Cambial tissue culture and subsequent shoot regeneration from mature black locust (Robinia pseudoacacia L.)

Callus initiation and subsequent shoot regeneration were obtained from cambial tissue of mature black locust trees. Shoot regeneration was highly tree specific, and was only achieved when calli derived from a particular genotype (tree #1) were transferred to medium containing 6-benzylaminopurine. The studies described here show that the immediate use of a mature genotype as starting material for tissue cultural manipulation is possible by using cambial explants with the proper in vitro conditions. We also found that stems could be stored at 4°C for 8 months prior to culture initiation, with no decline in the viability of the cultures. Tissue sources can thus be continuously available.Abbreviations BAP 6-benzylaminopurine - NAA 1-naphthyleneacetic acid - IBA indolebutyric acid     

Mycorrhizae between black locust (Robinia pseudoacacia) and Terfezia terfezioides

 In the present paper we report a mycorrhizal association between the hypogeous white truffle Terfezia terfezioides and the black locust (Robinia pseudoacacia) growing at various sites in Hungary. The mycorrhiza can be considered as being of the endo- or ectendo-type, since both mantle and Hartig net are absent. Morphological features of the septate hyphae colonizing cortical root cells were investigated by light microscopy on cryosections and on ultra-thin sections studied by transmission electron microscopy. Artificial infection of micropropagated black locust plantlets with the mycelium of the fungus was successful and had the same characteristics as naturally occurring associations. Accepted: 8 March 1996     

Advances in somatic embryogenesis and plant production of black locust (Robinia pseudoacacia L.)

Summary Black locust (Robinia pseudoacacia L.) immature seeds of different developmental stages were tested for the ability to initiate embryogenic cultures. Best results (average of 12% embryogenic cultures) were obtained when seeds collected 2–3 weeks post-anthesis were cultured for 3 weeks on modified Finer and Nagasawa medium containing 2,4-D (45–90 M) and BA (2.2 M) and then transferred to the same medium without growth regulators. Embryo conversion was obtained from naked or encapsulated somatic embryos derived from a long-term embryogenic line. Without cold treatment, 71% of naked embryos and 41% of the encapsulated embryos converted into plants. Fifteen days of cold treatment increased conversion rates up to 95% for naked embryos and 80% for encapsulated embryos. Recovered plantlets were acclimatized and grown in the greenhouse.Abbreviations BA 6-benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - FM modified Finer & Nagasawa (1988) medium - MS modified Murashige & Skoog (1962) medium - PEM proembryogenic mass - SH modified Schenck & Hildebrandt (1972) medium     

Canker and wilt of black locust (Robinia pseudoacacia L.) caused by Fusarium species

From the pathological material of black locust trees showing symptoms of wilting of the foliage or canker of the bark the following Fusarium species were isolated: Fusarium avenaceum (Fr.) Sacc., Fusarium lateritium Nees., Fusarium semitectum Berk. & Rav., Fusarium solani (Mart.) Sacc., Fusarium sulphureum Schlecht. (syn.: Fusarium sambucinum Fuckel f. 6 Wollenw.) The results of the provocation infections of one-year-old black locust seedlings showed that all of the species--except Fusarium solani--are able to cause considerable necrosis in living bark and phloem. Fusarium sulphureum had by far the highest pathogenecity among the tested species. Fusarium semitectum isolated from withered black locust tree also caused necrosis on significant bark area. In the course of the penetration assay Fusarium sulphureum and Fusarium avenaceum were the most successful, and these species can cause cankers on the stem and twigs of black locust without frost effect.     

Comparison of photosynthesis and leaf ultrastructure on two black locust (Robinia pseudoacacia L.)

Polyploidy is common in many plant species. Up to date, few studies were reported on photosynthesis and leaf anatomy of tetraploid black locust (Robinia pseudoacacia L.), which has considerable value for agriculture and forest. This study compared photosynthesis and leaf ultrastructure on two black locusts. The values of P_n and C_i in tetraploid were significantly higher than those in the corresponding diploids. Significantly lower stomata dimensions (6.0 μm in length and 2.4 μm in width) and tomatal density were observed in 4×. Leaf trichome density was statistically different between 2× and 4×. However, no substantial difference in the ultrastructure of chloroplasts and mitochondria between diploid and tetraploid was observed under any stress. These ultrastructural characteristics may contribute to tetraploid a better protection mechanism than diploid.     

