Identification of Germplasm and Sugar Transporter Gene ZmSWEET1b Associated with Salt Tolerance in Maize

Soil salinity influences various aspects of crop growth and development. Identification of novel germplasm and genetic regulators of salt tolerance will help to alleviate the threat of land salinization. Here, we identified salt-tolerant SHEN5003 and -sensitive YZ26 maize germplasm from different heterotic groups. Salt-grown SHEN5003 (PA group) lines exhibited decreased reduction in fresh weight and dry weight, high SPAD value, total sugar and K + contents, as well as low Na + content relative to salt-treated YZ26 (BSSS group) plants. Salt-tolerant SHEN5003 and -sensitive YZ26 lines were followingly used for the discovery of genetic regulators of salt tolerance. Transcriptome outcome showed the expression of genes relevant to Na + /K + homeostasis, such as H + -ATPase , HKT1 , and HAKs together with CAT2 for ROS detoxification was altered in salt-treated SHEN5003 line. Moreover, GO enrichment analysis indicated differentially expressed genes of SHEN5003 upon salt treatment was significantly enriched in the stress response pathway (GO:0006950). By integrated transcriptome analyses of SHEN5003 and YZ26 lines grown in normal and salinity conditions, positive regulator of salt tolerance ZmSWEET1b was revealed, which exhibited the opposite expression pattern between salt-treated SHEN5003 and YZ26 lines. ZmSWEET1b interacted with multiple partners, such as Sucrose synthase 2 to shape a functional association network in the modulation of sugar metabolism upon salinity stress.