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171.
Micropropagation of the actinorhizal plant Hippophae rhamnoides L. (sea-buckthorn) was achieved on Murashige and Skoog (MS) medium supplemented with 1 M of benzylaminopurine (BA). A multiplication frequency of three to five shoots per explant was observed after 28 days. Rooting of these shoots was achieved in a medium containing 1/4 strength MS without growth regulators. The rooted plants were transferred to Turface R artificial substrate and inoculated with pure cultures of two Frankia strains. These plantlets subsequently developed nodules which fixed nitrogen. 相似文献
172.
The HU superfamily of proteins, with a unique DNA-binding mode, has been extensively studied as the primary chromosome-packaging protein of the bacterial superkingdom. Representatives also play a role in DNA-structuring during recombination events and in eukaryotic organellar genome maintenance. However, beyond these well-studied roles, little is understood of the functional diversification of this large superfamily. Using sensitive sequence and structure analysis methods we identify multiple novel clades of the HU superfamily. We present evidence that a novel eukaryotic clade prototyped by the human CCDC81 protein acquired roles beyond DNA-binding, likely in protein-protein interaction in centrosome organization and as a potential cargo-binding protein in conjunction with Dynein-VII. We also show that these eukaryotic versions were acquired via an early lateral transfer from bacteroidetes, where we predict a role in chromosome partition. This likely happened before the last eukaryotic common ancestor, pointing to potential endosymbiont contributions beyond that of the mitochondrial progenitor. Further, we show that the dramatic lineage-specific expansion of this domain in the bacteroidetes lineage primarily is linked to a functional shift related to potential recognition and preemption of genome invasive entities such as mobile elements. Remarkably, the CCDC81 clade has undergone a similar massive lineage-specific expansion within the archosaurian lineage in birds, suggesting a possible use of the HU superfamily in a similar capacity in recognition of non-self molecules even in this case. 相似文献
173.
Resistance to citrus canker induced by a variant of Xanthomonas citri ssp. citri is associated with a hypersensitive cell death response involving autophagy‐associated vacuolar processes 下载免费PDF全文
174.
Trade‐off relationship between productivity and thallus toughness in Laminariales (Phaeophyceae) 下载免费PDF全文
Trade‐off relationships are considered key to understanding the mechanisms supporting the coexistence of multiple species within kelp beds. Thus, information on trade‐offs is expected to contribute to conservation of kelp bed diversity. To test the existence of a trade‐off between productivity and thallus toughness, thallus traits and relationships between the traits were examined for seven species of Laminariales including 24 populations. For each population, photosynthetic capacity per unit biomass (as A mass) and nitrogen (i.e., photosynthetic nitrogen‐use efficiency, PNUE), nitrogen content (as N mass), thallus mass per unit thallus area (as TMA) and force required to penetrate the thallus (as F p, a common index of leaf toughness in land plants by punch test) were determined. A mass increased with increasing N mass. Blades with high N mass showed high A mass. These blades may invest a large proportion of nitrogen to the photosynthetic parts, and consequently exhibit high metabolic rates. Moreover, blades with high N mass tended to be associated with low TMA, and N mass decreased with increasing TMA. A significant negative correlation was observed between TMA and A mass because of the linkage of high A mass with high N mass and high N mass associated with low TMA, while a significant positive correlation was observed between TMA and F p. The two correlations indicate the existence of a trade‐off between productivity and thallus toughness in Laminariales. PNUE showed a significant negative correlation with TMA, which also showed a significant positive correlation with F p as the index of thallus toughness, and therefore a trade‐off relationship between productivity and thallus toughness. 相似文献
175.
176.
