Genetically Engineering Cold Stress-Tolerant Crops: Approaches and Challenges

Abstract

Low temperature is a major environmental constraint in high-latitude and high-altitude regions that adversely affects global crop productivity. In response to low-temperature stress, many plant species exhibit various injury symptoms such as chlorosis, necrosis, and growth retardation and ultimately lethality. In contrast, cold stress-tolerant species survive and grow under low temperatures. An incremental improvement in low-temperature stress tolerance is required to develop high-yielding cultivars of crops for enhancing agricultural productivity under low-temperature regimes. Low-temperature stress tolerance is a very complex phenomenon which involves cross talks between different development and stress response regulatory networks. Plants show differential responses toward low-temperature stress which is the result of orchestrated regulation of gene expression mediated by epigenetic, transcriptional, post-transcriptional, and post-translational mechanisms. Differential expression of cold-regulated (COR) genes under low temperatures is regulated by inducer of C-repeat binding factor expression (ICE)–CBF transcriptional pathway which is a major regulatory pathway of cold acclimation in diverse plant species. Small noncoding RNAs, viz., micro-RNAs (miRNAs) and small interfering RNAs (siRNAs), play significant role in post-transcriptional gene silencing. Progress in whole-genome and transcriptome sequencing, functional genomics, and QTLs mapping in diverse crops have provided deep insight into the complex mechanisms of cold acclimation and freezing tolerance. Conventional breeding methods showed limited success in improving cold stress tolerance in different crops through interspecific or intergeneric hybridization. This chapter covers recent advances in plant genomics that lead to the identification of various regulatory networks of low-temperature stress tolerance and highlights the progress of genetic engineering approach in designing cold-tolerant and economically important crops.