Transcription factor chbzip1 from alkaliphilic microalgae chlorella sp. Bld enhancing alkaline tolerance in transgenic arabidopsis thaliana

Saline-alkali soil has become an important environmental problem for crop productivity. One of the most effective approaches is to cultivate new stress-tolerant plants through genetic engi-neering. Through RNA-seq analysis and RT-PCR validation, a novel bZIP transcription factor ChbZIP1, which is significantly upregulated at alkali conditions, was obtained from alkaliphilic mi-croalgae Chlorella sp. BLD. Overexpression of ChbZIP1 in Saccharomyces cerevisiae and Arabidopsis increased their alkali resistance, indicating ChbZIP1 may play important roles in alkali stress re-sponse. Through subcellular localization and transcriptional activation activity analyses, we found that ChbZIP1 is a nuclear-localized bZIP TF with transactivation activity to bind with the motif of G-box 2 (TGACGT). Functional analysis found that genes such as GPX1, DOX1, CAT2, and EMB, which contained G-box 2 and were associated with oxidative stress, were significantly upregulated in Arabidopsis with ChbZIP1 overexpression. The antioxidant ability was also enhanced in trans-genic Arabidopsis. These results indicate that ChbZIP1 might mediate plant adaptation to alkali stress through the active oxygen detoxification pathway. Thus, ChbZIP1 may contribute to genet-ically improving plants’ tolerance to alkali stress.