Langsdorf G. Buschmann C. Sowinska M. Babani F. Mokry M. Timmermann F. Lichtenthaler H.K. 《Photosynthetica》2000,38(4):539-551
Fluorescence images of leaves of sugar beet plants (Beta vulgaris L. cv. Patricia) grown on an experimental field with different fertilisation doses of nitrogen [0, 3, 6, 9, 12, 15 g(N) m–2] were taken, applying a new multicolour flash-lamp fluorescence imaging system (FL-FIS). Fluorescence was excited by the UV-range (280–400 nm, max = 340 nm) of a pulsed Xenon lamp. The images were acquired successively in the four fluorescence bands of leaves near 440, 520, 690, and 740 nm (F440, F520, F690, F740) by means of a CCD-camera. Parallel measurements were performed to characterise the physiological state of the leaves (nitrogen content, invert-sugars, chlorophylls and carotenoids as well as chlorophyll fluorescence induction kinetics and beet yield). The fluorescence images indicated a differential local patchiness across the leaf blade for the four fluorescence bands. The blue (F440) and green fluorescence (F520) were high in the leaf veins, whereas the red (F690) and far-red (F740) chlorophyll (Chl) fluorescences were more pronounced in the intercostal leaf areas. Sugar beet plants with high N supply could be distinguished from beet plants with low N supply by lower values of F440/F690 and F440/F740. Both the blue-green fluorescence and the Chl fluorescence rose at a higher N application. This increase was more pronounced for the Chl fluorescence than for the blue-green one. The results demonstrate that fluorescence ratio imaging of leaves can be applied for a non-destructive monitoring of differences in nitrogen supply. The FL-FIS is a valuable diagnostic tool for screening site-specific differences in N-availability which is required for precision farming. 相似文献
177.
Review of elevated atmospheric CO2 effects on agro-ecosystems: residue decomposition processes and soil C storage 总被引:15,自引:0,他引:15
A series of studies using major crops (cotton [Gossypium hirsutum L.], wheat [Triticum aestivum L.], grain sorghum [Sorghum bicolor (L.) Moench.] and soybean [Glycine max (L.) Merr.]) were reviewed to examine the impact of elevated atmospheric CO2 on crop residue decomposition within agro-ecosystems. Experiments evaluated utilized plant and soil material collected from
CO2 study sites using Free Air CO2 Enrichment (FACE) and open top chambers (OTC). A incubation study of FACE residue revealed that CO2-induced changes in cotton residue composition could alter decomposition processes, with a decrease in N mineralization observed
with FACE, which was dependent on plant organ and soil series. Incubation studies utilizing plant material grown in OTC considered
CO2-induced changes in relation to quantity and quality of crop residue for two species, soybean and grain sorghum. As with cotton,
N mineralization was reduced with elevated CO2 in both species, however, difference in both quantity and quality of residue impacted patterns of C mineralization. Over
the short-term (14 d), little difference was observed for CO2 treatments in soybean, but C mineralization was reduced with elevated CO2 in grain sorghum. For longer incubation periods (60 d), a significant reduction in CO2-C mineralized per g of residue added was observed with the elevated atmospheric CO2 treatment in both crop species. Results from incubation studies agreed with those from the OTC field observations for both
measurements of short-term CO2 efflux following spring tillage and the cumulative effect of elevated CO2 (> 2 years) in this study. Observations from field and laboratory studies indicate that with elevated atmospheric CO2, the rate of plant residue decomposition may be limited by N and the release of N from decomposing plant material may be
slowed. This indicates that understanding N cycling as affected by elevated CO2 is fundamental to understanding the potential for soil C storage on a global scale.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
178.
179.
结合田间观察和室内试验,对榆木蠹蛾HolcocerusvicariusWalker的生物学特性进行了较为系统的研究。结果表明,榆木蠹蛾在宁夏3年发生1代,幼虫主要危害枝干和根颈部,幼虫在蛀道内越冬,5月下旬老熟幼虫在被害树周围5—10cm深的沙土内分散化蛹,蛹期(21±5)d。6月初成虫开始出现,有2个羽化高峰,分别为6月中旬和7月下旬,成虫羽化当晚即可交尾,交尾当天或第2天产卵,每雌蛾产卵最多达720粒,卵期(17±5)d,孵化率为72%~88%。未交尾雌雄成虫寿命为5—6d,交尾后雌雄成虫寿命缩短为3—5d。初孵幼虫于6月中旬始见,10月下旬幼虫开始越冬。幼虫孵化后,先危害韧皮部,常10多条聚集在一起,稍大一点即蛀入木质部。本研究为制定切实可行的榆木蠹蛾有效防治提供理论依据。 相似文献
180.
In this study, conducted in French Guiana, a part of the native range of the fire ant Solenopsis saevissima, we compared the cuticular hydrocarbon profiles of media workers with previous results based on intraspecific aggressiveness tests. We noted a strong congruence between the two studies permitting us to delimit 2 supercolonies extending over large distances (up to 54 km), a phenomenon known as unicoloniality. Solenopsis geminata workers, taken as an out‐group for cluster analyses, have a very different cuticular hydrocarbon profile. Because S. saevissima has been reported outside its native range, our conclusion is that this species has the potential to become invasive because unicoloniality (i.e., the main attribute for ants to become invasive) was shown at least for the Guianese population. 相似文献