西藏青稞籽粒燕麦镰刀菌生物学特性研究

以西藏青稞籽粒中分离到的燕麦镰孢(Fusarium avenaceum)Hb39分离株为对象,研究了温度、湿度、pH、光照、营养对其菌丝生长和孢子萌发的影响,以便为进一步研究由燕麦镰孢引起的青稞病害发生规律、防治方法奠定基础,并为研究由此引致的人类疾病提供理论依据.该菌株在供试的10种不同固体、液体培养基上均能生长,但菌丝生长速度和生长量均有很大差异,PDBA、PDA、PSA培养基有利于该菌的生长,而HA、CMA和WA不利于该菌的生长.比较不同碳、氮源对菌丝生长的影响,发现该菌能利用多种单糖、多糖及可溶性淀粉作碳源,其中葡萄糖、蔗糖、麦芽糖较好;能利用蛋白胨等有机氮和硝酸钠等无机氮作氮源,其中蛋白胨最好.该菌最适生长温度为25℃,生长的温度范围为5～30℃.菌丝生长最适pH为6,也能在pH 3～12的范围内生长.连续光照不利于菌丝的生长,而光暗交替或黑暗条件下菌落生长无显著性差异.大型分生孢子萌发的温湿度范围分别为10～30℃、RH 85%～100%,pH值3～12,最适萌发条件为25℃、RH100%和pH 6.该菌株的致死温度为45℃10 min.     

Antagonistic activity of endophytic fungi towards <Emphasis Type="Italic">Diplodia corticola</Emphasis> assessed by in vitro and in planta tests

One isolate each of Trichoderma viride, Epicoccum nigrum, Fusarium tricinctum, Alternaria alternata, Sclerotinia sclerotiorum and Cytospora (teleomorph: Valsa sp.) present in epigeous declining oak tissues was evaluated for its ability to control Diplodia corticola (isolate 79). This fungus is the causal agent of cankers, vascular necrosis and dieback on various oak species. Among the isolates tested, T. viride and F. tricinctum showed maximum in vitro inhibition of mycelial growth of D. corticola (isolate 79). Species were also evaluated for their ability to reduce mortality caused by D. corticola (isolate 79) of Quercus cerris and Q. pubescens seedlings under controlled conditions. Two series of inoculations were carried out through wounds in the stem; in the first, the distance between the point of inoculation of the antagonist and the pathogen was 6 cm, whereas in the second series the distance was shortened to 3 cm. In seedlings of Q. cerris and Q. pubescens at a distance of 3 cm, inoculation with F. tricinctum and A. alternata significantly reduced mortality caused by D. corticola (isolate 79). Inoculation of T. viride through artificial cuticular wounds in the stem of seedlings prevented the proliferation of D. corticola (isolate 79) only on seedlings of Q. cerris. All Q. pubescens seedlings treated with T. viride manifested pathological symptoms subsequent to proliferation of D. corticola (isolate 79). These observations indicate that the interactions between endophytes in planta and D. corticola (isolate 79) are complex and merit further study.     

Management of resident plant growth-promoting rhizobacteria with the cropping system: a review of experience in the US Pacific Northwest

In view of the inconsistent performance of single or mixtures of plant growth-promoting rhizobacteria (PGPR) strains formulated for commercial use, and the high cost of regulatory approval for either a proprietary strain intended for disease control or a crop plant transformed to express a disease-suppressive or other growth-promoting PGPR trait, management of resident PGPR with the cropping system remains the most practical and affordable strategy available for use of these beneficial rhizosphere microorganisms in agriculture. A cropping system is defined as the integration of management (agricultural) practices and plant genotypes (species and varieties) to produce crops for particular end-uses and environmental benefits. The build-up in response to monoculture cereals of specific genotypes of Pseudomonas fluorescens with ability to inhibit Gaeumannomyces graminis var. tritici by production of 2,4-diacetylphoroglucinol (DAPG), accounting for take-all decline in the US Pacific Northwest, illustrates what is possible but apparently not unique globally. Other crops or cropping systems enrich for populations of the same or other genotypes of DAPG-producing P. fluorescens or, possibly and logically, genotypes with ability to produce one or more of the five other antibiotic or antibiotic-like substances inhibitory to other soilborne plant pathogens. In the U.S Pacific Northwest, maintenance of threshold populations of resident PGPR inhibitory to G. graminis var. tritici is the centerpiece of an integrated system used by growers to augment take-all decline while also limiting damage caused by pythium and rhizoctonia root rot and fusarium root and crown rot in the direct-seed (no-till) cereal-intensive cropping systems while growing varieties of these cereals (winter and spring wheat, barley and triticale) fully susceptible to all four root diseases.     

