“达效能”对水田杂草防除效果的试验总结

达效能(53%苯噻酰·苄WP)1050～1200g/hm2,于水稻插秧后5～7d,稻稗2叶前药肥法施药,水层3～4cm,保水5～7d,对稻稗、牛毛草、泽泻、鸭舌草、眼子菜、雨久花、矮慈姑等杂草具有很好的防除效果,对水稻安全。对三棱草也有明显的抑制作用。     

Shattering habit and dormancy of spikelets in a cultivated form of Echinochloa oryzicola recently found in China

Shattering habit and dormancy of spikelets were studied in a cultivated form of Echinochloa oryzicola , which was found in 1994 in the Yunnan Province of China, and compared with a weedy form of the same species. Spikelet weight of the cultivated form (8.3 mg) was nearly twice as large as that of the weedy form. The weedy form developed abscission layers in the spikelet rachis before detachment, but the cultivated form developed no particular structures at a comparable region of the spikelet rachis. The spikelet shattering percentage in the cultivated form was 4.2% at 80 days after heading, compared with 99.8% in the weedy form. Spikelets of the cultivated form, collected in the field at 60 days after heading, showed 96.3% germination in the laboratory at 20/30 °C in the light, and vivipary of the spikelets was observed in the field after persistent rainfall. The weedy form showed only 0.1% germination in the laboratory when collected at 60 days after heading, but this increased to 55% after 100 days of dry storage. We concluded that the cultivated form of E. oryzicola examined in the present study was characterized by large spikelets with non-shattering habit and no innate dormancy.     

云南省水稻细菌性条斑病菌的致病型划分和水稻抗性资源的鉴定

 为明确云南省水稻细菌性条斑病菌(Xanthomonas oryzae pv. oryzicola, Xoc)的致病力分化以及不同类型水稻品种对Xoc的抗感特性,通过针刺接种法将云南省8个稻区采集的86株Xoc菌株,接种于6个携带不同抗性基因的水稻鉴别品种(IRBB4、IRBB5、IRBB14、IRBB18、IRBB21和IR24)。根据这些菌株在鉴别品种上的毒力差异进行了UPGMA聚类分析,将其划分为9个致病型(Ⅰ型 ~ Ⅸ 型)。其中,Ⅰ型为优势菌群,分布频率为50.5%。对不同稻区的优势菌群进行分析,发现云南省各稻区Xoc的致病型呈多样性分布,以强毒力的Ⅰ型为高频率致病型。选用 Ⅰ 型、Ⅱ 型和 Ⅵ 型代表菌株对云南省的80个主栽和区试水稻品种进行抗性评价,对3个致病型表现抗性的材料比例分别为30.0%、35.0%和57.5%。筛选出9个对3种致病型都表现为抗性的品种,其中“Deyou16”和“Changgui2”表现为高抗。研究结果可为云南省防治水稻细菌性条斑病的水稻区域性布局和抗性品种的利用提供理论依据。     

Melatonin treatments reduce the pathogenicity and inhibit the growth of Xanthomonas oryzae pv. oryzicola

Rice bacterial leaf streak (BLS), caused by Xanthomonas oryzae pv. oryzicola (Xoc), is a prevalent disease worldwide. Melatonin, an indoleamine with the chemical name N-acetyl-5-methoxytryptamine, is known to inhibit the growth of human pathogenic bacteria. However, the impact of melatonin on agricultural pathogenic bacteria remains poorly understood. In this study, the effect of melatonin on Xoc was investigated. Exogenous melatonin (200 μg mL⁻¹) significantly inhibited the growth of Xoc and reduced the mRNA expression level of seven cell division-related genes. Melatonin reduced the pathogenicity of Xoc towards the susceptible rice IR24. The lesion length in IR24 infected by Xoc pretreated with melatonin (200 μg mL⁻¹) was more than 23% smaller than the lesion length of the control group. Similarly, infection of IR24 leaves by Xoc pretreated with melatonin (200 μg mL⁻¹) reduced the bacterial population by 45%. The biofilm formation, swimming motility and extracellular protease activities of Xoc also decreased under melatonin treatment. Melatonin only slightly changed the morphology of Xoc but significantly reduced the mRNA expression of toxin genes. Furthermore, treating leaves with exogenous melatonin reduced the incidence of BLS by 17%. It is reported for the first time that melatonin reduces pathogenicity and may serve as a bactericide for controlling BLS disease.     

