Relationship between fern development and CAM in Pyrrosia piloselloides (L.) Price

Pyrrosia piloselloides (L.) Price is a constitutive CAM plant in the sporophytic phase of its life-cycle. Newly developed sporophytes, still attached to the gametophytes, showed signs of CAM expression in terms of diurnal changes in titratable acidity of the tissues. The gametophytes did not exhibit CAM. This revised version was published online in June 2006 with corrections to the Cover Date.     

C3 photosynthesis in the gametophyte of the epiphytic CAM fern Pyrrosia longifolia (Polypodiaceae)

Sporophytes of some epiphytic species in the fern genus Pyrrosia exhibit Crassulacean acid metabolism (CAM), generally considered to be a derived physiological response to xeric habitats. Because these species alternate between independent sporophytic and gametophytic generations yet only the sporophyte has been characterized physiologically, experiments were conducted to determine the photosynthetic pathways present in mature sporophytes, immature sporophytes, and gametophytes of Pyrrosia longifolia. Diurnal CO₂ exchange and malic acid fluctuations demonstrated that although the mature sporophytes exhibited CAM, only C₃ photosynthesis occurred in the gametophytes and young sporophytes. Consideration of the above results and those from previous studies, as well as the life cycle of ferns, indicates that the induction of CAM probably occurs at a certain developmental stage of the sporophyte and/or following exposure to stress. Elucidation of the precise mechanisms underlying this C₃-CAM transition awaits further research.     

Density affects gametophyte growth and sexual expression of Osmunda cinnamomea (Osmundaceae: Pteridophyta)

BACKGROUND AND AIMS: To understand how gametophyte densities affect the sexual expression and sizes of Osmunda cinnamomea and to provide information on the density of growth needed to favour successful reproduction, fresh spores were sown at various densities and subsequent gametophyte growth was studied. METHODS: Spores were sown and cultured in the laboratory. Subsequent gameophytes at different population densities were sampled and their sexual expression and sizes were recorded. KEY RESULTS: One-year-old multispore cultures of the fern O. cinnamomea demonstrated that population density affected gametophyte growth and sexual expression. As density increased, gametophytes became significantly smaller and more slender. Female and asexual gametophytes dominated in populations of low and high densities, respectively. At intermediate population densities, hermaphroditic and male gametophytes were dominant. Female gametophytes were larger than gametophytes of all other types. Hermaphroditic gametophytes were larger than male gametophytes, which were larger than asexual gametophytes. Large gametophytes were wide-cordate, whereas smaller ones tended to be narrow-spathulate. CONCLUSIONS: Gametophyte size of O. cinnamomea is negatively related to the population density, which significantly affects gametophytes' sexual expression. The presence of unisexual and bisexual gametophytes at intermediate densities indicates that both intergametophytic and intragametophytic selfing may occur.     

Effect of temperature on the development of Saccharina japonica gametophytes

Spores (collected at 10?±?1 °C, 2 h after releasing) and young gametophytes (newly generated from spores cultured at 10?±?1 °C for 8 days) of Saccharina japonica were first cultured at 15?±?1, 19?±?1, and 23?±?1 °C for various times (2, 5, and 8 days) and then at 10?±?1 °C (culturing patterns S and G, respectively). Spores were also cultured at a constant of 10?±?1 °C (pattern C) and used as the control. The length and percentage of young gametophytes, size and percentage of gametophytes, and ratio of female to male gametophytes were measured in order to determine the effect of temperature on the development of gametophytes. Temperature and exposure time of spores and young gametophytes at the first culturing temperature significantly affected the development of gametophytes as were indicated by all biological parameters except the ratio of female to male gametophytes. The spores were more sensitive to temperature than young gametophytes. Gametophytes developed from the spores that survived temperature stress can recover their growth. High temperature selection at the early developmental stages of gametophytes was effective for screening gametophytes applicable for breeding high temperature-resistant varieties and hybrids.     

