The Cry1Ab Protein Has Minor Effects on the Arbuscular Mycorrhizal Fungal Communities after Five Seasons of Continuous Bt Maize Cultivation

Root colonization and rhizospheric community structure of Arbuscular Mycorrhizal Fungi in BADH transgenic maize BZ-136 and its recipient under salt stress and neutral soil

Betaine aldehyde dehydrogenase (BADH) transgenic maize has a capability to grow under drought and salt stress; the risk of planting BADH transgenic maize on symbiotic microorganisms remains problematic, however. A pot experiment was carried out to assess the impact of BADH transgenic maize BZ-136 on arbuscular mycorrhizal fungi (AMF) colonization in root and community structure in rhizosphere soil compared with that of parental maize Zheng58 in neutral and saline-alkaline soil. Microscope observation found that BZ-136 only had a significantly reduced effect on AMF colonization at the elongation stage (9-14%). High-throughput sequencing analysis revealed that the AMF taxonomic composition kept consistency at the genus level between transgenic BZ-136 and non-transgenic parental Zheng58. NMDS analysis verified the slight difference in community structure between BZ-136 and Zheng58 presented an agrotype-dependent pattern. AMF community indices showed that BZ-136 had a higher richness at the flowering stage in saline-alkaline soil and had a higher diversity at the mature stage in neutral soil. Heatmap analysis also illuminated AMF community structure of transgenic maize at species level was similar to that of non-transgenic maize. In summary, cropping transgenic BADH maize has minor or transient effects on AMF colonization and rhizospheric soil AMF community structure, while agrotype has a stronger effect on AMF community structure.

Fungal Systematics and Evolution: FUSE 5

Thirteen new species are formally described: Cortinarius brunneocarpus from Pakistan, C. lilacinoarmillatus from India, Curvularia khuzestanica on Atriplex lentiformis from Iran, Gloeocantharellus neoechinosporus from China, Laboulbenia bernaliana on species of Apenes, Apristus, and Philophuga (Coleoptera, Carabidae) from Nicaragua and Panama, L. oioveliicola on Oiovelia machadoi (Hemiptera, Veliidae) from Brazil, L. termiticola on Macrotermes subhyalinus (Blattodea, Termitidae) from the DR Congo, Pluteus cutefractus from Slovenia, Rhizoglomus variabile from Peru, Russula phloginea from China, Stagonosporopsis flacciduvarum on Vitis vinifera from Italy, Strobilomyces huangshanensis from China, Uromyces klotzschianus on Rumex dentatus subsp. klotzschianus from Pakistan. The following new records are reported: Alternaria calendulae on Calendula officinalis from India; A. tenuissima on apple and quince fruits from Iran; Candelariella oleaginescens from Turkey; Didymella americana and D. calidophila on Vitis vinifera from Italy; Lasiodiplodia theobromae causing tip blight of Dianella tasmanica 'variegata' from India; Marasmiellus subpruinosus from Madeira, Portugal, new for Macaronesia and Africa; Mycena albidolilacea, M. tenuispinosa, and M. xantholeuca from Russia; Neonectria neomacrospora on Madhuca longifolia from India; Nothophoma quercina on Vitis vinifera from Italy; Plagiosphaera immersa on Urtica dioica from Austria; Rinodina sicula from Turkey; Sphaerosporium lignatile from Wisconsin, USA; and Verrucaria murina from Turkey. Multi-locus analysis of ITS, LSU, rpb1, tef1 sequences revealed that P. immersa, commonly classified within Gnomoniaceae (Diaporthales) or as Sordariomycetes incertae sedis, belongs to Magnaporthaceae (Magnaporthales). Analysis of a six-locus Ascomycota-wide dataset including SSU and LSU sequences of S. lignatile revealed that this species, currently in Ascomycota incertae sedis, belongs to Pyronemataceae (Pezizomycetes, Pezizales).

The Influence of Bt Maize Cultivation on Communities of Arbuscular Mycorrhizal Fungi Revealed by MiSeq Sequencing

The cultivation of transgenic Bacillus thuringiensis (Bt) has received worldwide attention since Bt crops were first released. Its ecological risks on arbuscular mycorrhizal fungi (AMF) have been widely studied. In this study, after cultivation for five seasons, the AMF diversity and community composition of two Bt maize varieties, 5422Bt1 (event Bt11) and 5422CBCL (event MO10), which both express Cry1Ab protein, and their isoline non-Bt maize 5422, as well as Bt straw after cultivation had been returned to subsequent conventional maize variety, were analyzed using Illumina MiSeq sequencing. A total of 263 OTUs (operational taxonomic units) from 511,847 sequenced affiliated with the AMF which belonged to Mucoromycota phylum Glomeromycotina subphylum were obtained. No significant difference was detected in the AMF diversity and richness (Shannon, Simpson, ACE, and Chao 1 indices) and community composition in rhizosphere soils and roots between Bt and non-Bt treatment revealed by NMDS (non-metric multidimensional scaling) and NPMANOVA (non-parametric multivariate analysis). Moreover, Glomus was the most dominant genus in all samples. Although there was no significant difference in the AMF community in roots and rhizosphere soils between the Bt and non-Bt maize treatments, total phosphorus (TP), total nitrogen (TN), organic carbon (OC), and pH were driving factors affecting the AMF community, and their composition varied between rhizosphere soils and roots during the maturity period of the fifth season. Compared to our previous study, the results were identical. In conclusion, no significant difference was observed between the Bt and non-Bt treatments, and the Illumina MiSeq method had higher throughput and higher quality read cover, which gave us comprehensive insight into AMF communities in agro-ecosystems.

