Morphogenic Response of Leaf and Petiole Explants of Broccoli Using Thidiazuron

Broccoli (Brassica oleracea var. italica) is an important nutritionally rich vegetable cole crop grown in the world. Environmental stress, pests, and diseases cause enormous yield losses because of a limited gene pool. Genetic manipulation is becoming an important method for broccoli improvement. The objective of present study was to evaluate the potency of thidiazuron (TDZ) as a plant growth regulator in evoking morphogenic responses in leaf and petiole explants of broccoli. An efficient, reproducible, and high frequency plant regeneration protocol has been standardized in broccoli cv. Solan green head. Leaf and petiole explants were cultured on Murashige-Skoog (MS) medium, supplemented with a wide range of TDZ concentrations. The following treatments were designed for efficient in vitro shoot regeneration: TDZ alone, TDZ with adenine, TDZ with naphthalene acetic acid (NAA), and TDZ with indole acetic acid (IAA). Among the 36 combinations of growth regulators used, the highest percentage of leaf explants producing shoot (89.25%) was recorded on MS medium containing 1.0 μM TDZ and 0.107 μM NAA. The multiple shoot regeneration response of petiole explant producing shoots (91.55%) was obtained on MS medium containing 2.0 μM TDZ and 0.107 μM NAA. Shoot multiplication and elongation were obtained on the same medium. For root regeneration in in vitro regenerated shoots, different concentrations of NAA were applied. High frequency (100%) root regeneration response with healthy and vigorous roots was observed on MS medium supplemented with 0.54 μM NAA. The regenerated plantlets with well-developed shoots and root system were transferred to pots containing cocopeat and successfully acclimatized. We recommend 1.0 μM TDZ with 0.107 μM NAA and 2.0 μM TDZ and 0.107 μM NAA combinations for adventitious shoot regeneration from leaf and petiole explants in broccoli cv. Solan green head respectively. This is the first report on high frequency organogenesis from leaf and petiole explants of broccoli cv. Solan green head using thidiazuron.     

An improved and efficient micropropagation of Eclipta alba through transverse thin cell layer culture and assessment of clonal fidelity using RAPD analysis

An improved and efficient in vitro regeneration system has been developed for Eclipta alba, a medicinally important plant, through transverse thin cell layer culture (tTCL). The transverse section of the nodal segment of field grown plants was used as tTCL explants for plant regeneration. Shoot multiplication from tTCL nodal explants was influenced by BAP and their interaction with Kin or NAA. MS medium containing 13.2 μM BAP and 4.6 μM Kin was most effective for shoot multiplication from tTCL nodal explants. Upon this medium, percent response for shoot proliferation was 100% with an average of 32.6 shoot buds per tTCL nodal explant. Regenerated shoots from tTCL nodal explants were rooted on the growth regulator free MS medium. The rooted plantlets were successfully acclimatized and established in soil with a survival frequency of 90-100%. Random amplified polymorphic DNA (RAPD) markers were used to evaluate the genetic fidelity of the micropropagated plants. RAPD profile analysis indicated that micropropagated plants were genetically similar to mother plant.     

In vitro direct plant regeneration and Agrobacterium‐mediated transformation of lucerne (Medicago sativa L.)

In vitro direct plant regeneration of lucerne was achieved by simultaneous application of thidiazuron (TDZ) and 6‐benzyladenine (BA) in Murashige and Skoog (MS) medium. Seedlings were germinated and grown for 6 d on growth regulator–containing MS medium. The shoot tip, consisting of the apical meristem along with parts of the cotyledonary leaves and hypocotyl, was then cultured on a medium containing the growth regulator(s). Adventitious budding of the shoot tip was promoted synergistically by treatment with TDZ and BA, and a maximum of thirty‐five shoots per explant was obtained on a medium supplemented with 2 mg L^?1 TDZ and 1 mg L^?1 BA. Plant regeneration frequency varied from 67 to 93%, and five Indian lucerne cultivars responded well to the regeneration protocol. The Agrobacterium‐mediated transformation frequency from co‐cultivated explants was 13% following multiple shoot induction. Southern analysis of the T₀ plants and T₁ progenies confirmed stable inheritance of the hpt marker gene. Agrobacterium infection of the explant caused a significant reduction in the plant regeneration frequency (23%) and the number of shoots induced (11) when compared with uninfected explants. A single shoot tip provided sufficient material to regenerate and establish twenty‐seven lucerne plants, whereas only nine plants could be regenerated from an Agrobacterium co‐cultivated explant. This transformation protocol could represent a valuable improvement over existing ones for lucerne.     