Nitrogen stocks in a riparian area invaded by N-fixing black locust (Robinia pseudoacacia L.)

Fixation of river flow passages and riverbed degradation may facilitate the development of higher floodplains with the establishment of exotic species such as black locust (Robinia pseudoacacia L.). We quantitatively evaluated the relationship between nitrogen (N) levels in black locust trees and in sediments under different flood disturbance regimes in a riparian area of the Chikuma River. In this study, allometric equations were developed for relating leaf N content to diameter at breast height of black locust. The amount of leaf N in black locust increased with distance from the river, reaching 159 kg N ha⁻¹ at 180 m from the river. There was a small difference in N content between green and fallen leaves (0.2%), and so the leaf N was almost equivalent to N input to riparian sediments. Fine sediments accumulated on the riparian area, where the amount of sediments N increased with distance from the river, ranging from 1091 ± 767 to 4953 ± 2953 kg N ha⁻¹. The N accumulation rates also increased with distance from the river, corresponding with the amount of leaf N in black locust per unit area, but the former exceeded the latter. The sediment N accumulation might be accelerated by sediment trapping effect due to riparian vegetation itself. A large input of N provided by invaded black locust might alter nutrient dynamics and native plant community structure in the riparian area.     

In vitro propagation of willows (Salix spp.), European mountain-ash (Sorbus aucuparia L.) and black locust (Robinia pseudoacacia L.)

Willows were rapidly propagated by repeated division of cultured rooted shoots into a larger number of nodal segments. Rapid clonal propagation of mountain-ash and black locust was achieved by induction of shoots from axillary buds and a multiple shoot culture was used for rapid multiplication. Excised shoots were rooted in an agar medium with a low concentration of auxin and rooted plantlets were transplanted to soil.     

The influence of black locust (Robinia pseudoacacia) flower and leaf fall on soil phosphate

To investigate the influence of black locust (Robinia pseudoacacia) flower and leaf fall on soil phosphate, we monitored litterfall, litter decomposition, and soil membrane phosphate in a R. pseudoacacia forest on Mt. Ilzasan, Seoul, Korea. R. pseudoacacia flower litter was 30–50% of total litter production in May and the flowers decomposed rapidly. More than 11% of R. pseudoacacia leaf litter decomposed from February to May, while that of Quercus spp. decomposed very little. Fast decomposition of R. pseudoacacia flower and leaf litter significantly increased membrane phosphate in the soil. The rapid nutrient-cycling of R. pseudoacacia through flower litterfall and rapid decomposition benefits the plant itself in the growing season when nutrients demand is increasing. Rapid nutrient-cycling might be a strategy that helps R. pseudoacacia to persist in poor soil environments.     

The effects of elevated CO2 (0.5%) on chloroplasts in the tetraploid black locust (Robinia pseudoacacia L.)

Some ploidy plants demonstrate environmental stress tolerance. Tetraploid (4×) black locust (Robinia pseudoacacia L.) exhibits less chlorosis in response to high CO₂ than do the corresponding diploid (2×) plants of this species. We investigated the plant growth, anatomy, photosynthetic ability, chlorophyll (chl) fluorescence, and antioxidase activities in 2× and 4× black locusts cultivated under high CO₂ (0.5%). Elevated CO₂ (0.5%) induced a global decrease in the contents of total chl, chl a, and chl b in 2× leaves, while few changes were found in the chl content of 4× leaves. Analyses of the chl fluorescence intensity, maximum quantum yield of photosystem II (PSII) photochemistry (Fv/Fm), K‐step (V_k), and J‐step (V_J) revealed that 0.5% CO₂ had a negative effect on the photosynthetic capacity and growth of the 2× plants, especially the performance of PSII. In contrast, there was no significant effect of high CO₂ on the growth of the 4× plants. These analyses indicate that the decreased inhibition of the growth of 4× plants by high CO₂ (0.5%) may be attributed to an improved photosynthetic capacity, pigment content, and ultrastructure of the chloroplast compared to 2× plants.     

