The tillering phenotype of the rice plastid terminal oxidase (PTOX) loss-of-function mutant is associated with strigolactone deficiency

作者：Tamiru Muluneh^*; Abe Akira; Utsushi Hiroe; Yoshida Kakoto; Takagi Hiroki; Fujisaki Koki; Undan Jerwin R; Rakshit Sujay; Takaichi Shinichi; Jikumaru Yusuke; Yokota Takao; Terry Matthew J; Terauchi Ryohei

来源：New Phytologist, 2014, 202(1): 116-131.

DOI：10.1111/nph.12630

• carotenoid synthesis
• EcoTILLING
• mesocotyl elongation
• Oryza sativa (rice)
• PTOX
• strigolactone
• tillering

The significance of plastid terminal oxidase (PTOX) in phytoene desaturation and chloroplast function has been demonstrated using PTOX-deficient mutants, particularly in Arabidopsis. However, studies on its role in monocots are lacking. Here, we report cloning and characterization of the rice (Oryza sativa) PTOX1 gene. %26lt;br%26gt;Using Ecotype Targeting Induced Local Lesions IN Genomes (EcoTILLING) and TILLING as forward genetic tools, we identified the causative mutation of an EMS mutant characterized by excessive tillering, semi-dwarfism and leaf variegation that corresponded to the PTOX1 gene. %26lt;br%26gt;The tillering and semi-dwarf phenotypes of the ptox1 mutant are similar to phenotypes of known strigolactone (SL)-related rice mutants, and both phenotypic traits could be rescued by application of the synthetic SL GR24. The ptox1 mutant accumulated phytoene in white leaf sectors with a corresponding deficiency in beta-carotene, consistent with the expected function of PTOX1 in promoting phytoene desaturase activity. There was also no accumulation of the carotenoid-derived SL ent-2%26apos;-epi-5-deoxystrigol in root exudates. Elevated concentrations of auxin were detected in the mutant, supporting previous observations that SL interaction with auxin is important in shoot branching control. %26lt;br%26gt;Our results demonstrate that PTOX1 is required for both carotenoid and SL synthesis resulting in SL-deficient phenotypes in rice.

• 出版日期2014-4