Instituto Tecnológico Vale, Rua Boaventura da Silva 955, Belém, Pará, CEP 66055-090, Brazil.
Universidade Federal de Minas Gerais, Avenida Antônio Carlos 6627, Belo Horizonte, Minas Gerais, CEP 31270-901, Brazil.
BMC Genomics. 2022 Apr 19;23(1):313. doi: 10.1186/s12864-022-08449-0.
Canga is the Brazilian term for the savanna-like vegetation harboring several endemic species on iron-rich rocky outcrops, usually considered for mining activities. Parkia platycephala Benth. and Stryphnodendron pulcherrimum (Willd.) Hochr. naturally occur in the cangas of Serra dos Carajás (eastern Amazonia, Brazil) and the surrounding forest, indicating high phenotypic plasticity. The morphological and physiological mechanisms of the plants' establishment in the canga environment are well studied, but the molecular adaptative responses are still unknown. To understand these adaptative responses, we aimed to identify molecular mechanisms that allow the establishment of these plants in the canga environment.
Plants were grown in canga and forest substrates collected in the Carajás Mineral Province. RNA was extracted from pooled leaf tissue, and RNA-seq paired-end reads were assembled into representative transcriptomes for P. platycephala and S. pulcherrimum containing 31,728 and 31,311 primary transcripts, respectively. We identified both species-specific and core molecular responses in plants grown in the canga substrate using differential expression analyses. In the species-specific analysis, we identified 1,112 and 838 differentially expressed genes for P. platycephala and S. pulcherrimum, respectively. Enrichment analyses showed that unique biological processes and metabolic pathways were affected for each species. Comparative differential expression analysis was based on shared single-copy orthologs. The overall pattern of ortholog expression was species-specific. Even so, we identified almost 300 altered genes between plants in canga and forest substrates with conserved responses in the two species. The genes were functionally associated with the response to light stimulus and the circadian rhythm pathway.
Plants possess species-specific adaptative responses to cope with the substrates. Our results also suggest that plants adapted to both canga and forest environments can adjust the circadian rhythm in a substrate-dependent manner. The circadian clock gene modulation might be a central mechanism regulating the plants' development in the canga substrate in the studied legume species. The mechanism may be shared as a common mechanism to abiotic stress compensation in other native species.
Canga 是巴西术语，指的是在富含铁的岩石露头周围的类似于热带稀树草原的植被，通常用于采矿活动。Parkia platycephala Benth. 和 Stryphnodendron pulcherrimum (Willd.) Hochr. 自然存在于塞拉多·德·卡拉雅斯山脉（巴西亚马逊东部）的 cangas 和周围的森林中，这表明它们具有高度的表型可塑性。植物在 canga 环境中建立的形态和生理机制已经得到了很好的研究，但分子适应性反应仍然未知。为了了解这些适应性反应，我们旨在确定允许这些植物在 canga 环境中建立的分子机制。
将植物种植在 canga 和在 Carajás 矿区收集的森林基质中。从 pooled 叶组织中提取 RNA，并将 RNA-seq 配对末端reads 组装成代表 P. platycephala 和 S. pulcherrimum 的转录组，分别包含 31,728 和 31,311 个初级转录本。我们使用差异表达分析，鉴定了在 canga 基质中生长的植物的物种特异性和核心分子反应。在物种特异性分析中，我们分别鉴定了 1,112 和 838 个差异表达基因用于 P. platycephala 和 S. pulcherrimum。富集分析表明，每个物种都受到独特的生物过程和代谢途径的影响。基于共享的单拷贝直系同源物的比较差异表达分析。直系同源物表达的总体模式是物种特异性的。即便如此，我们还是在 canga 和森林基质中的植物之间鉴定了近 300 个差异表达基因，在这两个物种中都有保守的反应。这些基因与对光刺激和昼夜节律途径的反应有关。
植物具有应对基质的物种特异性适应性反应。我们的结果还表明，适应 canga 和森林环境的植物可以以基质依赖的方式调节昼夜节律。节律钟基因的调节可能是调节研究豆科植物在 canga 基质中发育的核心机制。该机制可能作为其他本地物种对非生物胁迫补偿的共同机制。
