Changes in IAA,Phenolic Compounds,Peroxidase, IAA Oxidase,and Polyphenol Oxidase in Relation to Flower Formation in Crocus sativus

Changes in levels of IAA, phenolic compounds, peroxidase, polyphenol oxidase, and IAA oxidase activities in the corm and the apical bud of Crocus sativusL. during bud growth and development, with special emphasis on the flowering stage, were studied. In the bud, flower formation was accompanied by enhanced activities of peroxidase, polyphenol oxidase, IAA oxidase, and higher contents of phenolic compounds as well as lower levels of IAA. In the corm, during the flower formation, these enzymes showed an opposite behavior. Moreover, the contents of phenolics and IAA in the corm tissues during flower formation and growth were higher than at the other developmental stages. It may be concluded that the transition of saffron plants to flowering is correlated with peroxidase, polyphenol oxidase, and IAA oxidase. Furthermore, these enzymes might exert their roles in the regulation of flowering through their participation in IAA catabolism. The hypothesis of regulation of bud development by an interaction between phenolics and the enzymes involved in IAA catabolism is discussed.     

芋侧球茎发生发育的形态学机理

观察了魁芋和多子芋腋芽、侧球茎发生发育的形态学变化规律,分析了主球茎顶芽和不同发育期腋芽中蛋白质的组成。结果表明,魁芋每一叶轮上腋芽数目为１;多子芋为３或３个以上,其中一个体积较大。魁芋侧球茎发育初期伸长的速度大于增粗,首先形成圆柱型,然后顶端膨大形成体积很小的侧球茎。多子芽腋芽伸的同时茎部明显变粗,首先形成圆锥型,然后发育成品种特有的形状。根据发育进程将腋芽发育分成ＡＢ１－ＡＢ９个时期,将主球茎     

红芽芋球茎片两步法离体快繁及其再生苗生理和光合特性研究

以江西铅山红芽芋(Colocasia esculenta L.Schott var.cormosus‘Hongyayu’)试管苗为材料,建立了芋球茎片两步法离体快繁体系,并对其再生苗的形态指标、染色体数目、生理和光合特性以及叶绿素荧光特性进行了检测。结果表明:(1)红芽芋球茎片单芽诱导的最佳培养基为MS+KT 2 mg/L+6-BA 1 mg/L+NAA0.1mg/L,诱导培养30d后将单芽从球茎片上分离,再接种到生根培养基(MS+KT 2mg/L+NAA 0.1mg/L)上培养30d即可形成完整植株,移栽成活率高达98%;(2)由球茎片单芽、丛生芽、不定芽离体快繁获得的红芽芋再生苗在形态指标、叶下表皮气孔参数、染色体数目、生理生化指标以及叶片光合特性参数和叶绿素荧光特性方面均无显著差异。说明红芽芋球茎片两步法离体培养的再生苗繁殖系数高、染色体数目稳定,该离体快繁体系可应用于江西铅山红芽芋的工厂化生产。     

In Vitro Organogenetic Responses of Gloriosa superba

An efficient protocol was developed for regeneration of healthy plant derived from six categories of explants from both in vivo and in vitro raised plants, viz. roots, corm buds (dormant and nondormant), young leaves, stems, pedicels, and shoot tips from aerial shoots. MS medium supplemented with various concentrations and combinations of auxin, cytokinin, and organic acids was used. 98% of callus induction occurred in nondormant corm bud explants. The greatest number of multiple shoots (57) was observed in corm-derived calluses. Vigorous root formation occurred in all cases when multiple shoots were derived. Histomorphogenetic studies revealed that not only the origin of shoot and root buds in in vitro systems, but the morphology and structure of leaves resemble those of in vivo plants too.     

Efficient micropropagation of <Emphasis Type="Italic">Ensete ventricosum</Emphasis> applying meristem wounding: a three-step protocol

