The growth, development and productivity of crop plants is negatively influenced by abiotic stresses like drought, salinity, heat and chilling leading to significant losses in crop yield. The modern technology of genetic engineering has enabled the scientists to move genes from distant sources into crop plants to develop resistance against insect pests, weeds and invading pathogens, some of them have already been commercialized. Similarly, efforts have been made to develop crop plants with enhanced tolerance against drought, salinity and chilling and waterlogging stress. Engineering crops against abiotic stresses has always been a challenge as this character is controlled by multigenes. The stress signaling and regulatory pathways have been elucidated using advanced molecular approaches and genes encoding tolerance to drought, salinity and chilling stress are being introduced in crop plants of economic importance using transformational technologies. The present review focuses the recent advances made in the development of transgenic crop plants of commercial importance with enhanced tolerance to abiotic stress; also the future prospects of stress tolerant crops have also been discussed.
Cotton (Gossypium hirsutum L.) is the most significant cash crop and backbone of global textile industry. The importance of cotton can hardly be over emphasized in the economy of cotton-growing countries as cotton and cotton products contribute significantly to the foreign exchange earnings. Cotton breeders have continuously sought to improve cotton's quality through conventional breeding in the past centuries; however, due to limited availability of germplasm with resistant to particular insects, pests and diseases, further advancements in cotton breeding have been challenging. The progress in transformation systems in cotton paved the way for the genetic improvement by enabling the researchers to transfer specific genes among the species and to incorporate them in cotton genome. With the development of first genetically engineered cotton plant in 1987, several characteristics such as biotic (insects, viruses, bacteria and fungi) resistance, abiotic (drought, chilling, heat, salt), herbicide tolerance, manipulation of oil and fiber traits have been reported to date. Genetic engineering has emerged as a necessary tool in cotton breeding programs, strengthening classical strategies to improve yield and yield contributing factors. The current review highlights the advances and endeavors in cotton genetic engineering achieved by researchers worldwide utilizing modern biotechnological approaches. Future prospects of the transgenic cotton are also discussed.
Insect pests are among the major constraints rendering drastic decreases in crop yield. The expression of stacked insecticidal genes in crops can lead to resistance durability and can delay the development of resistance in target insect pests. The present study was designed to introduce an insect resistance trait in locally cultivated Turkish tobacco cultivars (Basma and Nail) with pyramided insecticidal genes. Agrobacterium strain LBA4404 harboring plasmid pKGH4 with cry1Ac and cry2A genes under the control of 35S promoter was used to infect leaf discs of both cultivars; plasmid also contained uidA within the T-DNA region for earlier screening of putative transformants. The overall transformation efficiency was calculated as 30.7% and 18.8% in Basma and Nail, respectively. PCR results confirmed the integration of cry1Ac, cry2A, uidA, and nptII genes in 40 plants of Basma and 16 plants of Nail. ELISA results showed variation in expression of cry1Ac protein among transgenic plants varying from 0.017 to 0.607 µg/g of fresh tissue. Bioassay results with potato tuber moth (Phthorimea operculella Zeller) showed significant mortality of the targeted pest on primary transformants. Furthermore, T1 transgenic progeny exhibited the inheritance of T-DNA in Mendelian as well as non-Mendelian fashion. The results revealed that lines can serve as a source of germplasm in tobacco breeding programs.
The progenies of transgenic lines Bt-14 and Bt-17 developed as an independent transformation event from a local cotton variety CIM-482 harboring two insecticidal genes (cry1Ac & cry2a) were evaluated to determine resistance against lepidopterans, mainly Helicoverpa armigera L. under field conditions. The standard molecular techniques, i.e. polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA) and western dot blot were used to confirm gene presence and expression level of transformed Bt gene, and its transfer pattern to further progeny. PCR confirmed integration of insecticidal gene in most of the plants in transgenic progeny, while expression of Bt gene quantified by ELISA and western dot blot showed variation in cry1Ac expression levels but interestingly, it conferred full protection against targeted insect pests. The leaf bioassays were conducted to determine the effectiveness of Bt genes against Helicoverpa armigera by calculating the mortality percentage of larvae. Most of the transgenic lines showed 70-100% mortality % age of Helicoverpa armigera. The agronomic characteristics of the transgenic lines were also recorded along with non transgenic control variety CIM-482. Morphological, agronomic and fibre data of these transgenic lines was recorded and analyzed statistically. Our results show that these transgenic lines (especially Bt-17 line) are promising cotton germplasm to be used in an efficient breeding programme.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.