Photosynthetic leaf area modulates tiller bud outgrowth in sorghum

Journal Article · Sat Feb 14 04:00:00 UTC 2015 · Plant, Cell and Environment

DOI: https://doi.org/10.1111/pce.12500 · OSTI ID:1345708

KEBROM, TESFAMICHAEL H. ^[1]; MULLET, JOHN E. ^[1]

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1. Department of Biochemistry and Biophysics Texas A&,M University College Station TX 77843 USA

Abstract Shoot branches or tillers develop from axillary buds. The dormancy versus outgrowth fates of buds depends on genetic, environmental and hormonal signals. Defoliation inhibits bud outgrowth indicating the role of leaf‐derived metabolic factors such as sucrose in bud outgrowth. In this study, the sensitivity of bud outgrowth to selective defoliation was investigated. At 6 d after planting (6 DAP ), the first two leaves of sorghum were fully expanded and the third was partially emerged. Therefore, the leaves were selectively defoliated at 6 DAP and the length of the bud in the first leaf axil was measured at 8 DAP . Bud outgrowth was inhibited by defoliation of only 2 cm from the tip of the second leaf blade. The expression of dormancy and sucrose‐starvation marker genes was up‐regulated and cell cycle and sucrose‐inducible genes was down‐regulated during the first 24 h post‐defoliation of the second leaf. At 48 h, the expression of these genes was similar to controls as the defoliated plant recovers. Our results demonstrate that small changes in photosynthetic leaf area affect the propensity of tiller buds for outgrowth. Therefore, variation in leaf area and photosynthetic activity should be included when integrating sucrose into models of shoot branching.

• Sponsoring Organization: USDOE
• Grant/Contract Number: SC0009885
• OSTI ID: 1345708
• Journal Information: Plant, Cell and Environment, Journal Name: Plant, Cell and Environment Journal Issue: 8 Vol. 38; ISSN 0140-7791
• Publisher: Wiley-BlackwellCopyright Statement
• Country of Publication: United Kingdom
• Language: English