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Risk Assessment
Record information and status
Record ID
113823
Status
Published
Date of creation
2018-08-31 18:44 UTC (gutemberg.sousa@mctic.gov.br)
Date of publication
2018-09-03 21:57 UTC (dema@itamaraty.gov.br)

General Information
Country
  • Brazil
Title of risk assessment
Technical Report 4865/2015 - Risk Assessment of genetically modified corn named Event DP-32138-1 expressing the characteristic of fertility restoration in naturally male-sterile maize lines.
Date of the risk assessment
2015-12-10
Competent National Authority(ies) responsible for the risk assessment
National Technical Biosafety Commission
Setor Policial Sul -SPO Área 5 Quadra 3 Bloco B - Térreo Salas 10 à 14
Brasília, DF
Brazil, CEP - 70610-200
Phone:(5561) 3411-5516
Fax:(5561) 3317-7475
Email:ctnbio@mct.gov.br
Url:National Technical Biosafety Comission
Contact details of the main responsible risk assessor
Dra Maria Sueli Felipe Soares
President
National Technical Biosafety Comission (CTNBio)
Setor Policial Sul -SPO Área 5 Quadra 3 Bloco B - Térreo Salas 08 à 10
Brasília, DF
Brazil, CEP - 70610-200
Phone:(5561) 3411-5151
Fax:(5561) 3317-7475
Email:msueliunb@gmail.com
Url:National Technical Biosafety Comission
Risk assessment details
Living modified organism
DP-32138-1 - 32138 SPT Maintainer
Changes in physiology and/or production - Reproduction - Male sterility Selectable marker genes and reporter genes
Scope of the risk assessment
  • LMOs for Introduction into the environment
Risk assessment report / Summary
Methodology and points to consider
Potential adverse effects identified in the risk assessment
SPT 32138 was generated by Agrobacterium-mediated transformation into a naturally male-sterile maize line (ms45 / ms45) with a plasmid containing three expression cassettes essential for the operation of the SPT system: Ms45, zm-aa1 , and DsRed2 (Alt1) 1. Expression of the MS45 protein restores fertility in male-sterile materials of the SPT 32138 maintainer, enabling the production of pollen. However, the Ms45 gene in the SPT 32138 maintainer is hemizygote (Ms45 / -) and, as a consequence, only half of the pollen produced contains the Ms45 gene. This half of the pollen also contains the gene zm-aa1 that encodes the α-amylase enzyme that destroys the starch, leaving transgenic pollen (Ms45 / zm-aa1 / DsRed2 (Alt1)) infeasible. The remaining half of the pollen is non-transgenic for the insertion of SPT 32138, remaining then viable, and carries the endogenous ms45 recessive gene. When SPT 32138 is used as a pollinator to propagate the seeds of male-sterile lineages that are non-transgenic for SPT 32138, the resulting progenies retain their male-sterile genotype (ms45 / ms45) and do not contain the SPT 32138 insert, being, therefore, not transgenic. Thus, commercial F1 hybrids produced using this male-sterile progeny and their respective grains do not contain the insert of SPT 32138 and are also non-transgenic. The fluorescent colored marker gene (DsRed2 (Alt1)) imparts the rosy red phenotype to any seed expressing the SPT 32138 insert, which enables that under appropriate illumination the seeds containing the SPT 32138 insert can be readily detected and separated from the seeds that do not contain the insert, using mechanical separation by color.
Likelihood that the potential adverse effects will be realized
Event 32138 shows no potential to become a weed or pollinate other plants sexually, since SPT 32138 does not produce viable transgenic pollen. There is also no evidence of impact on other organisms that have contact with the non-viable pollen of SPT 32138, whereas the data demonstrate that the expressed proteins are non-toxic.
Considering that the context of risk assessment is a genetic modification event used only in the fields of seed production and that commercial seed of hybrid maize or grains consumed will not be genetically modified, the analysis of this risk assessment shows that the mechanisms that guarantee the efficiency of the process in terms of the absence of the SPT 32138 insert in the progeny are important. In this way possible scenarios, in which the genetic components of the SPT system could be separated, were presented by the applicant and should also be considered.
Possible consequences:
The risk assessment presented was carried out according to the context of the proposed use - that the SPT technology be used in the company's internal operations for seed production. The applicant presents and discusses in detail in her risk assessment some scenarios that could reduce the efficiency of the SPT process in terms of ensuring the absence of the transgene in the offspring. (Proposal: Appendix 7 - Potential scenarios for breaking the genetic insertion 32138 SPT and consequences for the SPT process). These scenarios consider the possibility that the genetic components of the SPT system are separated through genetic recombination mechanisms. According to the discussion presented by the applicant, based on the crossing-over rates, genome location and hemizygous status of the insert, this breakdown of the binding between the gene cassettes of the SPT 32138 insert would be rare events and, if they occur, could be detected and the seeds without compromising the efficiency of the SPT process. The scenarios presented by suppressing one or two of the three genes from the SPT 32138 insert from a single break would originate seeds of different color, which would be removed during the sorting, or would originate plants with phenotypes opposite to those expected (ie male-fertile or male-sterile) plants that would be recognized as off-type plants and eliminated during routine inspection as part of quality control practices. In the extremely rare occurrence of two breaks between the cassettes the elimination of zm-aa1, the proportion of seed observed in each spike in the classification process could indicate an abnormal genotype and the plant would be removed and no longer used. In the case of suppression of the Ms45 and DsRed2 (Alt1) genes, the zm-aa1 gene of the SPT insert would probably pass to the next generation, however, the progeny would be sterile and no longer propagated.
Estimation of the overall risk
The proposed use for event SPT 32138 is the production of seeds, so all the data provided in the proposal submitted by the applicant indicate that the maize grains of SPT 32138 should not be used for human or animal consumption. In the case of an unintended introduction of SPT 32138 into the human and animal food chain, the applicant submits data in the proposal to support the claim that the MS45, ZM-AA1 and DsRed2 proteins have no potential to cause toxicity or allergenicity.
Recommendation(s)
Female lineage seeds produced in this manner do not contain the insert of the SPT 32138 event, and consequently the hybrid F1 seeds produced with the use of these male-sterile parent lines as well as the commercially produced field beans contain no SPT 32138-derived insert and therefore are not transgenic for SPT
Need(s) for further information on specific issues of concern
The SPT process makes the transient use of event DP-32138-1 (SPT 32138) at the beginning of the process of basic seed multiplication. SPT 32138 is used as a pollinator to propagate seeds of male-sterile lineages. Female lineage seeds produced in this manner do not contain the insert of the SPT 32138 event, and consequently the hybrid F1 seeds produced with the use of these male-sterile parent lines as well as the commercially produced field beans contain no SPT 32138-derived insert and therefore are not transgenic for SPT. SPT technology uses transgenics in part of the process, without recombinant DNA molecules being present in commercial hybrids and corn kernels, producing so-called "null segregant / negative segregant".
Receiving environment(s) considered
fields of hybrid corn seed production
LMO detection and identification methods proposed
Molecular traditional methods

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