Preferential accumulation of d-pinitol in Acrostichum aureum gametophytes in response to salt stress

Growth and metabolic responses to salt stress were studied in gametophytes of Acrostichum aureum L. (a mangrove fern). Gametophytes were cultured in 0–170 m M NaCl solutions. The growth of gametophytes was best in low NaCl concentrations (35 and 85 m M ), and was retarded at higher NaCl concentrations. Photosynthetic rate of gametophytes was also significantly reduced when grown in high NaCl concentrations. Severe salt stress (>120 m M NaCl) led to a preferential accumulation of d -pinitol in gametophytes, whereas the sporophyte accumulated d -1- O -methyl- muco -inositol. The content of d -pinitol reached up to 50% of the soluble carbohydrate pool of gametophytes under 155 and 170 m M NaCl. The accumulation of d -pinitol and other cyclitols in gametophytes was correlated with the retention of photochemical efficiency of photosystem II and the survival of gametophytes after transfer to solutions containing 340 and 600 m M NaCl, respectively.     

不同光照度下水蕨配子体叶绿素荧光特性的研究

以模式植物水蕨的两性配子体和雄配子体为材料,研究了不同光照度下蕨类植物配子体叶绿素荧光参数的差异,探讨水蕨配子体光系统Ⅱ(PSⅡ)对不同光照的响应规律.结果表明:同一光照度条件下,水蕨两性配子体的实际光化学效率(Ф_(PSⅡ))和潜在光化学效率(F_v/F_m)均高于雄配子体,但无显著差异,此时两者间的光化学猝灭系数(q_p)和非光化学猝灭系数(q_N)值也无显著差异;在4 000 lx光照条件下,两性配子体PSⅡ驱动的电子传递速率(ETR_(PSⅡ))显著高于雄配子体.随着光照度的增加,水蕨两性配子体的Ф_(PSⅡ)、ETR_(PSⅡ)和q_p值逐渐增加,且在4 000 lx光照下显著增加,但F_v/F_m和q_N值无显著变化;而雄配子体的Ф_(PSⅡ)、ETR_(PSⅡ)、F_v/F_m、q_p和q_N值均呈先增后减趋势,但各光照处理间无显著差异.研究发现,水蕨两性配子体PSⅡ的活性相对比雄配子体高;两性配子体和雄配子体的光保护能力相似;光照度对水蕨雄配子体的光合能力没有显著影响,而4 000 lx的光照度对水蕨两性配子体的生长最有利.     

麦秆蹄盖蕨（Athyrium fallaciosum）配子体的发育规律及播种密度对配子体性别分化的影响

在组织培养条件下,对麦秆蹄盖蕨（Athyrium fallaciosum）配子体发育的连续过程进行了详细观察。结果表明:麦秆蹄盖蕨孢子为四面体型; 孢子萌发为书带蕨型（Vittaria-type）;原叶体发育为铁线蕨型（Adiantum-type）,成熟原叶体为对称的心形;精子器近圆球形,成熟颈卵器细长,常向原叶体基部倾斜或弯曲。常规播种条件下,发现麦秆蹄盖蕨配子体有雌配子体、雄配子体、雌雄同体配子体和无性配子体类型。配子体的性别随密度不同而呈现一定的变化趋势,雄配子体随密度增大呈上升趋势;雌配子体随密度增大先上升后下降;雌雄同体配子体和无性配子体随密度变化不大。雌配子体和雌雄同体配子体具颈卵器数目一般为10～15个;精子器数目随密度的增大逐渐减少,雄配子体中具有约50个精子器,雌雄同体配子体具有约20个精子器。     

Gametophyte contribution to sporophyte growth on the basis of carbon gain in the fern <Emphasis Type="Italic">Thelypteris palustris</Emphasis>: effect of gametophyte organic-matter production on sporophytes

