Abstract：

Subtilisin-like proteases (subtilases) are found in almost all plant species and are involvedin regulating various biotic and abiotic stresses. Although the literature on subtilases in differentplant species is vast, the gene function of the serine peptidase S8 family and its maize subfamilyis still unknown. Here, a bioinformatics analysis of this gene family was conducted by describinggene structure, conserved motifs, phylogenetic relationships, chromosomal distributions, gene duplications,and promoter cis-elements. In total, we identified 18 ZmSPS8 genes in maize, distributedon 7 chromosomes, and half of them were hydrophilic. Most of these proteins were located at thecell wall and had similar secondary and tertiary structures. Prediction of cis-regulatory elementsin promoters illustrated that they were mainly associated with hormones and abiotic stress. Maizeinbred lines B73, Zheng58, and Qi319 were used to analyze the spatial-temporal expression patternsof ZmSPS8 genes under drought treatment. Seedling drought results showed that Qi319 had thehighest percent survival after 14 d of withholding irrigation, while B73 was the lowest. Leaf relativewater content (LRWC) declined more rapidly in B73 and to lower values, and the nitrotetrazoliumblue chloride (NBT) contents of leaves were higher in Qi319 than in the other inbreds. The qPCRresults indicated that 6 serine peptidase S8 family genes were positively or negatively correlatedwith plant tolerance to drought stress. Our study provides a detailed analysis of the ZmSPS8s in the maize genome and finds a link between drought tolerance and the family gene expression, whichwas established by using different maize inbred lines.

KeyWords:

Zea mays L.; ZmSPS8s; inbred; expression pattern; survival rate