黔中地区马尾松林下杜鹃根部内生真菌群落组成及其生态功能

探索黔中马尾松(Pinus massoniana)林下杜鹃(Rhododendron simsii)根内生真菌物种多样性和生态功能。采集黔中乌当(WD)、孟关(MG)、龙里(LL) 3个地区马尾松林下杜鹃的发根,提取真菌DNA进行高通量测序。分析真菌Alpha多样性,借助FUNGuild注释平台解析真菌的生态功能类别,探索真菌群落中的核心微生物组,并结合网络图展示菌群之间的关联性。结果,3个地区的杜鹃根部内生真菌多样性非常丰富,WD地区杜鹃内生真菌多样性和丰富度最高。试验共获得有效序列425799条,817个可操作分类单元(OTU),分属于6门19纲52目103科154属,主要隶属于子囊菌门(81.2%)、接合菌门(5.8%)和担子菌门(4.7%);优势纲、目、科分别为:散囊菌纲(43.0%)、散囊菌目(39.2%)、发菌科(39.2%);在属的水平上,青霉属(38.60%)占比最高,其次是木霉属(7.20%)、拟盘多毛孢属(6.10%)。根部的真菌拥有多种生态功能群,如未定义腐生菌(194 OTU)、植物病原菌(20 OTU)、土壤腐生菌(18 OTU)、外生菌(14 OTU)、地衣...     

Adventitious shoot regeneration and appearance of sports in several azalea cultivars

Shoots can be regenerated from leaf explants of most azalea (Rhododendron simsii) cultivars using a two-step protocol with a callus induction and a regeneration phase. This procedure is unsuccessful for a few cultivars, because of excessive callus production. In most such cases, shoot regeneration could be obtained in one step, starting from petioles as explants. Flower colour variations (the induction of sports) were frequently observed after regeneration. This phenomenon offers prospects for the enlargement of the commercial assortment but can also be used for the study of gene regulation processes in flower colour variegation.     

Chromosome doubling in sterile Syringa vulgaris × S. pinnatifolia hybrids by in vitro culture of nodal explants

The aim was to produce tetraploid forms of hybrids of Syringa vulgaris × S. pinnatifolia to restore fertility and enable further breeding to be undertaken. Excised nodal sections of three selections were pre-cultured for 5 days then treated with a range of colchicine concentrations for 1, 2 or 3 days, after which they were washed three times in sterile distilled water and cultured on shoot proliferation medium. Frequent movement to fresh medium was beneficial to survival. Three successive experiments established the range of concentrations of colchicine, 0.05 mM to 0.25 mM, at which tetraploids were likely to be produced. Thus a protocol for the production of tetraploids was established. Cytometric analysis showed that tetraploid forms of two selections were produced. This revised version was published online in August 2006 with corrections to the Cover Date.     

<Emphasis Type="Italic">In vitro</Emphasis> plant regeneration of the heavy metal tolerant and hyperaccumulator <Emphasis Type="Italic">Arabidopsis halleri</Emphasis> (Brassicaceae)

Plants were regenerated from root explants of Arabidopsis halleri (L.) O’Kane and Al-Shehbaz via a three-step procedure callus induction, induction of somatic embryos and shoot development. Callus was induced from root segments, leaflets and petiole segments after incubation for 2 weeks in Murashige and Skoog medium (MS) supplemented with 0.5 mg/l⁻¹ (2.26 μM) 2,4-D (2,4-dichlorophenoxyacetic acid) and 0.05 mg/l⁻¹ (0.23 μM) kinetin. Only calli developed from root segments continued to grow when transferred to a regeneration medium containing 2.0 mg/l⁻¹ (9.8 μM) 6-γ-γ-(dimethylallylamino)-purine (2ip) and 0.05 mg/l⁻¹ (2.68 μM) α-naphthalenacetic acid (NAA) and eventually 40 of them developed embryogenic structures. On the same medium 38 of these calli regenerated shoots. Rooting was achieved for 50 of the shoots subcultured in MS medium without hormones. The regeneration ability of callus derived from root cuttings, observed in this study, makes this technique useful for genetic transformation experiments and in vitro culture studies.     

