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From 1997 to 1999Cycas debaoensis Y. C. Zhong & C. J. Chen andC. changjiangensis N. Liu were described from South China. The wild populations ofCycas szechuanensis were discovered in Fujian.Cycas guizhouensis K. M. Lan & R. F. Zou at the higher elevations andC. segmentifida D. Y. Wang & C. Y. Deng at the lower elevations along the Nanpanjiang River should be good species, which were treated by
Chen and Wang (1995) and Chen and Stevenson (1999) as synonyms forC. szechuanensis. However, 11 other new species have been reduced by Chen and Stevenson (1999) and the present authors. They areC. longlinensis Huang T. Chang & Y. C. Zhong,C. xilinensis Huang T. Chang & Y. C. Zhong, C.multifida Huang T. Chang & Y. C. Zhong, C.longiconifera Huang T. Chang & Y. C. Zhong, andC. acuminatissima Huang T. Chang & Y. C. Zhong, all treated as synonyms ofC. segmentifida. Cycas spiniformis J. Y. Liang,C. longisporophylla F. N. Wei,C. septermsperma Huang T. Chang & H. X. Zhang,C. brevipinnata Huang T. Chang et al. should be synonyms forC. exseminifera F. N. Wei.Cycas miquelii Warb, andEpicycas miquelii (Warb.) de Laub, should be the synonyms forC revoluta because their “stype” specimens are somewhat likeC. revoluta. The Honghe Nature Cycad Reserve forCycas multipinnata andC. hongheensis was recently established in Yunnan. The Debao Cycad Reserve will be established soon. However, most existing cycad reserves
in China have not been so successful because of shortages of funding and poor management. In ex situ conservation the Qingxiushan
Cycad Garden in Nanning, Guangxi, was established. Cycad nurseries have begun to appear in some villages in South China. 相似文献
74.
MiR‐342 controls Mycobacterium tuberculosis susceptibility by modulating inflammation and cell death
Beibei Fu Xiaoyuan Lin Shun Tan Rui Zhang Weiwei Xue Haiwei Zhang Shanfu Zhang Qingting Zhao Yu Wang Kelly Feldman Lei Shi Shaolin Zhang Weiqi Nian Krishna Chaitanya Pavani Zhifeng Li Xingsheng Wang Haibo Wu 《EMBO reports》2021,22(9)
Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb) that places a heavy strain on public health. Host susceptibility to Mtb is modulated by macrophages, which regulate the balance between cell apoptosis and necrosis. However, the role of molecular switches that modulate apoptosis and necrosis during Mtb infection remains unclear. Here, we show that Mtb‐susceptible mice and TB patients have relatively low miR‐342‐3p expression, while mice with miR‐342‐3p overexpression are more resistant to Mtb. We demonstrate that the miR‐342‐3p/SOCS6 axis regulates anti‐Mtb immunity by increasing the production of inflammatory cytokines and chemokines. Most importantly, the miR‐342‐3p/SOCS6 axis participates in the switching between Mtb‐induced apoptosis and necrosis through A20‐mediated K48‐linked ubiquitination and RIPK3 degradation. Our findings reveal several strategies by which the host innate immune system controls intracellular Mtb growth via the miRNA‐mRNA network and pave the way for host‐directed therapies targeting these pathways. 相似文献
75.
Effect of phosphorus deficiency on aluminium-induced citrate exudation in soybean (Glycine max) 总被引:5,自引:0,他引:5
Aluminium (Al) toxicity or phosphorus (P) deficiency can induce exudation of organic acids from the roots of some plants, which is believed to be a tolerance mechanism against Al toxicity or P deficiency. In the present study, the effect of P deficiency on Al-induced citrate exudation was investigated in three soybean varieties differing in low-P tolerance. P starvation alone failed to induce secretion of organic acids from all three soybean varieties. However, P deficiency altered Al-induced citrate exudation over time, showing a complex interaction. Short × term P starvation (4 days) produced up to 50% increase in Al-induced citrate secretion, while longer-term (10 days) starvation reduced Al-induced citrate secretion to trace amounts. However, after a further 1 day in complete nutrient solution for recovery, Al-induced citrate exudation from the recovered roots was approximately 6 times higher than that from the continuously P-starved plants, but still approximately 3.6 times lower than that from the P-sufficient control. With increasing P or Al supply, Al-induced citrate exudation increased, while Al accumulation in soybean roots decreased in parallel with the decrease of P supply. The photosynthetic rate, stomatal conductance and transpiration were decreased by P deficiency, whereas the intracellular CO2 concentration was increased. These findings indicate that P nutrition has a significant effect on Al-induced citrate exudation and Al accumulation in soybean root apices. 相似文献
76.
