The HD-ZIP Gene Family in Watermelon: Genome-Wide Identification and Expression Analysis under Abiotic Stresses

Abstract

Homeodomain-leucine zipper (HD-ZIP) transcription factors are one of the plant-specific gene families involved in plant growth and response to adverse environmental conditions. However, little information is available on the HD-ZIP gene family in watermelon. In this study, forty ClHDZs were systemically identified in the watermelon genome, which were subsequently divided into four distinctive subfamilies (I–IV) based on the phylogenetic topology. HD-ZIP members in the same subfamily generally shared similar gene structures and conserved motifs. Syntenic analyses revealed that segmental duplications mainly contributed to the expansion of the watermelon HD-ZIP family, especially in subfamilies I and IV. HD-ZIP III was considered the most conserved subfamily during the evolutionary history. Moreover, expression profiling together with stress-related cis-elements in the promoter region unfolded the divergent transcriptional accumulation patterns under abiotic stresses. The majority (13/23) of ClHDZs in subfamilies I and II were downregulated under the drought condition, e.g., ClHDZ4, ClHDZ13, ClHDZ18, ClHDZ19, ClHDZ20, and ClHDZ35. On the contrary, most HD-ZIP genes were induced by cold and salt stimuli with few exceptions, such as ClHDZ3 and ClHDZ23 under cold stress and ClHDZ14 and ClHDZ15 under the salt condition. Notably, the gene ClHDZ14 was predominantly downregulated by three stresses whereas ClHDZ1 was upregulated, suggesting their possible core roles in response to these abiotic stimuli. Collectively, our findings provide promising candidates for the further genetic improvement of abiotic stress tolerance in watermelon.

Genome-Wide Identification, Characterization, and Expression Analysis of the HD-Zip Gene Family in Lagerstroemia for Regulating Plant Height

“…HD-Zip III and IV subfamilies exhibited tissue-specific expression, with a preference for shoots and SAM, respectively. This might be because the members of HD-Zip III and IV subfamilies are known to be highly conserved lineages [45], with regulatory effects on SAM development, vascular development, leaf and shoot polarity regulation, and auxin transport [21][22][23][24]33]. These findings suggest that the four subfamilies of LinHDZ genes had different effects on the growth and development of L. indica.…”

“…HD-Zip TFs play a crucial role in affecting plant growth, development, and resilience to environmental stress [41]. To date, HD-Zip family genes have been systematically identified in several species, such as Chinese cabbage, chrysanthemum, oil palm, and watermelon [42][43][44][45]. Various studies have demonstrated that HD-Zip III and IV genes mainly contributed to shoot and root meristem development, as well as cell proliferation regulation.…”

Identification and Expression Profiling of the bZIP Gene Family Throughout the Genome in Phoebe bournei under Abiotic Stress

“…To examine how the PbbZIP gene responds to abiotic stressors like temperature, salt, and drought, ve genes in Table 2 (PbZIP32, PbZIP14, PbZIP26, PbZIP67, and PbZIP69) selected from ve representative PbZIP genes based on selection done by (Chang et al 2023;Ziyuan et al). The ve PbZIP genes originate from four distinct subfamilies, each re ecting the subfamily's reaction to abiotic stress.…”

Photosynthesis Response and Transcriptional Analysis: Dissecting the Role of SlHB8 in Regulating Drought Resistance in Tomato Plants

“…It is worth noting that HD-ZIP family transcription factors also play a regulatory role in the abiotic stress response in plants [19,25]. For instance, cold and salt stress can induce the expression of most HD-ZIP genes in watermelon [26]. Similarly, several ZmHDZ genes were found to be upregulated under drought stress and their promoter regions contain several regulatory elements associated with drought tolerance, suggesting that ZmHDZ genes may be involved in drought tolerance in maize [27].…”