Mass multiplication of Bixa orellana L. through tissue culture for commercial propagation

To reduce the time period for in vitro regeneration in annatto (Bixa orellana L.), a highly efficient two-stage plant regeneration protocol had been developed that can be used commercially. Different types of explants: nodal shoot tips, shoot tips and single nodes from in vitro grown seedlings were inoculated onto the Murashige and Skoog (MS) medium supplemented with different concentrations and combinations of plant growth regulators. Highest number of shoot buds was obtained when nodal shoot tip explants were inoculated onto MS medium supplemented with 31.1 μM N⁶-benzyladenine (BA) and 14.7 μM phenylacetic acid (PAA). PAA in combination with BA exhibited a synergistic effect on shoot multiplication and elongation. Sub-culturing of the shoots onto the MS medium supplemented with BA (13.3 μM) and PAA (7.3 μM) produced elongated shoots. Elongated shoots when inoculated onto the MS medium supplemented with 4.9 μM indole-3-butyric acid (IBA) produced optimal rooting. The rooted plantlets were hardened and their field survival rate after 6 weeks time was 73%.     

In vitro propagation and regeneration of an industrial plant kenaf (Hibiscus cannabinus L.)

The present study report a protocol for the efficient in vitro propagation of kenaf (Hibiscus cannabinus L., an industrial crop having high cellulosic fiber content) on hormone free MS medium using the shoot apex and nodal explants. Shoot tips and nodes were isolated from 15 days old seedlings cultivated on MS medium. Different combinations and concentrations of auxin/cytokinin were used and added to the MS medium to assess the shoot and root induction of theses explants. Several subcultures were drived in order to enhance the multiplication rate. Healthy and well developed in vitro propagated shoots were transferred for acclimatization under greenhouse conditions in pots filled with different substrates (sand + compost or perlite). Our results showed that shoots could elongate and root within 4-6 weeks on MS basal medium without any callus formation. However, addition of growth regulators to the MS medium leaded to a decrease in shoot and root induction rates. Indeed, the highest shoot regeneration frequency (90.5%) was obtained on MS control medium. Elongated shoots were transferred onto the same hormone free MS medium using five subcultures where the multiplication rate reached the highest value (3.66) at the fifth and last step. The in vitro rooted plantlets were acclimatized in greenhouse and successfully transplanted to natural conditions with 70% survival.     

马铃薯两个基因型不同外植体的组织培养与植株再生

以Favorita和东农303两个马铃薯基因型的幼叶、茎段、微型薯和种薯的块茎为外植体,在6种培养基中诱导愈伤组织和植株再生。试验中观察到马铃薯的分化率在不同外植体间差异较大,ZT有可能是诱导马铃薯芽分化的理想激素。     

Growth optimization and organogenesis of Gerbera jamesonii Bolus ex. Hook f. in vitro

Regeneration potentials in Gerbera jamesonii Bolus ex. Hook f. from tissues culture system was studied using leaf, petiole and root explants. In vitro regeneration, callus induction and root formation were optimized by manipulation of growth regulators during organogenesis. Various kinds of plant growth regulators such as 6-Benzylaminopurine (BAP), alpha-Naphthalene acetic acid (NAA), 2, 4-Dichlorophenoxyacetic acid (2,4-D), Indole-3-acetic acid (IAA), Indole-3-Butyric acid (IBA), N6-[2-Isopentenyl]adenine (2iP), Kinetin and Zeatin were used to initiate cultures. These plant growth regulators were added to Murashige and Skoog medium in different combinations and concentrations. Adventitious shoots were obtained from petiole explants cultured on Murashige and Skoog (MS) medium supplemented with 2.0 mg L(-1) BAP and 0.5 mg L(-1) NAA. Effectiveness of shoot regeneration medium, type of growth regulator used and duration of induction period were investigated. Leaf explants cultured on MS medium supplemented with 1.0 mg L(-1) BAP and 2.0 mg L(-1) 2, 4-D showed the best results for callus induction. Root explants were found to be non-regenerative in all experiments conducted. Petiole segment was identified as the best explant for regeneration of this species. Regenerated plants were rooted on Murashige and Skoog basal medium. Plantlets were then transferred to field with 75% survival rate.     

