Cold stress adversely affects plant growth, development, and yield. Also, the spatial and geographical distribution of plant species is influenced by low temperatures. Cold stress includes chilling and/or freezing temperatures, which trigger entirely different plant responses. Freezing tolerance is acquired via the cold acclimation process, which involves prior exposure to non-lethal low temperatures followed by profound alterations in cell membrane rigidity, transcriptome, compatible solutes, pigments and cold-responsive proteins such as antifreeze proteins. Moreover, epigenetic mechanisms such as DNA methylation, histone modifications, chromatin dynamics and small non-coding RNAs play a crucial role in cold stress adaptation. Here, we provide a recent update on cold-induced signaling and regulatory mechanisms. Emphasis is given to the role of epigenetic mechanisms and antifreeze proteins in imparting cold stress tolerance in plants. Lastly, we discuss genetic manipulation strategies to improve cold tolerance and develop cold-resistant plants.

Naturally occurring forage species in the high-altitude pasturelands of Western Himalaya are traditionally being utilized for feeding of livestock. However, the nutritional quality evaluation and validation of their potential as feed for livestock needs to be undertaken. Here, we evaluated proximate compositions, minerals and amino acids (AAs) of five high-altitude forage species, namely, Festuca kashmiriana L., Medicago sativa L., Trifolium pratense L., Medicago falcate L. and Melilotus indica L. The results revealed that proximate compositions, mineral and AAs varied significantly among the forage species. The carbohydrate, crude protein, moisture content, crude fat, crude fiber, crude ash, total phenol, oil absorption capacity and water absorption capacity were found in the range of 17.44-37.27 mg/100 mg, 3.34-14.71 mg/100 mg, 88.73%-90.72%, 0.98-2.32 mg/100 mg, 11.16-24.16%, 7.71-34.49%, 292.50-488.12 μg/100 mg, 3.91-4.67 g/g and 2.64-3.41 g/g, respectively. Elemental composition showed that calcium was the predominant element among the minerals (13.91-132.05 mg/kg DM) followed by magnesium (4.60-12.92 mg/kg DM), iron (2.04-76.13 mg/kg DM) and zinc (1.07-2.17 mg/kg DM). Furthermore, we found that these high-altitude forage species are rich in essential AAs like histidine, tryptophan, valine, leucine, phenylalanine and to some extent isoleucine and tyrosine. In addition, these five species showed distinct proteomes but shared a similar functional group. The proteome profiling of these forage species will help to understand the molecular basis of nutritional enrichment and stress tolerance potential against harsh environmental conditions of high altitudes. Overall, we conclude that traditionally used high-altitude forage species are nutritionally rich and can be recommended as part of the daily nutritive feed for livestock animals.

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