Genetic transformation of pigeonpea: An overview

Biotechnology over the years has emerged as a promising tool to overcome biotic and abiotic constraints in crop species that lack the required traits for crop improvement through conventional and molecular breeding approaches. New engineering tools are now available not only for single gene traits, but also to engineer multiple genes or plant regulatory machinery for driving the expression of different stress responsive genes. Here, we discuss the recent progress and current status of transgenic technology in pigeonpea towards developing host plant resistance to various biotic and abiotic stresses and its use in the improvement of this important pulse crop

A master switch to tackle drought stress

In SATrends issues 62 (Jan 2006) and 75 (Feb 2007), we reported that when the DREB1A gene driven by the promoter of a stress-inducible gene, rd29A, was genetically introduced into groundnuts, it not only improved the transpiration efficiency, but also induced a positive root respons

Peanut (Arachis hypogaea L.)

Arachis hypogea (peanut, groundnut), an annual oil seed belonging to the Leguminosae family and the Papillionacea subfamily, is a legume native to South America but now grown in diverse environments in six continents between latitudes 40°N and 40°S. Arachis hypogea can grow in a wide range of climatic conditions. The low yields of this crop are mainly attributed to unreliable rainfall patterns with frequent droughts, lack of highyielding adapted cultivars, damage by diseases and pests, poor agronomic practices, and limited use of inputs. Genetic engineering approaches have been shown to be comparatively fast, leading to better isolation and cloning of desired traits for combating the various biotic and abiotic stresses. This chapter describes an Agrobacterium-mediated transformation protocol in peanut using the cotyledon system. The system described here is potentially applicable to a vast range of genotypes with a high transformation frequency of >70% based on the preliminary molecular data, indicating the production of a large number of independently transformed transgenic plants. The method reported here provides opportunities for crop improvement of this important legume crop via genetic transformation

Tackling toxins

Aflatoxins are toxic and carcinogenic substances produced by fungi such as Aspergillus flavus and A. parasiticus on a variety of food products. Contamination of groundnut (peanut) with mycotoxins such as aflatoxin has assumed significance in semi-arid regions of the world where over 4.5 billion people are exposed to uncontrolled amounts of these toxins. Although aflatoxin contamination does not affect crop productivity, it makes the produce unfit for consumption. Aflatoxin B1, the most toxic, is a potent carcinogen associated with liver cance

Pearl Millet

With an alarming concern of global climate change and increasing demand for drought-tolerant cereal staples, pearl millet, a widely exo- geographically adopted member of the millet family, has caught the attention for a robust genetic improvement. This chapter focuses on the various gene transfer technologies, both horizontal and vertical, employed so far in pearl millet to improve the strategy of introgression of newer traits and validation of gene function through transgenic development. This chapter also compares the different gene transfer technologies based on their exploitation in pearl millet development. It also accounts for the details of genes transferred so far, especially for conferring biotic and abiotic stress tolerance, in this crop. This chapter also discusses the future possibilities regarding the introgression of genes of new traits and technologies already utilized in other millets, which are hitherto unexploited for pearl millet

Molecular insights into the functional role of nitric oxide (NO) as a signal for plant responses in chickpea

The molecular mechanisms and targets of nitric oxide (NO) are not fully known in plants. Our study reports the first large-scale quantitative proteomic analysis of NO donor responsive proteins in chickpea. Dose response studies carried out using NO donors, sodium nitroprusside (SNP), diethylamine NONOate (DETA) and S-nitrosoglutathione (GSNO) in chickpea genotype ICCV1882, revealed a dose dependent positive impact on seed germination and seedling growth. SNP at 0.1 mM concentration proved to be most appropriate following confirmation using four different chickpea genotypes. while SNP treatment enhanced the percentage of germination, chlorophyll and nitrogen contents in chickpea, addition of NO scavenger, cPTIO reverted its impact under abiotic stresses. Proteome profiling revealed 172 downregulated and 76 upregulated proteins, of which majority were involved in metabolic processes (118) by virtue of their catalytic (145) and binding (106) activity. A few crucial proteins such as S-adenosylmethionine synthase, dehydroascorbate reductase, pyruvate kinase fragment, 1-aminocyclopropane-1-carboxylic acid oxidase, 1-pyrroline-5-carboxylate synthetase were less abundant whereas Bowman-Birk type protease inhibitor, non-specific lipid transfer protein, chalcone synthase, ribulose-1-5-bisphosphate carboxylase oxygenase large subunit, PSII D2 protein were highly abundant in SNP treated samples. This study highlights the protein networks for a better understanding of possible NO induced regulatory mechanisms in plants

Horizontal Gene Transfer Through Genetic Transformation

Gene transfer technology in crop plants has tremendous potential to introduce newer and better traits through development of transgenics and broaden the genetic base of crop plants by transferring genes from novel sources overcoming the species and genus barriers. Nevertheless, development of efficient transformation systems remains a prerequisite and might involve many years of exhaustive research. This chapter overviews the different methods of alien gene transfer through genetic transformation and factors affecting efficient transformation across different crop species. A comparative study on Agrobacterium and biolistics-mediated transformation including methods for production of marker-free transgenics are described in detail. Addressing the growing concerns over the biosafety issue constraining wider application of GM products in agriculture this chapter also focuses on improved methods of choice with respect to a crop family and also deals with future strategies which can help in further exploiting the existing technologies to develop improved crop varieties which can help to combat poverty, hunger and global agro-climatic changes

NO to drought-multifunctional role of nitric oxide in plant drought: Do we have all the answers?

Nitric oxide (NO) is a versatile gaseous signaling molecule with increasing significance in plant research due to its association with various stress responses. Although, improved drought tolerance by NO is associated greatly with its ability to reduce stomatal opening and oxidative stress, it can immensely influence other physiological processes such as photosynthesis, proline accumulation and seed germination under water deficit. NO as a free radical can directly alter proteins, enzyme activities, gene transcription, and post-translational modifications that benefit functional recovery from drought. The present drought-mitigating strategies have focused on exogenous application of NO donors for exploring the associated physiological and molecular events, transgenic and mutant studies, but are inadequate. Considering the biphasic effects of NO, a cautious deployment is necessary along with a systematic approach for deciphering positively regulated responses to avoid any cytotoxic effects. Identification of NO target molecules and in-depth analysis of its effects under realistic field drought conditions should be an upmost priority. This detailed synthesis on the role of NO offers new insights on its functions, signaling, regulation, interactions and co-existence with different drought-related events providing future directions for exploiting this molecule towards improving drought tolerance in crop plants