角堇与大花三色堇染色体核型分析

以2份角堇与4份大花三色堇自交系为试验材料,采用染色体常规压片方法,观察和分析了它们的细胞染色体数目、相对长度、平均臂比等核型指标,以明确两种植物细胞学特点,为分类以及育种提供理论依据。结果表明:(1)2份角堇自交系染色体数目均为2n=2x=26,染色体基数为x=13,染色体核型公式分别为2n=2x=26=8m+12sm+6st、2n=2x=26=4m+16sm+6st,核型不对称系数为67.20%~70.10%,核型分类均属于3B。(2)4份大花三色堇自交系均为四倍体,其中2份(EYO-1-2-1-4、DSRFY-1-1-2)染色体数目为44,核型公式为2n=4x=44=4m+16sm+6st、2n=4x=44=16m+24sm+4st;2份(G10-1-3-1-4、XXL-YB-1-1-1-1)染色体数目为48,核型公式分别为2n=4x=48=8m+20sm+20st、2n=4x=48=4m+36sm+8st,核型不对称系数为66.74%~71.77%,核型分类属于2B、3B。     

东北地区被子植物新资料

东北地区位于中国东北部,地处欧亚大陆东缘,地域辽阔,环境复杂,植被类型多样,是我国北方植物种类较为丰富、植物区系起源演变发展的重要地区。该研究根据野外实地调查及资料分析,报道了东北地区2种新分布植物,分别是野生堇菜(Viola arvensis)、线叶毛膏菜(Drosera anglica)。野生堇菜为东北地区新归化种,分布于哈尔滨市帽儿山,该种在我国台湾地区有分布,原产于非洲北部、亚洲西南部和欧洲;线叶毛膏菜为中国新记录种,分布于东北长白山区。该属在东北地区还有1种,即圆叶茅膏菜(D.rotundifolia)。两者的主要区别:前者叶为线状匙形,花柱3,每个花柱2分裂至中部;后者叶片近圆形,花柱3,每个花柱深裂至基部。凭证标本保存于东北林业大学植物标本室(NEFI)。这些新资料种的发现,对于丰富东北地区植物种类及对本地区植物多样性的研究具有重要意义。     

Viola pluviae sp. nov. (Violaceae), a member of subsect. Stolonosae in the Pacific Northwest region of North America

As hirtherto circumscribed, the allo‐octoploid Viola palustris L. exists in three distinct races in North America. The race occurring in the Pacific Northwest of North America has previously been shown to have originated by polyploidy from a different set of ancestral tetraploids than the nominal, Amphi‐Atlantic race. These two races differ also in a number of morphological characters, which has been a historical source of confusion. We here propose a new name for the western plants, V. pluviae Marcussen, H.E. Ballard & Blaxland, and typify it with a specimen collected near Mt Rainier (USA, Washington) with known chromosome number. Distribution, phylogenetic history and taxonomy are discussed and an updated morphological key to the Pacific Northwestern species of Viola is presented.     

On the origin of the sweet-smelling Parma violet cultivars (Violaceae): wide intraspecific hybridization, sterility, and sexual reproduction

Parma violets are reputed for their double, fragrant flowers and have been cultivated for centuries in Europe. However, due to a rather atypical morphology their taxonomic affinity has not been clarified. Authors have proposed an origin from three possible species, Viola alba, V. odorata, or V. suavis, or a hybrid origin. Using both ITS sequence variation and allozyme variation in 14 putative loci, we showed that the Parma violet cultivars have their origin within Viola alba and that they are best included in the Mediterranean subsp. dehnhardtii. There is no trace of interspecific hybridization. However, the cultivars appear to have a single origin in a wide hybrid within V. alba, involving parental plants from the eastern and western Mediterranean region; historical literature sources seem to indicate Turkey and Italy, respectively. The Parma violet cultivars possess high levels of allozyme heterozygosity and to some extent also within-individual ITS sequence variation. Losses of heterozygosity and within-individual ITS sequence variation in some of the cultivars indicate subsequent rare events of sexual reproduction, presumably through cleistogamous seed set. We unambiguously identify the closest wild relative of this group of cultivars, allowing growers to develop new selection procedures, and show a peculiar molecular process associated with human selection.     

Floral Biology and Pollination Mechanisms in Two Viola Species—From Nectar to Pollen Flowers?

The genus Viola is represented by four related species in Brazil belonging to section Leptidium, one of the most primitive sections in the genus. Floral biology and pollination by bees were studied in Viola cerasifolia and V. subdimidiata in high-altitude areas in south-eastern Brazil. Flowers are zygomorphic and spurred. The five stamens are arranged in a cuff around the ovary, and pollen is released by means of apical connective projections, which form a cone surrounding the base of the style. The connective projections of the inferior stamens are elongated and curved to form a hook-shaped structure. Nectar-secreting tissue can occur in the basal connective appendages of the inferior stamens, which project into the spur. Flowers of V. subdimidiata secreted a mean volume of 0.14 micro l nectar over a 24-h period; approx. 40 % of flowers did not secrete any nectar. The main pollinators of these Viola species are female bees belonging to the genus Anthrenoides (Andrenidae), which search mainly for pollen. These bees seem to be oligolectic and obtain large amounts of pollen from Viola by vibrating the flowers or by moving the hook repeatedly back and forth. Males of Anthrenoides patrol Viola clusters and also feed on nectar, acting as secondary pollinators. The basic floral structure in the genus Viola fits that of 'nectar flowers'. The uncommon hook-shaped projections, scanty nectar production, and behaviour of pollinators suggest that V. cerasifolia and V. subdimidiata are shifting their reward for pollinators from nectar to pollen. Based on floral morphology, this shift may be widespread in Viola sect. Leptidium.     

