Magnolia Stellata Research Articles

Arbuscular Mycorrhizal Inoculation Affects Root Development of Acer and Magnolia Species

Abstract The effects of arbuscular mycorrhizal fungi (AMF) inoculation on fine root development of four woody landscape plants were studied during the first year after transplant. Test species included two members of obligately mycorrhizal Magnoliaceae (Magnolia virginiana and Magnolia stellata) and two members of facultatively mycorrhizal Aceraceae (Acer × freemanii and Acer buergerianum). Field-grown, balled and burlapped plants were treated with a commercial inoculant containing Glomus spp. and Gigaspora spp. mycorrhizal fungi and transplanted to a piedmont field site. Root architecture and demographics were evaluated in situ using minirhizotrons. One year after transplant, AMF colonization levels had increased in three of the four species regardless of whether they had been intentionally inoculated. AMF-treated M. virginiana and A. buergerianum had significantly lower standing root crops (total root length visible on minirhizotrons) than control plants, and a similar trend was observed in Acer × freemanii. Inoculated M. virginiana roots exhibited reduced branching and shorter life spans, but were less likely to develop brown pigmentation. Species-specific effects of inoculation on root longevity and browning were also observed in the maples. AMF inoculation had no effect on above ground growth or foliar nutrient concentrations. Investment of photosynthate in the growth and maintenance of AMF may represent a more efficient nutrient acquisition strategy than root proliferation, leading to lower fine root production in heavily mycorrhizal plants.

Estimation of outcrossing rates at hierarchical levels of fruits, individuals, populations and species in Magnolia stellata

In plant species with mixed mating systems, differences in diverse factors-including their pollination system, flowering phenology, life form and susceptibility to inbreeding depression-cause variation in outcrossing rates among fruits within individuals, among individuals within populations and among populations within species. To quantify this hierarchical variation, we examined outcrossing rates at the seed stage in five populations of Magnolia stellata, a self-compatible, insect-pollinated and protogynous tree species. For this purpose, we sampled 1498 seeds within 204 fruits obtained from 56 individuals of the five populations, determined genotypes of the sampled seeds and maternal individuals at six polymorphic microsatellite loci, then estimated outcrossing rates and their variance components at four hierarchical levels (fruits, individuals, populations and species) using a nested analysis of variance-type linear model with a Bayesian approach. The species-level outcrossing rate was 0.730 (95% credible interval, 0.595-0.842), indicating that this species has a mixed mating system. Outcrossing rates were not significantly different among populations, but were significantly different among individuals within populations. Variance components at the levels of individual and fruit were statistically supported and were highest for the former. Thus, factors influencing outcrossing rates at the individual level, such as differences in flowering phenology and early-stage inbreeding depression, appear to have important effects within these M. stellata populations, but not among them. The method of hierarchically estimating outcrossing rates using a Bayesian approach, as applied in this study, is compared with conventional methods for estimating outcrossing rates, and the statistical properties of the Bayesian approach are discussed.

The soil seed bank of the threatened plant Magnolia stellata is subordinate to the emergence of current-year seedlings

We studied seed bank formation of the threatened star magnolia, Magnolia stellata, to examine the early stage of regeneration. Forty-five seedling plots (2 × 2 m), each including a soil-sampling quadrat (40 × 40 cm), were established randomly under or around the crowns of mature M. stellata trees. Seeds of M. stellata were collected from each quadrat to a depth of 5 cm. Only four seeds of M. stellata were found (0.56 seeds/m2) and all were located under mature crowns. Current-year seedlings were abundant in water channels, on moss, or under mature crowns, suggesting that the seeds may require wet soil conditions for germination. Magnolia stellata seeds show considerable germination below the crowns of mature trees in the year following masting, while some seeds remain dormant in the soil. Considering the soil seed bank and the current-year seedling bank of M. stellata, a frequent supply of seed is essential for the regeneration of this species. Thus, it is important to maintain mature trees in addition to promoting seed production.