In vitro shoot regeneration and chromosome doubling in 2X and 3X potato clones

The possibility of scaling ploidy levels up and down offers several advantages for genetic studies and breeding work in potato. Shoot regeneration and chromosome doubling in plants regenerated fromin vitro cultures were investigated in 4 diploid (2n=2x=24) and 2 triploid (2n=3x=36) clones. Internode and leaf expiants were taken from plants propagated eitherin vitro as shoot cultures, orin vivo in a greenhouse. Two regeneration procedures were compared. Regeneration frequencies were significantly higher using a two-step regeneration protocol and from leaf explants, while doubling was more efficient starting fromin vivo grown plants. No doubling was observed in triploid clones. Considering altogether the percentage of regeneration and doubling, and the number of shoots regenerated per explant, the most efficient conditions were considered leaf explants taken fromin vivo grown plants, and cultured according to a two-step regeneration protocol.     

TDZ和暗培养对蝴蝶兰叶片不定芽发生的影响

以蝴蝶兰幼嫩花梗诱导的无菌苗叶片为外植体,以MS为基本培养基,研究不同暗培养时间和TDZ浓度对蝴蝶兰叶片诱导不定芽的影响。结果表明：暗培养和TDZ对接种的蝴蝶兰叶片的成活率均具有显著影响,暗培养60 d时,叶片的存活率在90%以上,而在同一暗培养时间条件下,叶片的存活率随着TDZ浓度的增加而上升;在TDZ浓度为3.0 mg/L,暗培养60 d时,蝴蝶兰存活叶片不定芽的诱导率最高,达到93.45%;诱导的不定芽数最多,平均每个外植体诱导的不定芽数为13.22个。综合考虑外植体的成活率、不定芽诱导率和诱导的不定芽数,蝴蝶兰叶片诱导不定芽的最佳条件为：MS＋TDZ 3.0 mg/L,暗培养60 d。     

Responses of jojoba explants to different salinity levels during the proliferation stage in vitro

Jojoba (Simmondsia chinensis Link Schneider) explants were cultured under four levels of sodium chloride salinity (0, 56.4, 112.8 and 169.2 mM) during the proliferation stage. The fresh and dry weight of explants, as well as their mean shoot length increased up to the medium salt concentration, while the mean shoot number decreased. Salinity enhanced the length and thickness of leaves as well as the thickness of shoots. Sodium and chloride ions accumulated significantly under saline conditions while the opposite stood for nitrate ions as well as for potassium, which concentration decreased significantly in the high salt treatment. Ethylene evolution was highest under the high salt concentration and low at the low and medium salt treatment, even lower than that of the control and therefore it exhibited a significant strong negative relationship with the changes of both fresh and dry weight during the third month under saline conditions. Explants were transferred separately from each salt treatment to the rooting stage at the end of the third month. There were not any significant differences among explants deriving from different salt treatments in the rooting percentage, the root number and length, 6 weeks after the incubation of explants into the rooting medium.     

