Investigation of wheat as a trap crop for control of Orobanche minor

Orobanche minor is a parasitic weed that attaches to the roots of red clover (Trifolium pratense) and a number of other broad‐leaved plant species in the Pacific Northwest USA. Orobanche minor seed must be stimulated by host plant exudates for germination and attachment to occur. However, plant species called false‐hosts can stimulate parasitic seed germination without attachment. These species could be utilized as trap crops to reduce the amount of parasitic seed in infested soil. Wheat (Triticum aestivum), was found to be a false‐host of O. minor; therefore, growth chamber, glasshouse and field soil experiments were conducted to evaluate the effect of six soft white winter wheats (T. aestivum), one durum wheat (Triticum turgidum), and one triticale (Triticale hexaploide) on O. minor germination. In growth chamber experiments, wheat and triticale induced 20–70% of O. minor seeds to germinate. In glasshouse studies, O. minor attachment was minimal on red clover plants grown in pots previously planted to wheat or triticale. In pots that did not receive a false‐host treatment, red clover plants averaged 4.2 O. minor attachments per plant. Red clover plants also had fewer O. minor attachments when grown in field soil taken from the plots where wheat or triticale were grown compared with plants grown in soil where no wheat or triticale were previously grown. Our results demonstrate that wheat may have the potential to be effectively integrated into an O. minor management system.     

Characterization of the Orobanche–Medicago truncatula association for studying early stages of the parasite–host interaction

There is an increasing interest in the legume species Medicago truncatula as a model plant for structural and functional genomic studies that can be used to identify agronomically important genes in legumes. Field screening has shown very high levels of resistance to Orobanche crenata in M. truncatula. However, in vitro studies with O. crenata, Orobanche foetida, Orobanche ramosa and Orobanche minor showed useful variation among accessions at early stages of the parasite–host interaction. Significant differences were observed in the levels of germination of O. crenata and O. foetida seeds induced by different accessions of M. truncatula. Only limited germination was observed on accession SA‐4327. All accessions induced little O. ramosa and O. minor germination. Accessions also varied in the number of O. crenata and O. foetida attachments supported, with few developing on accession SA‐27774. The variation observed for induction of germination and of subsequent attachment will be useful to isolating and characterizing genes involved in the early stages of Orobanche–host plant interaction and for the study of the biosynthetic pathways of production for germination stimulants.     

灰黄青霉对瓜列当的防效及对番茄根区土壤微生物的影响

根寄生杂草瓜列当（Orobanche aegyptiaca）严重危害番茄（Solanum lycopersicum）等多种经济作物的产量和品质。如何有效防除仍是当今瓜列当研究重点之一。真菌是列当的生防因子之一,但目前对农作物无致病性的列当生防真菌的研究尚少。本研究通过培养皿试验研究1株灰黄青霉（Penicillium griseofulvum,CF3）的无细胞发酵滤液对瓜列当种子萌发和发芽管生长的影响,通过盆栽试验研究CF3粉状制剂对瓜列当的防除效果及对寄主番茄生长和根区土壤微生物的影响。结果表明：1）培养皿试验中,CF3发酵液抑制了瓜列当种子萌发和发芽管生长。其中,在放有瓜列当种子与番茄幼苗的培养皿中,加入CF3发酵液后培养6 d,瓜列当种子的萌发均被完全抑制;添加CF3发酵液与霍格兰德营养液体积比为1∶2、1∶4、1∶6和1∶8的混合液培养8 d后,瓜列当种子的萌发率与对照相比分别减少80.26%、70.26%、68.10%和47.51%。CF3发酵液原液、10倍稀释液和100倍稀释液处理后使瓜列当发芽管长度与对照相比分别缩短100.00%、68.84%和19.24%。2）盆栽试验中,CF3菌剂抑制了瓜列当的出土和单株瓜列当的生长,并使番茄增产。施加1.0 g·kg^-1 CF3菌剂130 d后,瓜列当的出土数量、出土率和单株瓜列当干重分别降低76.19%、85.30%和28.48%,番茄果实鲜重增加51.57%。此外,灰黄青霉菌剂还调整了番茄根区土壤的微生物区系结构,使施加菌剂130 d后番茄根区土壤中除接入CF3外真菌数量与对照相比降低75.60%,细菌与真菌的数量之比增加117.57%。平均来看,CF3使番茄根区土壤中除CF3外真菌数量降低42.81%,放线菌总数增加84.15%。本研究表明,灰黄青霉CF3具有防除番茄上寄生瓜列当的能力,适宜作为瓜列当的生防真菌。     

吉林省向日葵列当生理小种鉴定

使用５份由西班牙提供的向日葵列当国际鉴别寄主，通过人工接种方法，对吉林省向日葵主产区３个点的向日葵列当群体进行了生理小种鉴定。结果表明．３个列当群体接种在向日葵列当国际鉴别寄主上反应完全一致，根据已知向日葵列当生理小种在鉴别寄主上的寄生性，该向日葵产区向日葵列当的生理小种定名为Ａ小种．     

