ABSTRACT
The idea of enhanced methanol production from cell wall by pectin methyl esterase enzymes (PME) combined with expression of cry genes from Bacillus thuringiensis as a strategy to improve insect pest control in cotton is presented. We constructed a cassette containing two cry genes (cry1Fa and Cry32Aa) and two pme genes, one from Arabidopsis thaliana (AtPME), and other from Aspergillus. niger (AnPME) in pCAMBIA1301 plant expression vector using CAMV-35S promoter. This construction was transformed in Eagle-2 cotton variety by using shoot apex-cut Agrobacterium-mediated transformation. Expression of cry genes and pme genes was confirmed by qPCR. Methanol production was measured in control and in the cry and pme transformed plants showing methanol production only in transformed plants, in contrast to the non-transgenic cotton plants. Finally, insect bioassays performed with transgenic plants expressing cry and pme genes showed 100% mortality for Helicoverpa armigera (cotton bollworm) larvae, 70% mortality for Pectinophora gossypiella (pink bollworm) larvae and 95% mortality of Earias fabia, (spotted bollworm) larvae, that was higher than the transgenic plants expressing only cry genes that showed 84%, 49% and 79% mortality, respectively. These results demonstrate that Bt. cry-genes coupled with pme genes are an effective strategy to improve the control of different insect pests.
Subject(s)
Bacillus thuringiensis , Moths , Animals , Bacillus thuringiensis/genetics , Bacillus thuringiensis Toxins , Bacterial Proteins/genetics , Endotoxins/genetics , Gossypium/genetics , Hemolysin Proteins/genetics , Insecticide Resistance , Larva , Methanol , Plants, Genetically ModifiedABSTRACT
Lack of precise information about the candidate genes involved in a complex quantitative trait is a major obstacle in the cotton fiber quality improvement, and thus, overall genetic gain in conventional phenotypic selection is low. Recent molecular interventions and advancements in genome sequencing have led to the development of high-throughput molecular markers, quantitative trait locus (QTL) fine mapping, and single nucleotide polymorphisms (SNPs). These advanced tools have resolved the existing bottlenecks in trait-specific breeding. This review demonstrates the significance of chromosomes 3, 7, 9, 11, and 12 of sub-genomes A and D carrying candidate genes for fiber quality. However, chromosome 7 carrying SNPs for stable and potent QTLs related to fiber quality provides great insights for fiber quality-targeted research. This information can be validated by marker-assisted selection (MAS) and transgene in Arabidopsis and subsequently in cotton.