Roles of glycine betaine and proline in improving plant abiotic stress resistance

When exposed to stressful conditions, plants accumulate an array of metabolites, particularly amino acids. Amino acids have traditionally been considered as precursors to and constituents of proteins, and play an important role in plant metabolism and development. A large body of data suggests a positive correlation between proline accumulation and plant stress. Proline, an amino acid, plays a highly beneficial role in plants exposed to various stress conditions. Besides acting as an excellent osmolyte, proline plays three major roles during stress, i.e., as a metal chelator, an antioxidative defense molecule and a signaling molecule. Review of the literature indicates that a stressful environment results in an overproduction of proline in plants which in turn imparts stress tolerance by maintaining cell turgor or osmotic balance; stabilizing membranes thereby preventing electrolyte leakage; and bringing concentrations of reactive oxygen species (ROS) within normal ranges, thus preventing oxidative burst ...

https://www.tandfonline.com/doi/pdf/10.4161/psb.21949

Role of proline under changing environments: a review.

The origin of plant cell and tissue culture can be found in a treatise published during the mid-18th century, entitled La Physique des Arbes, that describes the formation of callus tissue following the for mation of a ring of cortex from elm trees. Over the next two centuries, the discovery of plant growth hormones, in particular auxins and cytokinins, and detailed analyses on the nutritional requirements of plants, led to the formulation of media that could maintain actively dividing cultures derived from gymnosperms, and both dicotyledon ous and monocotyledonous angiosperms. However, much of the prog ress and technological development in the in vitro propagation of plant cells, tissues, and organs has occurred during the last 25 years. Recently, plant tissue culture techniques have been used as basic tools in the rapidly expanding field of plant biotechnology for the development and clonal propagation of new and/or improved plant varieties. Plant tissue culture is used for the micropropagation of commercially valuable cultivars that include ornamentals, oil palm, Glycyrrhiza, Pyrethrum, pine, Eucalyptus, sugar cane, and potatoes. Cultured plant tissue is also used for the selection of cells and, ul timately, the regeneration of plants that are tolerant to physical stresses such as pathogens, drought, and temperature extremes, and to chemical stress agents such as salinity, herbicides, proteins, and pyrethrins. In addition, new plants have been produced by the fusion of protoplasts prepared from cultured cells of different species in cluding sunflower and french bean, tomato and potato, and various cultivars of Datura. Finally, bacterial vectors and various mechanical methods have been used to introduce foreign genes into cultured plant tissues. Genetic transformation can result in profound changes in the phenotype and/or biochemical profile of the regenerated trans genic plants that are not characteristic of the wild type. An impressive variety of technologies in tissue culture, genetic manipulation, and molecular biology have been developed for nu merous plant species. Many of these techniques, sometimes referred to as plant biotechnology, have been extensively summarized and compiled in a well-balanced collection of easy-to-follow protocols presented in three separate, but complimentary, volumes. Plant Cell, Tissue and Organ Culture consists of 22 chapters (with 86 figures) and 5 appendices. The chapters cover critical aspects of (a) the es sential requirements for the operation of a plant tissue culture lab oratory; (b) the basic procedures of micropropagation, regeneration, and somatic embryogenesis; (c) some specific applications of organ culture systems such as embryo rescue and culture, and anther and microspore culture for haploid and double haploid production; (d) elementary transformation technology; and (e) useful microtechnique and analytical protocols specifically adapted to cultured tissues and cells. The appendices provide a convenient summary of media for mulations and commercial suppliers for the materials described in the text.

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Plant Cell, Tissue and Organ Culture

A method of identifying microorganisms with reduced adaptability to a particular environment, wherein (1) each microorganism is independent by insertional inactivation of a gene with a nucleic acid comprising a unique marker sequence. Mutating to provide a plurality of microorganisms, or clones of said microorganisms, such that each mutation has a different label sequence; (2) providing storage samples of each mutation produced by step (1), respectively, and providing storage nucleic acids each comprising a unique label sequence from each mutation; (3) introducing a plurality of mutations produced by step (1) into the specific environment such that the microorganisms capable of growing in the specific environment grow in the above environment; (4) recovering the microorganisms or selected portions thereof from the environment and separating nucleic acids from the recovered microorganisms; (5) comparing all label sequences in the nucleic acid isolated in step (4) with the unique label sequences of each of the stored mutations as in step (2); and (6) any label isolated in step (4). Screening for individual mutations that also do not have a sequence.

Identification of genes

Soil salinity is a major environmental constraint to crop productivity worldwide. The “biological” approach to this problem focuses on the management, exploitation, or development of plants able to thrive on salt‐affected soils. This chapter reviews strategies by which plants can be enabled to grow on saline soils. The first strategy is to prime seeds before planting by treating them with inorganic or organic chemicals and/or with high or low temperatures. The second strategy involves exogenous application of organic chemicals, such as glycine betaine, proline, or plant growth regulators, or inorganic chemicals to plants under salinity stress. Considerable improvements in growth and yield have been reported in a number of crops using these approaches. The third strategy is to employ selection and breeding. Major efforts have been made to develop salt‐tolerant lines or cultivars of crops using conventional plant breeding. However, the complexity of the tolerance mechanisms, lack of selection criteria, and variation in responses of plants at different developmental stages have resulted in only limited success. The emphases for developing salt‐tolerant lines/cultivars are now on marker‐assisted breeding and genetic transformation. The development of salt‐tolerant transgenic plants is still at an early stage but may become increasingly more effective as better knowledge of the complex mechanisms involved in plant salt tolerance is acquired. Furthermore, the rapid expansion in knowledge on genomics and proteomics will undoubtedly accelerate the transgenic and molecular breeding approaches However, to date, there are few conclusive reports indicating successful performance of transgenic cultivars under natural stressful environments.