应用免疫金探针定位和定量测定稻种中的水稻细菌性条斑病菌

 本文首次报道用免疫金染色和免疫金银染色对水稻细菌性条斑病病种的带菌部位及带菌量的研究。结果表明:病原细菌分布于谷壳、籽实皮、胚和胚乳,主要集中在谷壳上。谷壳外表带菌量多于内表面。籽实皮外表面由于受谷壳污染较之内表面的带菌量多。籽实皮内表面、胚和胚乳的带菌量均较少,差异不显著。谷壳、谷壳内表面、籽实皮、胚乳(或胚)的带菌量之比为36:13:9:1。     

水稻品种对水稻细菌性条斑病抗性研究进展

水稻细菌性条斑病是水稻的重要病害。该病主要经带菌种子传播，对水稻的生产可造成严重危害。选育抗病品种是防治该病经济、安全有效的措施。国内外学者致力于研究该病原菌与水稻的互作关系，并广泛筛选和培育优良的抗病种质，以期通过利用水稻品种对该病原菌的抗性实现对该病的有效控制。作者对水稻品种抗性鉴定技术、抗源筛选、抗性机理和抗性遗传等方面的研究进展进行了评述，并对这一研究领域存在的问题进行了讨论，为我国植保及育种工作者提供参考。     

辣椒疮痂病菌(Xanthomonas vesicatoria)和水稻细菌性条斑病菌(X. oryzae pv. oryzicola)的质粒及其与耐链霉素和耐铜性关系

 从不同省份收集到辣椒疮痂病菌Xanthomonas vesicatoria (XV)7个菌株和水稻细菌性条斑病菌X. oryzae pv. oryzicola (XOZ)14个菌株,进行了质粒微量制备。XV菌株除XV1外都检测到质粒,单个菌株拥有的质粒数为2~5个,大小在10~100kb,没有发现为所有菌株所共有的质粒,但XV2、XV3、XV4、XV5、XV6共享1个大约55 kb的质粒。14个XOZ菌株都含有1个质粒,除XOZ5外,其余的13个菌株都含1个约40 kb的质粒。所有菌株都不耐铜。XOZ菌株仅XOZ7对链霉素表现耐性,4个XV菌株即XV4、XV5、XV6和XV7耐链霉素。用XV质粒转化无质粒菌株,发现XV5的1个76 Kb质粒与耐链霉素有关。     

Differential gene expression of the α-chain of mitochondrial H+-transporting ATP synthase between dormant and non-dormant seeds of paddy Echinochloa weeds

Gene expression was compared under favorable germination conditions between dormant and non-dormant seeds of rice paddy Echinochloa weeds and a domesticated Echinochloa species lacking dormancy. Two dormancy-specific cDNAs, Ecd1 and Ecd2 , were identified by differential display. Northern blot analysis revealed that these genes were more strongly expressed in dormant seeds than in non-dormant seeds. A database search for the Ecd1 sequence revealed no significant homology with any known proteins, but the Ecd2 sequence was highly homologous with the α-chain of mitochondrial H⁺-transporting adenosine triphosphate (ATP) synthase in rice ( Oryza sativa L.). These findings indicate that the gene encoding the enzyme associated with conventional aerobic respiration is more abundantly transcribed in dormant seeds. The results reported in the present study suggest that dormant seeds of paddy Echinochloa weeds, which appear during the period when paddy soil becomes aerobic by drainage, may maintain viability primarily by efficient conventional aerobic respiration, including ATP synthesis catalyzed by the mitochondrial H⁺-transporting ATP synthase.     

Molecular identification of Echinochloa oryzicola Vasing. and E. crus-galli (L.) Beauv. using a polymerase chain reaction–restriction fragment length polymorphism technique

Polymerase chain reaction (PCR) and polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) techniques were applied for establishing the reliable practice in identification of Echinochloa oryzicola Vasing. and E. crus-galli (L.) Beauv. (barnyardgrass). Total DNA was extracted from 18 accessions and 86 individuals of E. oryzicola , 33 accessions and 140 individuals of E. crus-galli var. crus-galli , 23 individuals of E. crus-galli var. praticola , and six individuals of E. crus-galli var. formosensis that were collected from Japan. A partial region of intergenetic spacer between trn T and trn L, and an intron of trn L were amplified separately using a trn-a and trn-b1 primer set, and a trn-c and trn-d primer set, respectively. All individuals of E. oryzicola showed the same fragment amplified by the trn-a and trn-b1 primer set. The fragment was 481 bp in length, and was undigested by Eco R I, whereas all individuals of E. crus-galli , including three botanical varieties, showed the same fragment with a 449-bp length. The fragment was digested by Eco R I into two fragments (178 and 271 bp). The fragment amplified by the trn-c and trn-d primer set in all individuals of E. oryzicola was digested by Alu I into two fragments (174 and 452 bp), but undigested by Dra I. In contrast, the fragment amplified by the trn-c and trn-d primer set in all individuals of E. crus-galli was digested by Dra I into two fragments (134 and 487 bp), but undigested by Alu I. There was no intraspecific variation in these regions; thus, these two species are easily identifiable by using our method.