Replication and encapsidation of the viroid-like satellite RNA of lucerne transient streak virus are supported in divergent hosts by cocksfoot mottle virus and turnip rosette virus

. 2008. The Biology of Canadian Weeds. 137. Brassica napus L. and B. rapa. Can. J. Plan Sci. 88: 951Á996. Brassica napus and B. rapa are native to Eurasia. In Canada, these species are commonly referred to as volunteer canola, while feral populations of B. rapa are referred to as birdrape. Brassica napus and B. rapa have been grown commercially for their seed oil content in western Canada since the middle of the last century and volunteer populations are common in fields. Escaped populations of both species are also found along roadways, railways and in waste areas; however, only B. rapa is known to have naturalized, self-sustaining feral populations in these habitats in eastern Canada. Despite these escaped and feral populations, B. napus and B. rapa are mainly a concern in agricultural fields where their combined relative abundance has increased over the past few decades. In the mid 1990s, herbicideresistant genotypes of B. napus were released for commercial production. Herbicide-resistance and the stacking of genes in volunteer populations conferring resistance to multiple herbicides have contributed to increased difficulties in controlling volunteer B. napus in some crops. However, yield loss resulting from volunteer populations is not well documented in Canada.Key words: Brassica napus, Brassica rapa, herbicide resistance, transgene escape, volunteer canola, weed biology Gulden, R. H., Warwick, S. I. et Thomas, A. G. 2008. La biologie des mauvaises herbes au Canada. 137. Brassica napus L. et B. rapa L. Can. J. Plant Sci. 88: 951Á996. Brassica napus et B. rapa sont des plantes originaires d'Eurasie. Au Canada, on les de´signe souvent sous l'expression « canola spontane´», tandis que les peuplements sauvages de B. rapa sont appele´s « navette ». Dans l'Ouest canadien, Brassica napus et B. rapa sont cultive´s commercialement pour l'huile que renferment leurs graines depuis le milieu du sie`cle dernier et les repousses spontane´es sont devenues monnaie courante dans les champs. On observe des peuplements des deux espe`ces le long des routes et des voies ferre´es ainsi que dans les terrains vagues, cependant on sait que seule B. rapa s'est acclimate´e pour donner des populations sauvages et stables dans les meˆmes habitats, dans l'est du pays. Malgre´cela, B. napus et B. rapa demeurent surtout pre´occupants dans les cultures, oul eur abondance relative, une fois combine´s, s'est accrue au cours des dernie`res de´cennies. Au milieu des anne´e 1990, des ge´notypes de B. napus re´sistants aux herbicides ont e´te´homologue´s pour la culture commerciale. Cette re´sistance et l'accumulation des ge`nes qui la codent dans les peuplements spontane´s ont concouru a`compliquer la lutte contre les repousses de B. napus dans certaines cultures. Quoi qu'il en soit, les pertes de rendement qui en re´sultent sont mal e´taye´es au Canada.

Section: Response To Other Human Manipulationsmentioning

confidence: 99%

The Biology of Canadian Weeds. 137. Brassica napus L. and B. rapa L.

Gulden¹,

Warwick²,

Thomas³

2008

“…Viral host ranges can be extended by the presence of other viral systems. For example, Sehgal et al (1993) found that replication and encapsidation of the viroid-like satellite RNA of lucerne transient streak virus (LTSV) were supported in the presence of turnip rosette sobemovirus (TROV) in crucifer species S. arvensis, Brassica rapa, and Raphanus raphanistrum, but not in Thlaspi arvense, indicating that host species markedly influenced this interaction. Mamula et al (1997) indicated that S. arvensis could serve as a potential host plant to belladonna mottle (BeMV, isolate from Croatia) and turnip yellow mosaic tymoviruses (TYMV, isolate from Slovenia) in greenhouse studies.…”

Section: Response To Parasitesmentioning

confidence: 99%

The biology of Canadian weeds. 8. Sinapis arvensis. L. (updated)

