Cytokinin induces bacterial pathogen resistance in tomato

Phytohormones are involved in the regulation of plant responses to biotic stress. How a limited number of hormones differentially regulate defence responses and influence the outcome of plant–biotic interactions is not fully understood. In recent years, cytokinin (CK) was shown to induce plant resistance against several pathogens. In the present study, we investigated the effect of CK in inducing tomato resistance against the hemibiotrophic pathogenic bacteria Xanthomonas campestris pv. vesicatoria (Xcv) and Pseudomonas syringae pv. tomato (Pst). We demonstrate that CK enhances tomato resistance to Xcv and Pst through a process that relies on salicylic acid and ethylene signalling. CK did not directly affect the growth or biofilm formation ability of these pathogens in vitro. Overall, our work provides insight into the underlying mechanisms of CK-induced immune responses against bacterial pathogens in tomato.     

利用SSH分离TDZ诱导金钗石斛成花相关基因

 以金钗石斛（Dendrobium nobile Lindl.）腋芽为材料,利用抑制消减杂交（SSH）技术构建了TDZ处理后金钗石斛腋芽的正向和反向SSH文库。通过PCR和反向Northern杂交验证后,得到的正向文库的314个阳性克隆和反向文库的59个克隆测序后经过聚类,最终得到39条受TDZ正向调控的EST序列,以及21条受其反向调控的EST序列。对其中某些差异基因进行半定量RT-PCR,结果显示这些基因的表达受TDZ的影响。利用Blastn和Blastx进行比对分析,其中20个没有同源序列,属于未知功能基因。其余序列的同源基因编码的产物参与包括光合作用、合成代谢、转录调控等多种生物学过程。在反向文库中分离到1个MADS-box基因的同源序列和1个Sos同源基因,而正向文库中存在多个反转录转座子,这些结果表明TDZ可以影响开花过程中的某些转录因子和信号基因的表达,进而促进金钗石斛开花。     

生长素和细胞分裂素对平邑甜茶组培苗PAs和NO含量的影响

 以平邑甜茶继代组培苗为试材,研究了NAA、IBA、ZT和6-BA作用下组培苗的生长、内源多胺（PAs）和一氧化氮（NO）含量的变化。结果表明,在MS培养基中添加0.02 ~ 1.00 mg·L^-1的NAA或IBA后,外植体鲜样质量增加率和蛋白质含量以及多胺含量和一氧化氮含量均明显增加,其中浓度在0.10 ~ 0.50 mg·L^-1 时增加最高;同样浓度下,NAA处理的外植体鲜样质量增加率和腐胺含量高于IBA。在0.08 ~ 4.00 mg·L^-1范围内,随着ZT或6-BA浓度的升高,外植体鲜样质量增加率、可溶性蛋白含量、多胺含量和一氧化氮含量均逐渐升高;同样浓度下,6-BA处理的外植体鲜样质量增率和腐胺含量高于ZT。生长素和细胞分裂素促进组培苗生长与促进内源PAs和NO的生成相伴随,组培苗生长动态与内源多胺和一氧化氮含量的变化趋势一致。     

水稻分蘖期干物质积累对大气CO2浓度升高和氮素营养的综合响应差异及其生理机制

【目的】探究不同类型水稻品种物质生产响应大气CO₂浓度升高和氮素营养的综合响应差异及其生理机制。【方法】以产量和物质生产对CO₂浓度升高响应有明显差异的水稻品种两优培九(LY)和南粳9108(NJ)为材料,在人工气候室进行水培试验。分别设置对照CO₂浓度(A-CO₂,400μmol·mol^-1)和CO₂浓度升高(E-CO₂,600μmol·mol^-1)两个CO₂处理,高氮(HN,1.25 mmol·L^-1 NH₄NO₃)和低氮(LN,0.25 mmol·L^-1 NH₄NO₃)两个氮水平。分析CO₂浓度升高对不同水稻品种根系形态与生理活性、叶片和根系中细胞分裂素(CTKs)含量、氮素同化酶活性、叶片生理特性、光合参数以及干物质积累的影响差异。...     