High-efficiency regnerationin vitro from potato petioles with intact leaflets

The shoot/plantlet regenerationin vitro of seven potato (Solanum tuberosum L.) cultivars from petioles with intact leaflets was assessed using six treatment combinations-a basal medium with or without silver thiosul-phate (STS) or thidiazuron (TDZ) at two concentrations (2 or 0.5 mg/l) of the indoleacetic acid (IAA). The basal medium consisted of Murashige and Skoog (MS) salts and vitamins supplemented with 3 mg/1 6-benzylaminopurine, and 1 mg/1 gibberellic acid, 30 g/l sucrose, and 7.0 g/l PHYTOAGAR. Two full sets repeats and one partial set repeat of independent experiments were conducted and all produced similar results. Silver thiosulphate decreased the regeneration frequency and number of shoots per callus. No significant changes were observed with thidiazuron. Regeneration rates of (100% ) with up to 20 shoots/plantlets per callus were achieved at 2 mg/1 IAA with cultivars Désirée, Kennebec, Niska, and Lenape. These cultivars still showed high regeneration rates (87%–98% ) on media with 0.5 mg/1 IAA, and good regeneration rates were also achieved by the other three cultivars (48%, 94%, and 50% for Chieftain, Russet Burbank, and Shepody, respectively). Even with the single medium protocol (0.5% IAA without thiosulphate or thidiazuron), Désirée, Lenape, and Niska exhibited a regeneration rate of 98%. The use of petiole-with-leaflet explants could be ideal for the regeneration step of potato genetic transformation protocol because of their high regeneration efficiency and their small cut surface area forAgrobacterium elimination after co-incubation.     

甘蓝型冬性和半冬性油菜子叶高效快速芽再生体系的建立

以甘蓝型油菜子叶为外植体,研究了不同激素浓度、组合以及预培养等条件对芽再生的影响.将子叶在含1mg/L 2,4-D和1mg/L BA的MSB5培养基上预培养3d后转入芽分化培养基,可明显提高芽再生频率,再生周期也可缩短三分之一,但延长预培养时间则导致再生频率下降.实验中10个冬性和半冬性油菜品种的平均再生频率达81.9%,其中9个品种的芽再生频率均在75%以上,最高可达98.9%.     

Regeneration in Jatropha curcas: Factors affecting the efficiency of in vitro regeneration

Factors influencing in vitro regeneration through direct shoot bud induction from hypocotyl explants of Jatropha curcas were studied in the present investigation. Regeneration in J. curcas was found to be genotype dependent and out of four toxic and one non-toxic genotype studied, non-toxic was least responsive. The best results irrespective of genotype were obtained on the medium containing 0.5 mg L⁻¹ TDZ (Thidiazuron) and in vitro hypocotyl explants were observed to have higher regeneration efficiency as compared to ex vitro explant in both toxic and non-toxic genotypes. Adventitious shoot buds could be induced from the distal end of explants in all the genotypes. The number of shoot buds formed and not the number of explants responding to TDZ treatment were significantly affected by the position of the explant on the seedling axis. Explants from younger seedlings (≤15 days) were still juvenile and formed callus easily, whereas the regeneration response declined with increase in age of seedlings after 30 days. Transient reduction of Ca²⁺ concentrations to 0.22 g L⁻¹ in the germination medium increased the number of responding explants.Induced shoot buds, upon transfer to MS medium containing 2 mg L⁻¹ Kn (Kinetin) and 1 mg L⁻¹ BAP (6-benzylamino purine) elongated. These elongated shoots were further proliferated on MS medium supplemented with 1.5 mg L⁻¹ IAA (indole-3-acetic acid) and 0.5 mg L⁻¹ BAP and 3.01-3.91 cm elongation was achieved after 6 weeks. No genotype specific variance in shoot elongation was observed among the toxic genotypes except the CSMCRI-JC2, which showed reduced response. And for proliferation among the toxic genotypes, CSMCRI-JC4 showed highest number of shoots formed. Among the rest, no significant differences were observed. The elongated shoot could be rooted by pulse treatment on half-strength MS medium supplemented with 2% sucrose, 3 mg L⁻¹ IBA (indole-3-butyric acid), 1 mg L⁻¹ IAA, 1 mg L⁻¹ NAA (α-naphthalene acetic acid) and subsequent transfer on 0.25 mg L⁻¹ activated charcoal medium. The rooted plants could be established in soil with more than 90% success. No significant differences were observed in rooting of shoots in the different toxic genotypes. However, rooting response was reduced in non-toxic genotype as compared to toxic genotypes.     