Relationships between flowering phenology and female reproductive success in the Japanese tree species Magnolia stellata

We have examined the earliness, duration, and amplitude of flowering genets in a Magnolia stellata (Sieb. et Zucc.) Maxim. population in relation to their size, environmental factors (temperature and light), and female reproductive success (ovule survival rate) over three consecutive years. Average flowering durations of individual flowers, genets, and the whole population in these 3 years were 10.2, 15.2, and 29.0 d, respectively. A bisexual phase (with both female and male phase flowers) in genets spanned 62.9% of the total flowering period, suggesting that geitonogamy can occur. The earliness, duration, and amplitude of flowering genets were all significantly correlated, indicating that genets flower early and long periods have high flowering amplitudes. The three parameters were also significantly correlated with the size of the genets (represented by the diameter at breast height of its thickest ramet) and relative photosynthetic photon flux density at the top of their crowns. Therefore, genets that are large and located in well-lit sites tend to have many flowers, and blossom both earlier and longer. Later-flowering genets have higher female reproductive success, probably because M. stellata is protogynous. Significantly positive correlation between flowering amplitude and female reproductive success suggests that large numbers of flowers increase the attractiveness of genets for pollinators, and this outweighs the negative effects of geitonogamy.

Genetic variation and differentiation in populations of a threatened tree, Magnolia stellata: factors influencing the level of within-population genetic variation

Genetic variation and differentiation in Magnolia stellata were studied in 20 populations distributed across most of the species' range using 10 microsatellite markers, and the factors influencing their levels of within-population genetic variation were examined. Generally, populations distributed intermittently from southern Gifu to central Aichi Prefectures showed substantially higher levels of genetic variation (exceptions included populations located at unusually high altitude sites or western and southern edges of the range) than more isolated populations on the Atsumi Peninsula of southern Aichi Prefecture and in northern Mie Prefecture. Significant isolation-by-distance patterns were detected in genetic differentiation among the studied populations, and a neighbor-joining tree based on D(A) distances among the populations reflected well the geographical positions of the populations. The level of within-population genetic variation was significantly influenced not only by the size of the populations (represented by the number of reproductive individuals) but also by their degree of isolation (represented by the number of populations within a radius of 0.5 km around them). Therefore, areas within radii of 0.5 km may encompass M. stellata metapopulations, in which gene flow may usually occur. We suggest that this area may be a suitable standard for constructing conservation units for the species.

Reduced seed production, inbreeding, and pollen shortage in a small population of a threatened tree, Magnolia stellata

We investigated how genetic factors and pollen shortage affect seed production in a small population of Magnolia stellata, a threatened insect-pollinated tree. We used microsatellite and manual pollination techniques, and compared a small population to a large one. Compared to the large population, the small population showed low allelic variation and had an F IS significantly greater than 0 in adults, indicating that genetic deterioration, including genetic drift and inbreeding, may have occurred in adults. Manual self-pollination lowered seed production relative to manual cross-pollination to a different extent between populations: δ (the magnitude of inbreeding depression due to self-fertilization) was lower in the small population than in the large population. However, under natural pollination, the estimated embryo mortality rates after ovules self-fertilized were similar between the two populations because the primary selfing rate was higher in the small population. The ovule mortality rate due to pollen shortage and that due to factors independent of pollen shortage and selfing were both approximately 10% higher in the small population, suggesting that pollen transfer may have decreased and genetic deterioration effects may have increased in that population. These factors reduced seed production in the small population (female reproductive success = 0.3%) compared to the large population (2.6%). Our results suggest that seed production in the small population of M. stellata is strictly limited by elevated pollen shortage, selfing, and genetic deterioration in adults, which accelerate the risk of extinction.

