Graduate School of Agricultural and Life Sciences, The University of Tokyo, Nishitokyo, Tokyo, Japan.
Ohio State University, Department of Horticulture and Crop Science, Columbus, OH, USA.
J Exp Bot. 2024 Nov 15;75(21):6762-6777. doi: 10.1093/jxb/erae082.
Plants grown under field conditions experience fluctuating light. Understanding the natural genetic variations for a similarly dynamic photosynthetic response among untapped germplasm resources, as well as the underlying mechanisms, may offer breeding strategies to improve production using molecular approaches. Here, we measured gas exchange under fluctuating light, along with stomatal density and size, in eight wild tomato species and two tomato cultivars. The photosynthetic induction response showed significant diversity, with some wild species having faster induction rates than the two cultivars. Species with faster photosynthetic induction rates had higher daily integrated photosynthesis, but lower average water use efficiency because of high stomatal conductance under natural fluctuating light. The variation in photosynthetic induction was closely associated with the speed of stomatal responses, highlighting its critical role in maximizing photosynthesis under fluctuating light conditions. Moreover, stomatal size was negatively correlated with stomatal density within a species, and plants with smaller stomata at a higher density had a quicker photosynthetic response than those with larger stomata at lower density. Our findings show that the response of stomatal conductance plays a pivotal role in photosynthetic induction, with smaller stomata at higher density proving advantageous for photosynthesis under fluctuating light in tomato species. The interspecific variation in the rate of stomatal responses could offer an untapped resource for optimizing dynamic photosynthetic responses under field conditions.
在田间条件下生长的植物会经历光照的波动。了解未开发种质资源中类似动态光合作用响应的自然遗传变异以及潜在机制，可能会提供利用分子方法提高产量的育种策略。在这里，我们测量了八种野生番茄和两种栽培番茄在波动光照下的气体交换，以及气孔密度和大小。光合作用诱导响应表现出显著的多样性，一些野生种的诱导率比两个栽培种快。具有更快光合作用诱导率的物种具有更高的日积分光合作用，但由于自然波动光照下较高的气孔导度，平均水分利用效率较低。光合作用诱导的变化与气孔响应的速度密切相关，突出了其在波动光照条件下最大限度提高光合作用的关键作用。此外，气孔大小与同一物种内的气孔密度呈负相关，在较高密度下具有较小气孔的植物比在较低密度下具有较大气孔的植物具有更快的光合作用响应。我们的研究结果表明，气孔导度的响应在光合作用诱导中起着关键作用，在波动光照下，较高密度的较小气孔有利于光合作用。种间气孔响应速率的差异可能为优化田间条件下动态光合作用响应提供了一种未开发的资源。
