Shoot regeneration from cultured leaves of Japanese pear (Pyrus pyrifolia)

Several experiments were conducted to investigate in vitro regeneration of adventious shoots from cultured leaves of Japanese pear (Pyrus pyrifolia). A protocol was developed and regeneration achieved from six cultivars. Leaves harvested from shoot cultures which had been preconditioned on B5 medium with 5 μM thidiazuron plus 0.25 μM gibberellic acid were placed on regeneration medium of the same composition. Frequency of regeneration per leaf was as high as 23% but cultivar and environmental factors influenced the result. More mature (basal) leaves regenerated more frequently than younger ones from the shoot tip. Leaf orientation during regeneration and photoperiod was not a strong influence but regeneration from leaf pieces was less than from uncut leaves. An alternative regeneration procedure was developed in which first, shoot cultures were grown on the preconditioning medium. Leaves of the intact shoot cultures were then induced to regenerate directly when adventitious shoots formed on leaves of the intact shoot culture leaves without excision. Adventitious shoots from both procedures developed into typical shoot cultures when transferred to shoot culture maintenance medium. This revised version was published online in June 2006 with corrections to the Cover Date.     

银杉(Cathaya argyrophylla)林林窗更新的研究

银杉（Ｃａｔｈａｙａ ａｒｇｙｒｏｐｈｙｌｌａ）在林窗内和非林窗群落内均占有最大的重要值,说明银杉是典型的林窗更新方式．银杉个体在林窗内呈集群分布,林窗边缘往往集中了较多的银杉植株。林窗内银杉直径分布中,出现胸径〉８ｃｍ 及胸径〈３ｃｍ的高峰和３～７ｃｍ的低谷。对最近１０ａ银杉幼树每年高生长量的研究发现,林窗内和荫蔽要完下的结果差异显著,林窗内的幼树高生长快于荫蔽林冠下。     

Shoot regeneration from tissue-cultured leaves of the American cranberry (Vaccinium macrocarpon)

A method for shoot regeneration from leaf explants in two cultivars of cranberry (Vaccinium macrocarpon Ait.) is described. Modified Anderson's medium supplemented with combinations of thidiazuron (TDZ) with or without 1 M NAA (-naphthaleneacetic acid) was used to optimize shoot regeneration. The effect of light or dark incubation was also determined. Maximum regeneration was obtained in the light in the presence of 10 M TDZ and 1 M NAA. While this medium was suitable for leaf explants obtained from shoot cultures, regeneration did not occur from leaves collected from greenhouse-grown plants. Elongation of the regenerated shoot tips did not occur until explants were transferred to growth regulator-free medium at which time only a minority of shoots elongated. Elongated shoots could be dissected away from leaf tissue, rooted easily, and acclimitized to ambient conditions.Abbreviations NAA -naphthaleneacetic acid - TDZ 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea     

不同郁闭度对野外回归的梓叶槭幼树形态和生理特征的影响

濒危植物野外回归是扩大极小种群野生植物种群的有效途径。适宜的回归生境是物种生长的必要条件, 研究植物的生理生态特征对不同野外回归生境的适应性, 是科学评价濒危物种种群回归生境适宜性的关键指标。本文以野外回归的极小种群野生植物梓叶槭(Acer catalpifolium)为研究对象, 探讨了无遮荫、林缘、林隙以及林下(郁闭度由小到大) 4种不同光照条件对梓叶槭幼树的形态特征、光合特征、类黄酮指数及叶绿素含量等的影响。结果表明: (1)随着郁闭度的增大, 梓叶槭幼树的基径、冠幅以及新生枝条数量产生差异, 均呈现先增大后减小的趋势; (2)在林缘生境中, 梓叶槭幼树的单叶面积及单叶质量均最大, 比叶面积随着郁闭度的增大而增大; (3)随着郁闭度的增大, 梓叶槭叶片胞间CO₂浓度、蒸腾速率及气孔导度均呈现先减小后增大的趋势, 叶绿素含量呈现上升趋势, 类黄酮指数则呈现先增大后减小的趋势。综上可知, 林缘适宜的光照条件更适合梓叶槭野外回归。这一结果可为梓叶槭以及其他极小种群野生植物的回归生境适宜性的探索研究提供借鉴。     

