Lysobacter gummosus OH17 induces systemic resistance in Oryza sativa ‘Nipponbare’

Although rice is one of the most cultivated, consumed, and essential crops worldwide, it is highly susceptible to a wide range of bacterial and fungal pathogens that significantly reduce the production and quality of rice. Recently, our research group reported that the plant growth-promoting rhizobacterium Lysobacter gummosus OH17 was able to enhance the ethylene levels in Oryza sativa ‘Nipponbare’ plants at the late interaction stages. In this work, L. gummosus OH17 was found to be capable of inducing the overexpression of relevant genes of the jasmonic acid and ethylene transduction pathways in Nipponbare plants, such as OsACC, OsACO, OsERF3, and OsLOX, which resulted in the up-regulation of a number of pathogenesis-related proteins. The observed metabolic effects enhanced the disease resistance of rice against the three most devastating rice pathogens: Magnaporthe oryzae causing rice blast, Rhizoctonia solani causing rice sheath blight, and Xanthomonas oryzae pv. oryzae causing bacterial leaf blight. Furthermore, it was shown that L. gummosus OH17 also enhanced ethylene production levels in other O. sativa varieties from both the japonica and indica subspecies. Here, we report for the first time the metabolic alterations produced by plant growth-promoting rhizobacterium L. gummosus OH17 at the late interaction stages and how these alterations induce systemic resistance.     

新型信息素诱剂对新疆梨园蛾类害虫的诱捕效果评价

利用性诱剂干扰交配或诱杀钻蛀性蛾类害虫是果园害虫生物防治的重要途径之一,研发既诱雄蛾也诱雌蛾的新型诱剂近年来颇受关注。本研究在苹果蠹蛾性信息素基础上,加入寄主植物挥发物--梨酯、苯乙酮、香叶醇、冬青油和苯乙醇等制成若干配方,在南疆两地(库尔勒与阿克苏地区)梨园中于蛾类害虫发生的早期和中期进行诱捕试验。对苹果蠹蛾诱集结果表明,虽然与仅含性信息素配方相比,添加植物挥发物的配方可诱集到雌蛾,但诱集虫量较少。对梨小食心虫的诱集结果表明,在库尔勒,大部分配方诱到的虫量多于商品诱剂(对照),其中,在性信息素中添加少量植物挥发性物质的配方诱集的虫量总体较多;在阿克苏,所有配方诱集的虫量均多于对照,在性信息素中是否添加植物挥发物质对诱集效果总体上没有影响。对优斑螟的诱集结果表明,仅含2种性信息素物质的配方诱集的虫量最大,与加入少量梨脂的配方接近。果园诱集试验结果说明,在苹果蠹蛾性信息素中添加梨脂等多种寄主植物挥发物的供试配方诱集雌蛾效果不理想,但对多种混合发生的夜蛾害虫雄性具有较好诱集效果。     

Attraction of bruchid beetles Callosobruchus chinensis (L.) (Coleoptera: Bruchidae) to host plant volatiles

Host-plant volatiles play an important role as cues for herbivores in search of resources, mates and oviposition sites in complex environments. Plant volatile-based attractants can be developed for pest monitoring and control. Previously, we indicated that mated female adults of Callosobruchus chinensis showed choice preference behavior toward 2-hexenal and benzaldehyde. Our objective here was to investigate the synergistic effect of host-derived attractive volatiles in attracting C. chinensis under laboratory and field conditions in Shanxi Province, China. We hypothesized that the ratio and concentration of volatiles derived from Vigna radiata play critical roles for C. chinensis in locating this host. Therefore, we collected and identified the volatiles of mungbean by using headspace collection and GC-MS. The effectiveness of different ratios and concentrations of two compounds (2-hexenal and benzaldehyde) that elicit C. chinensis searching behavior were examined in Y-tube olfactometer assays. The combination of 300 μg μL⁻¹ 2-hexenal and 180 μg μL⁻¹ benzaldehyde loadings exhibited a synergistic effect on attracting C. chinensis (82.35%). Compared to control traps, the adults were significantly attracted to traps baited with blends, and more attraction to females than males was found for blend traps in the field experiments. Our results suggest that blends of this specific concentration and ratio of benzaldehyde and 2-hexenal can be used in traps as attractants for C. chinensis monitoring and control in the field.     

