Apomixis: an enigma with potential applications

Apomixis has been the focus of research in plant sciences in recent years with lot of scope for crop improvement. It results in clonal progeny without fertilization, having maternal genetic constitution. The impact of introducing apomixis in crop plants could be significant mainly for its use in fixation of hybrid vigour. Because of epigenetic barriers, introgression of apomixis from a close relative to a sexual crop plant by conventional plant breeding methods could not generate expected results. Recent developments in plant molecular biology and biotechnology can help in developing potential strategies. This article summarizes various aspects of apomixis research that are being followed in India and abroad

Expression of a rice chitinase gene enhances antifungal potential in transgenic grapevine (Vitis vinifera L.)

To enhance the antifungal potential of grapevine, transgenic plants were generated by transferring rice chitinase gene under a maize-ubiquitin promoter along with its first intron into the leaf disc-induced somatic embryos via Agrobacterium mediated transformation. After co-cultivation for 2 days with recombinant Agrobacterium, somatic embryos were transferred onto WPM medium containing BAP 1.5 μM and NAA 0.1 μM supplemented with 25 mg/L hygromycin. Secondary or tertiary embryos were selected and the antibiotic resistant transgenic plantlets were analyzed. The integration and stability of the transgene were confirmed by PCR, RT-PCR, Southern blotting and by Western blot analyses. The transgenic plants exhibited higher chitinase activity than the non-transformed plants. These analyses indicated that the foreign gene was translated into the protein of expected molecular weight that showed chitinase activity. Following in vitro inoculation of powdery mildew (Uncinula necator), the transgenic plants showed delayed onset of the disease and smaller lesions. The transgenic plants were adapted to the greenhouse and did not show any phenotypic alterations.

Trust and Public Health Emergency Events:A Mixed-Methods Systematic Review

The systematic review examined the phenomenon of trust during public health emergency events. The literature reviewed was field studies done with people directly affected or likely to be affected by such events and included quantitative, qualitative, mixed-method, and case study primary studies in English (N = 38) as well as Arabic, Chinese, French, Russian, and Spanish (all non-English N = 30). Studies were mostly from high-and middle-income countries, and the event most covered was infectious disease. Findings from individual studies were first synthesized within methods and evaluated for certainty/confidence, and then synthesized across methods. The final set of 11 findings synthesized across methods identified a set of activities for enhancing trust and showed that it is a multi-faceted and dynamic concept

The communicative functions of metaphors between explanation and persuasion

In the literature, the pragmatic dimension of metaphors has been clearly acknowledged. Metaphors are regarded as having different possible uses, and in particular, they are commonly viewed as instruments for pursuing persuasion. However, an analysis of the specific conversational purposes that they can be aimed at achieving in a dialogue and their adequacy thereto is still missing. In this paper, we will address this issue focusing on the distinction between the explanatory and persuasive goal. The difference between explanation and persuasion is often blurred and controversial from a theoretical point of view. Building on the analysis of explanation in different theories and fields of study, we show how it can be conceived as characterized by a cognitive and a pragmatic dimension, where the transference of understanding is used pragmatically for different dialogical goals. This theoretical proposal will be applied to examples drawn from the medical context, to show how a pragmatic approach to explanation can account for the complexity of the cases that can be found in actual dialogical contexts

Deciphering the regulatory mechanisms of abiotic stress tolerance in plants by genomic approaches

Environmental constraints that include abiotic stress factors such as salt, drought, cold and extreme temperatures severely limit crop productivity. Improvement of crop plants with traits that confer tolerance to these stresses was practiced using traditional and modern breeding methods. Molecular breeding and genetic engineering contributed substantially to our understanding of the complexity of stress response. Mechanisms that operate signal perception, transduction and downstream regulatory factors are now being examined and an understanding of cellular pathways involved in abiotic stress responses provide valuable information on such responses. This review presents genomic-assisted methods which have helped to reveal complex regulatory networks controlling abiotic stress tolerance mechanisms by high-throughput expression profiling and gene inactivation techniques. Further, an account of stress-inducible regulatory genes which have been transferred into crop plants to enhance stress tolerance is discussed as possible modes of integrating information gained from functional genomics into knowledge-based breeding programs. In addition, we envision an integrative genomic and breeding approach to reveal developmental programs that enhance yield stability and improve grain quality under unfavorable environmental conditions of abiotic stresses

Novel light-activated protein kinases as key regulators of plant growth and development

Plants have evolved highly sensitive sensory photoreceptor systems to regulate various aspects of their growth and development. Many responses such as seed germination, flowering and dormancy are controlled by red and far-red regions of the solar spectrum through the phytochrome family of photoreceptors. However, several other responses such as stem growth inhibition, phototropism and opening of stomata are controlled by blue and/or ultraviolet light absorbing photoreceptors called cryptochromes and phototropin. Despite their central role in plant biology, the mode of action of these photoreceptors has been shrouded in mystery. Even the biochemical isolation of a photoreceptor, as in the case of phytochrome was accomplished decades ago, did not help in elucidating the mechanism of action. Nevertheless, due to advances in recombinant DNA technology, generation of extensive databanks and the capability to predict function by base sequence analysis, a breakthrough has now come about. It is clear that certain phytochromes, at least in the cyanobacteria and algae which represent the simplest plants, are hybrid photoreceptor-cum-kinases. These novel kinases utilize captured photons rather than conventional ligands to trigger conformational change and in consequence enzyme activity. The kinases apparently, then, cause phosphorylation of many other types of target molecules, leading eventually to various developmental changes. There is suggestive evidence that in higher plants, too, at least some phytochromes may operate as kinases. As compared to work on phytochromes, the blue light photoreceptors have begun to be studied only recently. However, the exciting discovery has been made of at least one photoactive kinase that is critically required for phototropism. This article summarizes the above discoveries from the perspective of general biology

A reliable protocol for transformation of Catharanthus roseus through Agrobacterium tumefaciens

Proliferation of axillary shoot buds and multiple shoot formation in Catharanthus roseus was obtained in 96 % explants on MS medium (3% sucrose) containing NAA+BA. 2,4-D induced callusing in both, the nodal as well as in leaf segments. Leaf-derived callus was used for transformation with Agrobacterium tumefaciens LBA4404/pBI-S1. Bacterial cell concentration, duration of co-cultivation and acetosyringone concentration influenced transformation efficiency. Under optimal co-cultivation conditions, 98 % of the explants showed GUS expression. PCR based amplification of the transformed and subsequently selected callus tissue indicated the presence of uidA, Gly I and nptII genes

Engineering apomixis in crops: a challenge lot plant molecular biologists in the next century

This article does not have an abstract