Sd. Siciliano et al., Differences in the microbial communities associated with the roots of different cultivars of canola and wheat, CAN J MICRO, 44(9), 1998, pp. 844-851
Plant characteristics are known to alter endophytic and rhizosphere microbi
al communities; however, the effect of crop breeding programs on the microb
ial endophytic and rhizosphere communities is not clear. The purpose of thi
s study was to determine if root-associated microbial communities differed
between three cultivars of canola (Brassica spp.) and wheat (Triticum spp.)
. Biolog(TM) analysis was used to characterize the microbial communities as
sociated with the root interior and rhizosphere: soil of field grown canola
(Parkland, Excel, and Quest cultivars) as well as wheat (PI 167549, Red Fi
fe,and CDC Teal cultivars). Fatty acid methyl ester (FAME) profiles of root
s and rhizosphere soil of the cultivars were also compared. These crop cult
ivars represent a continuum from older to the most recent crop cultivars, w
ith Quest being a transgenic canola variety tolerant of the herbicide glyph
osate. To the best of our knowledge, Quest is not directly related to Parkl
and or Excel. The endophytic community of Quest used the Biolog(TM) polymer
, carbohydrate, amino acid, and miscellaneous functional guilds at a slower
rate than the endophytic community of Excel or Parkland, Furthermore, ther
e were lower levels of the microbial FAMEs, 18:0, 18:3 w6c (6,9,12), 16:0 2
OH, and 15:0 2OH in the roots of Quest compared with Excel or Parkland. In
contrast, there were no differences in the utilization rate of Biolog(TM) f
unctional guilds or the microbial FAMEs in the roots of the three wheat cul
tivars studied. The correlation between the ability of endophytic and rhizo
sphere communities to utilize Biolog(TM) substrates was lower in Quest and
CDC Teal compared with earlier crop cultivars. Our results indicate that en
dophytic and rhizosphere microbial communities of the transgenic cultivar Q
uest were different from nontransgenic cultivars grown at the same field si
te.