Overexpression of Three Glucosinolate Biosynthesis Genes in Brassica napus Identifies Enhanced Resistance to Sclerotinia sclerotiorum and Botrytis cinerea

Abstract

Sclerotinia sclerotiorum and Botrytis cinerea are notorious plant pathogenic fungi with an extensive host range including Brassica crops. Glucosinolates (GSLs) are an important group of secondary metabolites characteristic of the Brassicales order, whose degradation products are proving to be increasingly important in plant protection. Enhancing the defense effect of GSL and their associated degradation products is an attractive strategy to strengthen the resistance of plants by transgenic approaches. We generated the lines of Brassica napus with three biosynthesis genes involved in GSL metabolic pathway (BnMAM1, BnCYP83A1 and BnUGT74B1), respectively. We then measured the foliar GSLs of each transgenic lines and inoculated them with S. sclerotiorum and B. cinerea. Compared with the wild type control, over-expressing BnUGT74B1 in B. napus increased the aliphatic and indolic GSL levels by 1.7 and 1.5 folds in leaves respectively; while over-expressing BnMAM1 or BnCYP83A1 resulted in an approximate 1.5-fold higher only in the aliphatic GSL level in leaves. The results of plant inoculation demonstrated that BnUGT74B1-overexpressing lines showed less severe disease symptoms and tissue damage compared with the wild type control, but BnMAM1 or BnCYP83A1-overexpressing lines showed no significant difference in comparison to the controls. These results suggest that the resistance to S. sclerotiorum and B. cinerea in B. napus could be enhanced through tailoring the GSL profiles by transgenic approaches or molecular breeding, which provides useful information to assist plant breeders to design improved breeding strategies.

Dissection of genetic architecture for glucosinolate accumulations in leaves and seeds of Brassica napus by genome‐wide association study

“…For example, increased levels of GSLs could reduce the extent of grazing by birds and slugs (Giamoustaris and Mithen, ), and increased aliphatic GSLs reduced the extent of generalist pest feeding (Beekwilder et al , ). Furthermore, elevated indolic GSLs were found to enhance plant resistance against Sclerotinia sclerotiorum and aphids (Pfalz et al , ; Stotz et al , ; Wu et al , ; Zhang et al , ), and increased the hydroxylation of butenyl GSLs reduced the extent of adult flea beetle feeding (Giamoustaris and Mithen, ).…”

Quantitative Resistance: More Than Just Perception of a Pathogen

“…This generates the possibility that variation in the P. syringae SAX loci can interact with the plants genetic variation in the associated defense compound to generate quantitative resistance within the interaction. These same defense compounds provide resistance to a number of other pathogens including nonhost microbes that each may also vary in their sensitivity to the compounds (Mithen et al, 1986(Mithen et al, , 1987Stotz et al, 2011;Zhang et al, 2015b;Bednarek and Osbourn, 2009;Clay et al, 2009). This generates a potential system whereby a plant has variation in defense compounds while a multitude of pathogens also have genetic variation in the ability to detoxify specific plant defense metabolites when investigated (Pedras and Khan, 1997;Ahiahonu, 2002, 2005;Pedras et al, 2011).…”

Fine mapping and candidate gene analysis of the white flower gene Brwf in Chinese cabbage (Brassica rapa L.)

“…The Brassica genus includes important oil crops and vegetables 15 with yellow flower color as the most common form, while there are other colors, such as pale yellow, white, orange, and tangerine [16][17][18][19][20][21][22] . Compared with the studies of other traits in Brassica genus, such as yield [23][24][25][26][27][28] , fertility [29][30][31][32] , disease resistance [33][34][35] , the genetic studies of flower colors have been conducted earlier 16,17,36 . However, only the molecular mechanisms of white flower formation were understood [11][12][13][14]37,38 .…”