A co-culture system leads to the formation of microcalli derived from microspore protoplasts ofBrassica napus L. cv. Topas

Summary This paper describes a procedure in which protoplasts are obtained from microspores and pollen of rapeseed to induce callus formation aided by a feeder cell system with embryogenic microspores. Microspores at late unicellular stage and pollen at early bicellular stage were isolated and precultured for 24 h at 32 °C before enzymatic treatment. Eleven enzymes were tested in various combinations and concentrations. The optimal enzyme combination was 1.0% cellulase, 0.8% pectinase, 0.3% macerozyme, and 0.02% pectolyase, in which 26.3% of the microspores released protoplasts. A successful co-culture system was set up by employing embryogenic microspores as feeder cells. To this end, microspores were cultured in a medium with high osmotic pressure at 32 °C. Up to 37% of the microspores exhibited cell division and embryos developed to the heart-shape stage without changing medium. Microspore protoplasts were cultured in Millicells surrounded by the embryogenic microspores as feeder. In growth-regulator-free medium 14.5% of the protoplasts divided but only formed budding-like multicellular structures. Only after pretreatment with 4 mg of 2,4-dichlorophenoxyacetic acid and 1 mg of naphthaleneacetic acid per liter protoplasts divided and formed microcalli. Pollen tubes or tubelike structures were not observed. The experiments reveal that selection of the specific developmental stage of microspores, which is a prerequisite for microspore embryogenesis, is also important in microspore protoplast culture. Compared to other methods used before, microculture fed with embryogenic microspores has obvious superiority.Abbreviations CPW basic protoplast washing medium according to Power and Chapman - CPW972 CPW basic medium supplemented with 9% mannitol and 7.2% sorbitol - DAPI 4,6-diamidino-2-phenylindole - NLN nutrient medium according to Lichter modified by Pechan and Keller - NLN13 NLN medium supplemented with 13% sucrose - NLNP NLN13 supplemented with 7.2% sorbitol     

Improved isolated microspore culture efficiency in medium with maltose and optimized growth regulator combination in japonica rice (Oryza sativa)

The influence of maltose and growth regulators on microspore culture response was investigated in japonica rice. High frequency of callus induction of isolated microspores was obtained with liquid medium containing MS salts, 100 mg l^–1 myo-inositol, 1 mg l^–1 thiamine-HCl, 500 mg l^–1 glutamine, 60 g l^–1 maltose, and several growth regulators. The effect of maltose on promoting callus formation was associated with keeping a high proportion of swollen microspores after 5 day preculture and increasing the microspore division rate on the 3rd day after culture initiation. No significant effect of maltose in place of sucrose on plantlet regeneration was seen in regeneration medium. Among the growth regulators tested, the combination of auxin 2,4-dichlorophenoxyacetic acid (1 mg l^–1), naphthaleneacetic acid (1 mg l^–1), and cytokinin (6-benzyl-aminopurine 1 mg l^–1) in the medium proved to be much better for callus formation than in the other media, and the percentage of callusing microspores of that medium reached 0.86%. Indole-3-acetic acid (0.5 mg l^–1) and kinetin (2 mg l^–1) in regeneration medium were beneficial for green plantlet differentiation. The results also showed that the frequencies of microspores initial division, callus formation and green plant regeneration varied among genotypes no matter what kind of growth regulator and sugar were used. Xiushui 117 was the best variety for callusing followed by 02428 & Taipei 309. Taipei 309 showed a good ability for green plantlet regeneration.Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid - NAA naphthaleneacetic acid - 6-BA 6-benzylaminopurine - KT kinetin - IAA indole-3 acetic acid     

Manipulation of division symmetry and developmental fate in cultures of potato microspores

