Schlumbergera Truncata Research Articles

The plastomes of Lepismium cruciforme (Vell.) Miq and Schlumbergera truncata (Haw.) Moran reveal tribe-specific rearrangements and the first loss of the trnT-GGU gene in Cactaceae.

Recent studies have revealed atypical features in the plastomes of the family Cactaceae, the largest lineage of succulent species adapted to arid and semi-arid regions. Most plastomes sequenced to date are from short-globose and cylindrical cacti, while little is known about plastomes of epiphytic cacti. Published cactus plastomes reveal reduction and complete loss of IRs, loss of genes, pseudogenization, and even degeneration of tRNA structures. Aiming to contribute with new insights into the plastid evolution of Cactaceae, particularly within the tribe Rhipsalideae, we de novo assembled and analyzed the plastomes of Lepismium cruciforme and Schlumbergera truncata, two South American epiphytic cacti. Our data reveal many gene losses in both plastomes and the first loss of functionality of the trnT-GGU gene in Cactaceae. The trnT-GGU is a pseudogene in L. cruciforme plastome and appears to be degenerating in the tribe Rhipsalideae. Although the plastome structure is conserved among the species of the tribe Rhipsalideae, with tribe-specific rearrangements, we mapped around 200 simple sequence repeats and identified nine nucleotide polymorphism hotspots, useful to improve the phylogenetic resolutions of the Rhipsalideae. Furthermore, our analysis indicated high gene divergence and rapid evolution of RNA editing sites in plastid protein-coding genes in Cactaceae. Our findings show that some characteristics of the Rhipsalideae tribe are conserved, such as plastome structure with IRs containing only the ycf2 and two tRNA genes, structural degeneration of the trnT-GGU gene and ndh complex, and lastly, pseudogenization of rpl33 and rpl23 genes, both plastid translation-related genes.

RNase-based self-incompatibility in cacti.

Approximately one-half of all flowering plants express genetically based physiological mechanisms that prevent self-fertilisation. One such mechanism, termed RNase-based self-incompatibility, employs ribonucleases as the pistil component. Although it is widespread, it has only been characterised in a handful of distantly related families, partly due to the difficulties presented by life history traits of many plants, which complicate genetic research. Many species in the cactus family are known to express self-incompatibility but the underlying mechanisms remain unknown. We demonstrate the utility of a candidate-based RNA-seq approach, combined with some unusual features of self-incompatibility-causing genes, which we use to uncover the genetic basis of the underlying mechanisms. Specifically, we assembled transcriptomes from Schlumbergera truncata (crab cactus or false Christmas cactus), and interrogated them for tissue-specific expression of candidate genes, structural characteristics, correlation with expressed phenotype(s), and phylogenetic placement. The results were consistent with operation of the RNase-based self-incompatibility mechanism in Cactaceae. The finding yields additional evidence that the ancestor of nearly all eudicots possessed RNase-based self-incompatibility, as well as a clear path to better conservation practices for one of the most charismatic plant families.

In vitro plant regeneration of Christmas cactus (Schlumbergera truncata (Haw.) Moran) by indirect morphogenesis

Abstract Plants of Schlumbergera truncata (Haw.) Moran were obtained by indirect morphogenesis from the segment section of shoots in vitro, they were multiplied and rooted. Also were determined the effect of the lighting regime, the composition of the nutrient medium on the consistency and frequency of callus formation. The studies were conducted during 2016–2018. The mode of effective sterilization (more than 90%) of S. truncata plant explants using 0.1% HgCl2 for 7–8 min was established. Optimal conditions for the induction of callus formation in stem node segments of S. truncata plants (rate more than 90% and significant growth) were created on MS (Murashige and Skoog 1962) nutrient medium supplemented with 1.0 mg/l BAP (6-benzylaminopurine) and 0.3 mg/l NAA (1-naphthylacetic acid) under conditions of placement on the nutrient medium and doing a significant number of cuts on the explants. The light intensity of 2.0–3.0 klx, obtained by a callus of dense consistency of dark green pigmentation, when using the thermostat condition without illumination, the callus had loose consistency, dark yellow pigmentation. It is established that the influence of the lighting regime and the composition of the nutrient medium on the frequency of callus formation is statistically significant. The largest number of shoots was obtained on the MS medium with the addition of 2.0 mg/l of BA. At the same times, shoot proliferation and root induction in such numbers were observed on MS culture medium with the addition of 0.5 mg/l BA and 0.5 mg/l kinetin (multiplication factor – 8.8±0.6 per 60-day cultivation cycle).