Genetic diversity and differentiation of the endangered Japanese endemic tree Magnolia stellata using nuclear and chloroplast microsatellite markers

Genetic diversity and differentiation were analyzed in 11 populations of Magnolia stellata (Sieb. and Zucc.) Maxim. (Magnoliaceae) in the Tokai district, Japan. Variation at four nuclear microsatellite (nSSR) loci was examined, three chloroplast microsatellite (cpSSR) markers were developed and 13 haplotypes identified. The 11 populations were divided into three groups (A, B and C). Each population within the group was separated less than 40 km. Group B harbored the highest gene diversity (H) and allelic richness (Ar) for nSSR (H=0.74 and Ar=8.02). Group C had the highest diversity of chloroplast haplotypes (H=0.79 and Ar=6.8): 2.5 times more haplotypes than the other groups. Each population contributed differently to the total diversity, with respect to nSSR and cpSSR. AMOVA revealed that 58% of haplotypic and 15% of nSSR variation was partitioned among populations within groups. A Mantel test revealed significant correlations between population pairwise geographic ln(distance) and FST/(1−FST) for both nSSR (r=0.479; P=0.001) and cpSSR (r=0.230; P=0.040). Dendrograms of populations for nSSR, based on Nei’s genetic distance, were constructed using UPGMA and the neighbor-joining method. These results suggest that populations in group C have diverged from the other populations, while those in group B are similar to each other. For group B, fragmentation between populations should be avoided in order to maintain gene flow. For group C, the uniqueness of each population should be given the highest priority when planning genetic conservation measures for the species.

Effects of pollen shortage and self-pollination on seed production of an endangered tree, Magnolia stellata

Pollen limitation is a significant determinant of seed production, and can result from both insufficient pollen quantity (pollen shortage) and quality (mainly relating to self-pollination). For animal-pollinated tree species with large floral displays, pollen limitation may be determined by a balance between increased pollen quantity due to increased attractiveness for pollinators, countered by increased self-pollination due to increased geitonogamy. The contributions of pollen shortage and self-pollination on seed production were quantitatively examined in the natural pollination of an insect-pollinated, dichogamous, endangered tree, Magnolia stellata, which has a large, showy floral display. Manual self- and cross-pollinations were conducted to determine the effects of selfing on seed production. The outcrossing rate was measured using microsatellite analyses of open-pollinated seeds, and the embryo mortality rate caused by self-pollination was indirectly estimated. The frequency of ovule mortality due to pollen shortage was also inferred using the embryo mortality and ovule survival rates from natural pollination. The average fruit set, seed set per fruit, and ovule survival rate per tree from hand cross-pollination were 1.37, 3.15, and 3.34 times higher than those from hand self-pollination, respectively, indicating that self-pollination causes inbreeding depression for fruit and seed set. The multilocus-outcrossing rate (t(m)) was intermediate, 0.632, and the primary selfing rate was 0.657. This indicates that frequent geitonogamous selfing occurs. The ovule mortality rate due to pollen shortage and the embryo mortality rate due to self-pollination were estimated to be 80.8 % and 45.9 %, respectively. It is concluded that seed production of M. stellata is strongly limited by both pollen shortage and self-pollination. Inefficient beetle-pollination and the automimicry system via asynchronous flowering might be responsible for the high level of pollen shortage and frequent geitonogamy. This is despite a large, showy floral display and the dichogamous system of the species.

Synergistic effect of benzolinone with IBA and fungicides on the vegetative propagation of ornamental plants, park, and fruit woody species