Variability of the essential oil of Viola etrusca

Essential oils obtained from different populations of Viola etrusca from Italy have been analysed to verify the phenotypic discontinuity observed in a previous study. All of the essential oils contained methyl salicylate as a main constituent. However, multivariate analysis showed differences among some populations, in particular between northern and southern ones. Results suggest that this species could be undergoing a slow schizogenetic differentiation process due to its genetic isolation.     

Differential effects of interspecific interactions and water availability on survival, growth and fecundity of three congeneric grassland herbs

Fitness of individual plants and of populations depends on the rates of survival, growth and fecundity. This study tested whether vital rates were differentially affected by biotic interactions and water availability. The effects of manipulations of above-ground competition (through clipping) and water availability (through water addition) on the vital rates of seedlings of three species (Viola elatior Fries, Viola pumila Chaix and Viola stagnina Kit.) were analysed in dry, mesic and wet grasslands. Water addition and grassland type had the largest effects on survival (accounting for 41 and 24% of total variation, respectively) across species. Height growth rate was positively affected by grassland type (19%) and water addition (12%) and varied among species (8%), while leaf accumulation rates and reproduction were affected by grassland type and clipping. The data suggested facilitative effects of the canopy on seedling survival in the dry grassland. This study presents evidence that environmental conditions and biotic interactions may have differential effects on seedling survival, growth and reproduction. The findings highlight the complex interplay between spatial and temporal environmental variation and biotic interactions in structuring plant communities.     

Spread of violets in polluted pine forests: morphological and molecular evidence for the ecological importance of interspecific hybridization

Hybridization between plant species occurs frequently but hybrids are often restricted to ecotones or disturbed habitats. In this study we show that introgressive hybrids between the tetraploid Viola riviniana and the diploid V. reichenbachiana invaded pine forests of the Dübener Heide (central Germany), an area affected by calcareous pollutants. The spread of these violet populations was correlated with the impact of pollution on habitat conditions. We compared morphology, cytology and random amplified polymorphic DNA (RAPD) bands among six Viola populations from the Dübener Heide and three populations of each pure species. RAPD analysis using 12 primers revealed 141 scorable bands. We considered bands as species specific if they occurred in at least 75% of the plants in one pure violet species but in none of the other. Seven bands were specific to V. riviniana and 11 bands were specific to V. reichenbachiana . Two plants of a V. reichenbachiana population were identified as hybrids. Of the Viola populations from the Dübener Heide, one was diploid and could be classified as V. reichenbachiana by morphology and RAPD markers. However, the majority of the Dübener Heide populations were tetraploid, and of a more variable morphology than V. riviniana and V. reichenbachiana , showing different combinations of intermediate characters, characters of the pure species and extreme characters. Despite their overall genetic similarity to V. riviniana , these plants could be identified as introgressive hybrids between V. riviniana and V. reichenbachiana by species-specific RAPD bands. Therefore, we propose that recurrent hybridization and backcrossing resulted in novel genotypes adapted to the changed environment of polluted pine forests.     

Two new species of Viola (Violaceae) from the Intermountain West,U.S.A.

Viola lithion andV. franksmithii are rock-dwelling endemics that belong to the North American perennial, caulescent, simple-leaved, blue-, purple-, or white-flowered group of species.Viola lithion, from the White Pine and Pilot mountain ranges of eastern Nevada and adjacent Utah, belongs to sectionChamaemelanium subsectionCanadenses. It most closely resembles the reniform-leaved, Olympic MountainV. flettii, together with which it possibly shares an ancestry with the widespread and allopatricV. canadensis. Viola franksmithii, restricted to the Logan Canyon drainage of the Bear River Range in northern Utah, belongs to sectionRostellatae subsectionRosulantes. It comes closest morphologically toV. howellii of the Coast Range, but likely evolved from the widespreadV. adunca or a common ancestor.     

不同采样策略对细距堇菜遗传多样性估算的影响

采用水平淀粉凝胶电泳技术对分布于北京金山、檀枯寺、香山樱桃沟的细距堇菜（Ｖｉｏｌａ ｔｅｎｕｉｃｏｒｎｉｓ Ｗ．Ｂｅｃｋ．）的遗传变异和群体分化进行了初步研究。对８个酶系统１１个等位酶位点的检测表明,该种在上述地区的遗传变异水平明显高于多年生草本的平均值,多成位点百分率Ｐ＝７２．７％,等位基因平均数Ａ＝２．４,平均期望杂合度Ｈｅ＝０．２４３;群体间的遗传分化略小于多年生草本的平均值,杂和性基因多样