New breakthrough in tobacco expansin gene research

Recently, the tobacco functional genomics innovation team at the Tobacco Research Institute of the Chinese Academy of Agricultural Sciences made new progress in research on expansin genes involved in cell wall polysaccharide metabolism.

Tobacco is an important cash crop in China. Cell wall substances are the main components of tobacco leaves. The structure and composition of the cell wall determine the looseness of tobacco leaves and are closely related to the combustibility, harmfulness and smoking quality of tobacco leaves. How to improve the structure and composition of the tobacco leaf cell wall is one of the most fundamental and core aspects of improving tobacco leaf quality and reducing harm and tar in tobacco. Expansins are a class of proteins that can cause plant cell walls to loosen. They loosen the structure of the cell wall by breaking the hydrogen bonds between cellulose microfibrils or between cellulose and other cell wall polysaccharides.

Using information from the common tobacco genome database, the tobacco functional genomics innovation team conducted a systematic analysis of the tobacco expansin gene family, identified more than 50 expansin subfamily genes in tobacco, and analyzed their gene structure, evolutionary relationships, possible cis-acting elements (cis-elements) in the gene promoter regions, and trans-acting factors that regulate gene expression. Through expression microarray and real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) analysis, they discovered expansin genes NtEXPA11, NtEXPB3, NtEX-LA1, NtEXLB2 and others that are specifically highly expressed in tobacco leaves or senescent leaves.