A sub-chronic feeding study of dual toxin insect-resistant transgenic maize (CEMB-413) on Wistar rats

Genetically modified (GM) crops expressing insecticidal crystal proteins are widely accepted worldwide, but their commercial utilization demands comprehensive risk assessment studies. A 90-day risk assessment study was conducted on Wistar rats fed with GM maize (CEMB-413) expressing binary insect-resistant genes (cry1Ac and cry2Ab) at low (30%) and high (50%) dose along with a control diet group. The study used fifty Wistar rats randomly distributed in five treatment groups. Our study revealed that compared to controls, GM diet had no adverse effects on animal's health, including body weight, food consumption, clinical pathological parameters, serum hormone levels and histological parameters of testes and ovaries of rats. Differences were observed in transcripts levels of fertility related genes, but these were independent of treatment with GM diet.

Heterologous expression of cry1Ia12 insecticidal gene in cotton encodes resistance against pink bollworm, Pectinophora gossypiella (Lepidoptera: Gelechiidae); an alternate insecticidal gene for insect pest management

BACKGROUND

Cotton is continuously exposed to sucking and chewing insect pest pressure since emergence to harvesting. Pink bollworm (Pectinophora gossypiella) has become major chewing insect pest to reduce the cotton yield and results in bad lint quality even in transgenic crops. The efficiency of insecticidal genes has been compromised due to extensive utilization of transgenic crops.

METHODS AND RESULTS

The present study was conducted to evaluate the efficacy of an alternate cry1Ia12 insecticidal gene against pink bollworm (PBW) in cotton. Agrobacterium tumefaciens strain LBA4404 harboring pCAMBIA2300 expression vector containing cry1Ia12 gene under the control of 35S CaMV was used to transform a local cotton cultivar GS-01. The various molecular analyses revealed the transgene integration and expression in primary transformants. Among five selected transgenic plants, tcL-08 showed maximum (16.06-fold) mRNA expression of cry1Ia12 gene whereas tcL-03 showed minimum (2.33-fold) expression. Feeding bioassays of 2nd and 3rd instar pink bollworm (PBW) larvae on immature cotton bolls, flowers and cotton squares revealed up to 33.33% mortality on tcL-08 while lowest mortality (13.33%) was observed in tcL-03 and tcL-15. Furthermore, the average weight and size of survived larvae fed on transgenic plants was significantly lesser than the average weight of larvae survived on non-transgenic plants.

CONCLUSIONS

The present study suggests the cry1Ia12 gene as an alternate insecticidal gene for the resistance management of cotton bollworms, especially PBW.

Expression of ice recrystallization inhibition protein in transgenic potato lines associated with reduced electrolyte leakage and efficient recovery post freezing injury

Potato (Solanum tuberosum L.) is considered to be frost-susceptible as short spells of frost can reduce the tuber yield and quality. Ice recrystallization inhibition (IRI) protein helps prevent growth of ice crystals in the cell apoplast during frost and help prevent damage associated with freezing stress. In this study, we investigated the in planta potential of Lolium perenne derived IRI3 transgene in improving the tolerance of transgenic potato lines for freezing stress. The codon optimized IRI3 transgene was introduced into potato cultivar Diamant through Agrobacterium mediated transformation. Three transgenic potato lines were successfully generated which were confirmed for transgene insertion and genomic integration by polymerase chain reaction and Southern blot. It was evident that the IRI3 transcript decreased in initial 24 h of cold stress treatment while the IRI3 mRNA expression up regulated in subsequent hours of cold treatment with maximum increase to 20 folds at 96 h post stress. A similar trend was also revealed in ion-leakage assay which showed that during cold stress, the transgenic potato lines depicted reduced ion leakage of 14-22% as compared to non-transgenic control plants. Further, the generated transgenic potato lines were tolerant to the frost spell in quarantine field conditions as compared to the non-transgenic potato lines. Additionally, the transgenic lines exhibited efficient recovery post frost injury in field conditions. The biochemical profiles of chlorophyll, proline and higher levels of antioxidant enzyme (superoxide dismutase, Catalase) activity and malondialdehyde levels showed that despite the phenotypic impact of low temperature, the transgenic potato lines quickly adjusted to maintain their cellular homeostasis post freezing stress by increasing the antioxidant defenses. This study suggests that up regulation of IRI3 transcript and regulatory network of cold stress response in transgenic potato lines improve frost tolerance and help stabilize yield in cultivated potato.