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INTRODUCTION The most obvious manifestation of gravitys effect on plants is the downward bending of roots and the upward growth of shoots. Gravity is an important factor in plant development (Barlow, 1995). The starch-statolith hypothesis proposed by Haberlandt and Nmec (Audus, 1962) is the most widely accepted view of how plants perceive gravity. Physiological data suggested that the amyloplast containing starch granules act as the statolith in higher plants. Sedimented amyloplasts ar… 相似文献
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Jiang-hua Shi Xi Hao Zhong-chang Wu Ping Wu 《Journal of Zhejiang University. Science. B》2009,10(10):777-783
Root gravitropism is one of the important factors to determine root architecture. To understand the mechanism un-derlying root gravitropism, we isolated a rice (Xiushui63) mutant defective in root gravitropism, designated as glsl. Vertical sections of root caps revealed that glsl mutant displayed normal distribution of amyloplast in the columella cells compared with the wild type. The glsl mutant was less sensitive to 2,4-dichlorophenoxyacetic acid (2,4-D) and a-naphthaleneacetic acid (NAA) than the wild type. Genetic analysis indicated that the phenotype of glsl mutant was caused by a single recessive mutation, which is mapped in a 255-kb region between RM16253 and CAPSI on the short arm of chromosome 4. 相似文献
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Ammonium (NH4
+) is an important form of nitrogen nutrient for most plants, yet is also a stressor for many of them. However, the primary
events of NH4
+ toxicity at the cellular level are still unclear. Here, we showed that NH4
+ toxicity can induce the root cell death in a temporal pattern which primarily occurs in the cells of root maturation and
elongation zones, and then spreads to the cells in the meristem and root cap. The results from the NH4
+-hypersensitive mutant hsn1 further confirmed our findings. Taken together, NH4
+ toxicity inhibits primary root growth by inhibiting cell elongation and division and inducing root cell death. 相似文献
4.
Hong-bo Zhang Hai-feng Zhang Qi-he Chen Hui Ruan Ming-liang Fu Guo-qing He 《Journal of Zhejiang University. Science. B》2009,10(10):769-776
Proteinase A (PrA), encoded by PEP4 gene, is a key enzyme in the vacuoles of Saccharomyces cerevisiae. We characterized the effects of PrA on cell growth and glucose metabolism in the industrial S. cerevisiae WZ65. It was observed that the lag phase of cell growth of partial PEP4 gene deletion mutant (36 h) and PrA-negative mutant (48 h) was significantly ex-tended, compared with the wild type strain (24 h) (P<0.05), but PrA had no effect on glucose metabolism either under shaking or steady state cultivations. The logistic model was chosen to evaluate the effect of PrA on S. cerevisiae cell growth, and PrA was found to promote cell growth against insufficient oxygen condition in steady state cultivation, but had no effect in shaking culti-vation. The effects of glucose starvation on cell growth of partial PEP4 gene deletion strain and PrA-negative mutant were also evaluated. The results show that PrA partial deficiency increased the adaption ofS. cerevisiae to unfavorable nutrient environment, but had no effect on glucose metabolism under the stress of low glucose. During heat shock test, at 60 ℃ the reduced cell viability rate (RCVR) was 10% for the wild type S. cerevisiae and 90% for both mutant strains (P<0.01), suggesting that PrA was a negative factor for S. cerevisiae cells to survive under heat shock. As temperatures rose from 60 ℃ to 70 ℃, the wild type S. cerevisiae had significantly lower relative glucose consumption rate (RGCR) (61.0% and 80.0%) than the partial mutant (78.0% and 98.5%) and the complete mutant (80.0% and 98.0%) (P<0.05), suggesting that, in coping with heat shock, cells of the PrA mutants increased their glucose consumption to survive. The present study may provide meaningful information for brewing industry; however, the role of PrA in industrial S. cerevisiae physiology is complex and needs to be further investigated. 相似文献
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Understanding the growth and physiological responses of rice to upland conditions would be helpful for designing treatments
to improve the tolerance of rice under a rainfed system. The objective of this study was to investigate the initiation, elongation
and membrane stability of seminal, lateral and adventitious roots of upland rice after 9-d upland condition treatment. Compared
with control roots under waterlogged conditions, upland water deficiency conditions favor seminal and lateral root growth
over adventitious root growth by accelerating seminal root elongation, promoting lateral root initiation and elongation, and
reducing the elongation and number of adventitious roots. Enhanced total root number and length resulted in increase of total
root dry weight and thereby increasing the root-to-shoot ratio. Organic compound leakage from seminal root tips and adventitious
roots increased progressively to some extent with upland culture duration, while significant increases in semial root tips
were the consequence of loss of membrane integrity caused by the upland-condition enhanced growth.