A highly efficient three-step protocol for in vitro propagation of Ensete ventricosum (enset) was developed that consisted of initiation, bud proliferation, and shoot elongation and rooting stages. At the initiation stage, it was crucial to use shoot tips (5–8 mm) with subtending corm tissues as explants to obtain growth. The addition of 0.5–1% (w/v) activated charcoal to the medium was essential to prevent phenol exudation which otherwise leads to the loss of cultures. During the bud proliferation stage, modified MS macronutrients and micronutrients together with a combination of cytokinins (1.6 M naphthaleneacetic acid, 4.4 M 6-benzylaminopurine, 23.2 M kinetin, 22.6 M N⁶ 2-isopentyladenine) was used. This novel composition of macronutrients was based on the analysis of leaf nutrient content of glasshouse-grown enset sprouts. Multiple bud formation on the enlarged corm tissue was induced only when the meristem region was wounded before transfer to the bud proliferation medium. Up to 75 healthy shoots per explant were produced, whereas unwounded explants produced, only one to two shoots per explant. A third stage with a low concentration of cytokinin enabled shoot elongation as well as root development. The plantlets were acclimatized with 100% success and they showed no apparent phenotypical deviation.Abbreviations BAP 6-Benzylaminopurine - IBA Indole-3-butyric acid - DW Dry weight - EV Ensete ventricosum medium - 2-iP N⁶ 2-Isopentyl adenine - NAA -Naphthaleneacetic acid     

In vitro corm production of Gladiolus dalenii and G. tristis

The ability of the summer flowering Gladiolus dalenii Van Geel and the winter flowering G. tristis L. to form corms in vitro was investigated. G. dalenii spontaneously formed corms on a shoot induction medium consisting of the basal medium of Murashige & Skoog (1962) with up to 2.0 mg l^-1 benzyladenine (BA), 3% sucrose and solidified with 2 g l^-1 Gelrite^®. The effect of different BA and sucrose concentrations as well as different temperatures on in vitro corm production of G. tristis was further investigated. The best production of shoots per explant was achieved on a medium containing 0.5 to 1.0 mg l^-1 BA, sucrose concentrations of 6 to 9% and cultured at 15°C. The best corm production was achieved at the same temperature and with the same medium with the exception that BA was omitted from the medium. To test the effect of the osmotic potential on the formation of shoots and corms, sucrose was substituted by mannitol at various concentrations. Sucrose proved to be essential for both shoot and corm production and the use of mannitol had no beneficial effect.     

江西铅山红芽芋脱毒苗球茎愈伤组织诱导及其再生体系的建立

以江西铅山红芽芋脱毒苗为试材,研究不同因素对红芽芋脱毒苗球茎愈伤组织诱导及其再生体系的影响,以期对红芽芋脱毒苗的再生体系进行优化。结果表明,红芽芋脱毒苗球茎愈伤组织诱导的最佳培养基是MS+TDZ 2 mg·L^-1+2,4-D 1 mg·L^-1。红芽芋脱毒苗球茎愈伤组织分化的最佳培养基是MS+TDZ 2 mg·L^-1+NAA 1 mg·L^-1。红芽芋脱毒苗不定芽生根的最佳培养基是1/2MS+NAA 0.5 mg·L^-1+PP₃₃₃ 0.5 mg·L^-1。红芽芋再生苗最好的移栽基质为发酵后的腐锯木屑。红芽芋脱毒苗球茎愈伤组织再生苗移栽时最佳的PP₃₃₃浓度为20～50 mg·L^-1。本试验成功建立了红芽芋脱毒苗球茎愈伤组织的再生体系,为红芽芋脱毒苗转基因的研究和种质创新奠定了基础。     

In vitro propagation of Iphigenia indica,an alternative source of colchicine

The present study involves in vitro propagation of Iphigenia indica (Kunth.) through multiplication of whole corms and corm buds. The whole corms produced very small micro-corms, which developed plants individually whereas corm buds multiplied to produce numerous shoots at variable rates in presence of -naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP). The best response in corm and bud multiplication was obtained in Murashige and Skoog's basal medium (MS) supplemented with 2.69 M NAA and 8.88 M BAP. The shoots regenerated were further cultured on MS medium containing NAA and indole-3-butyric acid (IBA) for initiation of roots. MS medium with 5.38 M NAA and 4.92 M IBA induced highest percentage of roots (81%) within 2 weeks in culture.     

