Granier C, Tardieu F
Institut National de la Recherche Agronomique, Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 2 Place Viala, 34060 Montpellier, France.
Plant Physiol. 1999 Feb;119(2):609-20. doi: 10.1104/pp.119.2.609.
We analyzed the effect of short-term water deficits at different periods of sunflower (Helianthus annuus L.) leaf development on the spatial and temporal patterns of tissue expansion and epidermal cell division. Six water-deficit periods were imposed with similar and constant values of soil water content, predawn leaf water potential and [ABA] in the xylem sap, and with negligible reduction of the rate of photosynthesis. Water deficit did not affect the duration of expansion and division. Regardless of their timing, deficits reduced relative expansion rate by 36% and relative cell division rate by 39% (cells blocked at the G0-G1 phase) in all positions within the leaf. However, reductions in final leaf area and cell number in a given zone of the leaf largely differed with the timing of deficit, with a maximum effect for earliest deficits. Individual cell area was only affected during the periods when division slowed down. These behaviors could be simulated in all leaf zones and for all timings by assuming that water deficit affects relative cell division rate and relative expansion rate independently, and that leaf development in each zone follows a stable three-phase pattern in which duration of each phase is stable if expressed in thermal time (C. Granier and F. Tardieu [1998b] Plant Cell Environ 21: 695-703).
我们分析了向日葵（Helianthus annuus L.）叶片发育不同时期的短期水分亏缺对组织扩展和表皮细胞分裂的时空模式的影响。设置了六个水分亏缺时期，这些时期土壤含水量、黎明前叶片水势和木质部汁液中[脱落酸]的值相似且恒定，光合作用速率的降低可忽略不计。水分亏缺不影响扩展和分裂的持续时间。无论水分亏缺的时间如何，亏缺都会使叶片内所有位置的相对扩展速率降低36%，相对细胞分裂速率降低39%（细胞停滞在G0-G1期）。然而，叶片给定区域的最终叶面积和细胞数量的减少在很大程度上因亏缺时间而异，最早的亏缺影响最大。单个细胞面积仅在细胞分裂减缓的时期受到影响。通过假设水分亏缺独立影响相对细胞分裂速率和相对扩展速率，并且每个区域的叶片发育遵循稳定的三相模式，其中如果以热时间表示，每个阶段的持续时间是稳定的（C. Granier和F. Tardieu [1998b] Plant Cell Environ 21: 695-703），可以在所有叶区域和所有时间模拟这些行为。
