Endophytic microbial community in two transgenic maize genotypes and in their near-isogenic non-transgenic maize genotype

Abstract

BackgroundDespite all the benefits assigned to the genetically modified plants, there are still no sufficient data available in literature concerning the possible effects on the microbial communities associated with these plants. Therefore, this study was aimed at examining the effects of the genetic modifications of two transgenic maize genotypes (MON810 – expressing the insecticidal Bt-toxin and TC1507 – expressing the insecticidal Bt-toxin and the herbicide resistance PAT [phosphinothricin-N-acetyltransferase]) on their endophytic microbial communities, in comparison to the microbial community found in the near-isogenic non-transgenic maize (control).ResultsThe structure of the endophytic communities (Bacteria, Archaea and fungi) and their composition (Bacteria) were evaluated by denaturing gradient gel electrophoresis (DGGE) and the construction of clone libraries, respectively. DGGE analysis and the clone libraries of the bacterial community showed that genotype TC1507 slightly differed from the other two genotypes. Genotype TC1507 showed a higher diversity within its endophytic bacterial community when compared to the other genotypes. Although some bacterial genera were found in all genotypes, such as the genera Burkholderia, Achromobacer and Stenotrophomonas, some were unique to genotype TC1507. Moreover, OTUs associated with Enterobacter predominated only in TC1507 clone libraries.ConclusionThe endophytic bacterial community of the maize genotype TC1507 differed from the communities of the maize genotype MON810 and of their near-isogenic parental genotypes (non-Bt or control). The differences observed among the maize genotypes studied may be associated with insertion of the gene coding for the protein PAT present only in the transgenic genotype TC1507.

No adverse effects of transgenic maize on population dynamics of endophyticBacillus subtilisstrain B916-gfp

“…There were no significant differences in the population dynamics of B916-gfp colonies in transgenic and nontransgenic maize under laboratory or field conditions. This was consistent with the colonization of AMF (Cheeke et al, 2011(Cheeke et al, , 2014Zeng et al, 2014) and endophytic bacterial communities (da Silva et al, 2014;Prischl et al, 2012) in Bt maize. After inoculation, the growth curve of B916gfp followed the same trend of first increasing then subsequently declining in tissues of cry1Ah maize and isogenic lines.…”

“…A recent study reported that desorbed Bt protein was quickly mineralized by microbial degradation (Valldor, Miethling‐Graff, Martens, & Tebbe, ). Several studies have investigated the effect of growing Bt maize on the diversity and population size of microbial rhizosphere communities, especially AMF (Castaldini et al., ; Cheeke et al., , ; Turrini et al., ; Zeng et al., ); only two examined endophytic bacterial communities, which were not significantly affected by transformation of maize with cry1Ab (da Silva et al., ), cry3Bb1 , cry1A105 , or cry1Ab2 genes (Prischl et al., ). Here, we used Bs strain B916 expressing the GFP marker to monitor the population dynamics and colonization of Bt maize and its parental line.…”

“…Recent studies reported that plants of different species or even different genotypes assembled specific endophytic community (Cotta et al, 2013;Donn, Kirkegaard, Perera, Richardson, & Watt, 2014;Gaiero, McCall, Thompson, Day, & Dunfield, 2013). Two studies have investigated the influence of crops transformed with Bt genes on endophytic bacterial communities, and reported no significant effects (da Silva et al, 2014;Prischl et al, 2012).…”

Symbiotic nitrogen fixation and endophytic bacterial community structure in Bt-transgenic chickpea (Cicer arietinum L)

“…The above analyses clearly indicated that the bacterial community structure of root is highly diverse in nature compared to that of nodule. Similarly, da Silva et al reported that bacterial community structure of transgenic maize TC1507 tended to separate from those of MON810 and its near-isogenic parent 52 .…”

Investigación de microorganismos promotores del crecimiento vegetal en cultivos de interés agronómico mediante análisis metagenómico y microbiológico

“…Las cianobacterias son bacterias fotosintetizadoras oxigénicas, aeróbicas, pueden fijar N2 en vida libre en diferentes ambientes como suelos áridos, ambientes acuáticos y agua de deshielo [173], [307], [308], o asociadas con plantas y microorganismos [309]. Son componentes endófitos de varias especies de interés agronómico como arroz, papa, chontaduro, trigo, tomate, maíz y en cultivos forestales com pino [275] [81], [122], [269], [310]- [313]. En nuestro laboratorio Calderoli et al (2016) [289] reportan al orden Nostocales como uno de los grupos diazotróficos abundantes, asociados principalmente al estrato superficial de suelos agrícolas de la región pampeana argentina.…”