Abstract
Owing to climate change impacts, waterlogging is a serious abiotic stress that affects crops, resulting in stunted growth and loss of productivity. Cassava (Manihot esculenta Grantz) is usually grown in areas that experience high amounts of rainfall; however, little research has been done on the waterlogging tolerance mechanism of this species. Therefore, we investigated the physiological responses of cassava plants to waterlogging stress and analyzed global gene transcription responses in the leaves and roots of waterlogged cassava plants. The results showed that waterlogging stress significantly decreased the leaf chlorophyll content, caused premature senescence, and increased the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in the leaves and roots. In total, 2538 differentially expressed genes (DEGs) were detected in the leaves and 13364 in the roots, with 1523 genes shared between the two tissues. Comparative analysis revealed that the DEGs were related mainly to photosynthesis, amino metabolism, RNA transport and degradation. We also summarized the functions of the pathways that respond to waterlogging and are involved in photosynthesis, glycolysis and galactose metabolism. Additionally, many transcription factors (TFs), such as MYBs, AP2/ERFs, WRKYs and NACs, were identified, suggesting that they potentially function in the waterlogging response in cassava. The expression of 12 randomly selected genes evaluated via both quantitative real-time PCR (qRT-PCR) and RNA sequencing (RNA-seq) was highly correlated (R2 = 0.9077), validating the reliability of the RNA-seq results. The potential waterlogging stress-related transcripts identified in this study are representatives of candidate genes and molecular resources for further understanding the molecular mechanisms underlying the waterlogging response in cassava.
Highlights
Waterlogging, or soil flooding, is estimated to affect more than 17 million km2 of land area per year worldwide
The results showed that the expression patterns determined via quantitative real-time PCR (qRT-PCR) were highly consistent with the RNA sequencing (RNA-seq) data, with a relative R2 of 0.9077 (Fig 8B)
Genes associated with functional categories related to mRNA surveillance, RNA transport and degradation were most highly enriched in the roots, but they were dramatically enhanced in the waterlogged conditions (WR) samples, which indicated a large scale of energy savings under hypoxic conditions
Summary
Waterlogging, or soil flooding, is estimated to affect more than 17 million km of land area per year worldwide. Waterlogging events are expected to increase in frequency, severity, and unpredictability in the future because of global climate change [1]. It has been reported that the intensification of rainfall and evaporation in response to global warming will cause wet regions such as most tropical and subtropical zones to experience waterlogging [2]. In China, losses in crop production due to flooding were second to those due to drought in 2013, accounting for more than RMB 300 billion Yuan [5]. This abiotic stress causes problems for agricultural production in Australia, North America and Central Europe, especially in regions with heavy-textured soils [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
