An assessment of morphogenic and transformation efficiency in a range of varieties of potato (Solanum tuberosum L.)

Summary To provide a truly genotype-independent transformation system, it is necessary to be able to transform a wide range of potato genotypes. The ability to regenerate shoots in vitro was determined for 34 potato varieties using tuber disc explants. Following a culture regime used extensively in previous studies with the variety Desiree, half of the varieties could be regenerated from tuber discs and half could not. From a sample of varieties that could be regenerated from tuber discs, all but one variety gave transgenic plants. Twelve varieties were evaluated for the capacity to regenerate shoots from leaf and internode explants excised from in vitro grown plants. All of the varieties tested regenerated adventitious shoots. Leaf and internode explants from 5 varieties were subsequently used for transformation, and transgenic plants were produced from two potato varieties that did not give transgenic plants from tuber disc explants. Some varieties could not be transformed by either method, and will require modification of the in vitro regeneration and transformation system to be successful.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid     

Genotypic and exogenous factors affecting shoot regeneration from anther callus of linseed (Linum usitatissimum L.)

Summary The objective of this study was to investigate factors affecting the regeneration capacity of linseed anther culture. Four different environmental conditions in a phytotron were tested with regard to their effects on anther donor plants of cv. Hella. Anther response and shoot regeneration from anther callus was maximal when donor plants were grown in a 16 hrs-day at 14°C day/8°C night temperature. Anthers of four linseed genotypes were cultured on different media. Maximum shoot regeneration was achieved when the induced calli were transferred onto a modified N6 medium containing zeatin (1 mg l^-1). Most of the calli regenerated shoots in the second subculture on regeneration media. Shoots were rooted on modified B5 or MS media containing NAA (0.1 mg l^-1). Cytological examinations of incubated anthers and root tips of regenerated plants indicated that the anther calli were derived from microspores.Abbreviations B5 Gamborg's (1975) medium - BAP 6-benzylaminopurine - 2,4D dichlorophenoxyacetic acid - N6 Chu's (1978) medium - NAA -naphthaleneacetic acid - MS Murashige & Skoog's (1962) medium - ZEA zeatin     

新疆大叶紫花苜蓿(Medicago sativa.L)子叶、下胚轴、根的植株再生

随着植物抗逆性研究和植物转基因技术的发展，通过异源目的基因转化培育耐盐碱苜蓿品种的研究已引起人们的关注，植物受体高频再生体系的建立是异源转化高效的基础。选取新疆大叶紫花苜蓿种子萌发5~7d无菌苗的子叶、下胚轴及根为外植体，诱导愈伤培养基为MS+2,4-D 0.1~3.0 mg/L(8种不同水平)或MS+2,4-D 2.0 mg/L+ KT 0.01~0.5 mg/L(10种不同水平)，诱导芽培养基为MS+6-BA 0.5 mg/L+ NAA 0.05 mg/L，生根培养基为MS。结果表明，外植体在MS+2,4-D 2.0 mg/L+ KT 0.2 mg/L培养基中能够产生状态较好可再分化的愈伤组织，子叶、下胚轴、根的平均出愈率分别为93.1%、100%、100%。愈伤组织在MS+6-BA 0.5 mg/L+ NAA 0.05 mg/L培养基中培养40~80d中均可分化芽，子叶、下胚轴、根的芽平均分化率为50%、78%、50%，将2 cm以上的芽转入MS培养基中诱导生根，14d后，生根的小植株炼苗移入花土中，成活率达90%以上。子叶、下胚轴、根在该体系中均能获得再生植株，根也是一种较好的植株再生材料，以根为外植体进行植株再生的研究报道还较少。     

Callus induction and plant regeneration from immature and mature embryos of winter durum wheat genotypes

Seven genotypes of winter durum wheat (Triticum durum Desf.) were cultured to establish an efficient method of callus formation and plant regeneration from mature embryo culture, and to compare the responses of immature and mature embryo cultures. Immature embryos were aseptically dissected from seeds and placed, with the scutellum upwards, in dishes containing Murashige and Skoog's (MS) mineral salts and 2mg 2,4- dichlorophenoxyacetic acid (2,4-D) per litre. Calli and regenerated plants were maintained on 2,4-D-free medium. Mature embryos were moved slightly on the imbibed seeds. For callus formation, the seeds with moved embryos were placed, furrow downwards, in dishes containing 8 mg 2,4-D per litre. The developed calli and regenerated plants were maintained on the MS medium. Plants regenerated from both embryo cultures were vernalized and grown to maturity in soil. Variability was observed among the wheat genotypes tested for various culture responses in both explant cultures. Callus induction rate and regeneration capacity of callus were independent of each other. Mature embryos have a low frequency of callus induction but a high regeneration capacity. Considering availability, rapidity and reliability, this form of mature embryo culture can be used as an alternative method for immature embryo culture.     