Effect of Benzylamino Purine (BA) and Gibberellic Acid (GA3) on Growth and Flowering in Schlumbergera truncata

Effect of Benzylamino Purine (BA) and Gibberellic Acid (GA3) on Growth and Flowering in Schlumbergera truncata

INVESTIGATION OF ALOE VERA EXTRACT EFFECT ON MORPHOGENETIC REACTIONS DURING MICROCLONAL PROPAGATION OF ORNAMENTAL SUCCULENTS

Aim. The aim of the work was to elucidate the effect of Aloe vera extract on the efficiency of in vitro introduction into the culture and morphogenetic reactions under the conditions of microclonal propagation of the representatives of ornamental succulents. Methods. The work used standard biotechnological methods of microclonal propagation by induction of adventitious shoot formation. The source material was selected from donor plants of decorative succulents – Crassula ovata Hobbit (Mill), Kalanchoe blossfeldiana (Poelln)., Hatiora salicornioides and Schlumbergera truncata. As explants, die cuts of mature leaves were used, which, after surface phased sterilization, were cultivated on Murasige-Skoog (MS) regeneration medium with the addition of synthetic growth regulators, 6-benzylaminopurine (BAP) of cytokinin type of action and α-naphthylacetic acid (NAA) of auxin action. In the control variant, the regeneration medium (RS) in its composition contained a half set of macro- and microelements and synthetic phytohormones – ½ MS + 3.0 mg/l BAP + 0.5 mg/l NAA, and in the experimental version, Aloe vera extract was added to the nutrient medium 1:100 ratio. The efficiency of sterilization and the formation of mericlones for introduction into culture and the speed and efficiency of various morphogenetic reactions: callus formation, shoot formation, and root formation were studied. Results. According to the results of the research, it was found that in the composition of the nutrient medium Aloe vera extract does not affect the efficiency of sterilization of leaf explants in the studied representatives of ornamental succulents. The morphogenetic potential of leaf explants is realized through the development of callus formation process during the first week of cultivation and intensive adventitious shoot formation after 6–8 weeks of cultivation. Intensive root formation is indicated only for leaf explants Schlumbergera truncata. Aloe vera extract in the nutrient medium stimulates the efficiency of the shoot formation process, increases the number of meristematic clones on one explant by 1.3–2.3 times and accelerates the process speed by 7–8 days. The studied decorative succulents differ in the efficiency of microclonal propagation – the maximum values are for Crassula ovata Hobbit (Mill) and Hatiora salicornioides, the minimum are for Kalanchoe blossfeldiana. Conclusions. Aloe vera extract in the composition of the nutrient medium for microclonal propagation of ornamental succulents exhibits a stimulating effect and can be offered as an effective biostimulator for increasing the propagation coefficient of the studied cultures.

Viruses of ornamentals emerging in Florida and the Caribbean region

Historically, Tomato spotted wilt virus and Impatiens necrotic spot virus have been significant constraints to crop production worldwide. With the emergence of Tomato chlorotic spot virus (TCSV) and a natural Groundnut ringspot virus (GRSV) reassortant in Florida and the Caribbean region, the significance of tospoviruses in production of major solanaceous vegetables including tomato and pepper has increased. In addition, TCSV has been reported in common solanaceous weeds including American black nightshade (Solanum americanum) and jimsonweed (Datura stramonium), in Florida and/or Puerto Rico. Experimental host range studies demonstrated that TCSV and/or GRSV can also infect solanaceous (Petunia and Brugmansia) and non-solanaceous (Garden Impatiens) ornamentals. During 2014, the first natural TCSV infections of non-solanaceous ornamentals porcelainflower (Hoya wayetii), false Christmas cactus (Schlumbergera truncata) and annual vinca (Catharanthus roseus) were detected in Florida. Since then, TCSV has been documented in other important crop and weed species, indicating host and geographic range expansion of this tospovirus. Several other viruses have also been detected in plants with symptoms similar to those induced by TCSV. In view of projected climate change-driven shifts in cropping systems, further knowledge of emerging plant viruses in Florida and the Caribbean region will help strengthen agricultural security.