  A study was made of the stimulating effect of benzolinone (3-benzyloxycarbonyl-methyl)-2-benzothiazolinone in powder form (P) and its mixture with indole butyric acid (IBA), the biofungicide Supresivit and fungicide Captan 50 WP on the root formation of 17 species of ornamental plants, park and fruit woody species. Under the action of benzolinone, the yield of rooted cuttings in the category of ornamental plants amounted to 44.5% (in the Dianthus sp.) up to 83.7% (in Rosa canina), in the category of park woody species it was from l6.7 (in Magnolia stellata) to 100% (in Forsythia intermedia). In fruit trees represented by two species, viz. Actinidia arguta and cherry rootstocks, the yield was between 20 and 86.7%, and in two allochthonous species Cotoneaster horizontalis and Philadelphus coronarius it was from 96.7 to 100% in rooted cuttings. In the case of herbaceous and semi-lignified cuttings, lower concentrations of benzolinone below 0.1% were more effective, while on the contrary, higher concentrations of 0.1–0.2% proved more effective with lignified cuttings. In the species with difficult root formation, such as Magnolia stellata, Viburnum farreri and Actinidia arguta, benzolinone demonstrably stimulated both the rhizogenesis, and thereby the overall yield of rooted cuttings, and the quality of the root system. In the case of the species with naturally high rooting ability, the positive effect of benzolinone was manifest mainly in the quality of the root system. The synergistic action of the above stimulants on root formation was achieved in two and three-component benzolinone mixtures with IBA and fungicides on the basis of the active ingredients captan and Trichoderma harzianum. The most evident stimulating effects on the rooting of cuttings in Dianthus sp., Ficus schlechteri and the deciduous species Acer saccharinum Pyramidale, Prunus padus Colorata and Prunus kurilensis Brilliant was obtained in three-component mixtures.

The primary structure of 5S ribosomal RNAs from Magnolia cobus and Magnolia stellata

The primary structure of 5S ribosomal RNAs from Magnolia cobus and Magnolia stellata

Magnostellin A and B, novel lignans from Magnolia stellata

The phytochemistry of fresh leaves of Magnolia stellata was compared with that of M. kobus. Two new lignans, viz. magnostellin A and magnostellin B were isolated together with sesamin, kobusin, eudesmin and (+)-piperitol. The structures of magnostellin A and B were determined. An α-ionone, vomifoliol (blumenol A) was also isolated from the same source.

各地産植物精油に関する研究(第44報)シデコブシの精油成分

各地産植物精油に関する研究(第44報)シデコブシの精油成分

INTEGUMENTARY STUDIES IN THE POLYCARPICAE

SUMMARY The histogenetic development of the integuments of two representatives of the Magnoliaceae, Magnolia stellata and M. virginiana, was studied. The mode of development is the same in these two species. The two integuments have a different form of initiation: The inner integument (i.i.) is wholly of dermal derivation, whereas the primordium of the outer integument (o.i.) is formed as the result of cell divisions in the first subdermal cell layer. There is no apical initial or apical growth in either integument. The initials of the i.i. form rows of cells by repeated periclinal cell divisions, which rows develop independently in mutual juxtaposition to form a ring-shaped wall, the whole structure remaining meristematic. The i.i. is mainly three-layered, the o.i. is (in the younger stages at least) four-layered. The micropyle is formed by both integuments. The i.i. only becomes thicker by “secondary” cell divisions in the micropylar region. After fertilization appreciable changes take place in the o.i., the innermost cell layer forming the sclerotesta and the outer layers the vascularized sarcotesta.

Studies on the Alkaloids of Magnoliaceous Plants. VII

The authors synthesized from isovanillin, salicifoline chloride (I), viz., β-(3-hydroxy-4-methoxyphenyl)-ethyl-trimethylammonium chloride, a main base of Magnolia salicifolia Maxim., Magnolia Kobus DC., and Magnolia stellata Maxim., belonging to the Magnoliaceae, which grow in Japan. Thus, the structure of salicifoline chloride has synthetically been confirmed as being represented by formula (I). In this connection, β-(3-methoxy-4-hydroxyphenyl)-ethyl-trimethylammonium chloride (IV), β-(2-hydroxy-3-methoxyphenyl)-ethyl-trimethylammonium chloride (VI), and β-(2, 3-dimethoxyphenyl)-ethyl-trimethylammonium iodide (VII), having the structure analogous to that of salicifoline chloride, have also been synthesized.