F-box protein COI1 functions upstream of MYB305 to regulate primary carbohydrate metabolism in tobacco (Nicotiana tabacum L. cv. TN90)

• Published in: Journal of experimental botany Vol. 65; no. 8; pp. 2147 - 2160
• Main Authors: Wang, Wenjing, Liu, Guanshan, Niu, Haixia, Timko, Michael P, Zhang, Hongbo
• Format: Journal Article
• Language: English
• Published: UK Oxford University Press [etc.] 01.05.2014; Oxford University Press
• Subjects: Amino Acid Sequence; Anthers; Base Sequence; Carbohydrate metabolism; Carbohydrate Metabolism - genetics; Corolla; Cyclopentanes - metabolism; Developmental biology; F-box proteins; F-Box Proteins - chemistry; F-Box Proteins - genetics; F-Box Proteins - metabolism; Fertility; Gene expression; Gene Expression Regulation, Plant; Gene Silencing; Genes; jasmonic acid; Metabolism; Nectaries; Nicotiana - genetics; Nicotiana - metabolism; Nicotiana tabacum; Oxylipins - metabolism; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; Pollen; RESEARCH PAPER; RNA Interference; Sequence Alignment; Starch - genetics; Starch - metabolism; Starches; tobacco; starch; tobacco; COI1; primary metabolism; jasmonate
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/eru084

Jasmonate (JA) plays an important role in regulating plant male fertility and secondary metabolism, but its role in regulating primary metabolism remains unclear. The F-box protein CORONATINE INSENSITIVE 1 (COI1) is a critical component of the JA receptor, and mediates JA-signalling by targeting JASMONATE ZIM-domain (JAZ) proteins for proteasomal degradation in response to JA perception. Here, we found that RNA interference-mediated knockdown of NtCOI1 in tobacco (Nicotiana tabacum L. cv. TN90) recapitulated many previously observed phenotypes in coi1 mutants, including male sterility, JA insensitivity, and loss of floral anthocyanin production. It also affected starch metabolism in the pollen, anther wall, and floral nectary, leading to pollen abortion and loss of floral nectar. Transcript levels of genes encoding starch metabolism enzymes were significantly altered in the pollen, anther wall, and floral nectary of NtCOI1-silenced tobacco. Changes in leaf primary metabolism were also observed in the NtCOI1-silenced tobacco. The expression of NtMYB305, an orthologue of MYB305 previously identified as a flavonoid metabolic regulator in Antirrhinum majus flowers and as a floral-nectar regulator mediating starch synthesis in ornamental tobacco, was extremely downregulated in NtCOI1-silenced tobacco. These findings suggest that NtCOI1 functions upstream of NtMYB305 and plays a fundamental role in coordinating plant primary carbohydrate metabolism and correlative physiological processes.