Tomato chlorotic spot virus Identified in Marsdenia floribunda in Florida

Marsdenia floribunda (Brongn.), also known as Madagascar jasmine, waxflower, and Hawaiian wedding flower, is a flowering plant in the milkweed family, Apocynaceae, and is native to Madagascar. Marsdenia floribunda plants with typical tospovirus symptoms were found in a Miami-Dade County nursery. Representative leaf tissue tested positive in serological testing with commercially available reagents, indicating the presence of one or more tospoviruses. RT-PCR analysis was used to confirm Tomato chlorotic spot virus (TCSV). This is the first report of TCSV infection of M. floribunda in Florida or any other location. The recent identification of TCSV in annual vinca, Hoya wayetii, and Schlumbergera truncata, together with the current report, demonstrates that the TCSV host range has expanded into ornamental crops.

A new mineral fertilizer for cacti and other succulents cultivated in restricted artificial environments

The growing enthusiasm currently seen for the cultivation of ornamental plants has aroused interest in exotic plants, principally cacti and other succulents. Although they need little care when planted directly in the soil, they become vulnerable if growing in restricted environments that vary greatly from their natural habitats. In these cases, in addition to requiring more care with respect to illumination, watering and environmental temperature, it is also important to sprinkle them periodically with a mineral nutrient solution consisting of the macronutrients and micronutrients required for physiological growth and development. The excellent results obtained experimentally with the Schlumbergera truncata cactus, treated for 90 days with a mineral solution specifically prepared for this study and compared with the results obtained with the same species of plant watered with distilled or tap water, encourage us to propose this solution as a new mineral fertilizer for cacti and other succulents when cultivated in small, restricted spaces.

우리나라 비자생 관엽식물에서 발견된 뿌리가루깍지벌레 2종 (노린재목, 뿌리가루깍지벌레과)의 보고

온실에서 재배되는 수입 드라세나묘목 및 게발선인장에서 채집된 뿌리깍지벌레 2종 Ripersiella multiporifera Jansen 및 Rhizoecus albidus Goux를 우리나라에서 처음으로 보고한다. 이들은 수입된 식물을 통해 온실에 도입된 것으로 추정되며 우리나라에 추가적인 유입과 정착을 방지하기 위해 이들 종의 진단형질, 사진자료, 기주 및 분포정보를 제공하고자 한다. Two root mealybugs, Ripersiella multiporifera Jansen and Rhizoecus albidus Goux, were collected on imported Dracaena plants (Dracaenaceae) and Schlumbergera truncata (Haw.) Moran (Cactaceae) grown in greenhouses in Korea. Both species were probably introduced into greenhouses via the plant trade. Therefore, it reiterates the need to focus attention on the detection of root mealybugs at the ports of entry to prevent their introduction and establishment in the Korean environment. In this paper, additional information for the two species is provided with diagnoses, photographs along with host plant and distribution data for accurate species identification.

First Report of Stem Wilt and Root Rot of Schlumbergera truncata Caused by Fusarium oxysporum f. sp. Opuntiarum in Southern Italy.