柳叶鬼针草的解剖结构及生态适应性

[目的]揭示柳叶鬼针草与环境的生态适应性。[方法]通过切片和离析方法对柳叶鬼针草叶、茎和根进行解剖观察。[结果]叶片为异面叶,但栅栏组织和海绵组织细胞的形态分化不明显;下表皮气孔指数较高,上表皮无气孔。茎分化为地上茎和根状茎,两者的皮层均有发达的通气组织,其中地上茎维管柱具有发达的厚壁细胞群和木质部导管,起支持和输导功能;地下茎皮层细胞富含淀粉,起储藏功能。根是起源于根状茎的不定根,内皮层无凯氏带,输导组织发育微弱。[结论]柳叶鬼针草的上述特征均与其介于水生和陆生环境之间的生态习性有关。     

Study of some resistance mechanisms to Orobanche spp. infestation in faba bean (Vicia faba L.) breeding lines in Tunisia

The behavior of seven faba bean breeding lines toward Orobanche foetida and Orobanche crenata infestation was examined under field, pots, and in vitro conditions and compared to reference cultivars. The breeding lines presented resistance reaction to Orobanche spp. in different experiment conditions. In infested field by O. foetida, the grain yield reduction ranged from 55.7 to 83% for the breeding lines compared to 97% for the susceptible cultivar Badï. Lines L6 and L7 were the less affected by Orobanche parasitism considering severity, number of emerged Orobanche, and yield. In pots, the number of attachments varied from .6 to 3.4 and from 1.4 to 6.4 for the breeding lines against 10.4 and 12.3 for Badï inoculated, respectively, by O. foetida and O. crenata. In Petri dish experiment, Orobanche germination reached the highest rates; 69.9 and 59.7%, respectively, with O. crenata and O. foetida for Badï. For the breeding lines, it ranged from 6.3 to 44.9% for O. crenata and from 4.8 to 40.8% for O. foetida. Moreover, all breeding lines showed low tubercles number and delay in Orobanche attachments as compared to Badï. All breeding lines, except L5, maintained an acceptable level of resistance to Orobanche species manifested by a reduced Orobanche germination rate, low Orobanche number and dry weight, delay of attachments, and higher grain production compared to Badï. L5 seems to be less resistant even it behaves better than Badï in different culture conditions. The studied breeding lines could be recommended as resistance sources or candidates for varieties registrations.     

青藏地区中草药浸提液诱导瓜列当和向日葵列当种子萌发的研究

本试验采用甲醇和蒸馏水浸提法,从69种青藏地区传统中草药中筛选具有诱导瓜列当(Phelipanche Aegyptiaca Pers.)和向日葵列当(Orobanche Cumana Wallr.)种子萌发作用的植物,旨在通过寻找稳定的种子萌发刺激物质来为根寄生杂草列当防除提供依据。结果表明:1)供试材料中,16种中草药的甲醇或蒸馏水浸提液诱导瓜列当种子的萌发率≥20%,21种中草药的甲醇或蒸馏水浸提液诱导向日葵列当种子的萌发率≥20%;2)其中,黄花蒿、雪参、鸡血藤、青兰、甘松和独一味6种中草药诱导2种列当的发芽率均高于20%,表明上述中草药种含有较高活性或较高浓度的列当种子萌发诱导物质,上述6种中草药可作为列当诱捕作物或列当种子萌发刺激物的潜在供体而应用于列当的生物防除。     

瓜列当对新疆甜瓜的危害及化学防治初探

调查瓜列当对新疆甜瓜的危害,探索瓜列当化学防控方法,为瓜列当防治措施制定及实施提供技术支撑。以新疆伽师县4个甜瓜主产乡镇为代表,调查瓜列当对甜瓜的危害程度及规律。结合新疆甜瓜栽培模式,进行2种除草剂各2种浓度对瓜列当的防治试验。调查的4个乡镇瓜列当都有不同程度的发生。甜瓜播种后50 d直到收获,都有瓜列当寄生危害。75%磺酰磺隆和甲基咪草烟都可用于对甜瓜列当的防治,磺酰磺隆效果优于甲基咪草烟。结合浇水冲施37.5 g a.i.·hm-275%磺酰磺隆,是最有效的新疆甜瓜瓜列当化学防治的施用方式和浓度。     

The long-term approach to parasitic weeds control: manipulation of specific developmental mechanisms of the parasite

Parasitic weeds pose a tremendous threat to world agriculture, mainly because they are at present almost uncontrollable. The root parasites Striga (witchweed) and Orobanche (broomrape) are vicious pests in both tropical and sub-tropical areas. A thorough understanding of their biology, including detailed knowledge of the specific mechanisms of parasitism, is needed in order to develop novel control methods. Some main developmental steps are described for the root parasites: seed conditioning and germination, haustorium formation, penetration into host tissues, maturation of the haustorium, and seed production. All these stages can be targeted in order to achieve parasite control. For example, based on our findings regarding gibberellin synthesized during seed conditioning, we were able to prevent parasitism by soil application of an inhibitor of gibberellin synthesis. Other developmental stages, such as germination stimulation, the enzymatic penetration of the haustorium into host tissues, and the source–sink relations between host and parasite are also possible targets for control, and the mechanisms involved may be manipulated for specific control of the parasites.