At an early stage of growth gametophytes support the sporophytes of ferns. Young sporophytes become independent of gametophytes when the first leaves develop. Although large fern gametophytes produce multiple archegonia simultaneously, only one sporophyte is typically established on one gametophyte. The number of sporophytes is believed to be controlled in two possible directions, from gametophyte to sporophyte or from preceding sporophyte to another sporophyte. To investigate the effects of gametophytes on their sporophytes, we studied the relationship between organic matter production by gametophytes and the growth of young sporophytes of Thelypteris palustris. We cut gametophytes in half (CGs) to reduce the gametophytes’ production of matter. There was no significant difference between the growth of sporophytes on intact gametophytes (IGs) and that on CGs. According to our estimates, based on the rate of organic matter production, the large gametophyte was able to produce two or more sporophytes. The resources required for CGs to make similar-sized sporophytes was twice that for IGs. In polyembryony each of the multiple sporophytes was similar in size to the single sporophytes. Resource limitation does not seem to explain why fern gametophytes establish single sporophytes.     

Growth and gender in the gametophyte of Blechnum spicant L

The growth and gender in the gametophyte of Blechnum spicant L. were strongly affected by its origin, spore or mature homogenized gametophytes, and also by the addition of plant growth regulators to the culture medium. Spore-derived gametophytes cultured in Murashige and Skoog liquid medium were females and heart-shaped, whereas those derived from mature homogenized gametophytes were shorter and male or asexual (1:3) because of the release of antheridiogen to the culture medium. In the latter, maleness was especially increased by the addition of BA. This cytokinin is a strong inductor of maleness in homogenized cultures; however, even though BA influenced sexual organ formation in spore-derived gametophytes, it does not change the␣female sexual pattern that these gametophytes have. Separate male and female populations of gametophytes were obtained in this work.     

海带(Laminaria japonica)丝状体遗传多样性的比较研究

采用垂直板式聚丙烯酰胺凝胶电泳技术对分别来自中国青岛与日本北海道海带(Laminaria japonica)丝状体的6种酶系统（乙醇脱氢酶、谷氨酸脱氢酶、异柠檬酸脱氢酶、乳酸脱氢酶、山梨醇脱氢酶和超氧化物歧化酶）进行了检测,发现存在22个基因位点,分析了不同来源海带丝状体的遗传多样性与遗传分化程度。结果表明：日本北海道海带丝状体的预期杂合度、每个位点有效等位基因数等遗传参数均大于中国青岛海带丝状体。对日本北海道海带丝状体与中国青岛海带丝状体的遗传相似系数和遗传距离进行了计算分析,显示两者发生了遗传分化。日本北海道海带丝状体的遗传多样性高于中国青岛海带丝状体。研究结果还发现在中国青岛海带丝状体的Idh、Ldh 和Sdh中,以及日本北海道海带丝状体的Adh、Gdh、Idh、Ldh、Sdh和Sod中存在着不同迁移率的不等距双带酶,可能由特殊基因控制,并集中在第3个基因位点上。     

蕨类植物配子体发育的研究

研究了福建观音座莲、华南紫萁、粗齿紫萁、粗齿桫椤、溪边凤尾蕨、娱蚣草、狭翅铁角蕨、乌毛蕨等21种庆类植物的配子体发育过程。结果如下：(1)对孢子和配子体性状的UPG—MA法聚类分析结果表明,秦仁昌分类系统中亲缘关系近的种类在孢子和配子体性状方面相似性也高,但也有少数例外的情况;(2)蕨类植物的配子体发育有许多共性,但也存在许多不同点;(3)配子体发育中出现的某些性状是稳定的,可以作为分类的依据。     