Specialization for ureide biogenesis in the root nodules of black locust (Robinia pseudoacacia L.), an amide exporter

Summary Black locust (Robinia pseudoacacia L.), a member of the legume tribe Robinieae, has indeterminate root nodules and is primarily an amide exporter. However, in greenhouse-grown seedlings inoculated with rhizobia, ureide-N comprises approximately 8% of the total soluble-N in the xylem sap. Ultrastructurally, young interstitial cells (i.e., uninfected cells in the infected region near the nodule meristem) develop enlarged peroxisomes and abundant tubular ER, properties heretofore found to be characteristic only of members of the Phaseoleae, which have determinate nodules and are exporters principally of ureides. Many of the peroxisomes in the interstitial cells of black locust nodules react strongly for uricase (EC 1.7.3.3) activity in a cytochemical test employing diaminobenzidine, but some of the peroxisomes, particularly those farther back from the meristem, react weakly or not at all, even though enlarged. The ultrastructural specializations of the interstitial cells seem disproportionately large in comparison to the relatively low levels of ureides in the xylem transport stream. We suggest that similar specialization of some of the interstitial cells might be found in other legumes that export low amounts of ureides.Abbreviations DAB 3,3'diaminobenzidine - ER endoplasmic reticulum Dedicated to the memory of Professor Oswald Kiermayer     

Genetic structure of natural populations of black locust (Robinia pseudoacacia L.) at Coweeta, North Carolina

Natural population of black locust maintains very high levels of genetic diversity within populations without any noticeable geographic patterns. In order to assess the species' potential for manipulation through breeding programs, more detailed spatial pattern analyses of fine-scale population structure was attempted in the two study sites (watershed 2 and 21) in the Coweeta River Basin of southern Appalachian mountains using allozyme markers. Of the 200 and 420 plants examined in watershed 21 and 2 respectively, 13 and 15 major genotypes of clone were distinguished. Within watersheds 2 and 21, 60% of the pairwise clone combinations had three or four loci differences out of the 8 loci investigated. No correlation between distance between clones and the number of allele difference was found. The similarity values (16 highest and 0 lowest value) among clones for watershed 2 and 21 were 12.82 and 10.19 respectively. Typical distances between clones on both watershed 2 and 21 were from 90 and 190 m, but the range varied from several meters up to 300 m. An average distance among clones were 140.9±66.0 m and 239.4±108.6 m in watershed 2 and 21 respectively, whereas an average distance within clone was 38.7±36.2 m and 145.0±123.6 m in watershed 2 and 21. Genotype diversity indices (DG) for watershed 2 and 21 were 0.89 and 0.86 respectively. The largest clones on both watersheds covered more than 100 m×100 m. On the other hand, some clones on watershed 2, which had a few fallen trees with many young sprouts (up to 200 individuals), were 45 m×30 m in size under the open habitat. Although clonal substructure and limited seed dispersal may cause near neighbor mating interaction, significant genetic patchiness among clones of black locust was not evident. Although the first establishment of a black locust population would have relied on an off-site seed source, it is more likely that asexual reproduction has occurred for many generations in these black locust populations because of the presence of many different sizes of trees (or ages) in one clone despite widespread opportunities for sexual reproduction. Presence of three or four different sizes of trees within a clone implies that the trees has developed from a clone at each different time. The current study suggested that the amount of sexual reproduction and dispersal rate (especially seed dispersal) should be determined. It would be useful to examine whether or not clonal strategies and patterns of clonal growth of black locust are influenced by density dependent regulation of ramet recruitment and death.     

Changes in phenology of the locust tree (Robinia pseudoacacia L.) in Hungary

 Intense research is being carried out on climate variability and change and the estimation and detection of anthropogenic effects. In addition to statistical methods, the use of plants, as biological indicators is becoming more popular as they are sensitive to environmental conditions. In this article we compare maps of the flowering dates of the locust tree (Robinia pseudoacacia L.) for three different time intervals between 1851 and 1994. The maps revealed noticeable shifts of dates, of approximately 3–8 days, towards earlier flowering. This change is related to the average temperature of spring (15 March–15 May), via a simple statistical model that is accurate enough to be able to quantify phenological changes and to calculate the corresponding warming. The model developed can estimate spring mean temperature using phenological data from R. pseudoacacia L. with an accuracy of 0.2° C. Estimates of mean temperature based on phenological changes are compared to climatic series. This comparison emphasizes the possibility of using R. pseudoacacia. L. as a bio-indicator. Estimates of temperature changes are also given. Received: 5 August 1996 / Revised: 14 April 1997 / Accepted: 11 November 1997     