Effectiveness of three micropropagation techniques to dissociate cytochimeras in Musa spp

In vitro mutagenesis of multicellular meristems of Musa spp. leads to a high degree of chimerism. Repeated vegetative propagation must be carried out to dissociate chimeras but the minimum number of cycles required is unknown. In general, mutated cells are difficult to monitor but mutations which result in a change in genome number are an exception. We simulated this case by colchicine treatment, followed by flow cytometric analysis. Colchicine treatment induced ploidy chimerism (mixoploidy), and chimera dissociation was assessed using three different propagation systems (shoot-tip culture technique - ST, multi-apexing culture technique - MA and corm slice culture technique - CS). The average percentage of cytochimeras was reduced from 100% to 36% after three subcultures using shoot-tip culture, from 100% to 24% when propagating by the corm slice culture technique and from 100% to 8% after the same number of subcultures using the multi-apexing technique. All propagation systems failed to eliminate chimerism completely. Factors that may influence chimera dissociation in vitro are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

GA3和Spd对杜鹃开花期光合特性和抗氧化系统的影响

为探讨GA_3和Spd对杜鹃(Rhododendron simsii)开花花期和开花品质的影响,研究了外源GA_3和Spd对杜鹃开花期光合特性和抗氧化系统的变化。结果表明,外源GA_3对花期有显著的提前作用,Spd对花期有明显的延迟作用,但两者均使花期延长、花径增大且成花率提高。GA_3和Spd处理提高了花期叶片的光合色素含量和净光合速率(Pn)、气孔导度(Gs)和胞间CO_2浓度(Ci);GA_3处理提高了叶片的蒸腾速率(Tr),而Spd使叶片的Tr下降,两者均有效缓解了末花期叶绿素含量的下降。GA_3和Spd处理显著降低了花瓣MDA含量,提高了抗氧化酶SOD、POD和CAT活性,并减缓了末花期SOD的下降,有效延缓了衰老进程,延长花期。以1 600 mg L~(–1) GA_3和0.10 mmol L~(-1) Spd处理效果较好,能有效提高杜鹃花的观赏品质。     

The Effect of a Submersion Pretreatment on In Vitro Explant Growth and Shoot Regeneration from Hypocotyls of Flax (Linum Usitatissimum)

This study was carried out to determine the effect of temporary submersion of hypocotyl segments in water on in vitro explant growth and shoot regeneration on MS (Murashige and Skoog, 1962) medium supplemented with 1 mg l⁻¹ BAP (6-benzylaminopurine) and 0.02 mg l⁻¹ NAA (naphthaleneacetic acid) in three flax cultivars. It was observed that water-treated hypocotyl explants gave rise to the highest values with respect to shoot regeneration percentage, shoot number per hypocotyl, shoot length and total shoot number per Petri dish, successful rooting and plantlet establishment. This procedure may be applicable for other species cultured in vitro.     

Somatic embryogenesis from callus cultures ofNardostachys jatamansi

Callus cultures ofNardostachys jatamansi DC, an endangered medicinal and aromatic plant, were established using petiole explants on MS medium supplemented with 16.1 µM -naphthaleneacetic acid and 1.16 µM kinetin. Embryogenesis in these callus cultures took place only upon sequential subculture of the callus on media having gradually decreasing auxin (16.1 to 1.34 µM NAA) and simultaneously increasing cytokinin (1.16 to 9.30 µM kinetin) concentrations over a period of 7 months. Somatic embryo to plantlet conversion took place on a medium containing 9.30 µM kinetin and 1.34 µM NAA.     

The hyperhydricity ofin vitroregenerants of grass pea (Lathyrus sativus L.) is linked with an abnormal DNA content

The grass pea (Lathyrus sativus) is a wild relative of the protein pea which may be a useful genetic resource for the acquisition of interesting stress resistance traits. However, grass pea is cross incompatible with pea, leaving protoplast fusion as the only alternative to produce interspecific hybrids of grass pea and pea. In addition, as all grass pea seeds contain a toxic aminoacid, low-toxin containing genotypes will have to be produced by gene transfer. In this context, it is therefore essential that regenerated plants are fertile, true-to-type and not chimaeric in nature when they have been obtained in absence of any selection treatment. In the present study, shoot buds were regenerated from hypocotyls of three grass pea genotypes, and flow cytometry permitted us to characterise them in terms of nuclear DNA content. Plant regeneration competence was genotype-dependent and strongly also was correlated with a normal DNA content. The auxin/cytokinin balance of regeneration media affected the DNA level of regenerants. In turn, an abnormal DNA content was systematically associated with severe hyperhydricity symptoms, which hampered the regeneration of rooted, fertile plants.     