Schlumbergera truncata (Haw.) Moran, belonging to the Cactaceae, is a very common ornamental cactus in southern Italy. In November 2011, sudden stem wilt and root rot was observed in about 45% of vegetatively propagated plants cultivated as potted ornamental plants in a commercial greenhouse in Cerignola (Foggia Province, Apulia, Italy). The roots and collars of the plants showed brown rot. Yellow sunken lesions that were similar to cortical cankers were detected at basal level of the stem. Ten plants with these symptoms were analyzed by fungal isolation techniques. Small (0.5 cm) tissue portions from root, collar, and basal stem were plated on potato dextrose agar (PDA) after disinfection with 75% ethanol for 1 to 2 min, 0.2% NaOCl for 1 to 2 min, and a wash with sterile distilled water. A fungal isolate that was morphologically similar to Fusarium sp. was isolated from 85% of these tissue samples. It had nucleotide sequences of the internal transcribed spacer region (ITS1-5.8S-ITS2) of ribosomal DNA (GenBank Accession No. KC196121) 100% identical to those of the comparable sequences of Fusarium oxysporum (HQ651161). The nucleotide sequences of its translation elongation factor 1-α (EF-1α) gene (KC196120) showed 100% identity to sequences of F. oxysporum f. sp. opuntiarum (DQ837689, AF246881) retrieved from GenBank. Pathogenicity tests were performed at 22 ± 3°C on 18 45-day-old plants of S. truncate by adding of a 5-ml aliquot of conidial suspension adjusted to 5 × 106 conidia/ml to soil of each plant. Six non-inoculated plants were used for a control treatment and sprayed with 5 ml of sterilized water. Plants were maintained in greenhouse at 22 ± 3°C. After 10 days, nine of the inoculated plants showed wilting, and after 45 days, all of them were dead, with root and collar rot and lesions on the basal stem. Control plants were symptomless. Koch's postulates were fulfilled as the pathogen was reisolated from all of the symptomatic tissues and identified as Fusarium sp. On the basis of 3-septate macroconidia (mean 31.75 × 3.21 μm; range, 26 to 35 μm long, 3.0 to 4.2 μm wide), aseptate microconidia, single chlamydospores, and monophialide conidiophores on carnation leaf agar, and molecular analyses, the fungus was identified as F. oxysporum f. sp. opuntiarum (Speg) (1,2,3). In Italy, F. oxysporum f. sp. opuntiarum was reported as basal stem rot of Echinocactus grusoni (4). To our knowledge, this is the first report of stem wilt and root rot of S. truncata caused by F. oxysporum f. sp. opuntiarum in Italy.

Temperatura e substrato para germinação de sementes de flor-de-maio (Schlumbergera truncata (Haw.) Moran)

Schlumbergera truncata é uma cactácea de hábito epífito conhecida popularmente como flor-de-maio ou flor-deseda. É uma planta ornamental, cultivada em vasos e muito apreciada pela beleza de suas flores. O objetivo deste trabalho foi avaliar o efeito da temperatura e do substrato na germinação de sementes de S. truncata. Os substratos utilizados no experimento foram: papel mata-borrão, areia de granulação média, casca de arroz carbonizada e bagaço de cana triturado, e as temperaturas avaliadas foram 20, 25 e 30 ºC. As variáveis analisadas foram: porcentagem de germinação, índice de velocidade de germinação e tempo médio de germinação. As maiores porcentagens de germinação ocorreram em 20 e 25 ºC em papel, areia e casca de arroz carbonizada. Na casca de arroz carbonizada, observaramse os maiores valores de índice de velocidade de germinação e os menores valores de tempo médio de germinação. Concluiu-se que a temperatura de 20 ºC e o substrato casca de arroz carbonizada foram mais adequados para a germinação de sementes de S. truncata e que o bagaço de cana não foi adequado como substrato para a germinação da espécie.

Potexvirus diversity in cactaceae from São Paulo state in Brazil

SUMMARY Northwestern Brazil is a major center of diversity for cactaceous plants, most of which are grown as ornamentals. Cactus virus X (CVX), the only virus reported so far from Brazilian cactaceae, is widely spread. In this study we have characterized viruses of Opuntia tuna (OT), Hylocereus undatus (HU) and Schlumbergera truncata (ST) from the State of Sao Paulo, showing chlorotic spots and mosaic symptoms. Mechanically inoculated Gomphrena globosa reacted with local lesions, except when OT extracts were used as inoculum, whereas Chenopodium amaranticolor showed erratic systemic symptoms following inoculations from HU and ST. Transmission electron microscopy showed flexuous particles ca. 550 nm in length and bundles of virus particles in leaf cells from naturally and experimentally infected plants. Virus particles reacted faintly with an antiserum to CVX. Nucleotide sequences of the RNA dependent RNA polymerase gene obtained from cloned RT-PCR products, revealed the occurrence of Zygocactus virus X (ZyVX) in OT, mixed infection by ZyVX and Schlumbergera virus X (SchVX) in HU, and mixed infection by ZyVX, SchVX and Opuntia virus X (OpVX) in ST. This is the first report of ZyVX, SchVX and OpVX in Brazil.