Shoot regeneration of hybrid seed geranium (Pelargonium x hortorum) and regal geranium (Pelargonium x domesticum) from primary callus cultures

Procedures have been developed that increase the rate of shoot regeneration of hybrid seed geranium from month-old primary callus cultures. Hybrid geranium callus tissue covered with green nodular structures was initiated by placing shoot tip explants on solidified Murashige & Skoog medium (MS) supplemented with 2.0 mgl^-1 zeatin and 1.9 mgl^-1 indoleacetic acid. Hybrids Red Orbit, White Orbit and Scarlet Orbit were shown to produce 5–50 shoot primordia per explant when callus was initiated on this medium. Regal geranium callus was initiated by placing leaf explants on MS medium supplemented with 2.0 mgl^-1 6-benzylaminopurine and 2.0 mgl^-1 naphthaleneacetic acid. Regal geranium cultivars Tiny Tot and Lavender Grand Slam were shown to produce between 2–50 shoot primordia per explant when initiated on the same medium.     

中国槭树科二新记录种

三裂枫Acer calcratum Gagnep．和长裂枫Acer acuminatum Wall．exD．Don两种分布于东南亚和喜马拉雅地区的珍稀树种,最近分别发现在我国云南和西藏有分布,属于我国新记录种。三裂枫属于广义鸡爪槭组sect．Palmata中华槭系ser．Sinensia,主要形态特点为叶片三裂,叶片基部圆形,伞房花序,通常只有一个发育完全的果实,坚果近卵球形。长裂枫属于尖齿槭组sect．Arguta,主要特点为叶片3裂和5裂,侧裂片和中央裂片近等长,裂片先端长渐尖,花序长达12-20cm。     

Interacting effects of warming and drought on regeneration and early growth of Acer pseudoplatanus and A. platanoides

Climate change is acting on several aspects of plant life cycles, including the sexual reproductive stage, which is considered amongst the most sensitive life‐cycle phases. In temperate forests, it is expected that climate change will lead to a compositional change in community structure due to changes in the dominance of currently more abundant forest tree species. Increasing our understanding of the effects of climate change on currently secondary tree species recruitment is therefore important to better understand and forecast population and community dynamics in forests. Here, we analyse the interactive effects of rising temperatures and soil moisture reduction on germination, seedling survival and early growth of two important secondary European tree species, Acer pseudoplatanus and A. platanoides. Additionally, we analyse the effect of the temperature experienced by the mother tree during seed production by collecting seeds of both species along a 2200‐km long latitudinal gradient. For most of the responses, A. platanoides showed higher sensitivity to the treatments applied, and especially to its joint manipulation, which for some variables resulted in additive effects while for others only partial compensation. In both species, germination and survival decreased with rising temperatures and/or soil moisture reduction while early growth decreased with declining soil moisture content. We conclude that although A. platanoides germination and survival were more affected after the applied treatments, its initial higher germination and larger seedlings might allow this species to be relatively more successful than A. pseudoplatanus in the face of climate change.     

Phylogenomic,morphological, and niche differentiation analyses unveil species delimitation and evolutionary history of endangered maples in Acer series Campestria (Sapindaceae)