The effect of media composition on microspore culture was investigated in one tetraploid and two diploid potatoes. The viability of microspores isolated from 4.5 to 5 mm buds was in the range of 33 to 52%. In media for anther culture, microspores showed no further development and lost viability within 2 days. In M1 medium containing mineral components, sucrose, uridine, cytidine, myo-inositol, glutamine and lactalbumin hydrolysate, 18 to 37% of microspores underwent mitosis within 14 days. Up to 95% of the divisions were symmetric and produced equal nuclei. Some symmetrically divided microspores eventually produced structures with 3 to 10 nuclei. The proportion of the total microspore population producing multinuclear structures reached 9% in diploid clones responsive to anther culture and 1 to 2% in recalcitrant cv. Borka. Symmetric mitoses in M1 medium were induced in the presence of glutamine and lactalbumin hydrolysate. Nucleosides and myo-inositol had no effect on microspore division. In the absence of all organic components except sucrose, most mitoses were asymmetric, formation of multinuclear structures was reduced and most pollen accumulated starch indicative of gametophytic fate. In complete M1 medium, starch accumulation was suppressed. Suppression also occurred in asymmetrically divided microspores, indicating a direct inhibition of pollen development independent of the mode of microspore division. This inhibitory effect of M1 medium might present a stress which triggers the induction of symmetric microspore division and subsequent formation of multinuclear structures. This revised version was published online in June 2006 with corrections to the Cover Date.     

Viability,cell division and microcallus formation of barley microspores in culture

Barley microspores were viable when cultured in a sugarless medium. Adding 2g of glucose to 1l of this medium resulted in a significant reduction in the frequency of viable microspores. The frequency of viable microspores was further reduced when 50g of cellobiose, glucose, maltose, melezitose, raffinose or sucrose were added to 1l of the culture medium containing 2g/l glucose. Adding 50g of melibiose, Ficoll, polyethylene glycol (PEG) or a combination 50g each of Ficoll and PEG to 1I of the medium containing 2g/l glucose had very little effect on the viability of the microspores.Up to 66% of the viable microspores were able to divide and many of these developed into microcalli in the basal medium complemented with melibiose, maltose, melezitose, raffinose, Ficoll, PEG or a combination of Ficoll with PEG. Sucrose, cellobiose and glucose added in large quantities inhibited cell division in microspores or destabilized the microspores and only very few of them developed into microcalli.The microcalli in the PEG, Ficoll, Ficoll-PEG and melibiose media were smaller in size than those grown in the melezitose, maltose and raffinose media. Sustained cell division and microcallus formation were observed in a medium with melibiose or maltose as sole source of sugars.Abbreviations 2.4-D 2,4-dichlorophenoxyacetic acid - NAA 1-Naphthaleneacetic acid - PEG Polyethylene glycol     

Plant regeneration from isolated cells ofLavandula latifolia medicus

Summary Single cells were obtained from hypocotyl-derived callus ofLavandula latifolia Medicus. Cells were plated in Murashige and Skoog medium supplemented with indoleacetic acid (IAA), benzyladenine (BA), and several IAA-BA combinations. Cell division required the simultaneous presence of IAA and BA in the culture medium, but callus formation was only achieved with 0.1 or 1 mg/liter IAA and 2 mg/liter BA. To induce organogenesis, calli were transferred to various regeneration media. Shoot-bud differentiation efficiency depended on the composition of both the callus induction and the shoot regeneration media, best results being obtained when calli grown in 1 mg/liter IAA and 2 mg/liter BA were subcultured to media containing 2 mg/liter BA and 15% coconut milk. Under these conditions, up to 75% of calli formed shoots that subsequently were rooted and established in soil.     

绞股蓝悬浮细胞的原生质体再生植株

绞股蓝(Gynostemma pentaphyllum (Thumb)Mak．)是葫芦科多年生草本药用植物,现已得到广泛的开发利用,本文首次报道了绞股蓝悬浮细胞的原生质体再生植株。     

Induction of callus formation from difficile date palm protoplasts by means of nurse culture

We report here for the first time callus formation from protoplasts in date palm (Phoenix dactylifera L.). Protoplasts were isolated from young leaves of offshoots and embryogenic calli in Deglet nour and Takerboucht genotypes. The protoplast yield depended on genotype, donor plant material, mixture of enzyme solution, and incubation time. With regard to the donor material, the best response was obtained with callus. Cell division was induced in both liquid culture and nurse culture. The best donor material for cell division was callus and the best response was obtained with the feeder layer, which induced a division rate of 30% in Deglet nour and 15% in Takerboucht genotypes. The dividing cells developed to microcalli on the feeder layer; the microcalli developed to calli on modified MS medium; however, the calli failed to regenerate into roots or shoots.     

Improved callus formation and plant regeneration for shed microspore culture in asparagus (Asparagus officinalis L.)

