Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland.
Department of Plant Sciences, Section of Biology, Faculty of Sciences, University of Geneva, 30 Quai E. Ansermet, Geneva 1211, Switzerland.
Plant Cell Physiol. 2024 Jan 19;65(1):35-48. doi: 10.1093/pcp/pcad113.
As sessile, photoautotrophic organisms, plants are subjected to fluctuating sunlight that includes potentially detrimental ultraviolet-B (UV-B) radiation. Experiments under controlled conditions have shown that the UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8) controls acclimation and tolerance to UV-B in Arabidopsis thaliana; however, its long-term impact on plant fitness under naturally fluctuating environments remain poorly understood. Here, we quantified the survival and reproduction of different Arabidopsis mutant genotypes under diverse field and laboratory conditions. We found that uvr8 mutants produced more fruits than wild type when grown in growth chambers under artificial low-UV-B conditions but not under natural field conditions, indicating a fitness cost in the absence of UV-B stress. Importantly, independent double mutants of UVR8 and the blue light photoreceptor gene CRYPTOCHROME 1 (CRY1) in two genetic backgrounds showed a drastic reduction in fitness in the field. Experiments with UV-B attenuation in the field and with supplemental UV-B in growth chambers demonstrated that UV-B caused the cry1 uvr8 conditional lethal phenotype. Using RNA-seq data of field-grown single and double mutants, we explicitly identified genes showing significant statistical interaction of UVR8 and CRY1 mutations in the presence of UV-B in the field. They were enriched in Gene Ontology categories related to oxidative stress, photoprotection and DNA damage repair in addition to UV-B response. Our study demonstrates the functional importance of the UVR8-mediated response across life stages in natura, which is partially redundant with that of cry1. Moreover, these data provide an integral picture of gene expression associated with plant responses under field conditions.
作为固着、自养的生物体，植物会受到包括潜在有害的紫外线-B（UV-B）辐射在内的间歇性阳光照射。在受控条件下进行的实验表明，UV-B 光受体 UV 抗性基因座 8（UVR8）控制拟南芥对 UV-B 的适应和耐受；然而，其对自然波动环境下植物适应性的长期影响仍知之甚少。在这里，我们在不同的田间和实验室条件下量化了不同拟南芥突变体基因型的生存和繁殖能力。我们发现，在人工低 UV-B 条件下生长在生长室中的 uvr8 突变体比野生型产生更多的果实，但在自然田间条件下并非如此，这表明在没有 UV-B 胁迫的情况下存在适应性成本。重要的是，在两个遗传背景下，UVR8 和蓝光受体基因 CRYPTOCHROME 1（CRY1）的独立双突变体在田间的适应性急剧下降。在田间进行的 UV-B 衰减实验和生长室中的补充 UV-B 实验表明，UV-B 导致 cry1 uvr8 条件致死表型。使用田间生长的单突变体和双突变体的 RNA-seq 数据，我们明确鉴定了在田间存在 UV-B 时，UVR8 和 CRY1 突变显示出显著统计相互作用的基因。它们在 GO 类别中富集，与氧化应激、光保护和 DNA 损伤修复有关，此外还与 UV-B 反应有关。我们的研究表明，在自然条件下，UVR8 介导的响应在生命各阶段都具有重要的功能重要性，这在一定程度上与 cry1 冗余。此外，这些数据提供了与植物在田间条件下的响应相关的基因表达的整体情况。
