Department of Integrated Biology, University of Texas at Austin, Austin, 78712, TX, USA.
Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, Austin, 78712, TX, USA.
Am J Bot. 2024 May;111(5):e16349. doi: 10.1002/ajb2.16349. Epub 2024 May 23.
Leaf tensile resistance, a leaf's ability to withstand pulling forces, is an important determinant of plant ecological strategies. One potential driver of leaf tensile resistance is growing season length. When growing seasons are long, strong leaves, which often require more time and resources to construct than weak leaves, may be more advantageous than when growing seasons are short. Growing season length and other ecological conditions may also impact the morphological traits that underlie leaf tensile resistance.
To understand variation in leaf tensile resistance, we measured size-dependent leaf strength and size-independent leaf toughness in diverse genotypes of the widespread perennial grass Panicum virgatum (switchgrass) in a common garden. We then used quantitative genetic approaches to estimate the heritability of leaf tensile resistance and whether there were genetic correlations between leaf tensile resistance and other morphological traits.
Leaf tensile resistance was positively associated with aboveground biomass (a proxy for fitness). Moreover, both measures of leaf tensile resistance exhibited high heritability and were positively genetically correlated with leaf lamina thickness and leaf mass per area (LMA). Leaf tensile resistance also increased with the growing season length in the habitat of origin, and this effect was mediated by both LMA and leaf thickness.
Differences in growing season length may promote selection for different leaf lifespans and may explain existing variation in leaf tensile resistance in P. virgatum. In addition, the high heritability of leaf tensile resistance suggests that P. virgatum will be able to respond to climate change as growing seasons lengthen.
叶片拉伸阻力是指叶片承受拉力的能力，是植物生态策略的一个重要决定因素。叶片拉伸阻力的一个潜在驱动因素是生长季节的长度。当生长季节较长时，强韧的叶片（通常比弱韧的叶片需要更多的时间和资源来构建）可能比生长季节较短时更具优势。生长季节的长度和其他生态条件也可能影响构成叶片拉伸阻力的形态特征。
为了了解叶片拉伸阻力的变化，我们在一个共同的花园中，测量了广泛分布的多年生草本植物柳枝稷（蒲草）的不同基因型的大小相关的叶片强度和大小无关的叶片韧性。然后，我们使用定量遗传方法来估计叶片拉伸阻力的遗传力，以及叶片拉伸阻力与其他形态特征之间是否存在遗传相关性。
叶片拉伸阻力与地上生物量（代表适应性）呈正相关。此外，两种叶片拉伸阻力的测量值都具有较高的遗传力，并且与叶片叶层厚度和比叶重（LMA）呈正相关。叶片拉伸阻力也随着起源栖息地的生长季节长度而增加，这种效应受到 LMA 和叶片厚度的共同调节。
生长季节长度的差异可能促进了不同叶片寿命的选择，这可以解释在柳枝稷中存在的叶片拉伸阻力的变化。此外，叶片拉伸阻力的高遗传力表明，随着生长季节的延长，柳枝稷将能够应对气候变化。