Project (No. G1999011700) supported by National Key Basic Research Special (863) Foundation of China 相似文献
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近年来，土壤中可溶性铝增加，对作物生长产生重要影响，本文研究了酸性条件下不同浓度Al^3＋对玉米根芽生长的影响。结果表明，Al对玉米根芽的生长有显著的抑制作用．且随着浓度的升高抑制作用显著加强，但时于根的生长Al^3＋浓度有一个相对促进其生长的浓度（0．5mg／L）；同时，高浓度的Al^3＋能诱导玉米根尖染色体发生多种类型畸变。 相似文献
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Disparity in the root morphology of six rice (Oryza sativa L.) genotypes varying in potassium (K) efficiency was studied with three K levels: 5 mg/L (low),10 mg/L (moderate) and 40 mg/L (adequate) in hydroponic culture.Morphological parameters included root length,surface area,volume and count of lateral roots,as well as fine (diameter<0.2 mm) and thick (diameter>0.2 mm) roots.The results indicate that the root growth of all genotypes was reduced under low K,but moderate K deficiency increased the root length of the efficient genotypes.At deficient and moderate K levels,all the efficient rice genotypes developed more fine roots (diameter<0.2 mm) than the inefficient ones.Both fine root count and root surface area were found to be the best parameters to portray K stress in rice.In accordance with the root morphology,higher K concentrations were noted in shoots of the efficient genotypes when grown at moderate and deficient K levels,indicating that root morphology parameters are involved in root uptake for K and in the translocation of K up to shoots.K deficiency affected not only the root morphology,but also the root ultra-structure.The roots of high-efficient genotypes had stronger tolerance to K deficient stress for root membrane damage,and could maintain the developed root architecture to adapt to the low K growth medium. 相似文献
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用化工厂废水、皮革厂废水和该两厂的混合废水分别对水稻种子和蚕豆根尖进行处理,观察水稻种子发芽率及幼苗的生长状况,以及蚕豆根尖细胞的微核率、异形核率和有丝分裂指数等情况.结果表明：化工厂废水对水稻种子的发芽率及幼苗的生长均有极其显著的抑制作用;皮革厂废水及皮革厂与化工厂的混合废水对水稻的发芽率及幼苗生长的影响均不显著.工业废水能诱发蚕豆根尖细胞产生较高的微核率和异形核率.皮革厂废水61.20‰,两厂混合废水为34.34‰,化工厂废水为10.10‰;异形核率：化工厂废水为10%,两厂混合废水为5.16%皮革厂废水为1.38%;化工厂废水及两厂混合废水对蚕豆根尖细胞分裂具有明显的抑制和危害,皮革厂废水对蚕豆根尖细胞有丝分裂指数影响不显著.说明化工厂和皮革厂废水对农作物具有明显的细胞遗传毒性. 相似文献
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用不同浓度（１００—５００ｍ ｇ／１）的硝酸锌溶液处理蒜小鳞茎,发现随着培养时间的延长和浓度的增加,毒害加重,外观表现为根尖生长受阻,内部表现为细胞有丝分裂指数下降,而分裂细胞异常率增高。分裂细胞异常主要表现为染色体粘连,染色体解体,微核及核解体等,但锌对蒜的毒害作用明显低于镉和铅 相似文献
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S_(3307)和PP_(333)对龙眼实生苗生长发育和抗寒力的影响 总被引：2，自引：0，他引：2
本试验研究了两种三唑类植物生长延缓剂S_(3307)和PP_(333)对龙眼实生苗生长发育和抗寒力的影响,结果表明:1mg/L的S_(3307)和10mg/L的PP_(333)浸种、浸根均能促进幼苗根系的生长,显著提高根冠比,幼苗断根移栽时,S_(3307)和PP_(333)均能促进主根断口处萌发侧根,使幼苗迅速恢复生长发育,在低浓度下,S_(3307)的“控上促下”活性明显大于PP_(333),高浓度(S_(3307)>50mg/L,PP_(333)>100mg/L)会严重抑制幼苗生长,适宜浓度的S_(3307)和PP_(333)不仅可以加快龙眼砧木育苗速度,而且能明显提高幼苗对低温的抵抗能力。 相似文献
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洋葱水培试验碱法造纸黑液对洋葱根系生长影响研究的结果表明 :黑液对洋葱根系生长影响极为显著 ,影响程度随黑液浓度高低而异 ;高浓度黑液胁迫下 ,洋葱根系不能生长、生长缓慢或出现腐烂 ,其平均长度和生长速率远小于清水或低浓度黑液培养下的根系 ;黑液对根系生长影响不显著的低限稀释倍数为 10 0 0倍 ;Logistic模型可以准确模拟洋葱根系生长过程 相似文献
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姜叶琴 《湖州师范学院学报》2005,27(2):59-61
大蒜在铜、铬、铅、钡四种金属离子溶液中分别培养的实验证明：实验重金属均对大蒜根生长有抑制作用,且随着各重金属离子溶液浓度的增加和处理时间的延长,大蒜根生长的速度变慢或停止.同浓度的不同重金属离子溶液对大蒜根生长的抑制作用,从强到弱依次为：Cu^2＋〉 Cr^3＋〉 Pb^2＋溶液.非重金属Ba^2＋对大蒜根生长无明显影响. 相似文献
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YANG Xiao-cheng DING Jian-ping WANG Bo-chu 《重庆大学学报(英文版)》2007,6(4):227-230