植物激素配比对大蒜茎盘愈伤组织再生体系的影响

植物激素对大蒜茎盘愈伤组织再生的各个环节都发挥着重要的作用。试验结果表明：2,4．D对茎盘愈伤组织的诱导具有主要作用，高浓度的2，4-D有利于大蒜愈伤组织的诱导，但并不利于其增殖分化。MS＋NAA 2mg／L＋BA 1mg／L培养基适宜于愈伤组织的继代增殖，MS＋NAA 1mg／L＋BA 5mg／L培养基适宜不定芽的分化，只添加NAA或无激素的MS培养基有利于不定芽生根。     

甘薯（Ipomoea batatas (L.) Lam.）及其近缘野生种原生质体的植株再生

对甘薯品种高系14号及其近缘野生种I.triloba L、和I.lacunosa L,进行原生质体植株再生研究。从离体培养植株的叶柄分离出原生质体,将其培养在含有0.05mg/L 2,4-D和0.5mg/L激动素(KT)的MS培养基中,从原生质体获得了高频率的愈伤组织。培养8-12周后,将直径达2—3mm的小愈伤组织转移到添加0.05mg/L 2,4-D的MS培养基上。转移3-6周后,将愈伤组织进一步转移到添加吲哚乙酸(IAA)和6-苄基嘌呤(BAP)的MS培养基上,一些愈伤组织再生出植株。未再生植株的愈伤组织进一步在MS基本培养基上培养,它们也再生出植株。本研究从I.triloba原生质体获得高频率的植株再生;首次从I.lacunosa原生质体再生出植株;从高系14号原生质体也再生出完整植株。     

Efficient In Vitro Shoot-regeneration Systems in Cassava (Manihot esculenta Crantz)

Two different protocols for in vitro regeneration of cassava using zygotic embryos and nodal axillary meristems have been developed. In both cases, buds were regenerated directly from excised explants without an intervening callus phase after a two-step culture procedure. In cotyledonary explants derived from zygotic embryos, prolific shoot formation occurred within 2—3 weeks on MS medium supplemented with 0.5—5 mg/1 BAP alone or in combination with 0.1 mg/1 NAA. Nodal explants with axillary meristems derived from aseptically grown seedlings or stem cuttings were used to initiate a round compact bulb-like structure on MS medium containing 10 mg/1 BAP. These latter structures, when cultured on MS medium supplemented with 0.1 mg/1 NAA, 1 mg/1 BAP and 0.1 mg/1 GA₃, produced multiple shoots. Somatic embryos isolated at the globular/torpedo stage from zygotic embryo explants were also capable of multiple shoot production on medium with 1 mg/1 BAP. Rooting of regenerated shoots exceeded 95 % in phytohormone-free MS medium. No change in their ploidy levels was observed. Therefore, the protocols developed should be of use in the particle gun and Agrobacterium-mediated genetic transformation of cassava.     

Influence of genotype and culture medium on callus formation and plant regeneration from immature embryos of Triticum turgidum Desf. cultivars

Twelve durum wheat cultivars were evaluated for their response to in vitro tissue culture. Zygotic immature embryos were used to induce callus formation using four different Murashige and Skoog‐based media. Each contained 9.05 μM 2,4‐dichlorophenoxy acetic acid but differed in their carbon source (sucrose or maltose) and the presence of NaCl (0 mM or 40 mM). The influence of both genotype and medium on the type and percentage of callus produced was observed. Calli were either compact and frequently embryogenic, or soft and watery. Percentages ranged from 54 to 100%, depending upon genotype and induction medium. All calli were then plated on a regeneration medium containing 20 g/l sucrose, 2.68 μM 1‐naphthaleneacetic acid and 2.22 μ 6‐benzylaminopurine. The regeneration of plantlets was higher from compact than from soft calli, with a strong dependence on genotype and type of induction medium used. MSm induction medium (30 g/l maltose) and MS40s (30 g/l sucrose plus 40 mM NaCl) were best for inducing compact calli, and gave the highest proportion of regenerated plants. The in vitro response (number of total shoots from a compact callus/number of embryos plated) was higher for immature embryos of ‘Baztan’, ‘Bradano’ and ‘Don Pedro’. These cultivars are a good starting material for experiments involving transformation of calli from zygotic immature embryos.     