HAPLOID PARTHENOGENETIC SPOROPHYTES OF LAMINARIA JAPONICA (PHAEOPHYCEAE)1

Parthenogenetic sporophytes were obtained from three strains of Laminaria japonica Areschoug. These sporophytes grew to maturity in the sea, producine spores that all grew into female gametophytes. These female gametophytes gave rise to another generation of parthenogenetic sporophytes during the next year, so that by the year 1990 parthenogenetic sporophytes had been cultivated for 12, 9, and 7 generations, respectively, for the three strains. When female gametophytes from parthenogenetic sporophytes were combined with normal male gametophytes, normal sporophytes that reproduced and gave rise to both female and male gametophytes were obtained. The parthenogenetic sporophytes were shorter and narrower than the normal sporophytes of the same strain. Chromosome counts on mature sporophytes showed that normal sporophytes (from fertilized eggs) were diploid (2n = approximately 40) and that the spores they produced were haploid (n = approximately 20), while nuclei from both somatic and sporangial cells in parthenogenetic sporophytes were haploid. All gametophytes were haploid. Young sporophytes derived from cultures with both female and male gametophytes were diploid, while young, sporophytes obtained from female gametophytes from parthenogenetic sporophytes had haploid, diploid, or polyploidy chromosome numbers. Polyploidy was associated with abnormal cell shapes. The presence of haploid parthenogenetic sporophytes should be use in breeding kelp strains with useful characteristics, since the sporophyte phenotype is expressed from a haploid genotype which can be more readily selected.     

Tolerance of gametophytes of Acrostichum aureum (L.) to salinity and water stress

Tolerance of gametophytes of Acrostichum aureum to NaCl and dehydration was investigated under controlled conditions following the changes in chlorophyll fluorescence parameters (Fv/Fm, qP, qN). Salt tolerance was increased by growing gametophytes in low concentrations of NaCl. However, such treatment could not increase the tolerance of gametophytes to dehydration. Under water stress, a decrease in photochemical quenching (qP) was accompanied by an increase in non-photochemical quenching (qN). Under salt stress, qP also decreased, but qN did not change significantly in salt-hardened gametophytes.     

WILD GAMETOPHYTES OF PHANEROSORUS MAJOR (MATONIACEAE)

The gametophytes of Phanerosorus major collected from wild populations in Seram Island are described. Young gametophytes are slender, ribbon-like and uniformly one cell thick. They develop to old gametophytes with a broad thick cushion and coarsely ruffled wings. The gametophytes are monoecious and protandrous, although archegonia-bearing thalli occasionally become antheridia-bearing. Massive antheridia form on the ventral surface of young and old gametophytes while archegonia are borne on the cushion of old ones. Both young and old gametophytes reproduce vegetatively. The gametophytic characters are compared with those of Matonia. The life cycle of P. major is discussed with reference to its ecology.     

Arbuscular mycorrhizal colonization in field-collected terrestrial cordate gametophytes of pre-polypod leptosporangiate ferns (Osmundaceae,Gleicheniaceae, Plagiogyriaceae,Cyatheaceae)

To determine the mycorrhizal status of pteridophyte gametophytes in diverse taxa, the mycorrhizal colonization of wild gametophytes was investigated in terrestrial cordate gametophytes of pre-polypod leptosporangiate ferns, i.e., one species of Osmundaceae (Osmunda banksiifolia), two species of Gleicheniaceae (Diplopterygium glaucum, Dicranopteris linearis), and four species of Cyatheales including tree ferns (Plagiogyriaceae: Plagiogyria japonica, Plagiogyria euphlebia; Cyatheaceae: Cyathea podophylla, Cyathea lepifera). Microscopic observations revealed that 58 to 97 % of gametophytes in all species were colonized with arbuscular mycorrhizal (AM) fungi. Fungal colonization was limited to the multilayered midrib (cushion) tissue in all gametophytes examined. Molecular identification using fungal SSU rDNA sequences indicated that the AM fungi in gametophytes primarily belonged to the Glomeraceae, but also included the Claroideoglomeraceae, Gigasporaceae, Acaulosporaceae, and Archaeosporales. This study provides the first evidence for AM fungal colonization of wild gametophytes in the Plagiogyriaceae and Cyatheaceae. Taxonomically divergent photosynthetic gametophytes are similarly colonized by AM fungi, suggesting that mycorrhizal associations with AM fungi could widely occur in terrestrial pteridophyte gametophytes.     