Induction and characterization of in vitro corms of diploid-taro

When in vitro plantlets were cultured in Murashige and Skoog liquid medium supplemented with 8–10% sucrose and 22–44 μM 6-benzylaminopurine, all of the stem explants formed corms. 170–850 μM paclobutrazol increased corm formation, whereas 1700 μM paclobutrazol inhibited corm development. Inclusion of 66 μM 6-benzylaminopurine in 170 μM paclobutrazol treatment resulted in smaller corms, and bigger corms formed in the combination of 1700 μM paclobutrazol and 66 μM 6-benzylaminopurine. No corms formed in 63–630 μM cycocel treatments. In vitro corm growth was also affected by the culture methods. Deep-layer agitated culture yielded corms of up to 2.03 g, with an average fresh weight of 0.7 g, 40 days after induction. In thin layer cultures, corms were up to 1.87 g, with an average fresh weight of 0.5 g. SDS-PAGE analysis of water-soluble proteins revealed changes of polypeptides with corm growth. Compared to smaller ones, corms over 0.2 g had higher dry matter, carbohydrate and anthocyanin content. These corms had a 99–100% survival rate upon transplanting directly to soil after storage at 4 °C for 10 months. This study indicates that the most economic production method of diploid taro seed corm is by thin-layer liquid culture in Murashige and Skoog medium supplemented with 22–44 μM benzylaminopurine and 8–10% sucrose for 6 weeks. The formed corms can be stored at 4 °C up to 10 months and transplanted directly into soil without acclimatization. This revised version was published online in June 2006 with corrections to the Cover Date.     

Improved <Emphasis Type="Italic">in vitro</Emphasis> micropropagation method with adventitious corms and roots for endangered saffron

The objective of this study was to investigate development of an efficient in vitro tissue culture system for saffron (Crocus sativus L.) complete with roots and corms. In indirect organogenesis, Murashige and Skoog (MS) media with 3% (w/v) sucrose, 100 mg L⁻¹ ascorbic acid, and the combination of 0.25 mg L⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) and 1 mg L⁻¹ 6-benzylaminopurine (BAP) were best for callus initiation and growth while 1.5 mg L⁻¹ BAP was excellent for high rate of adventitious shoot formation. 1 mg L⁻¹ indole-3-butyric acid (IBA) was more preferable for adventitious corm and root initiation as well as growth. Overall, 64% rooting and 33% corm production rates were achieved in indirect organogenesis. In direct organogenesis, MS medium supplemented with 3 % sucrose, 100 mg L⁻¹ ascorbic acid and 1 mg L⁻¹ BAP was optimum for shoot growth. While 1 mg L⁻¹ IBA was best for adventitious corm formation, 2 mg L⁻¹ IBA promoted adventitious root initiation and growth. Overall, 36% and 57% of explants had corm and contractile root, respectively. The high rates suggest that efficient tissue culture system could be achieved for mass propagation and ex situ conservation of threatened saffron genetic resources.     

Seasonal Allocation and Efficiency Patterns of Biomass and Resources in the Perennial Geophyte Sparaxis grandiflora Subspecies fimbriata (Iridaceae) in Lowland Coastal Fynbos, South Africa

The seasonal allocation and efficiency of biomass and resources(starch, soluble carbohydrates, N, P, K, Ca, Mg, Na, Zn, Fe,Mn and Cu) within and between the constituent plant parts ofSparaxis grandiflora subspecies fimbriata , a deciduous, synanthousgeophyte, are described. The sequential production of roots,leaves and a new daughter corm, with fruit production phasedin during the development of the daughter corm, results in continualtransfer of resources when the plant is not dormant. The newdaughter corm serves as the major sink for the allocation ofdry matter and resources during the vegetative, reproductiveand senescent periods. The parent corm is the major source ofresources in the early stages of the vegetative period. Theamount of resources allocated to the reproductive structureswas comparatively low when compared with that allocated to vegetativeplant parts. The corms have highly flexible storage capacitiesfor a variety of nutrients, particularly the better conservednutrients such as nitrogen, phosphorus, potassium, and carbohydrates.The dynamic patterns for the majority of the resources revealedhigh allocation when metabolic activity was also highest. Efficientrecovery or recycling of important resources from senescingorgans results in a similar or greater allocation to the daughtercorm than the amount that was present in the parent corm ofthe previous growth season. This is seen as an advantage tothese plants that grow in a seasonal environment where soilsare of low nutrient status.Copyright 1994, 1999 Academic Press Dry mass, efficiency, phenophase, resource allocation, Sparaxis grandiflora, fynbos     

荸荠营养器官的发育与解剖学研究

荸荠同化茎起源于肉质主茎倒２或倒３叶的叶腋内。同化茎基部着生二鞘状叶,鞘状叶对早期同化茎穿出土面具保护作用。匍匐茎大多起源于同化茎基部鞘状叶的叶腋内。当植株开始抽生花茎时,地下匍匐茎顶端开始膨大。球茎的膨大是匍匐茎顶端５－６节的基本组织经细胞有丝分裂,增加细胞数目,然后由细胞体积的扩大来实现的。球茎具足够的营养物质供来年顶芽萌发的需要,故属水生植物冬芽的性质。     