Trait correlation of immature embryo culture in bread wheat

Immature embryo culture of 45 cultivars in bread wheat was conducted to investigate trait correlation in tissue culture response. Plantlets were regenerated mainly through somatic embryos confirmed by histological examination, but also confirmed by the trait correlation analysis. The incidence of calli with leaf‐like green spots as opposed to the time, rate and fresh weight of callus induction in dedifferentiation culture was significantly positively related to organogenesis both in differentiation and maintenance culture. It indicated the plant regeneration potential might be predicted early by the incidence of calli with leaf‐like green spots in the dedifferentiation stage. Significant positive correlation also occurred among all the organogenesis traits such as the rate of shoot and root regeneration, or the number and length of shoots.     

Powdery mildew resistance in Kentucky bluegrass genotypes regenerated from excised seed pieces

Summary Severity of powdery mildew was assessed on seven cultivars and lines of Kentucky bluegrass propagated by seed and tissue culture. Tissue culture plants were started from embryo axes cultured on Murashige and Skoog medium containing different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BAP), and incubated (1 to 4 weeks) or not incubated in the dark prior to transfer to a lighted culture room. There were significant differences in disease severity (DS) among seed propagated and tissue culture regenerated plants. DS ranged from highly susceptible (100% of leaf covered by mildew) (DS=9) to resistant (DS=3.0). In some tissue culture regenerants the disease severity was significantly affected by the tissue culture process. Ten clones expressing resistance were selected, and plants propagated vegetatively. In six clones, disease resistance was sustainable in subsequent vegetatively propagated plants, while resistance was lost in four of the selected clones. Results are discussed with a view to using tissue culture to produce Kentucky bluegrass genotypes with resistance to powedery mildew.Abbreviations BAP benylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - DS disease severity - MS Murashige & Skoog - SDW sterile distilled water     

黄檗茎段不定芽分化过程中生理生化指标变化研究

以黄檗茎段为外植体,研究其不定芽分化过程中生理生化指标的变化。将黄檗无菌苗的茎段接种到MS+1.5 mg/L BA+0.5 mg/L NAA+20 g/L葡萄糖的培养基上,于20天左右大量形成不定芽,30天左右形成小苗。通过比色法,对茎段不定芽再生过程的生理生化指标测定表明,在不定芽形成过程中,SOD酶活性呈现出逐渐下降的趋势,而其他2种抗氧化酶（CAT和POD）活性、可溶性蛋白及可溶性糖含量在不定芽形成的高峰期之前均呈不同程度的上升趋势,随后则呈下降趋势。实验表明,抗氧化酶活性,可溶性蛋白及可溶性糖含量与不定芽再生有着明显的相关性。     

白魔芋快繁体系研究

以优良白魔芋新品种——大青秆不同组织为外植体,进行愈伤组织的诱导和植株再生,试验结果表明：以叶柄为外植体,污染率低,愈伤诱导率达85.71%,继代培养中以MS+BA2mg/L+NAA0.01mg/L作为芽分化增殖的最佳培养基,将芽转接到MS+NAA0.5mg/L生根培养基上诱导生根,生根率达100%。     

影响小麦K199不同外植体愈伤组织诱导的因素

以小麦科农199(K199)的完整种子、离体成熟胚和幼叶作为外植体,探讨了取材时间、取材部位、激素浓度和培养方式对小麦离体培养的影响。结果表明,刨碎的离体成熟胚和叶片基段为小麦组织培养的良好起始材料,种子萌发4 h为最佳取材时间,2 mg/L 2,4-D更有利于获得II型愈伤,光培养比暗培养更适用于叶片愈伤培养。     

High frequency direct plant regeneration from leaf and petals of Cape Primrose (<Emphasis Type="Italic">Streptocarpus</Emphasis>)

