant regeneration system via direct organogenesis was established for Teucrium stocksianum Boiss. (Lamiaceae), an endangered and valuable medicinal plant. Hypocotyl explants excised from seedlings germinated in vitro were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations of kinetin and indoleacetic acid (IAA) to induce shoot formation. Differentiation of multiple shoots was initiated within 3 weeks of culture. Optimal regeneration was achieved on medium containing 3 mg/l kinetin and 0.5 mg/l IAA. This particular medium composition significantly improved the production of multiple shoots directly from hypocotyl explants compared to other combinations of plant growth regulators. Root induction was achieved on half-strength MS medium containing indole-3-butyric acid. Rooted plantlets were successfully acclimatized, with a survival rate of 75–80%. The protocol developed in this study could be used for long-term in vitro conservation and mass propagation of this species.     

Relative efficacy of paclobutrazol, propiconazole and tetraconazole as stress protectants in wheat seedlings

The stress protective effects of triazoles including paclobutrazol, a plant growth regulator, and two fungicides, propiconazole and tetraconazole, are compared. Wheat (Triticum aestivum L. cv Katepwa) seeds were imbibed for 18 h in distilled water (Ck) or in aqueous solutions of each triazole (50 mg L-1). Seeds were then air dried, planted in sectioned plastic flats and grown in a greenhouse. After 10 days, one set of seedlings were allowed to continue growing under optimal conditions while additional sets were exposed to various stresses including high temperatures, drought and spray with the herbicide paraquat. Compared to wheat leaves from plants grown under optimal conditions, heat stress decreased shoot fresh weight, fluorescence values and chlorophyll levels. It also increased ion leakage. All symptoms of damage were alleviated by the triazoles, with paclobutrazol being the most potent. Similar trends were found under acute drought conditions, where seedlings treated with paclobutrazol had the highest percent survival and the most shoot regrowth upon rewatering. Paclobutrazol was also the best triazole in protecting wheat leaves from damage caused by paraquat, a free radical generator. It is concluded that while all the triazoles have the potential to be stress protectants, paclobutrazol was consistently the most effective.     

Zinc soil application enhances photosynthetic capacity and antioxidant enzyme activities in almond seedlings affected by salinity stress

Zinc is a critical mineral nutrient that protects plant cells from salt-induced cell damage. We tested whether the application of Zn at various concentrations [0, 5, 10, or 20 mg kg^?1(soil)] would protect almond (Prunus amygdalus) seedlings subjected to salt stress (0, 30, 60, or 90 mM NaCl). All concentrations of Zn, particularly the application of 10 and 20 mg kg^?1, increased the net photosynthetic rate, stomatal conductance, the maximal efficiency of PSII photochemistry, and a proline content in almond seedlings grown under salt stress; 20 mg(Zn) kg^?1 was the most effective concentration. The activity of superoxide dismutase showed a significant increase under salinity stress and Zn application. The catalase activity decreased in the salt-treated seedlings, but recovered after the Zn treatment. Our results proved the positive effects of Zn on antioxidant enzyme activity scavenging the reactive oxygen species produced under salt stress.     

NaCl胁迫下高纬度移植桐花树幼苗的生理生态效应

通过砂培试验,研究了不同浓度NaCl(0、100、200、300和400 mmol·L-1)处理对高纬度移植桐花树幼苗生物量、离子吸收、碳氮代谢、叶片光合色素和叶片抗氧化系统的影响.结果表明:100 mmol·L-1NaCl处理对桐花树生长有轻微的促进作用,当NaCl浓度达到300mmol·L-1时,桐花树根、茎、叶器官的干鲜质量、根冠比、株高和基径均显著下降.高盐胁迫抑制了叶片抗氧化系统中超氧化物歧化酶(SOD)和过氧化物酶(POD)的活性,提高了丙二醛含量,降低了叶片中叶绿素、类胡萝卜素总量以及根茎叶的可溶性总糖和游离氨基酸总量.不同浓度NaCl胁迫下,桐花树根茎叶中Na+含量快速上升,K+含量相对下降,K+/Na+快速下降,导致各器官中离子平衡失调.当NaCl浓度高于300 mmol·L-1时,桐花树根茎叶的碳氮代谢运转失调,抑制了植株的正常生长,导致各器官的生物量显著下降.     

