Abstract
Cytokinins (CKs) function in plant development and during stress responses, but their role in drought tolerance in wheat is unknown. In the present study, 24 isopentenyltransferase (IPT) genes, encoding rate-limiting enzymes in CK biosynthesis were identified in the wheat genome. The chromosomal locations and structures of the genes, protein properties, and phylogenetic relationships were characterized. ATP/ADP TaIPT genes showed tissue-specific expression. TaIPT2, TaIPT7, and TaIPT8 expression was rapidly induced by 0.5–1 h drought treatments, which decreased to low levels after 2 h drought treatment, as did most other TaIPT genes. TaIPT8-5a/5b/5d triple mutants showed decreased levels of tZ-type CK under normal and drought conditions and reduced drought tolerance, which, however, did not manifest as phenotype alterations. By contrast, transgenic wheat plants with drought-induced TaIPT8 showed increased drought tolerance. Our study provides a foundation for further investigation of TaIPT genes and novel insights into the role of CKs in the drought response of wheat.