The Cold Awakening of <Emphasis Type="Italic">Doritaenopsis</Emphasis> ‘Tinny Tender’ Orchid Flowers: The Role of Leaves in Cold-induced Bud Dormancy Release

Massive flowering of tropical Phalaenopsis orchids is coordinated by the cold-induced release of reproductive bud dormancy. Light and temperature are the two key factors integrated by the dormancy mechanism to both stop and reactivate the meristem development of many other angiosperm species, including fruit trees and ornamental plants. It is well established that leaves and roots play a major role in inducing flower development; however, currently, knowledge of molecular events associated with reproductive bud dormancy release in organs other than the bud is limited. Using differential gene expression, we have shown that the leaves of a hybrid of Phalaenopsis species, Doritaenopsis ‘Tinny Tender’, undergo major metabolic modifications. These changes result in the production of sucrose and amino acids, both of which can sustain bud outgrowth, and auxin and ethylene, which may play important roles in awaking the dormant buds. Intake of abscisic acid and synthesis of the hormone jasmonate may also explain the inhibition of vegetative growth that coincides with bud growth. Interestingly, many genes that were upregulated by cold treatment are homologous for genes involved in flower induction and vernalization in Arabidopsis, indicating that processes regulating flowering induction and those regulating reproductive bud dormancy release may use similar pathways and effector molecules.     

MICROSPOROGENESIS IN PEANUT (ARACHIS HYPOGAEA)

The stage of pollen development at the time of anther culture is an important factor in the production of haploids. The objectives of the current study were to develop a staining procedure for peanut (Arachis hypogaea L., ssp. hypogaea) microspores, to describe and document the stages of microsporogenesis in peanut, and to confirm a previous report concerning correlations of peanut floral bud shape with stage of microspore development. A staining procedure using propionic carmine provided adequate staining of pollen mother cells, microspores, and pollen. Pollen mother cells and microspores could easily be differentiated by their size and cell wall structure. Plants grown in a controlled environment were found to have highly synchronized microspore development, both within an anther and among anthers contained in the same bud. In addition, floral bud shape was confirmed as a reliable indicator of anther stage in peanuts.     

Summer-drought constrains the phenology and growth of two coexisting Mediterranean oaks with contrasting leaf habit: implications for their persistence and reproduction

This study analyses how coexisting evergreen and deciduous oaks adjust their phenology to cope with the stressful Mediterranean summer conditions. We test the hypothesis that the vegetative and reproductive growth of the winter deciduous (Quercus faginea Lam.) is more affected by summer drought than that of the evergreen [Quercus ilex L. subsp. ballota (Desf.) Samp.]. First, we assessed the complete aboveground phenology of both species during two consecutive years. Shoot and litter production and bud, acorn and secondary growth were monitored monthly. Second, we identified several parameters affected by summer conditions: apical bud size, individual leaf area (LA), leaf mass per area (LMA) and acorn yield in both species, and leaf-fall in Q. faginea; and analysed their variation over 10 years. Q. ilex performed up to 25% of shoot growth and most leaf development during summer, whereas Q. faginea completed most of both phenophases during spring. Secondary growth was arrested in summer under drought conditions. Approximately, 30–40% of bud and 40–50% of acorn growth was undertaken during summer in both species. Summer drought related to differences in LA, LMA and leaf senescence, but not to acorn yield. Both species had similar year-to-year patterns of acorn production, though yields were always lower in Q. faginea. Bud size decreased severely in both species during extremely dry years. In Q. ilex, bud size tended to alternate between years of large and small buds, and these patterns were followed by opposite trends in stem length. In Q. faginea, bud size was more stable through time. Q. ilex was more phenologically active during summer than Q. faginea, indicating a higher tolerance to drought. Furthermore, bud and fruit growth (the only two phenophases that both species performed during summer) were more severely affected by summer drought in Q. faginea than in the evergreen. The differential effects of summer drought on key phenophases for the persistence (bud growth) and colonization ability (fruit production) of both species may have consequences for their coexistence.     

DISTRIBUTION OF CALCIUM OXALATE CRYSTAL IDIOBLASTS IN CORMS OF TARO (COLOCASIA ESCULENTA)

The morphology and distribution of intracellular crystals of calcium oxalate in taro (Colocasia esculenta) was studied by light microscopy. The modified Pizzolato (AgNO₃-H₂O₂) method was used to localize crystals in cleared corm cross sections. Crystals of two forms were found: druses and raphides. The numbers and density of the crystals in corms increase rapidly in early development, then level off, and eventually decrease in older and larger corms. An especially high concentration of druses was observed 2-3 mm from the exterior edge of many corms. This corresponds to a ring of vascular tissue which circumscribes the corm at approximately the same distance from the surface. Observations suggest that the development of these highly specialized cells and the formation of calcium oxalate crystals is a dynamic process.     

