Tefarikis Delphine T, Morales-Briones Diego F, Yang Ya, Edwards Gerald, Kadereit Gudrun
AG Biodiversity and Evolution of Plants, Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55099, Mainz, Germany.
Department of Plant and Microbial Biology, University of Minnesota-Twin Cities, St Paul, MN, 55108, USA.
New Phytol. 2022 Jun;234(5):1876-1890. doi: 10.1111/nph.18098. Epub 2022 Apr 1.
C photosynthesis is characterised using recapturing photorespiratory CO by RuBisCo in Kranz-like cells and is therefore physiologically intermediate between C and C photosynthesis. C can be interpreted as an evolutionary precursor of C and/or as the result of hybridisation between a C and C lineage. We compared the expression of photosynthetic traits among populations of the Salsola divaricata agg. (C ) from humid subtropical to arid habitats on the coasts of the Canary Islands and Morocco and subjected them to salt and drought treatments. We screened for enhanced C -like expression of traits related to habitat or treatment. We estimated species trees with a transcriptome dataset of Salsoleae and explored patterns of gene tree discordance. With phylogenetic networks and hybridisation analyses we tested for the hybrid origin of the Salsola divaricata agg. We observed distinct independent variation of photosynthetic traits within and among populations and no clear evidence for selection towards C -like trait expression in more stressful habitats or treatments. We found reticulation and gene tree incongruence in Salsoleae supporting a putative hybrid origin of the Salsola divaricata agg. C photosynthesis in the Salsola divaricata agg. combines traits inherited from its C and C parental lineages and seems evolutionarily stable, possibly well adapted to a wide climatic amplitude.
C4光合作用的特点是在类花环细胞中通过核酮糖-1,5-二磷酸羧化酶/加氧酶（RuBisCo）重新捕获光呼吸产生的二氧化碳，因此在生理上介于C3和C4光合作用之间。C3 - C4中间型光合作用可以被解释为C4光合作用的进化前身和/或C3和C4谱系杂交的结果。我们比较了散枝猪毛菜复合体（C3 - C4中间型）种群中光合特性的表达，这些种群分布在加那利群岛和摩洛哥海岸从湿润亚热带到干旱的栖息地，并对它们进行了盐和干旱处理。我们筛选了与栖息地或处理相关的类似C4特性表达增强的情况。我们用猪毛菜科的转录组数据集估计了物种树，并探索了基因树不一致的模式。通过系统发育网络和杂交分析，我们测试了散枝猪毛菜复合体的杂交起源。我们观察到种群内部和种群之间光合特性存在明显的独立变异，没有明确证据表明在压力更大的栖息地或处理中选择了类似C4的特性表达。我们在猪毛菜科中发现了网状结构和基因树不一致，支持散枝猪毛菜复合体的假定杂交起源。散枝猪毛菜复合体中的C3 - C4中间型光合作用结合了从其C3和C4亲本谱系遗传的特性，似乎在进化上是稳定的，可能很好地适应了广泛的气候幅度。