 To establish an efficient asparagus microspore culture system, experiments were conducted to investigate the effects of medium components, period of cold pretreatment for flower buds, and period of anther co-culture on culture response. All factors affected the frequency of asparagus microspore division and the yields of microspore-derived calli. The best results were obtained by pretreating genotype G459 flower buds at 4  °C for 7–9 days, co-culturing anthers with shed microspores for 14 days, and including 6% sucrose, 2 mg l^–1α-naphthaleneacetic acid and 1 mg l^–1 N⁶-benzylaminopurine in the culture medium. After 4 days of culture, most shed microspores contained starch-like bodies and died. The 2% of shed microspores lacking these structures divided to produce microcalli. For the best treatments in the different experiments, about 140 calli per 100 anthers were recovered. Cultured on four different regeneration media, 19.6–21% and 3.9–8.0% of microspore-derived calli produced shoots and embryos, respectively, and ultimately plantlets, among which 49% were haploid, 34% diploid, 4% triploid and 11% tetraploid. Received: 3 September 1998 / Revision received: 25 November 1998 / Accepted: 5 December 1998     

Prospects of androgenetic induction in <Emphasis Type="Italic">Lupinus</Emphasis> spp.

Anthers cultures of six Polish cultivars of pasture lupin (Lupinus L.) were examined for their androgenic response. Anthers with microspores at the uninucleate stage were isolated from flower buds and cultured in liquid media. Better viability of androgenetic structures was obtained when donor plants had grown under field as opposed to greenhouse conditions. A density of five anthers per 0.5 ml medium was more conducive to androgenetic induction than 25 anthers per 0.5 ml medium. Addition of 5% maltose to the induction medium and culture at 25°C without pre-treatment of flowers, buds or anthers promoted microspore release and division. The greatest frequency of androgenic callus, ~70% was developed from cvs. Katon, Wat (white lupin), in contrast to cvs. Legat, Juno (yellow lupin), Polonez and Sonet (narrow-leafed lupin) with callus induction ~30–40%. Despite various combinations of media tested, plant regeneration was not obtained from anther derived callus.     

Clonal propagation byin vitro culture of Corchorus (jute)

Callus was produced on cotyledon, shoot tip, hypocotyl and root explants of twoCorchorus species on several media. Cytokinin was necessary for callus production on cotyledon explants. BothC.olitorius genotypes produced most callus on media with zeatin and either NAA or IAA, and theC.capsularis genotype produced most callus on media with IAA and either zeatin or BA. High frequencies of regenerated shoots were obtained from shoot tip explants of both species, from the apical meristem and from callus. Media with 2.0 mg 1⁻¹ BA were superior for both species, and media with zeatin were equally good forC.capsularis only. More regeneration was obtained for all genotypes after subculture of callus on media with 2.0 mg 1⁻¹ zeatin. Cotyledon callus produced less regeneration, also with differences between genotypes; explants of both genotypes ofC.olitorius produced regeneration on a medium with NAA and zeatin, and theC.capsularis genotype produced regeneration on a medium with IAA and BA. Limited regeneration from root explant callus was obtained forC.capsularis only on medium with BA and IAA. Regeneration was not obtained from hypocotyl callus. Further regeneration of shoots of both species was obtained from secondary callus after subculture, and from nodal segments of regenerated shoots and of seedling shoots cultured on basic MS medium without growth hormones. Roots were produced on about 80% of all shoots after transference to medium with 0.2 mg 1⁻¹ IBA, and rooted plantlets survived and flowered normally after transference to compost.     

茎用芥菜细胞质雄性不育系子叶原生质体培养和高效植株再生（英文）

利用茎用芥菜细胞质雄性不育系原生质体培养获得了再生植株,并研究了影响原生质体培养的因素.结果表明,子叶是茎用芥菜原生质体培养最佳的外植体,10 d苗龄的子叶原生质体在改良MS培养基上培养3 d后发生第1次细胞分裂,6 d后发生第2次分裂,3周后形成细胞团,5周后形成肉眼可见的小愈伤.培养基中缺少NAA或2,4-D都会降低愈伤组织的再生能力.在含一定浓度的NAA(0.25 mg/L)和2,4-D(0.25 mg/L)培养基上诱导的愈伤组织质地致密且有光泽,芽的分化能力高;在MS+BA l mg/L+NAA 0.2 mg/L的培养基上芽的分化频率高达近29%,再生芽在1/2MS+NAA0.1 mg/L培养基上生根,形成完整植株.     