Validation of a QTL for resistance to ascochyta blight linked to resistance to fusarium wilt race 5 in chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.)

Ascochyta blight caused by Ascochyta rabiei and fusarium wilt caused by Fusarium oxysporum. f. sp. ciceris are the two most serious diseases of chickpea (Cicer arietinum). Quantitative trait loci (QTL) or genes for ascochyta blight resistance and a cluster of resistance genes for several fusarium wilt races (foc1, foc3, foc4 and foc5) located on LG2 of the chickpea map have been reported independently. In order to validate these results and study the linkage relationship between the loci that confer resistance to blight and wilt, an intraspecific chickpea recombinant inbred lines (RIL) population that segregates for resistance to both diseases was studied. A new LG2 was established using sequence tagged microsatellite sites (STMS) markers selected from other chickpea maps. Resistance to race 5 of F. oxysporum (foc5) was inherited as a single gene and mapped to LG2, flanked by the STMS markers TA110 (6.5 cM apart) and TA59 (8.9 cM apart). A QTL for resistance to ascochyta blight (QTL_AR3) was also detected on LG2 using evaluation data obtained separately in two cropping seasons. This genomic region, where QTL_AR3 is located, was highly saturated with STMS markers. STMS TA194 appeared tightly linked to QTL_AR3 and was flanked by the STMS markers TR58 and TS82 (6.5 cM apart). The genetic distance between foc5 and QTL_AR3 peak was around 24 cM including six markers within this interval. The markers linked to both loci could facilitate the pyramiding of resistance genes for both diseases through MAS.     

甘薯根腐病病原菌粗毒素对甘薯生长的影响

 本文鉴定了茄病镰孢甘薯专化型[Fusarium solani(Mart)Sacc.f.sp. batatas McClure, 简称FSB]引起甘薯胜利百号根腐病以及诱导胜利百号显蕾开花, 并研究了菌株V100-93-06粗毒素对胜利百号组培苗生长的影响。结果表明, 菌株V100-93-06对不同甘薯栽培品种呈现不同的致病性, 其粗毒素能够诱导甘薯出现和病原菌寄生相似的部分症状。粗毒素原液处理胜利百号薯苗2、3、5和9 d, 病情指数分别为0.9、2.8、2.5和3.0, 而10倍稀释浓度的粗毒素处理2、3、5和9 d, 病情指数分别为0、1.5、2.8和2.5。1~1 000倍稀释浓度的粗毒素处理胜利百号组培苗3 h, 就能够诱导出现黄叶, 浓度越高诱导出现黄叶数越多;对基芽和根的影响则表现为抑制基芽和根的生长, 浓度越高基芽和根的数量越少;对根伸长生长的影响表现为1倍稀释浓度粗毒素抑制根的伸长生长, 10~1 000倍稀释浓度都能够促进根的伸长生长。     

禾谷镰刀菌侵染引致小麦穗组织细胞壁成分变化的细胞化学研究

 本文采用细胞化学方法, 对健康和禾谷镰刀菌(Fusarium graminearum)侵染的小麦穗组织中细胞壁主要成分进行了比较分析。电镜观察发现, 被侵穗部组织细胞壁中的主要成分如纤维素、木聚糖和果胶质的标记密度下降, 显著低于未接种的健康对照组织。结果表明病菌侵染和扩展过程中分泌产生了纤维素酶、木聚糖酶和果胶酶等细胞壁降解酶类, 造成寄主细胞壁成分的分解及细胞壁松弛, 从而有利于病菌在寄主穗部组织中的侵染和扩展。     