High frequency direct plant regeneration from leaf and petal explants was accomplished for the first time in Streptocarpus varieties. The shoot induction frequency varied with respect to the benzylaminopurine (BAP) concentration added to the Murashige and Skoog (MS) medium. MS medium with 0.5 mg l⁻¹ BAP exhibited the highest (69.9%) plant regeneration frequency with an average of 186 shoots per explant. A higher concentration of BAP inhibited shoot bud induction and plant regeneration along with necrosis of explants. Petal explants derived from the varieties ‘Branwen’ (pink and white) and ‘Chorus Line’ (violet and white) displayed plant regeneration frequency of 22.2–47.4% (within a total of 12 weeks) on MS medium containing 2.0 mg l⁻¹ α-naphthaleneacetic acid and 0.5 mg l⁻¹ BAP for 8 weeks followed by 4 weeks on MS medium with 1.0 mg l⁻¹ BAP. Scanning electron microscopy confirmed direct plant regeneration without callus. Regenerated plants from leaf explants with well-developed leaves and roots were hardened and successfully transferred to pots in glasshouse exhibiting 86% survival at the end of 4–6 weeks. Whereas, regenerated plants from flower petal explants upon transfer to pots in glasshouse exhibited 75–82% survival at the end of 4–6 weeks.     

In vitro tetraploid induction via colchicine treatment from diploid somatic embryos in grapevine (Vitis vinifera L.)

A protocol for in vitro induction of tetraploids via colchicine-treated somatic embryos from immature zygotic embryos of diploid grapevine (Vitis vinifera L.) is reported. Embryogenic callus was initiated from immature zygotic embryos cultured on Nitsch and Nitsch (NN) medium supplemented with 1.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D). The callus was transferred to NN medium containing 1.0 mg/l α-naphthalene acetic acid (NAA) and 0.5 mg/l benzyladenine (BA) to establish somatic embryogenesis. The vigorously growing globular embryos were selected and treated by 0, 10 or 20 mg/l colchicine for 1, 2 or 3 days, and then immediately transferred to NN medium supplemented with 0.03 mg/l NAA and 0.5 mg/l BA, for somatic embryo conversion and plant regeneration. The number of surviving embryos and regenerated plantlets following colchicine treatment decreased with increasing colchicine concentration and treatment time. Among 29 randomly investigated plantlets regenerated from colchicine-treated somatic embryos, five solid tetraploids (2n = 4× = 76) were identified by chromosome counting analysis; all others were diploid (2n = 2× = 38). Ploidy level of plant regenerated was also determined from leaves using flow cytometry. No chimeras with both 2C and 4C nuclei was produced from colchicine-treated somatic embryos. Significant differences in leaf stomata parameters were observed between diploid and induced tetraploid plantlets.     

High frequency of plant regeneration from anther culture in flax, Linum usitatissimum L.

The effects of induction medium compositions on flax anther culture were investigated in order to improve the efficiency of callus induction and plant regeneration. Anthers were inoculated onto the modified MS medium supplemented with five different combinations of plant growth regulators. The medium containing the combination of 2mg/l 2,4- dichlorophenoxy-acetic acid (2,4-D) and 1 mg/1 6-benzylaminopurine (BAP) produced a significantly higher number of calli forming shoots/100 responded anthers and a significant increase in overall efficiency of regeneration than the same basal medium containing 1 mg/1 a-naphthalene-acetic acid (NAA) and 2 mg/1 BAP (CK). Among the five levels of thiamin hydrochloride tested, the modified MS medium containing 10 mg/1 thiamin hydrochloride significantly increased the number of calli forming shoots/100 responded anthers and the overall efficiency of regeneration compared with the same basal medium containing 0.1 mg/1 thiamin hydrochloride. Maltose concentration had a significant effect on the percentage of anthers producing call, the number of calli forming shoots/100 responded anthers and the overall efficiency of regeneration. The medium containing 6% or 9% maltose produced the highest overall efficiency of regeneration among the five levels of maltose evaluated. Sucrose concentration significantly affected the number of calli forming shoots/100 responded anthers and the overall efficiency of regeneration, and dramatically affected the frequency of microspore-derived plants and the frequency of spontaneous chromosome doubling in microspore-derived plants. The efficiency of doubled haploid line production obtained in this study appears adequate for applied breeding programmes.     

