Following the incorporation of Brassicaceous seed meal (BSM) residues in soil, glucosinolates could be hydrolyzed into a variety of biocidal products, such as isothiocyanates, nitriles, and ionic thiocyanate (SCN -), with isothiocyanates being most toxic ( Brown and Morra, 1997 Morra and Kirkegaard, 2002). Glucosinolates are present in every Brassicaceous plant part but are most concentrated in the seed ( Borek and Morra, 2005). The mechanism of disease control has been attributed to allelopathy, which is defined as the inhibitory effect of a plant or microorganism (donor) on others (receivers) through the chemicals released from the donor to the environment ( Kobayashi, 2004 Hoagland et al., 2008), for example, the glucosinolates within Brassicaceae.

Plants from the family Brassicaceae are usually used as a soil amendment because of their ability to control disease ( Lazzeri et al., 2003 Mazzola and Mullinix, 2005 Larkin and Griffin, 2007 Mazzola and Brown, 2010). One promising practice is the utilization of organic amendments, a biologically based protocol, for the control of soil-borne plant pathogens. Growth in sustainable agricultural production systems has generated unprecedented demand for environmentally friendly plant disease control strategies. This study is helpful for our understanding of the mechanisms that lead to contrasting plant disease severity after the addition of different BSMs. At the phylum/class and the genus levels, the changes in specific bacterial populations resulting from the PG and PG+IG treatments, especially the significant increase in Actinobacteria-affiliated Streptomyces and an unclassified genus and the significant decrease in Chloroflexi, were suspected to be one of the microbial mechanisms involved in PG-containing BSM-induced disease suppression. All BSM treatments altered the bacterial community structure and decreased the bacterial richness and diversity after 25 days of incubation, although this effect was weakened after an additional 35 days of pepper growth. The results show that the application of PG and PG+IG reduced the disease index by 100% and 72.8%, respectively, after 35 days of pepper growth, while the application of CAME did not have an evident suppressive effect. The changes in the bacterial community in the soil after 25 days of incubation and changes in the rhizosphere after an additional 35 days of pepper growth were investigated by 454 pyrosequencing technique. Then, a further 35-day pot experiment was established with pepper plants growing in the BSM treated soils. ‘IdaGold’ (IG) (PG+IG, 1:1 ratio), was performed. In this study, a 25-day microcosm incubation of a natural Fusarium wilt pathogen-infested soil supplemented with three BSMs, i.e., Camelina sativa ‘Crantz’ (CAME), Brassica juncea ‘Pacific Gold’ (PG), and a mixture of PG and Sinapis alba cv. However, little is known about the response of bacterial communities, especially the rhizosphere bacterial community, to BSM application to soil heavily infested with Fusarium wilt pathogen and cropped with peppers. Fusarium wilt is a devastating disease on pepper. Understanding the bacterial response to BSM at the community level is of great significance for directing plant disease management through the manipulation of resident bacterial communities. 5Department of Horticultural Sciences, Texas A&M University, College Station, TX, United StatesĪpplication of Brassicaceous seed meal (BSM) is a promising biologically based disease-control practice but BSM could directly and indirectly also affect the non-target bacterial communities, including the beneficial populations.4Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, United States.3Key Lab of Food Quality and Safety of Jiangsu Province–State Key Laboratory Breeding Base, Nanjing, China.2Key Laboratory of Agro-Environment in Downstream of Yangtze Plain, Ministry of Agriculture, Nanjing, China.1Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, China.

Gaidi Ren 1,2,3 Yan Ma 1,2,3* Dejie Guo 1,2,3 Terry J.

Seed treatment pepper bacterial blight