Comparative transcriptomics reveals osmotic and ionic stress key genes contributing to the difference in the salinity tolerance of two pak choi cultivars

Abstract

Pak choi is an important leafy vegetable crop. Salinity is among the most harmful agents that negatively influence the pak choi yield. However, the mechanism of salinity tolerance in pak choi has not been well understood. In this study, the root transcriptomics of two cultivars differing in salinity tolerance, i.e., Shanghaijimaocai (S, tolerant to salinity) and Te’aiqing (T, sensitive to salinity), were investigated under 0 and 100 mM NaCl treatments. A total of 6765, 2454, 2451 and 5798 differentially expressed unigenes (DEUs) were identified in comparison of S100/S0, T100/T0, S0/T0 and S100/T100, respectively. In Shanghaijimaocai is more sensitive to NaCl stress than Te’aiqing in terms of root transcriptomics. Based on GO and KEGG pathway analyses, the expression levels of several osmotic and ionic stress-related genes, including MP3K18, PYL8, PP2C15/16/49, ARF2, bHLH112, bZIP43, COL5, CDF1/3, ERF25/60, HSFA6, MYBS3/59/92/CCA1/PHL5, POD21, GOLS7, CIPK4/7/12, NHX7, SLAH1 and ALMT13, in Shanghaijimaocai were higher than those in Te’aiqing. Therefore, these genes might contribute to the difference in salinity tolerance. Moreover, the physiological shift of peroxidase activity was in accordance with the dynamic transcript profile of relevant unigenes. These findings would be useful for further functional analysis as potential targets to improve resistance to salinity stress via genetic engineering.