Response of potato grown under non-inductive condition paclobutrazol: shoot growth, chlorophyll content, net photosynthesis, assimilate partitioning, tuber yield, quality, and dormancy

The effect of foliar and soil applied paclobutrazol on potato were examined under non-inductive condition in a greenhouse. Single stemmed plants of the cultivar BP1 were grown at 35(±2)/20(±2) °C day/night temperatures, relative humidity of 58%, and a 16 h photoperiod. Twenty-eight days after transplanting paclobutrazol was applied as a foliar spray or soil drench at rates of 0, 45.0, 67.5, and 90.0 mg active ingredient paclobutrazol per plant. Regardless of the method of application paclobutrazol increased chlorophyll a and b contents of the leaf tissue, delayed physiological maturity, and increased tuber fresh mass, dry matter content, specific gravity, dormancy period of the tubers. Paclobutrazol reduced the number of tubers per plant. A significant interaction between rates and methods of paclobutrazol application were observed with respect to plant height and tuber crude protein content. Foliar application gave a higher rate of net photosynthesis than the soil drench. Paclobutrazol significantly reduced total leaf area and increased assimilate partitioning to the tubers. The study clearly showed that paclobutrazol is effective to suppress excessive vegetative growth, favor assimilation to the tubers, increase tuber yield, improve tuber quality and extend tuber dormancy of potato grown in high temperatures and long photoperiods.     

Apical callus formation and plant regeneration controlled by plant growth regulators on axenic culture of the red alga Gracilariopsis tenuifrons (Gracilariales, Rhodophyta)

Axenic cultures of Gracilariopsis tenuifrons (Bird et Oliveira) Fredericq et Hommersand (Gracilariales, Rhodophyta) were established in ASP12‐NTA solid medium (0.4% agar and 1.0% sucrose) supplemented with plant growth regulators to evaluate the effects on apical callus formation and plant regeneration. Indole‐3‐acetic acid (IAA), 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 6‐benzylaminopurine (BA) were added individually or in combinations (IAA : BA) over a range of concentrations from 0.5 to 5 mg L^?1. Growth of apical and intercalary segments was stimulated by high concentrations of 2,4‐D (5 mg L^?1) and a high IAA to BA ratio (IAA : BA = 5:1 mg L^?1) respectively. Apical calluses were originated from divisions of apical and cortical cells located at apical regions of thallus segments and lateral branches. Low concentration of IAA (0.5 mg L^?1) or a high IAA to BA ratio (IAA : BA = 5:1 mg L^?1) were the optimal treatments for inducing apical callus formation in apical segments, while high concentration of IAA (5 mg L^?1) stimulated the highest callus induction rate in intercalary segments. Conversely, equal parts IAA and BA (IAA : BA = 1:1 mg L^?1) and low concentration of 2,4‐D (0.5 mg L^?1) stimulated growth of apical calluses from apical and intercalary segments, respectively. Two processes of regeneration were observed: direct regeneration (upright axis originated from cells of proximal region of intercalary segments) and indirect regeneration (adventitious plantlet originated from cells of apical calluses). Direct regeneration was promoted significantly by treatment with a low IAA to BA ratio (IAA : BA= 1:5 mg L^?1), and treatments with IAA (0.5 mgL^?1) or 2,4‐D (0.5 or 5 mg L^?1) significantly stimulated the elongation of upright axis. Plant growth regulators are essential to inducing indirect regeneration, and a high concentration of IAA (5 mg L^?1) and BA (5 mg L^?1) were the optimal treatments for inducing the regeneration of plantlets from apical calluses in apical and intercalary segments, respectively. Regenerating plantlets grew into plants morphologically similar to those formed from germinating spores, and became fertile after 6 weeks. The results suggest that auxins and cytokinins are involved in developmental regulatory processes in G. tenuifrons. The regeneration process from calluses in species of Gracilariales was observed for the first time in the present study. The culture system described for G. tenuifrons could be useful for micropropagation and for biotechnological applications in agarophytic algae.     

Efficient in vitro regeneration of fireweed,a medicinal plant

Epilobium angustifolium L. (fireweed) is a medicinal plant that has been used to treat diarrhea, mucous colitis, irritable-bowel syndrome, skin problems, prostate problems, menstrual disorders, asthma, whooping cough, and hiccups. A highly efficient and rapid regeneration system via multiple shoot formation was developed for fireweed. Explants (leaf, petiole, root, and stem segments) excised from sterile seedlings were cultured on medium supplemented with different concentrations and combinations of various plant growth regulators. Explant browning, a major problem for regeneration, was overcome by adding 100 mg/l ascorbic acid to all prepared media containing growth regulator combinations. Root explants formed more shoots than other explants. Best shoot proliferation was obtained from root explants cultured on media with 0.1 mg/l BA and 0.5 mg/l IAA. Regenerated shoots were transferred to rooting media containing different concentrations of IAA, IBA, NAA or 2,4-D. Most shoots developed roots on medium with 0.5 mg/l IAA. Rooted explants were transferred to vermiculate in Magenta containers for acclimatization and after 3 weeks they were planted in to plastic pots containing potting soil and maintained in the plant growth room.