AgNO_3对甘蓝型油菜子叶外植体植株再生的影响

以甘蓝型油菜无菌苗子叶为外植体 ,接种不同生长调节剂组合的培养基 ,研究AgNO3 对油菜子叶外植体植株再生频率的影响。结果表明 ,AgNO3 2 .5mg/L处理可明显提高子叶外植体的植株再生频率 ,芽再生频率和平均每外植体再生芽数分别达到 4 3 .3 0 %和 2 .77。苗龄与子叶外植体的芽再生频率有关 ,苗龄 4d的子叶芽再生频率较高。     

紫色甘薯的茎尖培养与脱毒

以紫色甘薯品系为试材,研究6-BA和NAA及基因型对紫色甘薯茎尖培养的影响,并采用硝酸纤维素膜—酶联免疫法(NCM-ELISA)和症状法对再生植株进行病毒学检测。结果表明,培养基中6-BA和NAA浓度和配比对紫色甘薯茎尖培养的愈伤组织、不定根和不定芽的诱导有明显影响。6-BA可促进不定芽的诱导,附加1mg/L6-BA的MS培养基为最佳诱芽培养基。基因型对诱芽率也有一定的影响,其中品系B3和B7的诱芽率可达50%。通过病毒学检测,获得12个紫色甘薯品系的脱毒苗,其平均脱毒率为94.7%。     

水田七的组织培养和植株再生

用水田七成熟种子为材料进行无菌播种,得到无菌苗再用幼叶、叶柄为材料进行组织培养和植株再生。经试验得出各阶段适宜的培养基分别为：(1)诱导愈伤组织：MS＋2.0 mg/L TDZ;(2)诱导芽分化：MS＋1.5 mg/L 6-BA＋0.5 mg/L NAA;(3)生根培养：1/2MS＋0.5 mg /L IBA＋0.1 mg/L NAA。     

胚中段为外植体的花生高效再生体系构建研究

参考幼叶、子叶为外植体诱导丛生芽的方法,利用花生种子胚生长旺盛的特性,以花生种子胚中段为外植体材料建立一个新植株再生体系。结果表明,在含3.0mg/L的6-BA的MS培养基上,培养30d可以诱导出丛生芽,诱导率达到92.5%;丛生芽转至1/2MS＋0.2mg/LIBA＋0.1mg/LNAA的培养基中培养2～3周,生根形成完整植株。     

花生胚小叶外植体再生影响因素研究简报

胚小叶外植体再生是进行花生外源基因遗传转化的重要途径之一。研究表明,品种对花生胚小叶外植体再生有较大影响,BA／NAA比值与愈伤组织诱导、芽再生数量及速度关系密切,发芽势强的花生品种宜用低BA／NAA比值的MS培养基,发芽势弱的品种则宜用高BA／NAA比值MS培养基。     

Mycorrhizal fungi and growth and development of micropropagated Scutellaria integrifolia plants

Scutellaria species have been used in many traditional medical systems and is well known among the Native American tribes as a strong emmenagogue and as a female medicinal herb. The inoculation of arbuscular mycorrhiza fungi (AMF) into the roots of micropropagated plantlets could help not only mass propagate these species, but also help grow in marginal, phosphorus deficient soils. Leaves, shoot apices, and nodal segments from wild as well as from greenhouse-grown plants were used to initiate cultures in Murashige and Skoog (MS) medium supplemented with cytokinins benzyladenine (BA), kinetin, thidiazuron (TDZ), naphthalene acetic acid (NAA), and indole butyric acid (IBA) Among all the explants tested for shoot bud induction, only shoot tips and nodal explants were responsive. Explants swelled and became rough on the surface at the end of 3-week incubation with many green shoot buds. Two to 3 weeks after transfering to rooting media with or without IBA, all shoots developed roots. In vitro raised plants were acclimatized in a mist chamber and transferred to 6-l containers in the greenhouse to study the role of AMF on plant growth and development. Inoculation with AMF, showed positive effects on plant growth, particularly root development compared with the control plants. Among the five AMF strains tested, S3004 increased plant height and fresh weights of shoot, root, and seed.     

紫罗兰愈伤组织诱导及植株再生的研究

以紫罗兰幼苗子叶、子叶柄、下胚轴作外植体接种MS附加不同激素的培养基诱导愈伤组织，并进一步诱导分化出芽及再生植株。子叶和下胚轴外植体在MS＋0.1mg/LNAA培养基上愈伤组织发生率达100％，下胚轴愈伤组织转移MS 0.1mg/L 6-BA培养基上易诱导分化出小苗，分化频率达67％，再生小苗在1／2MSA＋0.2mg/L IBA培养基上生根率达86％。