拟南芥盐胁迫应答相关基因AtGRP9的克隆及表达

利用拟南芥cDNA文库在裂殖酵母中的功能性表达 ,从拟南芥中分离了一个编码富甘氨酸蛋白 (glycine richprotein ,GRP)的cDNA克隆 (其基因被命名为AtGRP9)。在裂殖酵母中大量表达AtGRP9cDNA能显著提高细胞的耐盐性。在拟南芥中 ,AtGRP9基因的表达受盐胁迫诱导 ,其表达具有根器官特异性 ;而且 35S启动子组成形成超量表达植株的耐盐性明显提高。这些实验结果表明拟南芥AtGRP9可能是一盐胁迫应答相关基因。     

Reproductive ecology of Rhododendron ponticum (Ericaceae) in relict Mediterranean populations

In the southern Iberian Peninsula, Rhododendron ponticum occurs in restricted and vulnerable populations as a Tertiary relict. Population structure and the main phases of the reproductive process were examined in order to shed light on recruitment patterns and limitations. Rhododendron ponticum flowers are self-compatible and attract a diverse array of insects, which are responsible for a considerable number of seeds set in the populations. Nevertheless, only adults form populations, whilst seedlings are scarce and saplings virtually absent (only two juveniles out of 2489 adults sampled). Non-specialized vegetative multiplication by layering was observed. Recruitment failure seems to depend on the scarcity of safe microsites, which are free from drought, for seedling establishment. The observations contrast with R. ponticum 's reputation as an aggressive invader in temperate Atlantic areas. It is proposed that the species shows a variable balance between sexual reproduction and vegetative multiplication depending on environmental conditions. At present, only the latter seems to be prevailing in relict populations in the Iberian Peninsula. This flexible reproductive strategy is also discussed as a mechanism allowing persistence during geological climatic oscillations.  © The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 297–311.     

Herbivory and growth in terrestrial and aquatic populations of amphibious stream plants

1. Many amphibious plant species grow in the transition between terrestrial and submerged vegetation in small lowland streams. We determined biomass development, leaf turnover rate and invertebrate herbivory during summer in terrestrial and aquatic populations of three amphibious species to evaluate advantages and disadvantages of aerial and submerged life.
2. Terrestrial populations had higher area shoot density, biomass and leaf production than aquatic populations, while leaf turnover rate and longevity were the same. Terrestrial populations experienced lower percentage grazing loss of leaf production (average 1.2–5.1%) than aquatic populations (2.9–17.3%), while the same plant dry mass was consumed per unit ground area.
3. Grazing loss increased linearly with leaf age apart from the youngest leaf stages. Grazing loss during the lifetime of leaves was therefore 2.4–3.1 times higher than mean apparent loss to standing leaves of all ages. The results imply that variation in density of grazers relative to plant production can account for differences in grazing impact between terrestrial and aquatic populations, and that fast leaf turnover keeps apparent grazing damage down.
4. We conclude that the ability of amphibious plants to grow submerged permits them to expand their niche and escape intense competition on land, but the stream does not provide a refugium against grazing and constrains plant production compared with the terrestrial habitat.     

Evaluation of a new culture method for mass-propagation of a photoperiod-temperature sensitive genic male sterile rice strain N19S

A newly established culture method was evaluated for application in mass-propagation of a photoperiod-temperature sensitive genic male sterile rice strain. It was found that the new culture method was very efficient for the regeneration of plants from callus of this strain, and a high concentration of 6-benzyladenine necessary for highly efficient plant regeneration culture did not seem to have negative effects on some agronomic traits investigated of the regenerated plants and their progenies. By the new culture method, a large number of plants could be regenerated in a relatively short time (approximately 8×10¹² plants within 300 days) from one naked seed-explant. Because of this, prominent drift of the PTGMS rice strain, which accumulates gradually during the course of propagation of the seeds through generations, in the response to photoperiod-temperature conditions could be avoided when this in vitro culture protocol is employed instead of seed propagation. Differences in rates of pollen fertility and seed setting were found between regenerated plants and seed-grown plants, and between their respective first and second progenies. These differences are also of important application value in two-line rice production: Higher pollen fertility of the regenerated plants can be applied with higher efficiency for the propagation of the strain seeds because they have much higher seed setting by self-fertilization; lower pollen fertility of the regenerated plant progenies will result in much lower seed setting by self-fertilization and is, therefore, conducive to the production of hybrid seeds of higher purity by natural crossing with the other line in the two-line system.     

