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增强的紫外线-B辐射对几种作物和品种生长的影响 总被引:28,自引:0,他引:28
在温室条件下,以每日2.2kJ/m^2(CK)、8.82kJ/m^2(T1)和12.6kJ/m^2(T2)紫外线-B辐射(UV-B,280~320nm)剂量研究了5个黄瓜(Cucumis satious L.)品种,7个番茄(Lycopsicon esculentum Mill)品种及大豆[Glycine max(L.)Metr.]、菜豆(Phaseolus vulgaris L.)和黄河密瓜(Cucumis melo L.)的生长反应。辐射处理25d后,测定了株高(PH)、叶重(LDW)及总生物量(TDW)、叶面积(LA)、特定叶重(SLW)、上胚轴长度(EL)和番茄品种的子叶节周长(GCN)。结果表明,种间和种内差异显著。但是大多数品种及种的反应指数为负值,并呈现强度负相关效应,说明UV—B辐射抑制了它们的生长发育,但大豆的反应指数在低剂量的处理下为正值反而促进其生长。UV—B胁迫下,大多数种类的上胚轴延伸明显受阻,特定叶重增加,叶面积和生物量减少,番茄的子叶节膨大。作物对UVB辐射的种内和种间反应是作物遗传特性上的差异和对环境的适应能力不同所致。 相似文献
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Phylogenetic diversity of bacteria isolates from the Qinghai-Tibet Plateau permafrost region 总被引:3,自引:0,他引:3
Zhang G Niu F Ma X Liu W Dong M Feng H An L Cheng G 《Canadian journal of microbiology》2007,53(8):1000-1010
The Qinghai-Tibet Plateau in east Asia is a unique and important permafrost environment. However, its microbiology remains largely unexplored to date. In this study, sediment samples were collected from the Qinghai-Tibet Plateau permafrost region, bacteria isolation procedures were performed 8 times, and the samples incubated at 4 degrees C for nearly 3 months. The number of colony forming units (cfu) ranged from 0 to 10(7)/(g dry soil). The quantity of culturable bacteria grew exponentially within the first few weeks, and then slowed gradually to a plateau. Phylogenetic analyses indicated that all the isolates fell into 6 categories: high G+C Gram-positive bacteria, low G+C Gram-positive bacteria, alpha-Proteobacteria, beta-Proteobacteria, gamma-Proteobacteria, and Cytophaga-Flavobacterium-Bacteroides group bacteria. The isolates belong to 19 genera, but the genera Arthrobacter and Pseudomonas were predominant. With the increase in incubation time, the isolated populations changed in terms of both species and their respective quantities. Of the 33 analyzed isolates, 9 isolates related to 8 genera might be new taxa. These results suggest that the Qinghai-Tibet Plateau permafrost region is a specific ecologic niche that accommodates an original microbial assemblage. 相似文献
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Hydrogen peroxide (H2O2), an active oxygen species, is widely generated in many biological systems. The present study demonstrates that H2O2 was generated in seedling explants after the primary roots were removed, and it mediates the auxin response prior to adventitious
root formation in cucumber (Cucumis sativus L. Ganfeng 8). When compared with the controls, treatment of cucumber seedling explants after primary roots removal with
either 20–40 mM H2O2 or 10 μM IAA significantly increased the number of adventitious roots, and treatment with 10–50 mM H2O2 significantly increased the fresh weight of adventitious roots. The effects of H2O2 on promoting the formation and growth of adventitious roots were eliminated by 2 mM ascorbic acid, 100 U CAT or 1 μM DPI,
and the effects of IAA were eliminated by 4 mM ascorbic acid, 100 U CAT or 5 μM DPI. Treatment with either 4 mM ascorbic acid
or 1–5 μM DPI inhibited the formation and growth of adventitious roots, and these inhibitory effects were partly reversed
by exogenous H2O2.Furthermore, a higher concentration of endogenous H2O2 was detected in seedling explants 3 h after the primary roots were removed. However, in 10 μM DPI-treated seedling explants,
the concentration of endogenous H2O2 was markedly reduced by DPI. Results obtained suggest that H2O2 may function as a signaling molecule, involved in the formation and development of adventitious roots in cucumber. 相似文献
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Anthropogenic disturbance equalizes diversity levels in arbuscular mycorrhizal fungal communities
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David García de León John Davison Mari Moora Maarja Öpik Huyuan Feng Inga Hiiesalu Teele Jairus Kadri Koorem Yongjun Liu Cherdchai Phosri Siim‐Kaarel Sepp Martti Vasar Martin Zobel 《Global Change Biology》2018,24(6):2649-2659
The arbuscular mycorrhizal (AM) symbiosis is a key plant–microbe interaction in sustainable functioning ecosystems. Increasing anthropogenic disturbance poses a threat to AM fungal communities worldwide, but there is little empirical evidence about its potential negative consequences. In this global study, we sequenced AM fungal DNA in soil samples collected from pairs of natural (undisturbed) and anthropogenic (disturbed) plots in two ecosystem types (10 naturally wooded and six naturally unwooded ecosystems). We found that ecosystem type had stronger directional effects than anthropogenic disturbance on AM fungal alpha and beta diversity. However, disturbance increased alpha and beta diversity at sites where natural diversity was low and decreased diversity at sites where natural diversity was high. Cultured AM fungal taxa were more prevalent in anthropogenic than natural plots, probably due to their efficient colonization strategies and ability to recover from disturbance. We conclude that anthropogenic disturbance does not have a consistent directional effect on AM fungal diversity; rather, disturbance equalizes levels of diversity at large scales and causes changes in community functional structure. 相似文献
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甘肃洮河流域种子植物区系的初步研究 总被引:19,自引:4,他引:15
甘肃洮河流域地黄土高原和青藏高原的交汇地带,植物种类比较丰富,据初步统计,有种子植物100科,448属,1346种,其种子植物区系具有下列基本特征;种类组成比较丰富,地理成分复杂,联系广泛,但以温带成分占绝对优势,具典型的北温带性质,区系成分过渡性强。根据特有种的分布情况和自然地理特征,洮河中上游植物区系应地横断山脉地区川西北,甘南,青东南地区,洮河下游应属于华北地区黄土高原亚地区。 相似文献
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Mediators,Genes and Signaling in Adventitious Rooting 总被引:3,自引:0,他引:3
Adventitious roots are a post-embryonic root which arise from the stem and leaves and from non-pericycle tissues in old roots
and it is one of the most important ways of vegetative propagation in plants. Many exogenous and endogenous factors regulate
the formation of adventitious roots, such as Ca2+, sugars, auxin, polyamines, ethylene, nitric oxide, hydrogen peroxide, carbon monoxide, cGMP, MAPKs and peroxidase, etc.
