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Drought, low temperature, and salinity are abiotic stresses cause strong effects on plant growth and development.Nevertheless, the molecular mechanisms that regulate biochemical and physiological changesare not well understood in response to stresses in plant. Drought, cold and high salt are some abioticstresses that are adopted by appropriate mechanisms evolved by plants acting like sessileorganism(Fujita et al., 2006). Whenever environmental stresses occurs, to protect cellular activities whole plant biochemical and physiological responses with forming an organized complex network of various signals. Genes that function in first perception and transmission of stress signals with those subsequently activated to enable the stress response isknowntogether with many stress induced genes.
Conversely, environmental effects such as limits of temperature, extremes of water status as well as deteriorating soil conditions cause major pressure to agriculture and food security. Employing modern tools and techniques from every branches of science, efforts are being made globally to understand how plants react to abiotic stresses with the plan to help control plant performance that will be improved suited to survive in these stresses.
Millet-This crop cereal is small-seeded varieties generally grown mostly in all parts of the world for human fodder and food. A number of tolerant lines and conditions are generated in which it has been grown and used commercially. Beside this, advanced productivity needs to be obtained in tolerant backgrounds.
Polyamines (PAs) for engineered and natural abiotic stress tolerance in plants
Widely distributed biogenic amines are polyamines, which are mixed up, in various cellular organismsââ‚¬â„¢ functions in extensively organisms. Association with different abiotic and biotic stresses pointed towards the fact that plants are mutant and transgenic with changed activities. Also, proteomic, transcriptomic and microarray approaches clears key functions of different PAââ‚¬â„¢s in plants in signaling networks subjected to biotic and abiotic stress, though the molecular mechanisms remained enigmatic.
It is necessary to focus on this point that it should not be taken only for protection of molecule but relatively like a double-faced molecule that gives a wide range for future research work and efforts.
There are lots of new advances in plant polyamine research from and mutant characterization and transgenic to potential mechanisms of action through environmental diseases and stresses.
Assumed effects of polyamines in plants under many abiotic and biotic stresses.
Several researches have confirmed that polyamine accumulation happens under abiotic stresses including salinity, extreme temperature, drought, UV-B, paraquat, hypoxia, heavy metals, herbicide treatment and mechanical wounding(Groppa and Benavides, 2008 and references 185 therein; Pang et al., 2007).Therefore, high cellular levels of polyamines compare with plant tolerance in a broadrange of environmental stresses. Though, the physiological importance of polyamine growth remains elusive and must be discovered whether these reactions are due to stress-induced injury or a shieldingreaction to abiotic stress.
Abiotic stress in Africa
Crop yields and plant growth areaffected by water availability,salinity, extremes of temperate and soil fertility. These abiotic stresses limit plant growth and produce a "gap in yieldââ‚¬Â. This is the variationamong the potential in yield and the yield attained by farmers.
Above the last 50 years, plant breeders have improved the potential in yield by improving crops although the gap in yield has remained same. This is because of a mixture of abiotic stresses, biotic stresses (pest and diseases) poor land and farm management. Yearly yields can differa lot as 33% in Europe as of abiotic stresses alone, but the influence is much bigger in Africa where failures of crop from droughts are general.
It is expected that worldwide food production may need to double by 2050 to feed growing human population. (This production requires to sustainable by falling the environmental effects of agriculture and at the mean time supporting food security. Climate change can make this all difficult with growing the frequency of severe weather changes and intensifyingabiotic stresses, particularly in context to water availability and high temperature.
To avoid present, and future, extensive crop failures causing increase hunger also malnutrition, its must to breed plants that will not only survive in bad conditions also can keep high crop yields. Drought is one of the most serious abiotic stresses affecting crops in Africa.
According to the Food and Agricultural Organization, only 11.6% (14.2 million hectares) of the land in South Africa is suitable for growing crops and 93% (13.17 million hectares) of this is already used for agriculture.ÂÂ
Drought is one of the most serious abiotic stresses affecting crops in Africa.
Transgenic plants have been made carrying gene and results of exposure to abiotic stresses presented like high salinity, intensity,and heat.
Limited knowledge of stress-associated metabolism remains a major gap in understanding.
Comprehensive profiling of stress-associated metabolites is most relevant to the successful molecular breeding of stress-tolerant crop plants.
Unravelling additional stress-associated gene resources, from both crop plants and highly salt- and drought-tolerant model plants, may enable future molecular dissection of salt-tolerance mechanisms in important crop plants.
Abiotic stresses, especially salinity and drought, are the primary causes of crop loss worldwide.
Plant adaptation to environmental stresses is dependent upon the activation of cascades of molecular networks involved in stress perception, signal transduction,and the expression of specific stress-related genes, metabolites.
Engineering genes that protect and maintain the function and structure of cellular components can enhance tolerance to stress.
New enhancement may have a significant impact on attempts to increase stress tolerance of crops. Ecological balance is the objective condition on which the process can continue. Human activities have affected the process and destroy the balance, which is major issue for concern. To avoid worse condition, we should keep environment balance by reducing.
The tolerance to abiotic stress is highly expected to cope with the unfavorable environmental challenges by the generation of new plant varieties. More information required to understand and ability to control difficult traits even with the existing knowledge on the systematic bases of drought tolerance. Some approaches and improved breeding given numerous tolerant varieties Genetic engineering provided plants with significant tolerance and is the best method to get superior plants having abiotic tolerance, between other agronomically main traits.
Progress is going on at the molecular level for biotic and abiotic stress tolerance in crops with biotechnological improvement. Detail study and analysis of the genes involved in stress tolerance and expressions, functions of PA genes will be useful in future. Intensiveresearch on PA and stress tolerance has already set the platform to understand functions of simple molecules.