Accurate species delimitation is crucial for biodiversity conservation. The Acer series Campestria comprises four species, A. campestre L., A. miyabei Maxim., A. miaotaiense P. C. Tsoong, and A. yangjuechi Fang & P. L. Chiu. To clarify controversies over the taxonomic status of the latter three endangered species, we undertook phylogenomic, morphological, and niche differentiation analyses in series Campestria. Our coalescent species tree of 544 and 77 single-copy nuclear genes supported series Campestria as monophyletic, with A. yangjuechi having the closest relationship with A. miaotaiense. However, in the plastome-derived tree based on 64 protein coding sequences, the four species did not cluster together, and each of them grouped with some other sympatric Acer species. Given this nuclear-cytoplasmic conflict, we hypothesize that A. yangjuechi have been subject to nuclear gene introgression and plastid (pt) capture involving another sympatric maple, that is, A. amplum Rehder. Principal component analysis and machine learning based on morphological data could not separate A. yangjuechi and A. miaotaiense, but they both could be clearly distinguished from A. miyabei. Moreover, the niche overlap tests of the two more widespread species, A. miyabei and A. miaotaiense, showed they clearly occupy distinct niches. Overall, we conclude that A. miyabei and A. miaotaiense are distinct species, while A. yangjuechi (endemic to Mt. Tianmu/East China) should be treated as a subspecies of A. miaotaiense. Our study points out that multiple lines of phylogenomic, morphological, and ecological evidence prove highly useful in species delimitation. Additionally, our results should help to inform conservation measures for endangered species of the genus Acer/series Campestria in East Asia.     

High Frequency of Shoot Regeneration from Hypocotyls and Stem Segments of Antirrhinum majus (Snapdragon)

A broadly applicable direct shoot regeneration method from hypocotyls and stem explants has been developed for six cultivars of Antirrhinum majus L. In order to establish a stable and high frequency of shoot regeneration system, leaves, hypocotyls and stem explants of six cultivars were tested with 72 combinations of auxin (naphthaleneacetic acid (NAA) or 3-indoleacetic acid (IAA)) and cytokinin (6-benzylaminopurine (BA) or zeatin (Z)). A few adventitious shoots were directly regenerated from hypocotyl segments of cv. Orchid on MS medium with NAA + BA, IAA + BA, NAA + Z and IAA + Z. High frequency of direct shoot regeneration was obtained from hypocotyl segments on MS medium with 0.05, 0.1 or 0.25 mg l⁻¹ NAA + 2 mg l⁻¹ Z and 0.5 mg l⁻¹ IAA + 2 mg l⁻¹ Z. Finally, stable and high frequency (92–100%) of shoot regeneration with more than 10 adventitious shoots per explant was achieved from the hypocotyls and stem explants of all six cultivars on MS medium with 0.25 mg l⁻¹ NAA + 2 mg l⁻¹ Z. The shoots emerged directly from the hypocotyls and stem segments 4 weeks after culture initiation.     

Influence of silver nitrate (ethylene inhibitor) on cucumber in vitro shoot regeneration

The effect of addition of silver nitrate (AgNO₃) on organogenesis of proximal and distal cotyledon and hypocotyl explants of five cucumber (Cucumis sativus L.) cultivars was investigated. Distal cotyledon and hypocotyl were unresponsive while only poor shoot regeneration was observed in proximal cotyledon and hypocotyl explants of all cucumber cultivars. The addition of different concentrations of AgNO₃ (10, 30 and 50 μM) to the medium, however, induced shoot regeneration in distal cotyledon except Suyo Long cultivar and effectively increased shoot regeneration response as well as the number of shoots per explant in proximal cotyledon and hypocotyl of all cucumber cultivars. This revised version was published online in June 2006 with corrections to the Cover Date.     

深圳槭--中国槭树科一新种

描述广东省深圳市马峦山发现的槭树科一新种Acer shenzhenensis R．H．Miao,X．M．Wang et J．S．Liang。该种与亮叶槭Acer lucidum Metc．接近,但本种叶顶端尾状渐尖,叶柄长达3 cm,小脉发育,两面网脉清楚,果翅直立,两翅宽1．2-1．5 cm,翅内弯,相叠,易与后者区别。     

A rapid and efficient method for regeneration of plantlets from embryo explants of cumin (Cuminum cyminum)

A new, simple and efficient method was developed for multiple shoot regeneration of cumin from imbibed embryo cultures. This method yielded a large number of shoots within short period of time (30–50 days) without any subculturing. The effects of different media, different embryo explants and various combinations of plant growth regulators (PGRs) on callus formation and shoot regeneration in cumin were investigated. Simultaneous callus formation and shoot regeneration was obtained. The best response for multiple shoot regeneration was observed on B5 medium containing 1.0 mg l^–1 BAP, 0.2 mg l^–1 NAA and 0.4 mg l^–1 IAA, with an average of 140 shoots per explant.     