Spatial differences in the radial growth responses of black locust (Robinia pseudoacacia Linn.) to climate on the Loess Plateau,China

The black locust (Robinia pseudoacacia Linn.) is the dominant tree species in the “grain for green” project on the Loess Plateau (LP) of China, and brings many ecological benefits to this planted region. However, there are concerns regarding its suitability as a plantation forest species in different regions of the LP. We used a dendroclimatological approach to investigate the radial growth response of black locust to varying climate in two sites on the LP with differing precipitation gradients. We took tree-ring samples from black locust in Yongshou County (in the semi-humid southern LP) and Shenmu County (in the semi-arid northern LP), and developed tree-ring width (TRW) chronologies for each. We performed moving correlation analyses between TRW chronologies and aggregated thermal (maximum temperature (TMX), minimum temperature (TMN), mean temperature (TMP)) and hydroclimatic factors (precipitation, self-calibrated Drought Severity Index (scPDSI), and humidity). The results demonstrated the increased influence of thermal factors during autumn, and the generally decreased influence of hydroclimatic factors on black locust radial growth in Yongshou, compared with the decreasing influence of thermal factors (during all seasons) and increasing influence of hydroclimatic factors (precipitation during summer, scPDSI and humidity during autumn) on black locust radial growth in Shenmu. The results indicated that black locust radial growth might benefit from the current climatic conditions in the southern LP. However, black locust radial growth stressed by water availability in the northern LP, which may reduce its vitality and productivity as climate warms in the future. These results have implications for regional forestry planning and ecological restoration strategies on the LP.     

Distribution of ectomycorrhizal and pathogenic fungi in soil along a vegetational change from Japanese black pine (Pinus thunbergii) to black locust (Robinia pseudoacacia)

The nitrogen-fixing tree black locust (Robinia pseudoacacia L.) seems to affect ectomycorrhizal (ECM) colonization and disease severity of Japanese black pine (Pinus thunbergii Parl.) seedlings. We examined the effect of black locust on the distribution of ECM and pathogenic fungi in soil. DNA was extracted from soil at depths of 0–5 and 5–10 cm, collected from the border between a Japanese black pine- and a black locust-dominated forest, and the distribution of these fungi was investigated by denaturing gradient gel electrophoresis. The effect of soil nutrition and pH on fungal distribution was also examined. Tomentella sp. 1 and Tomentella sp. 2 were not detected from some subplots in the Japanese black pine-dominated forest. Ectomycorrhizas formed by Tomentella spp. were dominant in black locust-dominated subplots and very little in the Japanese black pine-dominated forest. Therefore, the distribution may be influenced by the distribution of inoculum potential, although we could not detect significant relationships between the distribution of Tomentella spp. on pine seedlings and in soils. The other ECM fungi were detected in soils in subplots where the ECM fungi was not detected on pine seedlings, and there was no significant correlation between the distribution of the ECM fungi on pine seedlings and in soils. Therefore, inoculum potential seemed to not always influence the ECM community on roots. The distribution of Lactarius quieticolor and Tomentella sp. 2 in soil at a depth of 0–5 cm positively correlated with soil phosphate (soil P) and that of Tomentella sp. 2 also positively correlated with soil nitrogen (soil N). These results suggest the possibility that the distribution of inoculum potential of the ECM fungi was affected by soil N and soil P. Although the mortality of the pine seedlings was higher in the black locust-dominated area than in the Japanese black pine-dominated area, a pathogenic fungus of pine seedlings, Cylindrocladium pacificum, was detected in soil at depths of 0–5 and 5–10 cm from both these areas. This indicates that the disease severity of pine seedlings in this study was influenced by environmental conditions rather than the distribution of inoculum potential.     