Troop Extinction and Female Fusion in Wild Japanese Macaques in Yakushima

We observed three cases of troop extinction and two cases of female fusion in the wild population of Japanese macaques on Yakushima Island, Japan. Troops P and T decreased in size relatively slowly over a few years until each troop consisted of only three monkeys. Several months later, the remaining adult female of P merged with the adjacent troop S, followed by the remaining female of T. S subsequently also decreased in size and disappeared about 2 years later. In the early stage of troop decline, the mortality rate of adult females was as low as in a growing troop, but the birthrate was quite low. In the late stage of troop decline, the mortality rate increased and the birthrate remained low. An important factor leading to troop extinction may be an increase in population density and the resulting increase in intergroup competition. During the period when P and T declined and ceased to exist, the range of the adopted troop shifted to cover their previous ranges. In the fused troop, there was no severe aggression directed towards the immigrant females or harassment from residents of the adopted troop and there was affiliative social interaction between the immigrant females and resident members. These results agree with previous reports on female fusion: it occurs when the shrinking group consists of one or no adult member, and the immigrant females are not at a severe disadvantage in their adoptive group. A possible benefit for immigrant females is to avoid disadvantage of one-adult group in conflict with conspecifics. A possible cost for immigrant females is transfer to the other troop or to unfamiliar area or both. The cost to transfer to another group may not be high because the members of the adoptive troop are relatively tolerant to immigrants. The cost to transfer to unfamiliar range may be minimized by immigration to the troop whose range shifted to the immigrants' former range.     

Effects of Chilling Temperature on the Activity of Enzymes of Sucrose Synthesis and the Accumulation of Saccharides in Leaves of Three Sugarcane Cultivars Differing in Cold Sensitivity

The effects of short-term exposure to chilling temperature (10 °C) on sucrose synthesis in leaves of the cold-tolerant sugarcane cultivars Saccharum sinense R. cv. Yomitanzan and Saccharum sp. cv. NiF4, and the cold-sensitive cultivar S. officinarum L. cv. Badila were studied. Plants were grown at day/night temperatures of 30/25 °C, and then shifted to a constant day/night temperature of 10 °C. After 52-h exposure to the chilling temperature, sucrose content in the leaves of NiF4 and Yomitanzan showed a 2.5- to 3.5-fold increase relative to that of the control plants that had been left on day/night temperatures of 30/25 °C. No such increase was observed in Badila leaves. Similarly, starch content in the leaves of NiF4 and Yomitanzan was maintained high, but starch was depleted in Badila leaves after the 52-h exposure. During the chilling temperature, sucrose phosphate synthase (SPS; E.C.2.4.1.14) activity was relatively stable in the leaves of NiF4 and Yomitanzan, whereas in Badila leaves SPS activity significantly decreased. There was no significant change in cytosolic fructose-1,6-bisphosphatase activity for the three cultivars at the chilling temperature. This supports the hypothesis that: (1) on exposure to chilling temperature, sucrose content in sugarcane leaves is determined by the photosynthetic rate in the leaves, and is not related to SPS activity; (2) SPS activity in sugarcane leaves at chilling temperature is to be determined by sugar concentration in the leaves.     

Medicinal Plants in the Atlantic Forest (Brazil): Knowledge, Use, and Conservation

This study focuses on knowledge of medicinal plants among the Caiçaras (rural inhabitants of the Atlantic Forest coast, Brazil). In particular, we examine the use of medicinal plants according to sex and age to reveal general patterns of Caiçara knowledge and use of plant resources. Data collected through 449 interviews at 12 Caiçara communities (Rio de Janeiro and São Paulo coastal sites) include citations of 249 plants and identification of 227 species. We show the importance of introduced as opposed to native plants and of key individuals for the conservation of the Caiçaras-Atlantic Forest.     

High frequency of polyandry in a lek mating system

The adaptive significance of polyandry by female birds in theabsence of direct benefits remains unclear. We determined thefrequencies of polyandrous mating and multiple paternity inthe ruff, a lekking shorebird with a genetic dimorphism inmale mating behavior. More than half of female ruffs mate with, and have clutches fertilized by, more than one male. Individualfemales mate with males of both behavioral morphs more oftenthan expected. Polyandrous mating was more likely followingcopulation interference, but interference was uncommon. Themultiple paternity rate of ruffs is the highest known for avian lekking species and for shorebirds. The general hypothesis thatpair-bond constraints are the major selective factor favoringmultiple mating in birds does not predict our findings. Activegenetic diversification, which has been widely dismissed asa functional explanation for polyandrous mating in birds, mayapply with respect to the behavioral polymorphism in ruffs becauseof a Mendelian genetic basis for male behavioral morph determinationand aspects of male—male cooperation and female choice.However, rates of multiple paternity in other species of lekkingbirds are higher than generally realized, and the potentialbenefits of diversification in general deserve further consideration.