Climate prediction models suggest that agricultural productivity will be significantly affected in the future. The expected rise in average global temperature due to the higher release of greenhouse gases (GHGs) into the atmosphere and increased depletion of water resources with enhanced climate variability will be a serious threat to world food security. Moreover, there is an increase in the frequency and severity of long-lasting drought events over 1/3rd of the global landmass and five times increase in water demand deficits during the 21st century. The top three cereals, wheat (Triticum aestivum), maize (Zea mays), and rice (Oryza sativa), are the major and staple food crops of most people across the world. To meet the food demand of the ever-increasing population, which is expected to increase by over 9 billion by 2050, there is a dire need to increase cereal production by approximately 70%. However, we have observed a dramatic decrease in area of fertile and arable land to grow these crops. This trend is likely to increase in the future. Therefore, this review article provides an extensive review on recent and future projected area and production, the growth requirements and greenhouse gas emissions and global warming potential of the top three cereal crops, the effects of climate change on their yields, and the morphological, physiological, biochemical, and hormonal responses of plants to drought. We also discuss the potential strategies to tackle the effects of climate change and increase yields. These strategies include integrated conventional and modern molecular techniques and genomic approach, the implementation of agronomic best management (ABM) practices, and growing climate resilient cereal crops, such as millets. Millets are less resource-intensive crops and release a lower amount of greenhouse gases compared to other cereals. Therefore, millets can be the potential next-generation crops for research to explore the climate-resilient traits and use the information for the improvement of major cereals.

Epigenetic variation plays a role in developmental gene regulation and responses to the environment. An efficient interaction of zeatin-induced cytosine methylation and secondary compounds has been displayed for the first time in tissue-culture shoots/plants of lingonberry (Vaccinium vitis-idaea L.) cultivar Erntedank in vitro (NC1, in a liquid medium; NC2, on a semi-solid medium), ex vitro (NC3, node culture-derived plants; LC1, leaf culture-derived plants) and its cutting-propagated (ED) plants. Through methylation-sensitive amplification polymorphism (MSAP) assay, we observed highest methylated sites in leaf regenerants (LC1) from all primer combinations (108 bands), along with the highest secondary metabolites. The four types of tissue culture-derived shoots/plants (NC1, NC2, NC3, LC1) showed higher methylation bands than cutting propagated donor plants (ED) that exhibited 79 bands of methylation, which is comparatively low. Our study showed more methylation in micropropagated shoots/plants than those derived from ED plants. On the contrary, we observed higher secondary metabolites in ED plants but comparatively less in micropropagated shoots (NC1, NC2) and plants (NC3, LC1).

Increasing plant tolerance to sulfites/SO₂ can lead to the development of tolerant crops to biotic and abiotic stresses. Plant sulfite oxidase (SO) is a molybdo-enzyme that oxidizes excess SO₂/sulfite into non-toxic sulfate. The effect of toxic sulfite on leaves and fruits was studied in tomato plants with different SO expression: wild-type, SO overexpression (OE) and SO RNA interference (Ri). Sulfite-dipped ripe-fruits and sulfite treated leaf discs of Ri plants impaired in SO activity were more susceptible, whereas OE plants were more resistant, as revealed by remaining chlorophyll and tissue damage levels. Application of molybdenum further enhanced the tolerance of leaf discs to sulfite by enhancing SO activity in OE lines, but not in wild-type or Ri plants. Notably, incubation with tungsten, the molybdenum antagonist, overturned the effect of molybdenum spray in OE plants, revealed by remaining chlorophyll content and SO activity. The results indicate that SO in tomato leaves and ripe fruits determines the resistance to sulfite and the application of molybdenum enhances sulfite resistance in OE plants by increasing SO activity. Overall, the results suggest that SO overexpression can be employed, with or without molybdenum application, for developing fruit and vegetable crops tolerant to sulfite/SO₂ containing pre- and postharvest treatments.

Lingonberry (Vaccinium vitis-idaea L.) is an important and valuable horticultural crop due to its high antioxidant properties. Plant tissue culture is an advanced propagation system employed in horticultural crops. However, the progeny derived using this technique may not be true-to-type. In order to obtain the maximum return of any agricultural enterprise, uniformity of planting materials is necessary, which sometimes is not achieved due to genetic and epigenetic instabilities under in vitro culture. Therefore, we analyzed morphological traits and genetic and epigenetic variations under tissue-culture and greenhouse conditions in lingonberry using molecular markers. Leaf length and leaf width under greenhouse conditions and shoot number per explant, shoot height and shoot vigor under in vitro conditions were higher in hybrid H1 compared to the cultivar Erntedank. Clonal fidelity study using one expressed sequence tag (EST)—polymerase chain reaction (PCR), five EST—simple sequence repeat (SSR) and six genomic (G)—SSR markers revealed monomorphic bands in micropropagated shoots and plants in lingonberry hybrid H1 and cultivar Erntedank conforming genetic integrity. Epigenetic variation was studied by quantifying cytosine methylation using a methylation-sensitive amplification polymorphism (MSAP) technique. DNA methylation ranged from 32% in greenhouse-grown hybrid H1 to 44% in cultivar Erntedank under a tissue culture system. Although total methylation was higher in in vitro grown shoots, fully methylated bands were observed more in the greenhouse-grown plants. On the contrary, hemimethylated DNA bands were more prominent in tissue culture conditions as compared to the greenhouse-grown plants. The study conclude that lingonberry maintains its genetic integrity but undergoes variable epigenetic changes during in vitro and ex vitro conditions.