Root and detritus of transgenic Bt crop did not change nematode abundance and community composition but enhanced trophic connections

Transgenic Bacillus thuringensis (Bt) crops are widely deployed to control lepidopterous pests with minimal impact on non-target soil invertebrates. However, most of the results were obtained from field works, the great environmental variation may conceal the small spatial-temporal scaled changes in microhabitats, such as those created near the roots (rhizosphere) or around decomposing residues (detritusphere), which are expected to impact free-living soil organisms more than the bulk soils. The objective of this study was to assess the impact of root and straw residues of transgenic crops on soil, by comparing nematode communities in the rhizosphere (soil microsites only affected by living root), the detritusphere (soil microsites affected by crop aboveground residues) and the rhizosphere-detritusphere interface (soil microsites intensively co-affected by root and residues) of Bt rice and its non-Bt near isoline. Bt rice did not affect nematode abundance and community composition, however, it enhanced the network connections within nematode communities, in both the rhizosphere and detritusphere, indicating the frequency of co-occurring species increased due to the moderate stress of crystal (Cry) as a labile resource of protein or as a moderate pressure of toxic compounds. Furthermore, 60-80% of the correlation between Cry protein (Cry1Ab/Cry1Ac) and nematode genera were positive in the rhizosphere and detritusphere of Bt rice, suggesting that higher Cry protein concentration was associated with the intensive co-occurrence among nematode populations. This finding offers new insights into how the biotic interactions of non-target soil community response to both live and dead parts of transgenic crop, highlighting the moderate stress of Cry protein might affect the community structure and consequent functioning of soil ecosystem based on the elaborately developed knowledge of biotic interactions via ecological network analysis.

Reprint of "Fast and sensitive in vivo studies under controlled environmental conditions to substitute long-term field trials with genetically modified plants"

We introduce an easy, fast and effective method to analyze the influence of genetically modified (GM) plants on soil and model organisms in the laboratory to substitute laborious and time consuming field trials. For the studies described here we focused on two GM plants of the so-called 3rd generation: GM plants producing pharmaceuticals (PMP) and plant made industrials (PMI). Cyanophycin synthetase (cphA) was chosen as model for PMI and Choleratoxin B (CTB) as model for PMP. The model genes are expressed in transgenic roots of composite Vicia hirsuta plants grown in petri dishes for semi-sterile growth or small containers filled with non-sterile soil. No significant influence of the model gene expression on root induction, growth, biomass, interaction with symbionts such as rhizobia (number, size and functionality of nodules, selection of nodulating strains) or arbuscular mycorrhizal fungi could be detected. In vitro, but not in situ under field conditions, structural diversity of the bulk soil microbial community between transgenic and non-transgenic cultivars was determined by PLFA pattern-derived ratios of bacteria: fungi and of gram⁺: gram^- bacteria. Significant differences in PLFA ratios were associated with dissimilarities in the quantity and molecular composition of rhizodeposits as revealed by Py-FIMS analyses. Contrary to field trials, where small effects based on the transgene expression might be hidden by the immense influence of various environmental factors, our in vitro system can detect even minor effects and correlates them to transgene expression with less space, time and labour.

Fast and sensitive in vivo studies under controlled environmental conditions to substitute long-term field trials with genetically modified plants

We introduce an easy, fast and effective method to analyze the influence of genetically modified (GM) plants on soil and model organisms in the laboratory to substitute laborious and time consuming field trials. For the studies described here we focused on two GM plants of the so-called 3rd generation: GM plants producing pharmaceuticals (PMP) and plant made industrials (PMI). Cyanophycin synthetase (cphA) was chosen as model for PMI and Choleratoxin B (CTB) as model for PMP. The model genes are expressed in transgenic roots of composite Vicia hirsuta plants grown in petri dishes for semi-sterile growth or small containers filled with non-sterile soil. No significant influence of the model gene expression on root induction, growth, biomass, interaction with symbionts such as rhizobia (number, size and functionality of nodules, selection of nodulating strains) or arbuscular mycorrhizal fungi could be detected. In vitro, but not in situ under field conditions, structural diversity of the bulk soil microbial community between transgenic and non-transgenic cultivars was determined by PLFA pattern-derived ratios of bacteria: fungi and of gram⁺: gram^- bacteria. Significant differences in PLFA ratios were associated with dissimilarities in the quantity and molecular composition of rhizodeposits as revealed by Py-FIMS analyses. Contrary to field trials, where small effects based on the transgene expression might be hidden by the immense influence of various environmental factors, our in vitro system can detect even minor effects and correlates them to transgene expression with less space, time and labour.