Conserved molecular components for pollen tube reception and fungal invasion

During sexual reproduction in flowering plants such as Arabidopsis, a tip-growing pollen tube (PT) is guided to the synergid cells of the female gametophyte, where it bursts and releases the two sperm. Here we show that PT reception and powdery mildew (PM) infection, which involves communication between a tip-growing hypha and a plant epidermal cell, share molecular components. NORTIA (NTA), a member of the MLO family originally discovered in the context of PM resistance, and FERONIA (FER), a receptor-like kinase, both control PT reception in synergids. Homozygous fer mutants also display PM resistance, revealing a new function for FER and suggesting that conserved components, such as FER and distinct MLO proteins, are involved in both PT reception and PM infection.     

刺槐花粉萌发和花粉管伸长生长过程中柱头与花柱内钙离子的分布特征

以去雄后人工授粉的刺槐花为试验材料,并以去雄后不授粉的花为对照,利用焦锑酸钙沉淀法分析刺槐柱头和花柱内钙离子分布对花粉萌发和花粉管生长的影响。结果发现:花粉在萌发前,其萌发孔聚集了大量的钙沉淀。授粉作用会很快促使柱头表面泡状分泌物和胞外基质钙含量增加。随着大量花粉萌发完成,柱头泡状分泌物内的钙含量开始下降,但是柱头胞外基质的钙含量下降不明显,这表明柱头泡状分泌物的钙离子对花粉萌发可能有促进作用。刺槐的花柱含有一个中空花柱道,中空花柱道周围有一层通道细胞,不论授粉与否,通道细胞液泡和细胞壁上都有大量钙离子,这些钙离子对花粉管的生长可能有诱导作用。刺槐花柱内的钙离子梯度现象不明显。本研究结果有利于揭示刺槐乃至其他豆科植物柱头和花柱内钙离子分布对花粉萌发和花粉管生长的影响。      

The role of ocean-atmosphere interactions in tropical cooling during the last glacial maximum

A simulation with a coupled atmosphere-ocean general circulation model configured for the Last Glacial Maximum delivered a tropical climate that is much cooler than that produced by atmosphere-only models. The main reason is a decrease in tropical sea surface temperatures, up to 6 degrees C in the western tropical Pacific, which occurs because of two processes. The trade winds induce equatorial upwelling and zonal advection of cold water that further intensify the trade winds, and an exchange of water occurs between the tropical and extratropical Pacific in which the poleward surface flow is balanced by equatorward flow of cold water in the thermocline. Simulated tropical temperature depressions are of the same magnitude as those that have been proposed from recent proxy data.     

小麦品种资源耐盐性鉴定

目的研究TaERECTA基因超表达后对小麦耐盐性的影响。方法以转TaERECTA基因小麦为材料,分别在芽期和苗期高盐胁迫,测定种子发芽势、发芽率、发芽指数和相对盐害指数,以及植株枯萎数、幼苗抗氧化酶活性和丙二醛(MDA)含量。结果芽期盐胁迫下,与野生型(WT)株系相比,TaERECTA转基因小麦种子发芽势、发芽率和发芽指数较高,相对盐害指数较低(P<0.05);苗期盐胁迫下,转基因小麦幼苗平均枯萎数较低,抗氧化酶活性较高,且SOD活性显著高于CK株系(P<0.05)。结论一定盐胁迫下,TaERECTA基因超表达可以增强小麦耐盐性,其作用机制可能是TaERECTA激活组织细胞SOD酶活性,其他抗氧化酶相互协同减轻盐胁迫伤害。转基因株系L10相对盐害指数较小,综合抗盐能力较强,可作为下一步深入研究TaERECTA调控小麦耐盐性功能的重要材料。