In vitro regeneration of evergreen azalea from leaves

Rhododendron simsii Hellmut Vogel was regenerated using different types of explants, auxins and cytokinins. After a callus induction phase, with 2,4-dichlorophenoxyacetic acid or -naphthaleneacetic acid, adventitious shoot regeneration was obtained on a medium supplemented with thidiazuron or zeatin. With thidiazuron shoots were small and a subsequent elongation step was required before rooting. An elongation step was not required when zeatin was used. The duration of the callus induction phase was negatively correlated with the regeneration capacity.Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid - NAA -naphthaleneacetic acid - 2iP 6-(--dimethylallylamino)purine - NOA ß-naphthoxyacetic acid - BA 6-benzyladenine - IBA 1-H-indole-3-butyric acid - IAA 1-H-indole-3-acetic acid - TDZ thidiazuron - WPM woody plant medium     

濒危植物盘龙参种子的非共生萌发及种苗的快繁研究

以盘龙参种子为材料,筛选离体条件下适宜种子非共生萌发、种苗快繁的培养基。结果表明:盘龙参种子在无植物生长物质的培养基中能够萌发,但不能发育成苗;在含有1.0mg·L-1 KT、0.1mg·L-1 IAA和0.1mg·L-1 GA3的培养基中萌发,并能进一步发育形成种苗;在较高浓度生长素(1.2mg·L-1 NAA)的培养基中不能萌发。种苗在较高浓度细胞分裂素和较低浓度生长素配比的培养基中能够增殖,最高增殖系数可达到2.8,转入壮苗生长培养基中培养80d后可以移栽温室。最适增殖培养基为1/2MS+12.0mg·L-1 6-BA+0.1mg·L-1 NAA+10.0mg·L-1腺嘌呤;最适壮苗生根培养基为1/2MS+1.0mg·L-1 KT+0.1mg·L-1 IAA+10.0mg·L-1腺嘌呤。     

In vitro induction of tetraploid in pomegranate (Punica granatum)

Tetraploid plants were obtained in pomegranate (Punica granatum L. var. `Nana') by colchicine treatment of shoots propagated in vitro. Shoots cultured on MS medium supplemented with 10 mg l^–1 colchicine, 1.0 mg l^–1 BA and 0.1 mg l^–1 NAA for 30 days produced tetraploids at a high frequency of 20%. No tetraploids were detected by treating the shoots in 5000 mg l^–1 colchicine for 114 h. Shoots treated by 5000 mg l^–1 colchicine for 96 h produced three morphological mutants with narrow leaves, which were later confirmed as mixoploids that separated into diploids and tetraploids after further subculture. In vitro tetraploid plants had shorter roots, wider and shorter leaves than the diploid ones. Tetraploid pomegranate plants grew and flowered normally in pots, but possessed flowers with increased diameter and decreased length compared to diploids. The number of pollen grains per anther was higher in tetraploids, but the viability of pollen decreased significantly.     

Micropropagation of the endangered <Emphasis Type="Italic">Kniphofia leucocephala</Emphasis> Baijnath

Summary The species, Kniphofia leucocephala is extant at only one location, Langepan, KwaZulu-Natal in South Africa, where the population is threatened by afforestation and possibly grazing. Consequently, a continuous culture system was established as part of a program for the propagation and re-introduction of plants into the wild. The efficiency of the system in terms of shoot multiplication and, particularly, the frequency and rate of root initiation was strongly influenced by the concentration of benzyladenine in the shoot multiplication medium. The optimum shoot multiplication medium for subsequent root initiation contained 2 mgl⁻¹ (8.9 μM) benzyladenine alone. The shoots were successfully rooted and acclimatized. Approximately 200 shoots can be produced from one shoot after five 4-wk cycles. Thus, large numbers of plantlets can be propagated in this continuous culture system, serving conservation interests.     