Effect of Heavy Metals (Cd, Cu) on the Gametophytes of Laminaria japonica Aresch

Effects of various concentrations of two heavy metals, namely Cd and Cu, on gametophytes of Laminariajaponica Aresch were determined by recording morphological changes of gametophytes, determining pH values and the heavy metal content of the culture solution, calculating the germination rate of sporophytes, and observing heavy metal (Cd) distribution using a fluorescence microscope. The results showed that heavy metals damaged the gametophytes, and were even lethal, and that the higher the concentration of heavy metal ions, the greater the injury to gametophytes. Gametophytes could not survive in culture solutions containing more than 100 mg/L Cd and 50 mg/L Cu and were only able to survive in culture solution containing a mixture of Cd and Cu up to a concentration of 10 mg/L, which indicates that gametophytes have a higher tolerance to Cd than Cu and that multiple heavy metal ions in solution markedly aggravate the damage to gametophytes compared with individual heavy metal ions. With increases in the concentration of the heavy metal, the burgeoning rate of sporophytes decreased acutely, and solutions containing multiple heavy metal ions caused even more marked harm to sporophytes than solutions containing a single heavy metal ion, because most sporophytes died in mixed solutions. The pH value of the culture medium dropped immediately at the beginning (the first day) of treatment, increased over the following days, and then decreased again. The pH of culture media containing multiple heavy metal ions showed greater variation than media containing a single heavy metal ion, with the extent of the decrease in pH of culture media containing multiple ions being greatest during the last period of the experiment. With increases in the concentration of heavy metals, the capacity of gametophytes to accumulate these ions increased. The blue fluorescent light emitted by the Cd- and Cd-binding protein complex existing in gametophytes in media containing different concentrations of Cd showed clearly the distribution of the ion in gametophytes and the results obtained were consistent with distribution determined using other methods.All results of the present study showed that gametophytes of L. japonica play a remarkable role as heavy metal decontaminators, especially with regard to Cd.     

Growth Promotion of Vegetative Gametophytes of <Emphasis Type="Italic">Undaria pinnatifida</Emphasis> by Blue Light

Through an acclimation period of 10 days, compared to white light, the maximal net photosynthetic rates were significantly higher for gametophytes of Undaria pinnatifida cultivated under blue light (400–500 nm), and were lower under red light (600–700 nm). Chlorophyll c and the carotenoid content of gametophytes were similar under blue light and red light but were much lower under white light. The growth rate of female gametophytes under blue light was higher than that under other lights, and the growth rate of male gametophytes showed little variation with respect to blue and white light. Male and female gametophytes were mixed together to form sporophytes under white, blue and red light. After approximately 5 days, 50% gametophytes became fertile under blue and white light, but remained vegetative under red light after 10 days.     

Gametophytic phase of Alsophila odonelliana (Cyatheaceae)

The gametophytic morphology and development of Alsophila odonelliana (Alston) Lehnert, have been studied through in vitro cultures. This species grows in southern Bolivia and northwestern Argentina. The spores are uniform in structure, but not in size; a certain percentage being smaller than the average. 16 spores per sporangium were found. The germination is of the Cyathea type. It was found that spores stored at 4°C can maintain their viability for over two years. The maximum value of germination depends on spore age. The filamentous gametophytes are 4–16 cells long. Young gametophytes have 1–2 branches that give rise to new gametophytes. Male, female, bisexual and neuter gametophytes were found. Propagules were frequently found in neuter gametophytes, and female and bisexual gametophytes were found to have chlorophyll containing scales. The antheridia are made up of five cells and produce non‐viable spermatozoids. The archegonia have necks formed by four columns with four cells each. Most of the gametophytic phase is documented with photomicrographs.     

Tolerance of gametophytes of Acrostichum aureum (L.) to salinity and water stress

Tolerance of gametophytes of Acrostichum aureum to NaCl and dehydration was investigated under controlled conditions following the changes in chlorophyll fluorescence parameters (Fv/Fm, qP, qN). Salt tolerance was increased by growing gametophytes in low concentrations of NaCl. However, such treatment could not increase the tolerance of gametophytes to dehydration. Under water stress, a decrease in photochemical quenching (qP) was accompanied by an increase in non-photochemical quenching (qN). Under salt stress, qP also decreased, but qN did not change significantly in salt-hardened gametophytes. This revised version was published online in June 2006 with corrections to the Cover Date.