Propagação por sementes de <em>Schlumbergera truncata</em> (Haw.) Moran (flor-de-maio) em diferentes substratos

Schlumbergera truncata (Haw.) Moran (Cactaceae), known as “flor-de-maio”, is a Brazilian endogenous herbaceous epiphytic species, much appreciated as ornamental for the beauty of its flowers. This species is multiplied by seeds, but commercially it is propagated by cuttings and grafting. The aim of this research was to evaluate the germination of four varieties of colors of this species (pink, red, white and yellow) in five substrates (vermiculite, de-fibered tree ferns, sand, commercial substrate Rendmax® Floreiras and a mixture of 50% of the commercial substrate Rendmax® Floreiras + 50% tree ferns). The results showed that this species can be easily reproduced by seeds. The commercial substrate Rendmax® Floreiras provided the best germination result.

First detection of ?Candidatus Phytoplasma australiense? in Liquidambar styraciflua in Australia

The Christmas cactus ( Zygocactus truncatus ) is a perennial succulent and is native to the South American tropics of Brazil. It is one of the most widely cultivated plants and healthy Christmas cacti in full bloom are often sold as holiday plants around the Christmas season. A pot containing a Christmas cactus with cladodes showing conspicuous malformed branches giving witches’ broom symptoms and stunted growth was found at the Agricultural University, Kunming. Based on the symptomatology, a phytoplasma was suspected to be associated with the disease. Samples from the plant exhibiting witches’ broom and symptomless plants were analyzed for the presence of phytoplasmas using 16SrDNA PCR assays. Total nucleic acids were extracted from young cladodes using the DNeasy Plant Mini kit (QIAGEN) and were used as the template in a nested PCR reaction employing primers R16mF2/R16mR1 followed by R16F2/R16R2 (Gundersen & Lee, 1996). A water control was also included in all the PCR reactions to check for any contamination. A DNA fragment of the expected size (1·2 kb) was amplified by nested PCR from the diseased plant but not from symptomless plants, nor from the water control. After cloning and sequencing, the DNA sequence of 1249 bp was deposited in GenBank (Accession No. AY647459). Phylogenetic analysis of the 16S rDNA sequence delineated the Christmas cactus witches’ broom phytoplasma as a Peanut witches’-broom (16SrII) group member (putative Candidatus Phytoplasma aurantifolia), most closely related to the faba bean phyllody phytoplasma (Lee et al ., 1998). This is the first report of a phytoplasma disease of the Christmas cactus.

First report of a phytoplasma associated with Christmas cactus witches’ broom

The Christmas cactus (Zygocactus truncatus) is a perennial succulent and is native to the South American tropics of Brazil. It is one of the most widely cultivated plants and healthy Christmas cacti in full bloom are often sold as holiday plants around the Christmas season. A pot containing a Christmas cactus with cladodes showing conspicuous malformed branches giving witches’ broom symptoms and stunted growth was found at the Agricultural University, Kunming. Based on the symptomatology, a phytoplasma was suspected to be associated with the disease. Samples from the plant exhibiting witches’ broom and symptomless plants were analyzed for the presence of phytoplasmas using 16SrDNA PCR assays. Total nucleic acids were extracted from young cladodes using the DNeasy Plant Mini kit (QIAGEN) and were used as the template in a nested PCR reaction employing primers R16mF2/R16mR1 followed by R16F2/R16R2 (Gundersen & Lee, 1996). A water control was also included in all the PCR reactions to check for any contamination. A DNA fragment of the expected size (1·2 kb) was amplified by nested PCR from the diseased plant but not from symptomless plants, nor from the water control. After cloning and sequencing, the DNA sequence of 1249 bp was deposited in GenBank (Accession No.AY647459). Phylogenetic analysis of the 16S rDNA sequence delineated the Christmas cactus witches’ broom phytoplasma as a Peanut witches’-broom (16SrII) group member (putative Candidatus Phytoplasma aurantifolia), most closely related to the faba bean phyllody phytoplasma (Lee et al., 1998). This is the first report of a phytoplasma disease of the Christmas cactus. This work was supported by the National Natural Science Foundation of China (grant no. 30260064) and the Science Fund of Yunnan Province (grant no. 2000C0014Q).