A comparative study on the aluminium- and copper-induced organic acid exudation from wheat roots 总被引:1,自引:0,他引:1
Hai Nian Zheng Ming Yang Sung Ju Ahn Zhi Jun Cheng Hideaki Matsumoto 《Physiologia plantarum》2002,116(3):328-335
It is well established that aluminium (Al) and some heavy metals can elicit organic acid exudation from a range of species. In the present research we found that copper (Cu) can also induce organic acid exudation from the roots of wheat, rye, triticale, maize and soybean. Using intact wheat plants, we made a comparative study of Al- and Cu- induced organic acid exudation. In 5-day-old wheat seedlings, severe Cu stress (40 µ M CuCl2 ) mainly induced the exudation of malate and citrate, and Al-tolerant genotypes could release significantly greater amounts of malate than Al-sensitive genotypes. The time course of the exudation of malate and citrate from the roots of 5-day-old seedlings of wheat (cv. Atlas) in 200 µ M AlCl3 was similar to that in 40 µ M CuCl2 . In older wheat plants (15-day-old), moderate Cu stress (12 µ M CuCl2 ) induced the exudation of large amounts of citrate and addition of Al or La sharply reduced Cu-induced citrate exudation, while Cu or La did not affect Al-induced malate efflux. When half of the root system of Atlas wheat was immersed in Al- or Cu-containing solution and the remaining half in Al- or Cu-free solution, organic acids were only exuded into the solution containing Al or Cu. This suggests that no long distance signal transport is involved in organic acid exudation induced by Al or Cu, and that direct contact of Al or Cu with plant roots is a prerequisite for the induction of organic acid exudation. The anion-channel inhibitor niflumic acid (NIF) significantly stimulated the exudation of both citrate and malate from 5-day-old wheat seedlings under severe Al or Cu stress. Our results suggest that Cu-induced organic acid efflux may be a common response, which may play a role in alleviating Cu toxicity in plants. 相似文献
77.
烟叶贮存期害虫的控制技术 总被引:2,自引:0,他引:2
烟叶在贮存期中易受虫害 ,烟叶受害后损失在 2 %~ 3%。因而对其防治必须高度重视 ,采用综合性的控制对策能收到较好的防治效果。 相似文献
78.
详细研究了托叶铁科两属的2种代表植物Stangeria eriopus和Bowenia serrulata的羽片脉序和羽片解剖学,两个属在气孔器特征与不具副传输组织方面极为相似。而在气孔的分布,羽片脉序式样与叶缘形态,粘液道的有无,海绵组织与栅栏组织的分化。工字厚壁组织与表皮细胞垂周壁特征方面则有较大的差异。将这些特征与苏铁科和泽米铁科作了比较,并讨论了这些特征在系统学上的意义。研究结果支持Stevenson(1992)将该科分为两亚科以及托叶铁科是介入苏铁科与泽米铁科之间的观点。 相似文献
79.
NaCl处理引起小麦幼苗干重下降 ,盐敏感品种比耐盐品种下降幅度要大。盐敏感品种的拒Na 能力为 35 %左右 ,耐盐品种的拒Na 能力为 5 0 %~ 6 0 %左右 ,这表明耐盐品种的拒Na 能力远远大于盐敏感品种。不同耐盐性小麦的拒Na 部位不同 ,盐敏感品种的拒Na 部位主要在根茎结合部 ,而耐盐品种的拒Na 部位主要在根部 相似文献
80.