Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America.
Centro de Investigaciones Interdisciplinarias en Ciencias y Humanidades, Universidad Nacional Autónoma de México, Mexico City, Mexico.
PLoS One. 2020 Nov 16;15(11):e0236001. doi: 10.1371/journal.pone.0236001. eCollection 2020.
Responses to drought within a single species may vary based on plant developmental stage, drought severity, and the avoidance or tolerance mechanisms employed. Early drought stress can restrict emergence and seedling growth. Thus, in areas where water availability is limited, rapid germination leading to early plant establishment may be beneficial. Alternatively, germination without sufficient water to support the seedling may lead to early senescence, so reduced germination under low moisture conditions may be adaptive at the level of the population. We studied the germination response to osmotic stress of diverse chile pepper germplasm collected in southern Mexico from varied ecozones, cultivation systems, and of named landraces. Drought stress was simulated using polyethylene glycol solutions. Overall, survival time analysis revealed delayed germination at the 20% concentration of PEG across all ecozones. The effect was most pronounced in the genotypes from hotter, drier ecozones. Additionally, accessions from wetter and cooler ecozones had the fastest rate of germination. Moreover, accessions of the landraces Costeño Rojo and Tusta germinated more slowly and incompletely if sourced from a drier ecozone than a wetter one, indicating that slower, reduced germination under drought stress may be an adaptive avoidance mechanism. Significant differences were also observed between named landraces, with more domesticated types from intensive cultivation systems nearly always germinating faster than small-fruited backyard- or wild-types, perhaps due to the fact that the smaller-fruited accessions may have undergone less selection. Thus, we conclude that there is evidence of local adaptation to both ecozone of origin and source cultivation system in germination characteristics of diverse chile peppers.
同一物种对干旱的反应可能因植物发育阶段、干旱程度以及采用的避免或耐受机制而有所不同。早期干旱胁迫会限制种子的萌发和幼苗的生长。因此，在水分供应有限的地区，快速萌发以尽早建立植物可能是有益的。或者，在没有足够水分支持幼苗生长的情况下萌发可能导致早期衰老，因此在低水分条件下减少萌发可能是种群水平的适应性。我们研究了来自墨西哥南部不同生态区、种植系统和命名的地方品种的多种辣椒种质对渗透胁迫的萌发反应。通过聚乙二醇溶液模拟干旱胁迫。总体而言，生存时间分析表明，在所有生态区，PEG 浓度为 20%时，萌发时间延迟。在来自较热、较干燥生态区的基因型中，这种影响最为明显。此外，来自较湿润和较凉爽生态区的种质具有最快的萌发率。此外，如果来自较干燥的生态区，Costeño Rojo 和 Tusta 等地方品种的萌发速度较慢且不完整，这表明在干旱胁迫下较慢、减少的萌发可能是一种适应性的避免机制。在命名的地方品种之间也观察到了显著差异，来自集约化种植系统的驯化类型通常比小果后院或野生类型的萌发速度更快，这可能是因为小果品种可能经历了较少的选择。因此，我们得出结论，在不同辣椒的萌发特征中，存在对起源生态区和来源种植系统的局部适应的证据。