茎用芥菜细胞质雄性不育系子叶原生质体培养和高效植株再生

利用茎用芥菜细胞质雄性不育系原生质体培养获得了再生植株,并研究了影响原生质体培养的因素.结果表明,子叶是茎用芥菜原生质体培养最佳的外植体,10 d苗龄的子叶原生质体在改良MS培养基上培养3 d后发生第1次细胞分裂,6 d后发生第2次分裂,3周后形成细胞团,5周后形成肉眼可见的小愈伤.培养基中缺少NAA或2,4-D都会降低愈伤组织的再生能力.在含一定浓度的NAA(0.25 mg/L)和2,4-D(0.25 mg/L)培养基上诱导的愈伤组织质地致密且有光泽,芽的分化能力高;在MS+BA l mg/L+NAA 0.2 mg/L的培养基上芽的分化频率高达近29%,再生芽在1/2MS+NAA0.1 mg/L培养基上生根,形成完整植株.     

埃斯基红豆草下胚轴愈伤组织原生质体的培养与植株再生

埃斯基红豆幼苗的下胚轴切段在附加２,４－Ｄ０．５ｍｇ／Ｌ,ＫＴ１ｍｇ／Ｌ的ＭＳ中形成胚性愈伤组织。来自１１－１３个月龄、继代６－１５天的愈伤组织的原生质体,在改良的Ｖ－ＫＭ液体培养基中可持续分裂形成细胞团,培养１０天时的分裂率和克隆率分别为６５．８８％和５３．３８％周后就可将将原生质体形成的小愈伤组织转于培养基上。原生质体在改良的Ｂ５液体培养基也可以分裂形成小愈伤组织,但分裂率低于Ｖ－ＫＭ。来自原     

Production of haploid plantlets in anther cultures of Albizzia lebbeck L.

Anthers of Albizzia lebbeck on B₅ medium (BM) supplemented with kinetin (2 mg/l) and 2, 4-D (0.5 mg/l) showed callus initiation from microspores. Differentiation of embryoids and shoots was obtained on BM + BAP (1 mg/l) + IAA (0.5 mg/l) and of roots on BM. Root tip squashes of the regenerated plantlets showed the haploid chromosome number (n=13), confirming the microspore origin of the regenerants.     

Isolated microspore culture of wheat (Triticum aestivum L.) in a defined media I. Effects of pretreatment,isolation methods,and hormones

Significant improvements were achieved in the production of haploid and doubled haploid plants from isolated microspore culture of wheat c.v. Chris on a defined media. Procedures found to be of benefit included: A 7-day pretreatment of anthers in 0.4M mannitol plus the macronutrients from FHG medium; the inclusion of 4.5 mg/liter abscisic acid in the pretreatment solution; the isolation of microspores from pretreated anthers by vortexing; and the use of phenylacetic acid (PAA) as the auxin source in MS medium. The best response was achieved with 4.0 mg/liter PAA in MS medium containing 90 g/liter maltose as the sugar source. Under these conditions, 68% of viable microspores underwent division, and an average of 93 embryos and 92 green plants were regenerated per 100 anthers used. The root-tip chromosome number and the fertility of 114 regenerating green plants revealed that 75% were completely fertile spontaneously doubled haploids.     

Improved embryoid induction and green shoot regeneration from wheat anthers cultured in medium with maltose

Summary Anthers from spring wheat (Triticum aestivum L.) genotypes, including six F₁ hybrids, were cultured in a modified liquid N6 medium containing either sucrose or maltose. In every case, use of maltose resulted in greater microspore callus induction and green shoot regeneration than culture in sucrose-containing medium. Induction in maltose medium also allowed green shoots to be recovered from crosses that showed only a poor response in other media and from two genotypes that did not respond to modified N6 medium with sucrose. Replacement of sucrose with maltose generally resulted in microspores having a more embryogenic mode of development in which distinct embryoids often formed. The most responsive genotype produced over 200 green shoots/100 anthers when cultured in medium with maltose.NRCC publication no. 31494     

Early Microspore Divisions and Subsequent Formation of Microspore Calluses at High Frequency in Anthers of Hordeum vulgare L.