Plant regeneration via somatic embryogenesis in Schlumbergera truncata

Somatic embryogenesis was induced from phylloclade explants of Schlumbergera truncata cv. Russian Dancer. Callus developed on phylloclade explants and sub-cultured over a period of 16 months on MS medium containing mainly cytokinins was superior for the induction of somatic embryos compared to callus grown for a shorter time in the establishment medium. Sub-culture of callus grown in SH-or MS-based liquid media supplemented with 7.0 μM kinetin and transferred onto solid MS-based medium with either 0.45 μM 2,4-D or without hormones resulted in the differentiation into somatic embryos. SH-based medium proved better than MS-based medium when used as the first medium for the induction of somatic embryogenesis. However, somatic embryogenesis, contrary to adventitious shoot formation, was reduced when 2,4-D was included in the MS-based medium used for final transfer compared to the medium without growth regulators, indicating that a critical hormonal balance was reached. Somatic embryos developed root and shoot poles when grown on G medium. On this medium approximately 70% germination was recorded in the embryos that were differentiated earlier from the callus that was grown for a longer time in the establishment medium. This callus was grown on either SH- or MS-based medium supplemented with 7.0 μM kinetin, and then transferred after 30 days (from SH medium) onto MS medium without hormones or after 40 days (from MS medium) onto MS medium with 0.45 μM 2,4-D. Furthermore, plants from somatic embryos were successfully potted in soil and showed further growth and formation of a second set of phylloclades (secondary phylloclades). Histological studies showed that somatic embryos had no detectable connection with the mother explants and that advanced stages of somatic embryos had a contained vascular system. In addition to the normal dicotyledonous embryos, anomalous embryos with multiple cotyledons and vase-like embryos were observed. Secondary embryos were also recorded in this study.

The Relationship between Flower Age and Seed Production in Hatiora gaertneri and Schlumbergera truncata (Cactaceae)

Flowers of two cacti [Hatiora gaertneri (Regel) Barthlott `Crimson Giant' and Schlumbergera truncata (Haworth) Moran `Eva'] were pollinated at different times between anthesis and senescence to determine the effect of floral age on seed production. Studies were conducted in a growth chamber (20 ± 0.5°C) to minimize temperature effects. Mean flower longevity (time from anthesis to first signs of senescence) was 4.7 days for S. truncata and 10.5 days for H. gaertneri. Stigmas of both species were receptive to pollination on the day of anthesis. The maximum number of viable seeds per pollinated flower was obtained when flowers of S. truncata and H. gaertneri were pollinated (respectively) on the second and fourth days after anthesis. For both species, the relationship between floral age and number of viable seeds per pollinated flower was described by a second-degree polynomial. The rate of pollen tube growth in the style was about 1.7 mm·h–1 for S. truncata and about 0.9 mm·h–1 for H. gaertneri. Some senesced flowers of H. gaertneri were capable of setting fruit with viable seed. Flowers of S. truncata did not set fruit when pollinated during the late phase of flower opening or after they had senesced. Senesced flowers of S. truncata failed to set fruit due to an insufficient number of pollen tubes reaching the ovary.

First Report of Basal Stem Rot of Golden Barrel Cactus Caused by Fusarium oxysporum f. sp. opuntiarum in Italy.