The chemical composition of plant litter of black locust (Robinia pseudoacacia L.) and its ecological role in sandy ecosystems

Robinia pseudoacacia is a North American species and in Poland it is currently invasive in character. It is used to recultivate sand excavations and others, most often in order to make the process of plant and soil succession more advanced. It has been observed that in places were R. pseudoacacia dominated in plantations, the herbaceous vegetation under the trees is poor and sometimes other vascular plants are not appearing at all. Plants usually overgrow the space out of the canopy shade. The positive influence of R. pseudoacacia on a habitat is primarily connected with the chemical composition of plant litter, as well as with the biology of the species. Chemical composition of R. pseudoacacia litter has been researched. The greatest accumulation of elements has been observed in the following parts: green leaves (Ca > K > Mg > P > Si > Na > Fe > Zn > Al > Mn) and leaf litter (Ca > K > Mg > Si > Fe > P > Na > Al > Zn > Mn). Similar regularities are observed in the remaining litter of R. pseudoacacia. It must be emphasized that nitrogen occurs in similar quantities in particular samples and it varies from 1.01 to 2.65%. The plant litter reaction (pH) vary from acid to weakly acid. In a short period of time under the canopy of R. pseudoacacia a 10 cm organic and humus horizont (O/A) has developed.     

The effects of clonal integration on morphological plasticity and placement of daughter ramets in black locust (Robinia pseudoacacia)

We studied the field response of Robinia pseudoacacia L. to light, total soil nitrogen, available soil phosphorus and soil pH. Results indicated that there was very strong clonal integration between mother and daughter ramets. Mother ramets can provide nitrogen and phosphorus to daughter ramets sufficient for their continued growth through strong clonal integration, but cannot provide enough photosynthate. With clonal integration, soil nitrogen and phosphorus availability had no effect on biomass allocation to roots, number of ramets and length of connection roots. Biomass allocation to roots increased markedly and responded to nitrogen and phosphorus availability, when the connections were severed. Light had a significant effect on the percent of biomass allocation to leaves and number of ramets, but no effect on the length of connection roots. Daughter ramets allocated more resources to leaves, and clones placed more daughter ramets in high light patches than in low light patches. Soil pH had a significant effect on ramet number and connection root length. Clones concentrated in alkaline patches and escaped from acid patches through selective placement of daughter ramets and changing the length of connection roots. We suggest that the clonal integration may be very strong and provide sufficient soil resources to daughter ramets, then affect the daughter ramets’ morphology and placement, if the size of a specific ramet is significantly larger than the other ramets in an arbor clone.     

Development of microsatellite markers in black locust (Robinia pseudoacacia) using a dual‐supression‐PCR technique

Black locust (Robinia pseudoacacia) is an economically and ecologically important tree species in the world. We isolated seven polymorphic microsatellite loci from R. pseudoacacia using a dual‐suppression‐PCR technique. These loci provided microsatellite markers with high polymorphism ranging from three to 12 alleles per locus and expected heterozygosity between 0.538 and 0.944. The markers are now available for more detailed investigation of population genetic structure and pollen and seed dispersal.     

Effects of black locust (Robinia pseudoacacia) on soil properties in the loessial gully region of the Loess Plateau, China

Black locust (Robinia pseudoacacia) has been widely planted in the Loess Plateau for soil and water conservation. The effects of black locust on soil properties has significant role in land use and ecosystem management. However, this beneficial effect has been little studied in the Loess Plateau. The soil properties below black locust and native grass growing in Nanxiaohe and Wangdonggou watersheds, located in the loessial gully region of the Loess Plateau, were studied for changes in soil properties after establishment of black locust. The black locust significantly increased soil cation exchange capacity, organic carbon, total nitrogen, nitrate, and carbon:nitrogen and carbon:phosphorus (P) ratios, as well as some enzymes like alkaline phosphatase and invertase in 0–20 cm or 0–80 cm depths of soil compared to the native grassland in Nanxiaohe and Wangdonggou watersheds. However, the effects on ammonium, total P, and extractable P and potassium were not consistent in both watersheds. There were more obvious differences in soil properties between black locust land and grassland for Nanxiaohe watershed than for Wangdonggou watershed, suggesting that the effects of black locust on most soil properties increase with black locust age. The results indicate that black locust has potential to improve soil properties in the loessial gully region of the Loess Plateau and the improvements were greater in long-term than middle-term black locust stands.