Association between pollen fertility and elongation of uppermost internode in TGMS rice

摘要

Elongation of the uppermost internode (UI) of rice (Oryza sativa L.) is an adaptive characteristic that helps the panicle emerge from the flag-leaf sheath and complete anthesis. The elongated uppermost internode (eui) mutant Changxuan 3S (CX) of TGMS rice, which shows notably rapid elongation in UI during the heading phase and remarkable variation in UI length under different pollen fertility conditions, is a model plant for studying UI elongation. Dynamic elongation of CX plants revealed that detectable elongation growth of the UI in CX plants started 6 days prior to anthesis and ceased after anthesis. This growth was separated into three elongation phases: the exponential phase, linear phase, and slow-growth phase. Pollen fertility significantly influenced UI elongation growth during the linear and slow-growth phases. Temperature and pollen fertility during the pollen developmental phase in CX plants were significantly negatively correlated; moreover, the pollen fertility of the young panicle greatly affected the elongation growth of the UI. The variation in pollen fertility resulted in a significant difference in phytohormone levels in the UI and young panicle during the linear phase. Decapitation of the UI further confirmed that panicle fertility played a central role in UI elongation. We concluded that pollen fertility is mediated by the manipulation of phytohormones and that phytohormone levels are mediated by the manipulation of UI elongation.