Some Prospective Strategies for Improving Crop Salt Tolerance

The sex of Carica papaya, an angiosperm and Cycas circinalis, a gymnosperm was studied using ISSR and RAPD techniques in pre-flowering stage. One female-specific band generated from ISSR profile using primer (GACA) 4 was detected in papaya, which seems to have importance from agricultural point of view. Sequencing of a male-specific RAPD band (PCR with primer OPB 01) in C. circinalis revealed homology with putative retro elements of diverse plants, probably indicating its use in the detection of male C. circinalis in future.

Sex detection of Carica papaya and Cycas circinalis in pre-flowering stage by ISSR and RAPD

The implication of accumulation of both inorganic (Na+, K+) and organic (proline) solutes were evaluated in unadapted and NaCl-adapted callus of a salt-sensitive (Basmati 370) and a salt-tolerant (SR-26B) cultivar of rice (Oryza sativa L.) after a NaCl shock. Accumulation of Na+,K+ and/or proline in callus was co relatable and the relative presence of these components in tissues after shock treatment was found to be important factors to support differential regrowth capacities of the shock treated calluses. Presence or retention of K+ in rice callus was a key factor for salt tolerance as it was observed to be positively correlated with growth in both the varieties. The results indicated that K+ was the first candidate to counteract the negative water potential of outside milieu, while proline was probably the last metabolic device that rice calluses opted for when exposed to salt stress.

Salt tolerance in rice in vitro: implication of accumulation of na+, k+ and proline

Micro shoots developed from the meristematic basal portion of the innermost leaves of pineapple [ Ananus comosus (L.) Merr] were encapsulated in alginate beads for short-term storage as a prelude to the transformation programme. Among the four temperature regimes for storage, beads stored at 8 °C showed maximum percentage of shoot proliferation when placed again in MS medium; the rate of ‘conversion’ was satisfactory even beyond 45 days of incubation. The genetic fidelity of the pineapple plants growing out after storage in encapsulated form was ascertained by RAPD and ISSR techniques.

Encapsulation of pineapple microshoots in alginate beads for temporary storage

In the quest for cheap and suitable eco-friendly matrix with liquid culture to facilitate rooting three matrices, viz paddy straw, jute and coir were chosen Of the three matrices, coir was selected due to its higher water retention capacity compared to the other two matrices Coir was used with aseptic liquid media for rooting of ten plant species, viz, Nicotiana tabacum, Andrographis paniculata, Chenopodium album (2n=54), C album (Broad leaf diploid), C album (Narrow leaf diploid), C murale, Beta vulgaris (Sugar beet and Table beet), B palonga (Indian spinach), Tectona grandis and Musa spp Higher number of roots with profuse root hairs were recorded in all the plant materials in liquid medium with coir compared to conventional agar-gelled media Apart from rooting, the rate of multiplication, maintenance and concomitant hardening were also found to be more effective in comparison to agar-gelled media The economical aspect of use of coir instead of agar is also discussed

Enhanced rate of multiplication and rooting through the use of coir in aseptic liquid culture media

Growth, viability and proline content of adapted and unadapted calluses of Nicotiana tabacum L. var. Jayasri, affected due to osmotic stresses and particularly to stress-shocks treated with different osmotica like NaCl (ionic-penetrating), mannitol (non-ionic-penetrating) and polyethylene glycol, (PEG) (non-ionic-non penetrating) were studied to evaluate the physiological differences of stress effects. The tissues adapted to a low concentration of NaCl (85 mM) showed low growth with high proline content compared to the tissues adapted to a low concentration of mannitol (165 mM). Proline content was similar in tissues adapted to high concentrations of NaCl (171 mM) and mannitol (329 mM) but growth in the latter case was relatively low. Growth and viability were subsequently correlated with the pattern of retention in or diffusion of proline out of the tissues after shock-treatments. The loss of tissue viability of the adapted calluses was comparatively less than the unadapted callus even after shock-treatments with 1282 mM NaCl and 823 mM mannitol. The former calluses retained the capability of regrowth though at a slow rate. Such adapted tissues also retained more proline. The mannitol-adapted tissues, when shocked with PEG (200 g l-1), showed low viability with more diffusion and a very little retention of proline while, in the unadapted tissue, all the proline was leached out. The results indicated that the effects of different osmotica on plant tissue varied depending upon the physico-chemical nature of the compounds used as stress-inducing-agents, and retention and diffusion of proline was altered when the tissues were shocked with high concentrations of all these compounds.

Gaurab Gangopadhyay

Papers

Sex detection of Carica papaya and Cycas circinalis in pre-flowering stage by ISSR and RAPD

Salt tolerance in rice in vitro: implication of accumulation of na+, k+ and proline

Encapsulation of pineapple microshoots in alginate beads for temporary storage

Enhanced rate of multiplication and rooting through the use of coir in aseptic liquid culture media

Effects of salt and osmotic shocks on unadapted and adapted callus lines of tobacco