These mediators are thought to function as signaling and mediate auxin signal transduction during the formation of adventitious
roots. To date, only a few genes have been identified that are associated with the general process of adventitious rooting,
such as ARL1, VvPRP1, VvPRP2, HRGPnt3, LRP1 and RML, etc. Auxin has been shown to be intimately involved in the process of adventitious rooting and function as crucial role
in adventitious rooting. Great progress has been made in elucidating the auxin-induced genes and auxin signaling pathway,
especially in auxin response Aux/IAA and ARF genes family and the auxin receptor TIR1. Although, some of important aspects of adventitious rooting signaling have been
revealed, the intricate signaling network remains poorly understood. 相似文献
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Shi-Weng Li Lingui Xue Shijian Xu Huyuan Feng Lizhe An 《Environmental and Experimental Botany》2009,65(1):63-71
Hydrogen peroxide (H2O2), an active oxygen species, is widely generated in many biological systems and mediates various physiological and biochemical processes in plants. In this study we demonstrated that the exogenous H2O2 was able to promote the formation and development of adventitious roots in mung bean seedlings. Treatments with 1–100 mM H2O2 for 8–18 h significantly induced the formation and development of adventitious roots. Catalase (CAT) and ascorbic acid, which are H2O2 scavengers or inhibitors, eliminated the adventitious root-promoting effects of exogenous H2O2. H2O2 may have a downstream signaling function in the auxin signaling pathway and be involved in auxin-induced adventitious root formation. 2,3,5-Triiodobenzoic acid (TIBA), an inhibitor of auxin polar transport, strongly inhibited adventitious rooting of mung bean seedlings; however, the inhibiting effects of TIBA on adventitious rooting can be partially reversed by the exogenous IBA or H2O2. Diphenylene iodonium (DPI) strongly inhibits the activity of NADPH oxidase, which is one of the main sources of H2O2 formation in plant cells. DPI treatment strongly inhibited the formation of adventitious roots in mung bean, but the inhibitory effects of DPI on rooting can be partially reversed by the exogenous H2O2 or IBA. This indicates that the formation of adventitious roots was blocked once the generation of H2O2 through NADPH oxidase was inhibited, and H2O2 mediated the IBA-induced adventitious root formation. Furthermore, a rapid increase in the endogenous level of H2O2 was detected during incubation with water 12–36 h after the primary root removal in mung bean seedlings. Three hours after the primary root removal, the generation of endogenous H2O2 was markedly induced in IBA-treated seedlings in comparison with water-treated seedlings. This implies that IBA induced overproduction of H2O2 in mung bean seedlings, and that IBA promoted adventitious root formation via a pathway involving H2O2. Results obtained suggest that H2O2 may function as a signaling molecule involved in the formation and development of adventitious roots in mung bean seedlings. 相似文献
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To study the role of nitric oxide (NO) on enhanced ultraviolet-B (UV-B) radiation (280–320 nm)-induced damage of Cyanobacterium, the growth, pigment content, and antioxidative activity of Spirulina platensis-794 cells were investigated under enhanced UV-B radiation and under different chemical treatments with or without UV-B radiation
for 6 h. The changes in chlorophyll-a, malondialdehyde content, and biomass confirmed that 0.5 mM sodium nitroprusside (SNP), a donor of nitric oxide (NO), could markedly alleviate the damage caused by enhanced UV-B. Specifically,
the biomass and the chlorophyll-a content in S. platensis-794 cells decreased 40% and 42%, respectively under enhanced UV-B stress alone, but they only decreased 10% and 18% in the
cells treated with UV-B irradiation and 0.5 mM SNP. Further experiments suggested that NO treatment significantly increased the activities of superoxide dismutase (SOD)
and catalase (CAT), and decreased the accumulation of O
2
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in enhanced UV-B-irradiated cells. SOD and CAT activity increased 0.95- and 6.73-fold, respectively. The accumulation of
reduced glutathione (GSH) increased during treatment with 0.5 mM SNP in normal S. platensis cells, but SNP treatment could inhibit the increase of GSH in enhanced UV-B-stressed S. platensis cells. Thus, these results suggest that NO can strongly alleviate oxidative damage caused by UV-B stress by increasing the
activities of SOD, peroxidase, CAT, and the accumulation of GSH, and by eliminating O
2
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in S. platensis-794 cells. In addition, the difference of NO origin between plants and cyanobacteria are discussed. 相似文献