The root development of Actinidia chinensis plantlets was studied in exposure to environmental stress of mechanical vibration at respectively 1 Hz, 2 Hz, 3 Hz, 4 Hz and 5 Hz. The plantlets exposed to vibration stimuli at all those frequencies have a larger total number and a larger total length of roots and a smaller permeability of root plasma-membrane, compared with those cultivated in an environment without vibration stress. Vibration at respectively 1 Hz, 2 Hz, 3 Hz and 4 Hz enhances root activity and the 3 Hz vibration is the most favorable. There is an obvious negative correlation between root activity and permeability of root plasma-membrane. The effects may be explained by the likelihood that mechanical vibration at an appropriate frequency facilitates roots’ absorbing water and minerals which are indispensable to inducing and synthesizing in roots some active substances favorable to growth. Nevertheless, overstress damages the integrity of root plasm-membrane, increases the permeability, and results in the disability of protecting root cells. 相似文献
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Lan-lan Wan Da-qi Zhang Jin-nan Zhang Li-qun Ren 《Journal of Zhejiang University. Science. B》2017,18(6):522-531
Hepatocarcinoma is one of the malignant cancers with significant morbidity and mortality. Immunotherapy has emerged in clinical treatment, owing to the limitation and severe side effects of chemotherapy. In the immune system, natural killer (NK) cells are important effectors required to eliminate malignant tumor cells without the limitation of major histocompatibility complex (MHC) molecule issues. Hence, treatment which could stimulate NK cells is of great interest. Here, we investigated the efficacy of the combined therapy of TT-1 (a mutant of melittin) and interferon-α (IFN-α) on NK cells and human liver cancer HepG-2/Huh7 cells in vitro and in vivo, as well as the mechanism involved. The combination therapy significantly inhibited the growth of HepG-2/Huh7 cells in vivo, but this effect was impaired after depleting NK cells. TT-1 not only up-regulated MHC class I-related chain molecules A (MICA) expression, but also prevented the secretion of soluble MICA (sMICA). Both the mRNA and protein of a disintegrin and metallopeptidase 10 (ADAM 10) in HepG-2/Huh7 cells were decreased after TT-1 treatment. The combined therapy of TT-1 and IFN-α could suppress the growth of HepG-2/Huh7 xenografted tumor effectively via promoting the interaction of NK group 2, member D (NKG2D) and MICA, indicating that TT-1+IFN-α would be a potential approach in treating liver cancer. 相似文献
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本文采用细胞微核技术，研究了不同浓度的Ｈｇ２＋对豌豆根尖细胞哟危害作用，结果表明：当Ｈｇ２＋的浓度为０．０５ｐｐｍ～１．５ｐｐｍ时，豌豆根尖细胞微核细胞率（Ｙ）与Ｈｇ２＋的浓度（Ｘ）星线性正相关，Ｙ＝１．２６７１＋１．４１８３Ｘ，ｒ＝０．９００６。部分报失发黑。 相似文献
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淡水培养对桐花树幼苗根生长的影响 总被引：3，自引：1，他引：2
在全光照条件下用恒定淹水位淡水培养红树植物桐花树(Aegiceras corniculatum)幼苗1年,以人工海水(8g.Kg-1)培养为对照,研究了淡水驯化对桐花树幼苗根的生长指标和根系活力的影响。结果表明:桐花树幼苗根的生物量呈持续增长的趋势,后180d的增长量显著大于前180d,淡水组与人工海水组并未表现出显著差异;两组幼苗的根数、根长和根粗在同一时期没有明显差异,而在不同时期有显著差异;两种处理幼苗的根系活力均出现两个高峰值,分别在6月和9月份,幼苗的根系活力在5～7月份表现为人工海水组大于淡水组,而8～12月份则淡水组高于人工海水组;两种处理的冠根比在同一时期无显著差异。以上结果表明:淡水培养对桐花树幼苗根的生长没有显著不利的影响,表明桐花树对淡水环境具有较强的适应性。 相似文献
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稀土元素(La~(3+))在10~(-8)～10~(-5)mol/L浓度范围内,对绿豆下胚轴切段不定根形成(ARF)有促进作用。10~(-5)mol/LLa3~+与10~(-4)mol/LIBA混合处理时的生根数比用IBA处理的增加20％,即表现出协同效应,La~(3+)在不定根形成中的0～24h内处理时促进作用较大。这说明在ARF的诱导期和起始早期外施适当浓度的La~(3+)有利于根原基形成,并促进不定根形成。 相似文献