Genetic transformation of Eustoma grandiflorum Griseb. by microprojectile bombardment

Summary Foreign DNA was introduced into cell suspension cultures and leaf tissue of Eustoma grandiflorum Griseb. (lisianthus) by microprojectile bombardment. For this purpose a low-cost bombardment device that uses a helium flux to accelerate microprojectiles was built. When cell suspensions were used, an average of 4.1 Kan resistant calli were recovered per shot after 4 months' cultivation on selective medium. Most of the Kan resistant plants regenerated from calli were positive to GUS assay. Both the nptII and gus genes were successfully amplified from alkali-treated leaves of putative transgenic plants by PCR analysis. Transgenic plants were not recovered from bombarded leaves. Considering the host range specificity of Agrobacterium, and the response of the species to plant regeneration from suspension culture, microprojectile bombardment is, at present, the most efficient procedure for genetic transformation of lisianthus.Abbreviations BA 6-benzyladenine - Cx cefotaxime - 2,4 D (2,4-dichlorophenoxy) acetic acid - FDA fluorescein diacetate - gus -glucuronidase - IAA indole-3-acetic acid - IBA indole-3-butyric acid - 2iP (2-isopentenyl) adenine - Kan kanamycin - nptII neomycin phosphotransferase II - PCR polymerase chain reaction     

Plant regeneration from embryo-callus culture in barley

Summary Plants were regenerated from callus cultures initiated from immature embryos of barley, Hordeum vulgare L. Immature embryos from seven diverse genotypes were cultured on modified Murashige and Skoog (MS) medium supplemented with 1.5 mg 2,4-D and 6.5 mg IAA/l. Of the 249 embryos cultured, 30% initiated callus within 8 days. Subculture of callus for 80 to 100 days on half-MS medium supplemented with 0.5 mg/l 2,4-D and 1.0 mg/l zeatin resulted in organogenesis. Culture of organogenic calli for 30 days on half-MS medium without growth regulators produced plants which originated mostly via multiple shoot formation. Callusing response of the tested genotypes ranged from zero to 44%; however, only 23% of the calli were regenerative. Regenerated plants included variants for chlorophyll deficiency, plant height, stem thickness, spike shape, pollen fertility, seed set and ploidy.     

濒危药用植物天山雪莲高效植株再生体系的建立

以濒危药用植物天山雪莲叶片为研究材料进行组织培养和植株再生研究,旨在建立天山雪莲的高效植株再生体系,为其种群复壮、资源保护与可持续利用提供技术参考。研究结果表明:适合天山雪莲叶片愈伤组织诱导的最佳培养基为MS+2,4-D(0.5 mg/L)+6-BA(1.5 mg/L),诱导出愈率为97%;适合愈伤组织丛生芽分化的最佳培养基为MS+NAA(0.05 mg/L)+6-BA(0.4 mg/L)+水解乳蛋白(500 mg/L),分化率为66%,增殖倍数为5.1;适合生根的最佳培养基为1/2 MS+NAA(0.3 mg/L),在此条件下,根发育良好,生根率为76.9%,植株健壮;组培苗炼苗后移栽,成活率可达89%。     

Barley lines showing prominent high green shoot regeneration in cultures derived from immature embryos

Eighty‐four cultivars of barley (Hordeum vulgare) and 95 wild strains (82 of H. spontaneum and 13 of H. agriocrithon) were surveyed for the production of callus, callus growth, and shoot regeneration in cultures derived from immature embryos. All cultivars except for ‘Turkey 381′, induced calli from more than 90% of embryos. On the other hand, the wild lines showed a large variation in the percentage of callus induction from 0 to 100%. Among the cultivars, those with the brittle rachis genotype, bt Bt₂, on chromosome 3H, regenerated shoots with a significantly higher percentage than the cultivars with the Bt bt₂ genotype. Green shoots were produced in a higher ratio (0.84) in the cultivars than in the wild lines (0.52). Among the lines examined,‘Lenins’ regenerated shoots efficiently (90.4%) and produced the highest number of calli with green shoots per embryo (4.77) followed by ‘Golden Promise’ (3.15). Examination of callus growth and shoot regeneration from embryos at different developmental stages revealed that scutellum development affected the quantity and quality of callus and shoot regeneration.