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This work is licensed under Creative Commons Attribution 4.0 License AJBSR.MS.ID.000681

Jatropha curcas L. belongs to family Euphorbiaceae, Jatropha curcas is a valuable multi-purpose crop, historically it was used as medicine for wounds and leaves used as drinks against malaria, jatropha plants used to control soil degradation, alleviate erosion, desertification and increase soil fertility, however, in last decades there is more attention to use jatropha oil for produce biodiesel,  Jatropha curcas is easily propagated by seeds or stem cutting, it is tolerant for drought for longtime, it is grow well with treated wastewater, also, it can be grown on marginal land. Jatropha curcas seed have about 32-40% valuable oil used to produce biofuel, therefore, it could be the source for biodiesel production particularly in arid and semiarid regions.

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Climate change has a dramatic effect on growth and productivity of various crops, there are various environmental elements affect the life cycle of annual and perennial plants, like high temperature, heatwaves, drought, cool temperature and frost, rising carbon dioxide (CO2) levels. Climate change represents a dangerous challenge for mankind, there need for an efficient strategy to guarantee adequate crop production for humanity. Citrus is one of the main fruits all over the world, citrus can be grown in different climatic zones ranging from tropical, subtropical, arid and semi-arid areas, citrus grows properly in the range from 12.8 to 37˚C, which considered the optimum temperature for citrus growth and fruiting, while, sever high temperature (above 44-45˚C) stopped citrus growth completely. Low temperature considered the limiting factor for the geographical distribution of citrus, low temperature could stoop metabolism activity, whereas, chilling and frost cause severe injuries and demolish the whole tree. Temperature fluctuation affects negatively growth, decreases total yield, and reduces fruit quality particularly when occurred during the maturity stage, also, there are negative effects of heatwaves on the production of different citrus varieties particularly seedless varieties like Navel orange, and some Mandarin and lemon cultivars. On another side, rising carbon dioxide has positive effects on the growth of citrus seedlings and trees productivity.

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Epigenetics is the study of heritable changes in gene expression that happen without any change in the DNA sequence. The main epigenetic mechanisms, including DNA methylation, histone modifications, and microRNA expression, can be caused by environmental reasons. The aim of this work explains that epigenetic modifications may be due to effects of environmental stress on plant growth and productivity. The study of epigenetic-based mechanisms in the plant is an emerging field; gene expressions are modulated and reprogrammed in response to environmental stress challenges. Due to increasing global population, in the same time the availability of arable lands is decreased regularly and the severe effects of climate change problem, therefore, it is essential to understand the mechanisms that plants have progressed to adapt with varied environments stress, and in particular how plant types adapt with various kinds of biotic and abiotic stress. The main role of epigenetics study is understanding the role of the epigenetic component in regulates plant gene expression and the plant phenotype, and how the epigenome workings as a great source of diversity for main agronomical characters and on how it could use, in crop breeding and implementation programs, it would be of benefit to humanity for next era, numerous papers have studied the effects of environmental exposures and epigenetic markers that modify epigenetic states of plants and refers those epigenetic modifications may be one of the mechanisms by which abiotic stress can have positive effects on plant growth.