Shoot damage by Tomicus sp. (Coleoptera: Scolytidae) and effect on Pinus yunnanensis resistance to subsequent reproductive attacks in the stem

Abstract 1 In South‐western China, Yunnan pines Pinus yunnanensis, suffer considerable damage from an undescribed Tomicus sp. previously thought to be T. piniperda. 2 To assess the effect of shoot maturation feeding (during which an aggregation process appears to occur) on host resistance to attacks on the bole, the relationships between shoot damage, bole attack density and tree survival were studied. 3 Attack distribution in the crown and in the stem did not vary between killed and surviving trees, indicating that mortality is determined by the quantity of attacks. 4 The level of shoot damage and bole attack density were positively and linearly correlated. This can be explained by the fact that bole attacks are caused by beetles coming from the crown of the same tree. 5 A critical threshold of bole attack density (around 80 attacks/m²) above which trees die was observed. However, because attacks continue after this threshold is reached, the density of failed attacks on the killed trees was used as an estimator of the threshold density. It decreased when shoot damage increased. 6 The existence of a critical threshold of shoot damage (60% damaged shoots) was also demonstrated. Above this threshold, stem attack density was always sufficiently high to kill trees. 7 The results emphasize that concentration of shoot attacks is the main reason for the extensive tree damage observed in China. 8 A model of relationships between shoot and stem attacks is proposed, suggesting that management to reduce shoot attacks would protect trees from dying by both decreasing the number of bole attacks and raising the threshold for successful attack density on the bole to levels that could not be attained.     

Distribution and abundance of vines along the light gradient in a southern temperate rain forest

Question: Are vines light‐demanding species? Location: Temperate evergreen rain forest of southern Chile (40°39′S, 72°11′W). Methods: In 45 plots of 25 m² distributed in treefall canopy gaps, secondary forest stands and old‐growth forest (15 plots per light environment), all climbing and non‐supported vines were counted and identified to species level, and canopy openness was quantified using hemispherical photographs. Vine abundance and diversity (species richness and Simpson's index) were compared in the three light environments and similarity between vine communities was estimated using Jaccard's similarity coefficient. We also determined the relationship between light niche breadth and local dominance at the species level. Results: In total there were 2510 vine individuals of 14 species. Canopy openness was significantly different in the three light environments. Species richness, diversity, community composition and density of vines were similar in treefall gaps, secondary and old‐growth forest. Of the seven more common vine species, which accounted for 91% of all vines, three had even distribution, two were more abundant in the shaded understorey, and two had higher density in well‐lit sites. Local dominance of vine species and niche breadth were not significantly associated. Conclusions: Our study in a temperate rain forest questions the widespread notion of vines as pioneer‐like species, which may be a consequence of the abundance of some lianas in disturbed sites of tropical forests. Functional arguments are needed to justify a general hypothesis on light requirements of vines, which constitute a vast group of species.     

Shoot apical meristem: In vitro regeneration and morphogenesis in wheat (Triticum aestivum L.)

Summary We report a less genotype-dependent in vitro regeneration system capable of producing multiple shoot clumps and whole plants in four different wheat genotypes. Shool apical meristems from 7-d-old-seedlings produced axillary and adventitious shoots and somatic embryos on media containing N⁶-benzyladenine (BA) and 2,4-dichlorophenoxyacetic acid (2,4-D). All four genotypes responded positively to shoot multiplication depending upon media composition. Scanning electron microscopies of cultures showed a proliferating budding state that gave rise to adventitious shoots and somatic embryos on further multiplication. The percentage of relative shoot apical meristem multiplication was 80–90%, and the average number of shoot meristems per multiplied shoot was 40–50 in all genotypes. Among different concentrations of phytohormones, 2 and 4 mgl⁻¹ BA (8.8 and 17.7 μM) in combination with 0.5 mg l⁻¹ 2,4-D (2.26 μM) gave the best results. Actively multiplying shoot clumps were recovered with high frequency among 3-mo.-old cultures. These shoot clumps regenerated normally and produced fertile plants containing viable seeds. This in vitro system might prove useful for the production of transgenic plants of wheat in a relatively genotype-independent manner.     