GA3与6-BA复合剂对黄瓜产量的影响

用不同浓度的赤霉素(GA3)和细胞分裂素类生长调节剂(6-BA)及其复合剂对黄瓜幼果进行喷施试验，以求得到提高黄瓜产量的复合剂。试验结果表明，由高浓度的GA3和中浓度的6-BA复配的复合剂显增加前期黄瓜的果数，明显提高黄瓜前期产量，增产达52．89％。GA3和6-BA复合剂使前期单果重较对照降低，但对后期单果重及后期黄瓜果数无明显影响。     

紫外分光光度法测定6—苄基氨基嘌呤的含量

本文探讨了６－苄基氨基嘌呤的紫外分光光度分析方法,测定波长为２７５ｎｍ,在０￣９ｍｇ·ｋｇ＾－１范围内有良好的线性关系,相关系数为０．９９９７,变异系数为０．７２,用高效液相色谱法对紫外法测定样品的可靠性加以确证。     

Osmotic Adjustment and Growth of Salt-stressed Cotton as Improved by a Bioregulator

For examining links between growth of salinity-exposed cotton and corresponding changes in physiological characters, a bioregulator was used as a tool for specific manipulations. Greenhouse-grown cotton ( Gossy-pium birsutum L. cv. Paymaster 145 ) was subjected to NaCl levels up to 14.9 dS m⁻¹. The bioregulator MCBuTTB, a cytokinin analog with known ability in improving growth and yield in several salt-stressed crops, was applied by imbiding seed (0 or 268 ppm) plus one foliar spray in dosages equaling 0, 1, and 3 kg ha⁻¹ at 45 DAP. MCBuTTB improved germination, growth, flowering, and finally boll weight. This result coincided with lower osmotic and higher water potentials in leaves, higher leaf turgidity, and more agilely reacting stomata. Treated plants had higher K and preferably Na concentrations in its leaves but ion accumulation was not a precondition for osmotic adjustments, because in cotton exposed to a manmtol-simulated drought MCBuTTB triggered a similar osmotic adjustment and sustained vigour. Regression analyses indicated that osmotic adjustment alone did not cause the raised leaf turgidity. All characters which contribute to salinity resistance appeared as mutually depending and interacting but they respond to a regulatory agent of cytokinin-like activity.     

In vitro propagation of banana (Musa spp.) using thidiazuron and activated charcoal

Abstract

Rapid clonal propagation potential of banana was investigated by using excised shoot tips of Musa spp. Shoot tips isolated from young suckers of ‘Anamur 2’, ‘Dwarf Cavendish’, and ‘Gazipasa 6'genotypes were used. Excised shoot tips were transferred immediately to Murashige and Skoog (MS) medium with different concentrations of 6-benzylaminopurine (BAP) and thidiazuron (TDZ) either alone or with indoleacetic acid (IAA). Rooting was achieved with indole-3-butyric acid (IBA) and α-naphthaleneacetic acid (NAA) in the presence or absence of activated charcoal (AC). The results showed that shoot proliferation rate was statistically affected by cytokinin types and their concentration. The responses to TDZ were better than to BAP. BAP or TDZ with IAA increased shoot elongation compared with BAP or TDZ alone. An increase in plant height, root numbers and average number of roots per explant was obtained using AC. Hence, for multiplication of ‘Dwarf Cavendish’, the use of MS medium with 2.5 µM TDZ with 1 µM IAA followed by rooting with AC only is recommended. For multiplication of banana genotypes ‘Anamur 2’ and ‘Gazipasa 6’, the use of MS medium with 1 µM TDZ and 1 µM IAA followed by rooting with AC only is recommended.     

ipt基因表达及外源细胞分裂素对油菜幼苗侧根发育的影响

通过对转ipt基因油菜(Brassica napus L.)及野生型油菜种子的发芽培养,研究了ipt基因的表达及外源细胞分裂素对油菜种子幼苗侧根发育的影响。结果表明:ipt基因表达和高浓度的外源细胞分裂素对油菜幼苗主根长度、侧根原基的起始及侧根的发生均表现出明显的抑制作用。当KT和6-BA浓度达到1mg/L时,侧根的发生被完全抑制,外源生长素IBA可以缓解ipt基因超量表达对油菜种子侧根发育的抑制作用。