Cytokinin overproduction-caused alteration of flower development is partially mediated by CUC2 and CUC3 in Arabidopsis.
Cytokinin is an essential regulator of numerous plant growth and developmental processes. However, less is known about the mechanisms of cytokinin-regulated floral development. In the present study, we found that flower-specific elevation of cytokinin through transgenic expression of an Arabidopsis ATP/ADP isopentenyltransferase 4 (AtIPT4) gene under the control of the APETALA1 (AP1) promoter lead to floral developmental alterations. These changes included promotion of the number of flowers and abnormal development of flowers, which were correlated with enlarged inflorescence and flower meristems. Genome-wide expression profiling revealed that a large number of genes were responsive to increased cytokinin levels, including this first report that the expression of CUP-SHAPED COTYLEDON2 (CUC2) and CUC3 is elevated by cytokinin. Further analysis showed that mutation of cuc2 or cuc3 attenuates the phenotypes caused by the AP1Colon, two colonsAtIPT4 transgene. Mutation of the cytokinin receptors Arabidopsis histidine kinase 2 (AHK2) and AHK3 nearly abolished the transgene phenotypes and the enhanced CUC2 and CUC3 transcription induced by cytokinin. Our results indicate that the overproduced cytokinin in flower primordia results in alteration of floral development mainly through AHK2 and AHK3 signaling leading to increased expression of the effector genes CUC2 and CUC3. Thus, it is likely that the CUC2 and CUC3 expression mediated by AHK2 and AHK3 signaling may play roles in regulation of flower development.
Li
Xing Guo
XG
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong 271018, China.
Su
Ying Hua
YH
Zhao
Xiang Yu
XY
Li
Wei
W
Gao
Xin Qi
XQ
Zhang
Xian Sheng
XS
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D003583:Cytokinins / Q000494:pharmacology / Q000502:physiology*; D035264:Flowers / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D000071677:Histidine Kinase; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D029681:Arabidopsis Proteins; C107294:CUC2 protein, Arabidopsis; C478975:CUC3 protein, Arabidopsis; D003583:Cytokinins; D014157:Transcription Factors; D011494:Protein Kinases; D000071677:Histidine Kinase; C000605492:AHK2 protein, Arabidopsis; C000605493:AHK3 protein, Arabidopsis