K. Vijayakumari

Bio: K. Vijayakumari is an academic researcher from University of Calicut. The author has contributed to research in topics: Abiotic component & Abiotic stress. The author has an hindex of 3, co-authored 3 publications receiving 373 citations.

Seed priming for abiotic stress tolerance: an overview

Abstract: Plants are exposed to any number of potentially adverse environmental conditions such as water deficit, high salinity, extreme temperature, submergence, etc. These abiotic stresses adversely affect the plant growth and productivity. Nowadays various strategies are employed to generate plants that can withstand these stresses. In recent years, seed priming has been developed as an indispensable method to produce tolerant plants against various stresses. Seed priming is the induction of a particular physiological state in plants by the treatment of natural and synthetic compounds to the seeds before germination. In plant defense, priming is defined as a physiological process by which a plant prepares to respond to imminent abiotic stress more quickly or aggressively. Moreover, plants raised from primed seeds showed sturdy and quick cellular defense response against abiotic stresses. Priming for enhanced resistance to abiotic stress obviously is operating via various pathways involved in different metabolic processes. The seedlings emerging from primed seeds showed early and uniform germination. Moreover, the overall growth of plants is enhanced due to the seed-priming treatments. The main objective of this review is to provide an overview of various crops in which seed priming is practiced and about various seed-priming methods and its effects.

γ-Aminobutyric acid (GABA) priming enhances the osmotic stress tolerance in Piper nigrum Linn. plants subjected to PEG-induced stress

Abstract: The pretreatment of two black pepper varieties, Panniyur 1 (drought-sensitive) and Panniyur 5 (drought-tolerant) with GABA (2 mM) influenced various physiological and biochemical parameters positively and the PEG (poly ethylene glycol 6000; 10 % w/v)-induced stress tolerance was increased in both varieties of black pepper. Although both varieties primed with GABA showed positive responses while encountering PEG-stress, Panniyur 5 showed better performance. When compared to non-primed plants induced with PEG-stress, GABA primed black pepper plants showed enhanced rate of leaf RWC and also a faster reduction of cell osmotic potential. Proline and total sugars were found to accumulate earlier in primed plants and the activity of antioxidant enzymes like guaiacol peroxidase and superoxide dismutase also increased significantly, in response to PEG-stress. When compared to non-primed plants, GABA priming resulted in a reduced rate of lipid peroxidation, and comparatively lesser inhibition of photosynthetic and mitochondrial activity (measured in terms of O2 evolution/uptake) in primed plants during osmotic stress. Occurrence of GABA in plants of black pepper varieties was detected by HPTLC technique. In PEG-treated plants GABA content was higher than that of control; and a multifold enhancement of GABA was observed in black pepper plants subjected to PEG-stress, after priming with GABA.

GABA/BABA priming: a means for enhancing abiotic stress tolerance potential of plants with less energy investments on defence cache

Abstract: Abiotic stress is one of the major factors limiting plant growth and yield globally. Though substantial progress has been made in breeding and genetic manipulation of plants to enhance abiotic stress tolerance, the task remains as a challenge even today. Investigations on the priming activity of various chemicals in plants for enhancing abiotic stress tolerance have been undertaken over the past few years. Priming with γ-amino butyric acid (GABA) and β-amino butyric acid (BABA) gains greater attention, because priming with these non-protein amino acids equips the plants to resist abiotic stresses effectively without suffering costly energy investments in operating defence mechanisms. It is well documented that the protective effect of non-protein amino acids like BABA and GABA on plants is due to a potentiation of natural defence mechanisms against abiotic stresses but at the same time not activating the complete defence arsenal before the stress exposure. The exact mode of action of priming with GABA/BABA in plants is still a puzzle, though their importance as signaling molecules during stress is undoubtful. The better understanding of molecular, physiological, and ecological aspects of GABA/BABA priming might lead to the emergence of this technique as a successful strategy for enhancing the abiotic stress(es) tolerance potential of plants in the field, without compromising much on productivity.

Seed priming: state of the art and new perspectives.

Abstract: Priming applied to commercial seed lots is widely used by seed technologists to enhance seed vigour in terms of germination potential and increased stress tolerance. Priming can be also valuable to seed bank operators who need improved protocols of ex situ conservation of germplasm collections (crop and native species). Depending on plant species, seed morphology and physiology, different priming treatments can be applied, all of them triggering the so-called ‘pre-germinative metabolism’. This physiological process takes place during early seed imbibition and includes the seed repair response (activation of DNA repair pathways and antioxidant mechanisms), essential to preserve genome integrity, ensuring proper germination and seedling development. The review provides an overview of priming technology, describing the range of physical–chemical and biological treatments currently available. Optimised priming protocols can be designed using the ‘hydrotime concept’ analysis which provides the theoretical bases for assessing the relationship between water potential and germination rate. Despite the efforts so far reported to further improve seed priming, novel ideas and cutting-edge investigations need to be brought into this technological sector of agri-seed industry. Multidisciplinary translational research combining digital, bioinformatic and molecular tools will significantly contribute to expand the range of priming applications to other relevant commercial sectors, e.g. the native seed market.

Polyamines and abiotic stress in plants: a complex relationship1

Abstract: The physiological relationship between abiotic stress in plants and polyamines was reported more than 40 years ago. Ever since there has been a debate as to whether increased polyamines protect plants against abiotic stress (e.g., due to their ability to deal with oxidative radicals) or cause damage to them (perhaps due to hydrogen peroxide produced by their catabolism). The observation that cellular polyamines are typically elevated in plants under both short-term as well as long-term abiotic stress conditions is consistent with the possibility of their dual effects, i.e., being protectors from as well as perpetrators of stress damage to the cells. The observed increase in tolerance of plants to abiotic stress when their cellular contents are elevated by either exogenous treatment with polyamines or through genetic engineering with genes encoding polyamine biosynthetic enzymes is indicative of a protective role for them. However, through their catabolic production of hydrogen peroxide and acrolein, both strong oxidizers, they can potentially be the cause of cellular harm during stress. In fact, somewhat enigmatic but strong positive relationship between abiotic stress and foliar polyamines has been proposed as a potential biochemical marker of persistent environmental stress in forest trees in which phenotypic symptoms of stress are not yet visible. Such markers may help forewarn forest managers to undertake amelioration strategies before the appearance of visual symptoms of stress and damage at which stage it is often too late for implementing strategies for stress remediation and reversal of damage. This review provides a comprehensive and critical evaluation of the published literature on interactions between abiotic stress and polyamines in plants, and examines the experimental strategies used to understand the functional significance of this relationship with the aim of improving plant productivity, especially under conditions of abiotic stress.

Priming and memory of stress responses in organisms lacking a nervous system.

Abstract: Experience and memory of environmental stimuli that indicate future stress can prepare (prime) organismic stress responses even in species lacking a nervous system The process through which such organisms prepare their phenotype for an improved response to future stress has been termed 'priming' However, other terms are also used for this phenomenon, especially when considering priming in different types of organisms and when referring to different stressors Here we propose a conceptual framework for priming of stress responses in bacteria, fungi and plants which allows comparison of priming with other terms, eg adaptation, acclimation, induction, acquired resistance and cross protection We address spatial and temporal aspects of priming and highlight current knowledge about the mechanisms necessary for information storage which range from epigenetic marks to the accumulation of (dormant) signalling molecules Furthermore, we outline possible patterns of primed stress responses Finally, we link the ability of organisms to become primed for stress responses (their 'primability') with evolutionary ecology aspects and discuss which properties of an organism and its environment may favour the evolution of priming of stress responses