Chinese Bulletin of Botany ›› 2023, Vol. 58 ›› Issue (6): 866-881.DOI: 10.11983/CBB22261

• EXPERIMENTAL COMMUNICATIONS • Previous Articles     Next Articles

ZmICE2 Regulates Stomatal Development in Maize

Wenqi Zhou1,*(), Yuqian Zhou1, Yongsheng Li1, Haijun He1, Yanzhong Yang1, Xiaojuan Wang1, Xiaorong Lian1, Zhongxiang Liu1, Zhubing Hu2,*()   

  1. 1Crops Research Institute, Gansu Academy of Agricultural Sciences, Lanzhou 730070, China
    2State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China

Abstract: Plant epidermis is crucial in regulating photosynthesis, respiration, heat dissipation, and water utilization. Significant progress has been made in the study of stomatal development in dicotyledonous plants, such as Arabidopsis thaliana. Three important bHLH transcription factors (SPCH, MUTE, and FAMA) have been reported to be specifically expressed at different stages of cell division and differentiation in the stomatal lineage. They form heterodimers with another transcription factors SCRM/ICE1 and SCRM2/ICE2 to regulate the morphological transformation and changes of stomatal lineage cells across three stages of division, finally forming the stomatal complex. However, in monocots, especially in Poaceae plants such as maize (Zea mays), studies on genes regulating epidermal morphogenesis are less reported. In this study, two single-gene recessive mutants, Zmice1-1 (inducer of cbf expression1-1) and Zmice2-1, were isolated using reverse genetics approaches. Compared to the control B73, Zmice2-1 exhibited dwarfism, leaf chlorosis, reduced fertility, significantly lower stomatal density and index, disrupted arrangement of epidermal long cells, and absence of spacing between stomata. Zmice1-1 leaves gradually turned yellow from the five-leaf stage and displayed complete chlorosis at later stages. The homozygous Zmice1-1 plants are growth-arrested and sterile, but the stomatal density showed no significant difference compared to the control. Different allels of Zmice2 were obtained using CRISPR-Cas9 genome editing technology. Phenotypic identification showed that Zmice2-2 had an abnormal stomatal phenotype similar to Zmice2-1, indicating that ZmICE2 is involved in the regulation of stomatal development. Transcriptome analysis of B73 and Zmice2-1 revealed that ZmICE2 primarily regulated stomatal development by affecting cell division and differentiation, participating in the formation of maize epidermal morphology. These results contribute to a better understanding of the mechanisms of epidermal morphogenesis in maize and provide valuable genetic resources for improving crop resilience and yield traits.

Key words: maize, stomatal development, stomatal density, epidermal morphogenesis, CRISPR-Cas9 gene editing