Warwick¹,

Beckie²,

Thomas³

et al. 2000

. An updated review of biological information is provided for Sinapis arvensis L. Native to the Old World, the species is widely introduced and naturalized in temperate regions around the world. The species occurs in all the provinces, the Northwest Territories, and the Yukon. It is an important weed of field crops in the Canadian prairies. A strongly persistent seedbank, competitive annual growth habit and high fecundity all contribute to its weedy nature and ensure that it will be a continuing problem. Several cases of herbicide resistance have been documented for natural populations of S. arvensis in Canada, including biotypes resistant to: i) Group 2 herbicides, which inhibit acetolactate synthase (ALS), from Manitoba in 1992 and Alberta in 1993; ii) Group 4 herbicides or synthetic auxins from Manitoba in 1991; and iii) Group 5 herbicides, which inhibit photosynthesis at photosystem II, from Ontario in 1983. The species is a close relative of Brassica nigra (L.) Koch, black mustard, and is capable of limited genetic exchange with the Brassica crop species under laboratory hybridization conditions either by conventional crossing or with the aid of ovary/embryo recovery techniques.

“…For example, Sehgal et al (1993) found that replication and encapsidation of the viroid-like satellite RNA of lucerne transient streak virus (LTSV) were supported in the presence of turnip rosette sobemovirus (TROV) in R. raphanistrum.…”

Section: Response To Parasitesmentioning

confidence: 99%

The biology of Canadian weeds. 132. Raphanus raphanistrum L.

Warwick¹,

Francis²

2005

Warwick, S. I. and Francis, A. 2005. The biology of Canadian weeds. 132. Raphanus raphanistrum. Can. J. Plant Sci. 85: . A review of biological information is provided for Raphanus raphanistrum L. Native to the Mediterranean region, the species is widely introduced and naturalized in temperate regions around the world. In Canada, it currently occurs in all provinces except Saskatchewan and Manitoba, has only a limited distribution in Alberta, and is also absent from the Yukon, the Northwest Territories and Nunavut. It is most abundant in the Atlantic and Pacific regions and is an important weed of field crops in the Maritime provinces and Quebec. A persistent seed bank, competitive annual growth habit and high fecundity all contribute to its weedy nature and ensure that it will be a continuing problem. It can easily hybridize with cultivated radish, R. sativus L., and commonly does so when they occur together. Limited hybridization with canola, Brassica napus L., has been reported from several experimental field and greenhouse trials. Selective herbicide control is most difficult in canola and other cruciferous crops. It is the most important dicot weed in the southwestern region of Australia, primarily due to the evolution of several different herbicide-resistant biotypes. These include biotypes resistant to the acetolactate synthase (ALS)-inhibitors (group 2 herbicides) and/or photosystem II-inhibitors (group 5), and a biotype with multiple resistance to ALS-inhibitors, photosystem II-inhibitors, an auxin (2,4-D amine), and a phytoene desaturase (PSDS)-inhibitor (diflufenican). A biotype resistant to the ALS-inhibiting herbicide chlorsulfuron has also been detected in South Africa. Un réservoir de semences bien stocké, une croissance agressive pour une annuelle et une grande fécondité expliquent la nature problématique de l'espèce, qui le demeurera longtemps. La plante se croise facilement avec le radis cultivé R. sativus et le fait couramment aux endroits où les deux espèces se côtoient. On a aussi rapporté une hybridation partielle avec le canola, Brassica napus L., lors de quelques essais sur des parcelles expérimentales ou en serre. La lutte au moyen de désherbants sélectifs s'avère particulièrement délicate dans les champs de canola et d'autres crucifères. Il s'agit de la principale dicotylédone nuisible dans le sud-ouest de l'Australie, principalement en raison de l'apparition de biotypes résistants. Ces biotypes résistent notamment aux inhibiteurs de l'acétolactate-synthase (herbicides du groupe 2) ou du photosystème II (groupe 5) ou aux deux. On a aussi identifié un biotype résistant aux deux types d'inhibiteurs précités ainsi qu'à l'auxine (2,4-D amine) et à l'inhibiteur de la phytoène désaturase. Enfin, on a repéré un biotype résistant au chlorsulfuron (inhibiteur de l'acétolactate-synthase) en Afrique du Sud.