Transcript and metabolite signature of maize source leaves suggests a link between transitory starch to sucrose balance and the autonomous floral transition.
Little is known about the nature of floral inductive cues in day-neutral plants that are insensitive to photoperiod variations and, therefore, rely on endogenous signals to initiate reproductive growth. The INDETERMINATE1 (ID1) transcription factor is a key regulator of the transition to flowering in day-neutral maize. The ID1 gene is expressed exclusively in developing leaves, where it controls the production or transmission of leaf-derived florigenic signals. Florigen-producing source leaves were compared with mature leaves of late-flowering id1 plants, and metabolite and gene expression differences associated with the floral transition in maize were observed. While id1 mutants have a similar capacity for photosynthesis to wild-type siblings, id1 source leaves show quantitative differences in carbohydrate allocation prior to the floral transition stage, with a marked increase in sucrose and other soluble sugars, accompanied by a decrease in tricarboxylic acid (TCA) cycle organic acids. Importantly, source leaves of autonomous-flowering maize are typified by a higher transitory starch to sucrose ratio and a transcript profile enriched for sucrose synthesis and starch metabolism-related gene function. Finally, similar changes in transitory starch and sucrose are not observed in teosinte, the tropical progenitor of maize that requires short-day photoperiods to induce flowering. Together, these data define a transcript and metabolite signature associated with the autonomous floral transition in temperate maize leaves.
Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.
Viktoriya
V
Coneva
David
D
Guevara
Steven J
SJ
Rothstein
Joseph
J
Colasanti
D002244:Carbon / Q000378:metabolism; D002952:Citric Acid Cycle; D060405:Florigen / Q000378:metabolism; D035264:Flowers / Q000502:physiology*; D008401:Gas Chromatography-Mass Spectrometry; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D046529:Microscopy, Electron, Transmission; D017440:Photoperiod; D010788:Photosynthesis; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013213:Starch / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
D060405:Florigen; C112487:Id1 protein, plant; D010940:Plant Proteins; D014157:Transcription Factors; D013395:Sucrose; D002244:Carbon; D013213:Starch