Integration of mRNA and miRNA analysis reveals the differentially regulatory network in two different Camellia oleifera cultivars under drought stress

Abstract

Camellia oleifera Abel. (C. oleifera) is an edible oil tree species that provide an important guarantee for targeted poverty alleviation strategy in China. Severe difficulties in irrigation leading to drought stress have become a major obstacle to the development of the C. oleifera planting industry. Breeding of drought-tolerant cultivars is the main idea for solving the problem of water shortage stress in C. oleifera cultivation. The photosynthetic physiology traits of C. oleifera cultivars ‘Xianglin No.1’ and ‘Hengdong No.2’ were affected by drought stress to different degrees, which demonstrated that the two cultivars suffered different degrees of damage. In the present study, we applied mRNA-seq and miRNA-seq to analyze the difference in molecular responses between drought stress and control, drought-tolerant and -sensitive cultivars, at mRNA and miRNA levels. The differentially expressed genes (DEGs) involved in photosynthesis-related, porphyrin, and chlorophyll metabolism, circadian rhythm system, and plant hormone signal transduction pathways were identified that might be candidates for drought stress tolerance genes. Subsequently, the miRNA-mRNA regulatory networks connected the differentially expressed miRNAs (DEMs) to their predicted target genes were established. miR398 and miR408-3p in C. oleifera showed that associated with the response to drought stress by negatively regulating genes encoding Downy Mildew Resistance 6 (DMR6) and Enhanced Disease Resistance 2 (EDR2), respectively, which might further improve drought tolerance via crosstalk between different stress-responsive pathways. The quantitation results of miRNA and mRNA were validated by quantitative real-time PCR (qRT-PCR). In summary, the integrated mRNA-seq and miRNA-seq analysis deepen our understanding of the regulatory network response to drought stress and variety-specific responses improving drought tolerance in C. oleifera.

Identification of Camellia oleifera WRKY transcription factor genes and functional characterization of CoWRKY78

“…In addition, 70 (76.9%) CoWRKY genes have ABA-responsive element, implying they also plays a critical role in ABA signaling pathways. With ecological value, C. oleifera can grow well in drought and barren soil ( He et al., 2022b ). Our finding show that CoWRKY genes were important and necessary for the responses to drought stress and further exploration of the potential biological functions of CoWRKY genes is needed.…”

“…In the past several years, most C. oleifera studies have focused mainly on oil extraction technology ( Zhang et al., 2019a ), self-incompatibility ( Zhou et al., 2020 ), seed oil biosynthesis ( Zhang et al., 2021 ), seed development ( Wu et al., 2022 ), and fruit development ( He et al., 2022a ). Specifically, with ecological value, C. oleifera can not only live in the cold climate ( Wu et al., 2020 ), but also grow well in drought and barren soil ( He et al., 2022b ). However, C. oleifera is vulnerable to a number of fungal and bacterial infections, which seriously threaten the healthy and sustainable development of C. oleifera industry.…”

Comparison of Morphological, Physiological, and Related Gene Expression Responses to Drought Stress in Five Camellia vietnamensis Cultivars

“…Although this tree species has certain drought resistance, the growth and development of seedlings transplanted to mountainous areas during the dry season are often severely affected [35]. Without a sufficient water supply, the survival rate of seedlings will be greatly reduced [36,37]. At the same time, drought can also lead to a decrease in photosynthesis, oil content, flower buds and fruit setting of C. vietnamensis, and even lead to the death of drought-sensitive cultivars [37,38].…”

Multi-omics joint analysis reveals how Streptomyces albidoflavus OsiLf-2 assists Camellia oleifera to resist drought stress and improve fruit quality

“…C. oleifera, planted in the hilly southern mountains, is a drought-tolerant tree species. Even so, drought is the main obstacle limiting yield in summer and autumn (He et al, 2022). Drought can adversely affect plant growth through wilting, weakening photosynthesis, reducing fruit oil content, and decreasing flower bud numbers and fruit set rate, potentially eliminating droughtsensitive species (Dong et al, 2017).…”