Genome-wide characterisation of the Three Amino Acid Loop Extension (ClTALE) gene family of watermelon in response to abiotic stresses

Zongqing Qiu¹Jing Dong¹Liqin Chen¹Lijun Zhao¹Liangliang Hu^1,2*Huilin Wang^1*

• ¹College of Horticulture, Xinjiang Agricultural University, Ürümqi, China
• ²Postdoctoral Station of Horticulture, Xinjiang Agricultural University, Urumqi, Urumqi, China

The Three Amino Acid Loop Extension (TALE) gene plays vital roles in regulating plant growth, development, and stress responses, yet it has not been systematically characterized in watermelon (Citrullus lanatus L.). In this study, we identified the ClTALE gene family using the watermelon genome database and analyzed its genomic, structural, and functional features via a series of bioinformatics tools. Results demonstrated that 22 ClTALE members were extracted, and phylogenetic analysis clustered them into seven distinct subclades, classified as KNOX-I/STM, KNOX-II, and BELL-I through BELL-V. Their promoter regions contain predicted cis-acting elements associated with hormone regulation and stress responses, and STRING database analysis suggested that ClTALE proteins may function in conjunction with other key transcription factors involved in plant growth and development. Additionally, qRT-PCR analysis revealed elevated expression of ClTALE2, ClTALE3, ClTALE8, ClTALE11, and ClTALE20 in watermelon seedlings under drought stress, with ClTALE2 and ClTALE3 also showing increased transcriptional levels in response to low potassium (LK) stress and the combined treatment of melatonin and cold (MT+CT). Transient expression assay indicated that ClTALE3 is localized to the nucleus and overexpression of it increased yeast tolerance to PEG stress., The induced expression of ClTALE3 implies potential as a biological marker for developing drought-and cold-resilient watermelon varieties. These findings provide a foundation for elucidating the evolutionary characteristics and functional roles of the ClTALE gene family, and for addressing drought and cold stress challenges in watermelon cultivation.