Golden barrel cactus (Echinocactus grusonii Hildm.) is the most common landscape cactus in southern Italy. During 2000, 2001, and 2002, a basal stem rot of golden barrel cactus was observed in several plastichouses located in eastern Sicily with disease levels of nearly 100% on young plants (up to 15 cm in diameter). On the basal crown area, the plants showed pale brown or yellow-orange, sunken lesions bordered by a reddish orange strip up to 1 mm wide. A water-soaked rot or white mycelium at the soil line was also observed. Thirty pieces (0.5 to 1 cm) from the edge of symptomatic tissues were surface disinfected for 2 min in 0.8% (wt/vol) NaOCl, washed with sterile distilled water (SDW), and placed on potato dextrose agar (PDA). In addition, 20 pieces of affected tissue were ground in 400 μl of SDW (1:3, wt/wt), and the resulting suspensions were streaked by loops on PDA supplemented with 1.1 μl/ml of lactic acid (pH 4.4). A Fusarium sp. was consistently isolated from affected tissue pieces and streaks. Koch's postulates were performed at 25°C by inoculating 24 golden barrel cactus plants in 12-cm-diameter pots (12 plants previously sterile needle wounded) with 10 ml per plant of three suspensions (106 CFU/ml) of three isolates sprayed onto the basal stem. One milliliter per ten g of soil of each suspension was also added in the crown portion of golden barrel cacti. Twelve control cacti (six wounded) were sprayed only with SDW. Further pathogenicity tests were carried out on Thanksgiving cactus (Schlumbergera truncata (Haw.) Moran), devil's tongue barrel cactus (Ferocactus latispinus (Haw.) Britton & Rose), peruvian old man cactus (Espostoa lanata (Kunth) Britton & Rose), and Parodia spp. by inoculating eight plants for each host (four wounded) by placing 9-day-old 6-mm mycelial plugs at the base of the healthy cacti. An equal number of plants (four wounded) was inoculated only with a PDA plug. All cacti were maintained in polyethylene bags (90 to 95% for 72 hr) at 25°C. After 12 to 15 days, all wounded inoculated golden barrel, devil's tongue barrel, and peruvian old man cacti exhibited similar symptoms observed in the plastichouses. Typical symptoms were visible also in nonwounded and inoculated cacti 15 days later. Yellow-orange, tan, sunken, and roughly circular lesions were observed on the wounded and inoculated Thanksgiving and Parodia sp. cacti. Control plants were symptomless. The causal fungus was always reisolated from infected cacti. On the basis of 3-septate macroconidia (27 to 35 μm long × 3 to 4 μm wide [average 31.45 × 3.18 μm]), microconidia aseptate, single or double chlamydospores, and monophialide conidiophores observed on carnation leaf agar, and considering the susceptibility of all other inoculated hosts, the fungus was identified as F. oxysporum Schlechtend. f. sp. opuntiarum (Speg.) (1). To our knowledge, this is the first report of basal stem rot of golden barrel cactus in Italy. Reference: (1) W. Gerlach. Phytopathol. Z. 74, 197, 1972.

Intergeneric Hybridizaton between Schlumbergera Lem. and Hatiora Britt. & Rose (Cactaceae)

Post-pollination barriers to intergeneric hybridization between Easter cactus [Hatiora gaertneri (Regel) Barthlott, H. rosea (Lagerheim) Barthlott, and H. ×graeseri Barthlott ex D. Hunt] and holiday cactus [Schlumbergera truncata (Haworth) Moran and S. ×buckleyi (Buckley) Tjaden] were determined and procedures were devised for circumventing these barriers. Examination of Hatiora and Schlumbergera pistils at 72 hours after intergeneric crosses indicated no abnormalities in pollen germination or pollen tube growth in the upper style. Pollen tubes of Hatiora were arrested in the lower half of Schlumbergera styles and failed to enter the ovary. Schlumbergera pollen tubes exhibited normal growth in Hatiora styles but most tubes lost directionality, burst, or failed to penetrate the micropyles after reaching the ovary. Three growth regulators (BA, GA3 and NAAm) were applied individually to ovaries of `Crimson Giant' Easter cactus after intergeneric crosses. GA3 and NAAm increased fruit set compared to the control (lanolin alone) or BA but none of the fruit harvested 160 days after pollination contained mature embryos. Four progeny were obtained when a short-styled S. ×buckleyi clone was crossed as a female parent with H. ×graeseri. Isozyme patterns and morphological characteristics confirmed that the four progeny were intergeneric hybrids. This is the first report of successful intergeneric hybridization between Hatiora and Schlumbergera. Chemical names used: N-(phenylmethyl)-1H-purine-6-amine [benzyladenine (BA)]; gibberellic acid (GA3); α-naphthaleneacetamide (NAAm).

Efficacy of inhibitors of ethylene binding in improvement of the postharvest characteristics of potted flowering plants

Pre-treatment of potted plants of Campanula carpatica cultivars Dark Blue and Blue Clips and Schlumbergera truncata cultivar Dark Marie with the volatile ethylene binding inhibitor 1-methylcyclopropene (1-MCP) inhibited the effects of exogenous ethylene (bud abscission and wilting of flowers). In an ethylene-free simulated interior environment, display life of the 1-MCP treated plants was unaffected (Campanula) or slightly greater (Schlumbergera) than that of the controls, although not as good as that of plants pre-treated with the anionic silver thiosulfate complex (STS). Differences in effects of both blockers of ethylene binding sites are discussed.