In vitro plant regeneration from seed explants of wild groundnut species (Genus Arachis, Section Extranervosae)

In vitro regeneration of wild groundnut species from Section Extranervosae (Arachis villosulicarpa, A. macedoi, A. retusa, A. burchellii, A. pietrarellii, A. prostrata, A. aff. prostrata and a new species) was examined for the purpose of germplasm renewal and conservation. Seeds of different ages, stored at the seed bank of CENARGEN/EMBRAPA were either inoculated on culture medium or used as a source of embryo axis and cotyledon explants. Whole seeds failed to germinate on MS either without growth regulators (MS0) or supplemented with 10 M TDZ. Embryo axes cultured on MS0 produced only single plants. In the presence of 8.8 M BAP these explants showed multi-shoot formation. Cotyledons cultured on MS supplemented with 110 M BAP developed adventitious shoots through direct organogenesis. Plant regeneration was obtained from A. villosulicarpa, A. macedoi, A. retusa, A. burchellii and A. pietrarellii both from embryo axes and cotyledons. Explants from A. prostrata and A. aff. prostrata did not produce regenerants. Rooting of shoots was induced in the presence of 5.4 M NAA. Primary plants derived from these explants were further multiplied by culturing nodal segments on MS medium plus 2.7 M NAA.     

Propagation of mulberry variety – S54 by synseeds of axillary bud

Synseeds were produced from aseptic axillary buds of mulberry variety – S₅₄ (Morus indica L.) to investigate their in vitro and ex vitro conversion potential. The synseeds when cultured on Linsmaier and Skoog's basal medium supplemented with 6-benzyl amino purine (8.88 μM) and 2,3,5-tri iodo benzoic acid (2 μM), produced shoots after 21 days exhibiting 48.2±0.60 in vitro conversion response. The synseeds ex␣vitro conversion response was found to be 45.5±0.76 on soilrite mix containing half strength LS nutrients after 21 days of sowing. Further, synseeds stored at 4 °C for 1–4 months resulted in maximum conversion response under both in vitro and ex vitro conditions, followed by development into complete plantlets without any significant loss of conversion potential. Plants regenerated from the synseeds of axillary bud were hardened, acclimatized and established in soil with varying survival frequency.     

In vitro Shoot Regeneration from Leaves of Sweet Cherry (Prunus avium) 'Lapins' and 'Sweetheart'

Shoot regeneration was achieved from leaves of in vitro cultures of Prunus avium L. cv. 'Lapins' and 'Sweetheart' using woody plant medium (WPM) supplemented with 1-naphthalene-acetic acid (NAA) and thidiazuron (TDZ) or benzyladenine (BA). Percent regeneration was influenced by plant growth regulators and by explant type, orientation and wounding. Optimal regeneration was observed with whole-leaf explants wounded by transverse cuts along the midrib and incubated abaxial surfaces uppermost, on media supplemented with 2.27 or 4.54 µM TDZ plus 0.27 µM NAA. The percent regeneration of the two cultivars was not significantly different. Optimum conditions for regeneration resulted in 71.4% of 'Lapins' and 54% of 'Sweetheart' explants producing one or more shoots per explant.     

Adventitious shoot regeneration from ovaries of Hosta ‘Golden Scepter’

Summary The objective of this study was to evaluate the ability ofHosta Golden Scepter (GS) ovary explants to generate adventitious shootsin vitro. Ovaries were transversely cut into halves and transferred to petri dishes containingHosta initiation medium supplemented with naphthaleneacetic acid (NAA) at 2.5 μM and N⁶-benzyladenine (BA) at 10 μM. GS produced adventitious shoots from the ovary base via organogenesis. The number of adventitious shoots regenerated from callus increased linearly with repeated subculturing on Murashige and Skoog (MS) medium supplemented with 2.5 μM NAA and 10 μM BA. The number of multiple shoots developing from callus (15.8), shoot tip (8.4), leaf (6.7), and root (4.3) occurred on MS medium supplemented with 2.5 μM NAA and 20–30 μM BA. There were significant differences in the number of shoots regenerated from shoot tips and callus on MS medium with 50 and 100 mgmyo-inositol per l. Similarly, there were significant differences in the number of axillary shoots and adventitious shoots produced with 20 g/l sucrose treatment.