Ahmed Lina Q, Escobar-Gutiérrez Abraham J
INRAE, URP3F, Lusignan, France.
Front Plant Sci. 2022 Apr 8;13:856099. doi: 10.3389/fpls.2022.856099. eCollection 2022.
(L.) is one of the most important species in temperate grasslands. Temperature is a major factor controlling plant development. Breeding cultivars adapted to new ranges of temperature could be necessary under most climate change scenarios. However, before any breeding effort in such direction, knowing the intraspecific variability of responses to temperature is essential. Our objective was to analyze a sample of accessions of for their response to constant temperature during germination and initial heterotrophic growth. Eight accessions were taken out from a genebank containing 160 accessions. Six accessions were wild populations collected in different places in France and the other two were populations from a selection program. For germination, four replicates of 100 seeds per accession were tested in Petri dishes in the dark at eight constant temperatures, from 5 to 40°C with increases of 5°C. Germination countings were carried out at variable time intervals and durations that depended on treatments. For initial heterotrophic growth analysis, seeds were germinated at 25°C. Sets of 30 seedlings per accession were placed in polypropylene boxes on blotter blue paper and transferred to each one of the eight treatments in the dark. They were pictured at variable time intervals for root and shoot growth measurement by image analysis. Neither seed germination nor heterotrophic growth was observed at 40°C, for any accession. Temperature and time course response surfaces were markedly different between accessions. Equally, maximum germinability and the shape of the response curves to temperature were significantly different between accessions. This means that limited similarities between responses were observed. Furthermore, germination rates followed the non-linear beta function with significant differences between some accessions. These also showed significant differences in their root and shoot growth rate in response to temperature. In general, the relative growth rates of roots and shoots were slow at 5°C, peaked between 25 and 30°C, and showed a sharp reduction afterward. These results reveal, for the first time, high genetic variability within germplasm for the response to temperature in the initial life phases. This discovered variability should serve breeders to create perennial ryegrass varieties for the future.
（黑麦草）是温带草原最重要的物种之一。温度是控制植物发育的主要因素。在大多数气候变化情景下，培育适应新温度范围的栽培品种可能是必要的。然而，在朝着这个方向进行任何育种工作之前，了解种内对温度反应的变异性至关重要。我们的目标是分析黑麦草种质资源样本在萌发和初始异养生长期间对恒温的反应。从一个包含160份种质的基因库中选取了8份种质。其中6份是在法国不同地点收集的野生种群，另外两份是来自一个选育项目的种群。对于萌发，每个种质取4个重复，每个重复100粒种子，在培养皿中于黑暗条件下在8个恒定温度（5至40°C，间隔5°C）下进行测试。萌发计数在取决于处理的不同时间间隔和持续时间进行。对于初始异养生长分析，种子在25°C下萌发。每个种质30株幼苗被放置在铺有吸水蓝纸的聚丙烯盒中，并在黑暗中转移到8种处理中的每一种。在不同时间间隔对它们拍照，通过图像分析测量根和芽的生长。对于任何种质，在40°C下均未观察到种子萌发和异养生长。不同种质之间的温度和时间进程反应曲面明显不同。同样，最大发芽能力和对温度的反应曲线形状在不同种质之间也有显著差异。这意味着观察到的反应之间相似性有限。此外，发芽率遵循非线性β函数，一些种质之间存在显著差异。它们在根和芽生长速率对温度的反应上也显示出显著差异。一般来说，根和芽的相对生长速率在5°C时较慢，在25至30°C之间达到峰值，之后急剧下降。这些结果首次揭示了黑麦草种质在初始生命阶段对温度反应的高遗传变异性。这种发现的变异性应为育种者培育未来的多年生黑麦草品种提供帮助。