Spatial and temporal gene expression patterns occur during corm development.

We investigated gene expression patterns that occur during taro corm development. Two-dimensional gel electrophoresis identified several different prevalent proteins that accumulate during corm development. Microsequencing studies indicated that some of these proteins are related to taste-modifying proteins, such as curculin and miraculin, and proteins found in other storage organs, such as sporamin and the Kunitz trypsin inhibitor. A curculin-encoding cDNA clone, designated as TC1, was identified that corresponds to a highly prevalent 1-kb corm mRNA. The TC1 mRNA accumulates during corm development, is more prevalent in corm apical than basal regions, and is either absent, or present at low concentrations, in other vegetative organs such as the leaf and root. In situ hybridization experiments showed that the TC1 mRNA is highly concentrated in corm storage parenchyma cells and is absent, or present in reduced concentrations, in other corm cells and tissues. Our results show that corm development is associated with the differentiation of specialized cells and tissues, and that these differentiation events are coupled with the temporal and spatial expression of corm-specific genes.     

Precocious gladiolus corm formation in liquid shake cultures

Conditions were defined for precocious differentiation and improved growth of corms at the base of gladiolus shoots. Shoots were derived from explants cultured on agar solidified media, and corm regeneration was obtained in subsequent liquid shake cultures. Benzyladenine (BA), at 10^-7 M, was found to have a stimulating effect mainly when provided to the shoots prior to manifestation of corm growth. Paclobutrazol and sucrose promoted corm formation when supplemented to the liquid media. Paclobutrazol, at 10 mg l^-1, shifted assimilate allocation towards the growing corm. A differential promotion of corm development by sucrose was not observed, and the concentration of sucrose at which the sugar demand for maximal shoot and corm growth is satisfied (60 g l^-1) was unaltered by the presence of paclobutrazol. The rate of corm growth on shoots cultured in a liquid medium supplemented with paclobutrazol and a saturating sucrose concentration, was a function of the length of the shoot's leaf blades, and was similar in light and in dark.     

不同光周期对西红花开花和花丝品质的效应比较

为筛选促进西红花开花和提高花丝品质的最佳光周期,以3种不同规格(20~25 g、25~30 g、30~35 g)西红花种球为材料,设置4种光周期处理(8 h/16 h、10 h/14 h、12 h/12 h、14 h/10 h),考察光周期对西红花种球鲜重变化、主芽生长、展叶数量、开花后营养物质含量以及花朵性状和花丝品质的效应。结果表明:(1)光周期8/16 h最有利于促进西红花主芽生长、增加展叶的种球数量。(2)光周期8 h/16 h和12 h/12 h下的西红花花朵直径大且前5 d开花数量多。(3)不同光周期对西红花苷含量、花丝干重、鲜重、折干率、含水量等花丝品质无显著影响。(4)西红花开花后种球中可溶性糖、淀粉、可溶性蛋白等营养物质含量在光周期8 h/16 h处理下较高,而在光周期12 h/12 h和14 h/10 h处理下较低。研究认为该试验条件下适合西红花生长的最佳光周期是8 h/16 h(昼/夜),此光周期有利于西红花生长、促进初期提前开花,然而对花丝品质无明显影响。     

Changes in free and conjugated indole-3-acetic acid during early stage of flower bud differentiation in Polianthes tuberosa

Tuberose (Polianthes tuberosa L. cv. Double) corms at the vegetative, early floral initiation, and flower bud differentiation stages were assayed for free indole-3-acetic acid (IAA), esterified IAA, and peptidyl IAA. The corms in the vegetative stage contained higher free IAA than those from the early floral initiation stage. Free IAA in corm tissues increased 2.7-fold at flower bud differentiation as compared to the vegetative stage. In the vegetative corms, a marked promotion of leaf differentiation was recorded. In contrast, corms from the early floral initiation stage contained less free IAA, whereas esterified IAA and peptidyl IAA increased dramatically. It is concluded that the level of free IAA in vegetative corms is correlated with leaf differentiation, and that the early floral initiation stage is correlated with a reduction in free IAA and an increase in IAA conjugates in the corms. Moreover, increases in free IAA and decreases in IAA conjugates in the floral differentiation stage, as compared to the early floral initiation stage, indicates that free IAA is correlated with flower development.