Effect of antagonistic<Emphasis Type="Italic">Fusarium</Emphasis> spp. and of different commercial biofungicide formulations on Fusarium wilt of lettuce

Five experimental trials were carried out to test different biological control agents against Fusarium wilt of lettuce, cause byFusarium oxysporum f.sp.lactucae. In the presence of a very high disease incidence, the best results in terms of disease control as well as increased growth response were shown byTrichoderma harzianum T 22 (RootShield), which, at 3 gl ⁻¹ of substrate, provided very consistent results.F. oxysporum IF 23 gave good disease control but in two out of five trials reduced the biomass produced. Less consistent, but still significant results were provided byF oxysporium MSA 25, at 3 gl ⁻¹ of substrate, and byTrichoderma viride TV 1. The twoF. oxysporum agents Fo 251/2 and Fo 47 and the mixture ofT. harzianum + T. viride (Remedier) partially reduced disease incidence but were less effective than the above mentioned. Less interesting results were offered byStreptomyces griseoviridis (Mycostop). The results obtained show that biological control can play a role in the management of Fusarium wilt of lettuce.     

Induced suppressiveness to<Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f.sp.<Emphasis Type="Italic">radicis lycopersici</Emphasis> in rockwool substrate used in closed soilless systems

Tomatoes grown in soilless systems can be seriously damaged byFusarium oxysporum Schlect f.sp.radicis lycopersici (Forl) causing Fusarium crown and root rot (FCRR). FCRR suppression can be achieved through the use of chemicals, selected substrates, composts and artificially introduced antagonistic microorganisms. This study evaluated the natural capacity of a used rockwool to suppress FCRR infections. New and used rockwool, sampled from closed soilless systems, was either autoclaved or not, either artificially inoculated withForl or not and, finally, sown with tomato seeds cv. ‘Cuore di Bue’. The effects of autoclaved/non-autoclaved and used/new rockwool on FCRR incidence were assessed by evaluating the symptoms of crown rot on the root — shoot transition zone of tomato seedlings. Non-autoclaved and inoculated used rockwool significantly reduced FCRR incidence when compared with non-autoclaved and inoculated new rockwool. Autoclaved and inoculated used rockwool did not suppress FCRR, similarly to new and inoculated rockwool. These findings are in accordance with other research that, on a cucumber/Pythium host/pathogen complex in a closed rockwool soilless system, demonstrated the key role of resident microflora in suppressing the root rot disease. http://www.phytoparasitica.org posting Dec. 8, 2006.     

放线菌YIM34165发酵提取物抗水稻恶苗病菌的活性研究

从云南土壤中分离的放线菌YIM34165,优选3种不同培养基(1号、61号和301号)进行发酵,测定其发酵提取物对水稻恶苗病菌的活性,结果表明:61号培养基的发酵提取物对水稻恶苗病菌丝生长的抑制效果明显,病菌孢子萌发抑制率为84.27%,活体平均防治效果为82.45%。     

氰烯菌酯对禾谷镰孢菌分生孢子萌发及菌丝生长的影响

氰烯菌酯(2-氰基-3-氨基-3-苯基丙烯酸乙酯,JS399-19) 是一种对禾谷镰孢菌Fusarium graminearum具有专化活性的新型杀菌剂。离体条件下,采用菌丝生长速率法测定了该药剂对禾谷镰孢菌抗性菌株和敏感菌株的生长抑制活性;同时采用孢子萌发法测定了其对禾谷镰孢菌分生孢子萌发的影响。结果表明,氰烯菌酯能够强烈地抑制禾谷镰孢菌敏感菌株菌丝的生长,EC50值分布在0.092~0.141 μg/mL之间;并可降低敏感菌株分生孢子的萌发速率,以及影响其萌发的方式,使芽管从分生孢子基部和中间细胞萌发的比率增加;同时氰烯菌酯使敏感菌株分生孢子膨大、畸形,并使其芽管肿胀、扭曲,明显抑制其芽管的伸长生长;但对抗性菌株的抑制作用和致畸作用不明显。