Mechanism of Broccoli-Mediated Verticillium Wilt Reduction in Cauliflower

Abstract

Broccoli is resistant to Verticillium dahliae infection and does not express wilt symptoms. Incorporation of broccoli residues reduces soil populations of V. dahliae. The effects of broccoli residue were tested on the colonization of roots by V. dahliae, plant growth response, and disease incidence of both broccoli and cauliflower in soils with different levels of V. dahliae inoculum and with or without fresh broccoli residue amendments. The three soils included a low-Verticillium soil, a high-Verticillium soil, and a broccoli-rotation soil (soil from a field after two broccoli crops) with an average of 13, 38, and below-detectable levels of microsclerotia per g of soil, respectively. Cauliflower plants in broccoli-amended high-Verticillium soil had significantly (P </= 0.05) lower wilt incidence and severity than did plants in unamended soil. An immunohistochemical staining assay utilizing a monoclonal antibody specific to V. dahliae was used to determine colonization of the root cortex. Despite the absence of wilt symptoms, broccoli roots were colonized by V. dahliae. In high-Verticillium soil, the broccoli residue amendment caused a marked reduction in colonization rate of V. dahliae per unit of inoculum on both cauliflower and broccoli roots. In addition to its detrimental effects on the viability of microsclerotia in soil, broccoli residue may also have an inhibitory effect on the root-colonizing potential of surviving microsclerotia.

Diversity, Pathogenicity, and Management of Verticillium Species

“…In several studies, broccoli not only significantly reduced resident soil microsclerotia, but also wilt incidence and severity in subsequent susceptible crops, preventing the build up of soil inoculum (91,140,151,152,168). Unlike soil fumigants, rotations with broccoli did not eradicate the pathogen, but maintained soil microsclerotia below the threshold at which crop losses accrue, despite the cultivation of susceptible crops such as strawberry or cauliflower (140,152). Empirical data evaluating the mechanisms of broccoliinduced V. dahliae suppression are only now becoming available.…”

“…Colonization patterns of V. dahliae in cauliflower and broccoli were compared using immunohistochemical staining (140) and a GFP-tagged V. dahliae strain from cauliflower (102). Minimal differences in the colonization of cortical tissues were observed between broccoli and cauliflower (140) (Figure 4), but the vascular tissue in broccoli was uncompromised in contrast to the extensive colonization in cauliflower (102) (Figure 4). The type of glucosinolates and the range of their catabolic products have been associated with the suppressive effects of crucifer crops in general (98).…”

Effet du compost et de <i>Trichoderma harzianum</i> sur la suppression de la verticilliose de la tomate

“…(Boulter et al, 2002), Rhizoctonia spp. (Tuitert et al, 1998 ;Krause et al, 2001 ;Diab et al, 2003) et V. dahliae (Gent et al, 1999 ;Shetty et al, 2000 ;Tenuta et al, 2002 ;Bailey et Lazarovitz, 2003). Cette suppression a été souvent attribuée à la microflore du compost et un nombre de bactéries et de champignons, réputés pour leur antagonisme à l'égard des phytopathogènes telluriques, ont été isolés à partir de différents composts (Phae et al, 1990 ;Cotxarrera et al, 2002 ;Carisse et al, 2003 ;Mouria et al, 2007Mouria et al, , 2013a.…”

Behavioural response of Meloidogyne incognita to benzyl isothiocyanate

“…Brassica cover crops, green manures and seed meals have been used to suppress a variety of soil-borne pathogens (Shetty et al, 2000;Mazzola et al, 2001) including plant-parasitic nematodes (Mojtahedi et al, 1991;Walker, 1997;Potter et al, 1998;Walker & Morey, 1999;Mazzola et al, 2001). Plants in the family Brassicaceae produce glucosinolates, and when brassicaceous plant material is incorporated into soil, glucosinolates are hydrolysed by plant myrosinase enzymes into a variety of volatile hydrolysis products (Fahey et al, 2001).…”