*Article* **Genome-Wide Analysis of TCP Family Genes in** *Zea mays* **L. Identified a Role for** *ZmTCP42* **in Drought Tolerance**

**Shuangcheng Ding 1,2,**† **, Zhenzhen Cai 1,**† **, Hewei Du 1,3 and Hongwei Wang 1,2,\***


Received: 9 May 2019; Accepted: 4 June 2019; Published: 5 June 2019

**Abstract:** The Teosinte-branched 1/Cycloidea/Proliferating (TCP)plant-specific transcription factors (TFs)have been demonstrated to play a fundamental role in plant development and organ patterning. However, it remains unknown whether or not the *TCP* gene family plays a role in conferring a tolerance to drought stress in maize, which is a major constraint to maize production. In this study, we identified 46 *ZmTCP* genes in the maize genome and systematically analyzed their phylogenetic relationships and synteny with rice, sorghum, and *Arabidopsis TCP* genes. Expression analysis of the 46 *ZmTCP* genes in different tissues and under drought conditions, suggests their involvement in maize response to drought stress. Importantly, genetic variations in *ZmTCP32* and *ZmTCP42* are significantly associated with drought tolerance at the seedling stage. RT-qPCR results suggest that *ZmTCP32* and *ZmTCP42* RNA levels are both induced by ABA, drought, and polyethylene glycol treatments. Based on the significant association between the genetic variation of *ZmTCP42* and drought tolerance, and the inducible expression of *ZmTCP42* by drought stress, we selected *ZmTCP42*, to investigate its function in drought response. We found that overexpression of *ZmTCP42* in Arabidopsis led to a hypersensitivity to ABA in seed germination and enhanced drought tolerance, validating its function in drought tolerance. These results suggested that ZmTCP42 functions as an important TCP TF in maize, which plays a positive role in drought tolerance.

**Keywords:** maize; *ZmTCP*; natural variation; drought tolerance
