4.3.1 Glycometabolism provides carbon skeleton and energy forC. japonica in drought environment
Carbohydrates can provide carbon skeleton and energy for the growth and metabolism of organisms and enhance stress resistance. Glycometabolism is also the center of biological metabolism, which connects the metabolism of proteins, lipids, nucleic acids, and secondary substances (Sun et al., 2015). Based on the comparative genome, abundant glycometabolism-related genes were expanded or positively selected inC. japonica and further contributed to the desiccation tolerance of C. japonica . The reasons for the improvement in the desiccation tolerance of C. japonica by carbohydrate may be as follows: (i) carbohydrates can accumulate and regulate osmotic pressure and enhance the water retention of cells (Savitch et al., 2000; Wilson et al., 2001); (ii) carbohydrates can protect biological substances, such as biofilms and biological macromolecules, to maintain cytoskeletal integrity in drought environments (Hincha et al., 2002; Saadeldin et al., 2020); (iii) carbohydrates can produce energy for resistance to desiccation (Savitch et al., 2000); and (iv) carbohydrates can also be used as a signal molecule involved in some desiccation resistance regulation mechanisms (Paul et al., 2008).