Adamski Janete Mariza, Rosa Luis Mauro Gonçalves, Menezes Peixoto Carlos Roberto de, Pinheiro Clodoaldo Leites, Fett Janette Palma, Sperotto Raul Antonio
1Programa de Pós-Graduação em Botânica (PPGBot), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS Brazil.
2Escola de Química e Alimentos, Universidade Federal do Rio Grande (FURG), Campus Santo Antônio da Patrulha, Rio Grande, RS Brazil.
Physiol Mol Biol Plants. 2020 May;26(5):955-964. doi: 10.1007/s12298-020-00792-4. Epub 2020 Apr 14.
Incidence of cold during early stages is an obstacle for the growing progress of rice plants. Cold stress has strong negative effects on photosynthetic activity. Previously, our group evaluated plant survival of 90 rice genotypes after cold treatment. Two sister lines were characterized as cold-tolerant and cold-sensitive. Transcriptomic analyses of the same genotypes had indicated differential expression of genes related to photosynthesis. Previous work with rice had suggested that cold sensitivity was more related to photosystem II (PSII) than to photosystem I (PSI). Using our previously identified contrasting genotypes, we investigated the role of specific steps of the photosynthetic process in cold tolerance/sensitivity of rice plants during and after (recovery period) cold exposure. During both cold treatment and recovery period, the photochemical activity (including PSII and PSI) presented higher levels in the low temperature-tolerant genotype, when compared with the sensitive one. The higher photochemical efficiency during the cold treatment appears to be related to a lower fraction of reduced Q in PSII. We also observed lower transpiration rates and higher water use efficiency in the cold-tolerant genotype, due to stomatal closure. After the recovery period, the higher efficiency in the cold-tolerant genotype seems to be related to a lower fraction of reduced Q and a larger pool of final electron acceptors at the PSI. This work uncovered changes in photosynthetic performance including both photosystems and improved water use efficiency which may be important components of cold tolerance mechanisms in rice.
水稻生长早期的低温发生率是其生长进程的一个障碍。低温胁迫对光合活性有强烈的负面影响。此前，我们团队评估了90个水稻基因型在冷处理后的植株存活率。两个姊妹系被鉴定为耐冷和冷敏感型。对相同基因型的转录组分析表明，与光合作用相关的基因存在差异表达。先前对水稻的研究表明，冷敏感性与光系统II（PSII）的关系比与光系统I（PSI）的关系更大。利用我们之前鉴定出的对比基因型，我们研究了光合过程中特定步骤在水稻植株冷暴露期间及之后（恢复期）的耐冷性/敏感性中的作用。在冷处理和恢复期，与敏感基因型相比，耐低温基因型的光化学活性（包括PSII和PSI）水平更高。冷处理期间较高的光化学效率似乎与PSII中还原态Q的较低比例有关。我们还观察到，由于气孔关闭，耐冷基因型的蒸腾速率较低，水分利用效率较高。恢复期后，耐冷基因型的较高效率似乎与还原态Q的较低比例以及PSI处较大的最终电子受体库有关。这项工作揭示了光合性能的变化，包括两个光系统以及提高的水分利用效率，这些可能是水稻耐冷机制的重要组成部分。
