Brunel S, Teulat-Merah B, Wagner M-H, Huguet T, Prosperi J M, Dürr C
INRA et Agrocampus Ouest, UMR 1191 Physiologie Moléculaire des Semences, 16 boulevard Lavoisier, Angers, France.
Ann Bot. 2009 May;103(7):1103-17. doi: 10.1093/aob/mcp040. Epub 2009 Feb 27.
The framework provided by an emergence model was used: (1) for phenotyping germination and heterotrophic growth of Medicago truncatula in relation to two major environmental factors, temperature and water potential; and (2) to evaluate the extent of genetic differences in emergence-model parameters.
Eight cultivars and natural accessions of M. trunculata were studied. Germination was recorded from 5 to 30 degrees C and from 0 to -0.75 MPa, and seedling growth from 10 to 20 degrees C.
Thermal time to reach 50 % germination was very short (15 degrees Cd) and almost stable between genotypes, while base temperature (2-3 degrees C) and base water potential for germination (-0.7 to -1.3 MPa) varied between genotypes. Only 35 degrees Cd after germination were required to reach 30 mm hypocotyl length with significant differences among genotypes. Base temperature for elongation varied from 5.5 to 7.5 degrees C. Low temperatures induced a general shortening of the seedling, with some genotypes more responsive than others. No relationship with initial seed mass or seed reserve distribution was observed, which might have explained differences between genotypes and the effects of low temperatures.
The study provides a set of reference values for M. trunculata users. The use of the ecophysiological model allows comparison of these values between such non-crop species and other crops. It has enabled phenotypic variability in response to environmental conditions related to the emergence process to be identified. The model will allow simulation of emergence differences between genotypes in a range of environments using these parameter values. Genomic tools available for the model species M. trunculata will make it possible to analyse the genetic and molecular determinants of these differences.
采用了一个出苗模型提供的框架：（1）用于对蒺藜苜蓿的萌发和异养生长进行表型分析，涉及两个主要环境因素，温度和水势；（2）评估出苗模型参数的遗传差异程度。
研究了8个蒺藜苜蓿品种和自然居群。在5至30摄氏度以及0至 -0.75兆帕的条件下记录萌发情况，在10至20摄氏度的条件下记录幼苗生长情况。
达到50%萌发率的热时间非常短（15摄氏度日），并且在基因型之间几乎稳定，而萌发的基础温度（2 - 3摄氏度）和基础水势（-0.7至 -1.3兆帕）在基因型之间有所不同。萌发后仅需35摄氏度日就能使下胚轴长度达到30毫米，基因型之间存在显著差异。伸长的基础温度在5.5至7.5摄氏度之间变化。低温导致幼苗普遍变短，一些基因型比其他基因型更敏感。未观察到与初始种子质量或种子储备分布的关系，而这可能解释了基因型之间的差异以及低温的影响。
该研究为蒺藜苜蓿的使用者提供了一组参考值。生态生理模型的使用使得能够比较这些非作物物种与其他作物之间的这些值。它能够识别与出苗过程相关的环境条件下的表型变异性。该模型将允许使用这些参数值模拟一系列环境中基因型之间的出苗差异。可用于模式物种蒺藜苜蓿的基因组工具将有可能分析这些差异的遗传和分子决定因素。