The products of first microspore mitosis were studied in anthersof Hordeum vulgare. These anthers were obtained either directlyfrom plants at the binucleate stage or from tillers which hadbeen estimated visually as containing pollen at the mid-uninucleatestage and then pretreated by being clipped off at ground leveland allowed to stand in water for 2 d. In microspores from thelatter plants ten-fold increases in the failure of nuclear differentiation,alteration of the axis of division, or both were observed. Highfrequencies of further microspore response in individual antherswere subsequently induced through culture of the spikes fromthe pretreated tillers in agitated liquid medium. A five toten-fold increase in the percentage of anthers producing macroscopiccallus was observed in these spikes when compared with the controls.It is suggested that nucleo-cytoplasmic disturbances in themicrospores, brought about through the pretreatment period,stimulated the further divisions which eventually resulted inmicrospore callus formation. Microspore calluses were produced most often following an equalfirst division, although when mitosis resulted in differentiatednuclei further divisions of the vegetative nucleus also resultedin callus production. Haploid, diploid, polyploid, and mixaploidmicrospore calluses were produced but no evidence was obtainedto link haploid production with any particular developmentalpathway. Macroscopic calluses which emerged from the culturedanthers were probably mixtures of cell populations derived fromseveral or many different gametic genotypes.     

Increased frequency of dividing microspores and improved maintenance of multicellular microspores of Coffea arabica in medium with coconut milk

The number of dividing microspores of Coffea arabica L. cv. Catuai and Catimor could be drastically increased in microspore media containing 16% (w/v) coconut milk, allowing cell divisions to continue in the microspore and multicellular microspores to survive until day 60. After a cold treatment, the microspores were mechanically isolated prior to cultivation in Murashige and Skoog medium supplemented with sucrose and maltose and (mg l^-1) 2,4-d: 2, BAP: 1 or a combination of kinetin: .5, 2,4-d: .5 and NAA: .5 as stationary suspension at a density of 1,200/ml. The crucial stage during microsporogenesis suitable for in vitro androgenesis proved to be mid uninucleate till early binucleate in flowerbuds with the size of 13–15 mm two to three days before anthesis. The initial steps of androgenesis were determined.Abbreviations BAP 6-benzylaminopurine - 2,4-d 2,4-dichlorophenoxy-acetic acid - NAA 1-naphthaleneacetic acid     

In vitro development of plants from microspores of rice

Summary Rice (Oryza sativa L., 2n=24) anthers containing microspores in the early-uninucleate to first-mitosis stages were induced successfully to develop into plants in vitro through an intermediary step of callus formation. Callus initiation occurred with highest frequency in anthers containing mid-uninucleate microspores. The callus derived from different stages of microspore development differed in the potential to differentiate into plants. The plants regenerated from pollen callus were predominantly haploid or diploid; polyploid and aneuploid plants were relatively infrequent. The first division of the uninucleate microspores was asymmetrical, resulting in the formation of large vegetative and small generative nuclei. The vegetative nucleus divided repeatedly and assumed the major role in the formation of callus, whereas the generative nucleus degenerated rapidly. Simultaneous division of the two nuclei was observed in a few pollen grains. Nuclear fusion during the very initial stages of pollen development was postulated to account for the occurrence of the diploid and polyploid plants. This work was supported by the National Science Council, Republic of China.     

Haploid plants regenerated via anther culture in wild barley (Hordeum spontaneum C. Kock)

Summary Androgenic plants have been obtained via anther culture in four natural populations of Hordeum spontaneum. Microscopic observations revealed that androgenesis started with the formation of two vegetative-type nuclei derived from the mitotic division of the uninucleate microspores. In this species androgenesis was affected by the type and concentration of the sugars added to the culture medium: the highest response (17% of callusing anthers) was observed on media containing 80 g l^–1 maltose. The highest production of androgenic plants (per 100 anthers, 5.9 green and 4.3 albino plants) was obtained from callus grown on these same media. About half of the green plants regenerated were haploid, while the others were diploid and set seed.Abbreviations IAA indolacetic acid - BAP 6-benzylaminopurine