玫瑰黄链霉菌活性代谢产物RM诱导黄瓜抗病性的信号转导途径

为明确玫瑰黄链霉菌Streptomyces roseoflavus菌株men-myco-93-63活性代谢产物roflamycoin和men-myco-A(简称RM)诱导黄瓜产生抗病性的信号转导途径,采用高效液相色谱法、分光光度法和实时荧光定量PCR法,测定喷施玫瑰黄链霉菌代谢产物RM后黄瓜叶片中水杨酸含量和脂氧合酶活性,以及水杨酸信号转导途径和乙烯茉莉酸信号转导途径的标志基因——NPR1、PR-1a、CTR1的表达量。结果表明,喷施玫瑰黄链霉菌活性代谢产物RM后120 h,黄瓜叶片内水杨酸含量达到最高值,为7.22μg/g,是对照的1.75倍;喷施玫瑰黄链霉菌活性代谢产物RM后12 h,黄瓜叶片内脂氧合酶活性达到最高值,为52.69 U/g,是对照的1.32倍,并且在120 h内整体活性均高于对照;喷施玫瑰黄链霉菌代谢产物RM后,NPR1和PR-1a基因的相对表达量上调,其最大值分别为0.99和1.35,分别是对照的2.24倍和12.09倍,但抑制CTR1基因的表达。推测玫瑰黄链霉菌代谢产物RM通过水杨酸通路、乙烯通路和茉莉酸通路共同诱导黄瓜抗病性信号转导途径。     

EMS处理对草莓离体叶片再生植株耐盐性的影响

为了给草莓抗逆诱变育种提供技术和方法,以草莓继代苗为试材,用甲基磺酸乙酯(EMS)对其叶片进行处理后,叶片的存活率和再生率比对照均有所下降,再生植株以0.8%NaCl为选择压力进行初步筛选后,超氧化物歧化酶(SOD)、过氧化物酶(POD)活性增强,丙二醛(MDA)含量减少,游离脯氨酸含量增加,对盐渍环境表现出一定的抗性。     

3种寄主挥发物中引起旋幽夜蛾嗅觉反应的活性组分分析

为探究植物挥发物中引起旋幽夜蛾嗅觉电生理反应的活性组分, 本研究采用动态顶空吸附法收集藜、甜菜和棉花植株的挥发物, 利用气相色谱-触角电位联用仪(GC-EAD)和气相色谱-质谱联用仪(GC-MS)定性鉴定寄主挥发物中引起旋幽夜蛾嗅觉反应的活性组分。结果表明, 藜挥发物中有6种活性组分, 甜菜和棉花挥发物中各有5种, 其中乙酸叶醇酯、1, 2-二乙苯、对二乙苯、壬醛、二乙二醇丁醚为3种植物共有的挥发物组分, 异佛尔酮仅在藜挥发物中发现。触角电位(EAG)测定结果显示, 以上6种组分都能引起旋幽夜蛾雌雄成虫的EAG反应, 且随浓度增加EAG相对反应值增大。雌雄成虫对壬醛和异佛尔酮的EAG反应最强烈, 其次是乙酸叶醇酯和1, 2-二乙苯。在相同浓度条件下, 雌雄成虫对同种化合物的EAG反应无性别特异性。本研究为探明旋幽夜蛾定位寄主机制及开发行为调控产品提供基础。     

非饱和砂质黏性紫色土崩解特性及MICP加固试验

砂质黏性紫色土遇水极易崩解是导致西南山区土壤侵蚀流失等水土灾害的重要原因,为揭示其崩解规律和机制,改善土体的崩解性,采用自制崩解测量仪对不同初始干密度、含水率及颗粒级配条件下的紫色土进行浸水崩解试验,并从非饱和有效应力角度分析了其崩解演化机制,在此基础上,通过扫描电镜（Scanning Electron Microscope,SEM）探讨利用微生物诱导碳酸钙沉积（Microbial Induced Calcite Precipitation,MICP）加固技术对紫色土崩解性的改善效果。结果表明：1）紫色土浸水崩解全过程包含排气吸水期、平衡期、崩解发展期、崩解残余期4个阶段;2）崩解率与平均崩解速率随初始干密度及含水率的增大而减小,且细颗粒含量越高,平均崩解速率越大;3）紫色土浸水后非饱和有效应力的衰减过程受初始饱和度的影响较大,平均崩解速率随初始饱和度的增大呈指数函数衰减;4）MICP加固土的崩解率和平均崩解速率相较于素土分别下降了73～97个百分点和84%～99%,固化沉积的碳酸钙晶体使土体结构中的微裂隙与大孔隙大幅减少,形成较为致密的孔隙结构,大幅增强了粒间胶结强度,使土体抗崩解性能明显提升。MICP技术可以作为西南山区紫色土水土灾害防治的有效措施。