茶条槭不同海拔种群的表型多样性

为了揭示茶条槭（Acerginnala）不同海拔种群表型变异程度和变异规律,以山西七里峪天然分布的茶条槭为研究对象,调查不同海拔种群的种实和叶表型性状,采用方差分析、相关分析、聚类分析等方法,分析种群的表型多样性。结果表明：17个表型性状中16个存在显著差异,占总表型性状的94.12%。在物种水平上各个性状表现出较丰富的变异,变异系数（CV）在7.05%～38.12%之间。茶条槭种群具有高的表型多样性（1.9253）,5个不同海拔种群的平均表型多样性指数为1.9022～1.9837。种群间的表型分化系数均值（13.79%）小于种群内变异（82.71%）,种群内的变异是表型变异的主要来源。各表型性状及表型多样性指数与土壤中的N、K、AN、AK、AP、OR、MC表现出显著或极显著的相关关系（P〈0.05）,但与海拔高度呈现出不显著的相关性。UPGMA聚类分析显示5个种群形成明显的两组,与其地理分布相一致。不同海拔种群所处微生境的异质性是引起种群间差异的主要原因。茶条槭种群内、种群间变异的利用对其遗传改良具有重要的意义。     

Shoot regeneration and plant acclimatization of the wetland monocot Cattail (Typha latifolia)

A regeneration system for broadleaf cattail (Typha latifolia), a common freshwater wetland monocot, was established. Callus was induced from 3 day-old seedlings on Murashige and Skoog medium supplemented with picloram or 2,4-dichlorophenoxyacetic acid (2,4-D). Picloram induced more callus growth than 2,4-D. Callus proliferated predominantly from the root-shoot junction and sporadically from the roots. Upon transfer to N⁶-benzyladenine-supplemented medium, callus regenerated shoots. The mode of regeneration was organogenesis, with shoots arising from organized areas of callus. The regenerated shoots rooted in vitro and, on transfer to pots containing a commercial potting mix, were established in a greenhouse. The plants grew vigorously and produced a high root mass. No albinos and no morphological aberrations were observed in the regenerates. Received: 18 March 1998/ Revision received: 12 June 1998/ Accepted: 14 July 1998     

Structural acclimation and radiation regime of silver fir (Abies alba Mill.) shoots along a light gradient

Shoot architecture has been investigated using the ratio of mean shoot silhouette area to total needle area ( ) as a structural index of needle clumping in shoot space, and as the effective extinction coefficient of needle area. Although can be used effectively for the prediction of canopy gap fraction, it does not provide information about the within‐shoot radiative regime. For this purpose, the estimation of three architectural properties of the shoots is required: needle area density, angular distribution and spatial aggregation. To estimate these features, we developed a method based on the inversion of a Markov three‐dimensional interception model. This approach is based on the turbid medium approximation for needle area in the shoot volume, and assumes an ellipsoidal angular distribution of the normals to the needle area. Observed shoot dimensions and silhouette areas for different vertical and azimuth angles (A_S) are used as model inputs. The shape coefficient of the ellipsoidal distribution (c) and the Markov clumping index (λ₀) are estimated by a least square procedure, in order to minimize the differences between model prediction and measurements of A_S. This methodology was applied to silver fir (Abies alba Mill.) shoots collected in a mixed fir–beech–spruce forest in the Italian Alps. The model worked effectively over the entire range of shoot morphologies: c ranged from 1 to 8 and λ₀ from 0·3 to 1 moving from the top to the base of the canopy. Finally, the shoot model was applied to reconstruct the within‐shoot light regime, and the potential of this technique in upscaling photosynthesis to the canopy level is discussed.