Analysis of Dynamic Global Transcriptional Atlas Reveals Common Regulatory Networks of Hormones and Photosynthesis Across Nicotiana Varieties in Response to Long-Term Drought

Abstract

Land plants evolve drought acclimation. Existing knowledge of gene regulation mainly comes from short-term drought treatment. However, common regulatory mechanism shared by multiple varieties under long-term drought is little explored. Here we investigated changes in physiology, hormones and transcriptomes in leaves of Nicotiana varieties K326 and Basma Xanthi with/without drought treatment at time courses spanning 1 month. Analyses of deep RNA-Seq data and further full-length Iso-Seq data revealed an atlas of dynamic changes of transcripts, spliced isoforms, gene expression, associated Gene Ontology, and metabolism pathways. Fewer differentially expressed genes (DEGs) were induced by drought in high tolerance variety than susceptible variety. Comparison among seven hormone signal pathways identified that genes in both abscisic acid and auxin signaling pathways were highly induced although specific genes were depended on the variety. Common hormone regulatory network analysis revealed that genes encoding clade A protein phosphatase 2C gene (PP2C) in abscisic acid pathway was the pivotal hub. Expressional regulation in photosynthesis was also common and variety specific. We conclude that long-term drought inducing gene regulatory networks of hormones and photosynthesis are variety dependent, and PP2C is the center of the common hormone regulatory network. Thus, this study improves our understanding of gene regulatory network in drought response.

Brassinosteroid Priming Improves Peanut Drought Tolerance via Eliminating Inhibition on Genes in Photosynthesis and Hormone Signaling

“…Since plant hormone signaling could crosstalk [ 2 ], we checked the change of five hormones in response to BR priming. Without BR priming, a significant increase ( p < 0.05) was observed under drought compared with under well-watered condition for defense associated hormones abscisic acid (ABA), salicylic acid (SA), and 1-aminocyclopropane-1-carboxylic acid (ACC) which is the direct precursor for ethylene ( Figure 4 ), while a significant decrease was found in growth-promoting hormones indole-3-acetic acid (IAA) and gibberellin (GA) under drought compared to those with well-watered condition.…”

“…Drought or water deficit in soil adversely affects terrestrial crop productivity, thus threatening our food security. Most studies have focused on short-term drought responses, but few studies investigated long-term drought effects which cause agricultural loss [ 1 , 2 , 3 ]. Seasonal drought, mostly belonging to the long-term drought, is the most prevalent environmental factor affecting yield [ 4 ].…”

“…Drought triggers many phenotypic changes, physiological responses, biochemical changes, and gene expressional regulations [ 3 , 4 , 5 ]. Phytohormones, especially abscisic acid (ABA) and auxin, regulate gene expression under drought [ 1 , 2 , 3 , 6 ]. The expressional regulation of auxin transporter, e.g., ABCB transporters, plays important role in response to drought condition [ 7 , 8 ].…”

Shade Effects on Peanut Yield Associate with Physiological and Expressional Regulation on Photosynthesis and Sucrose Metabolism

“…In the cytokinine signal pathway, DEGs encoding histidine-containing phosphotransferase (AHP) and two-component response regulator ARR-A family (A-ARR4) were upregulated by shade treatments, which is known to interact with shade signal receptor phytochrome B, but the expression of ARR5 was down-regulated, which may be a feedback regulation on more stable ARR5 upon increased cytokinine [46] under shade. In the abscisic acid signal pathway, five DEGs encoding the same abscisic acid receptor PYL family (PYL) were upregulated, which suppressed downstream DEGs encoding protein phosphatase 2C type A (PP2C) and most of the other PP2C types as expected [47] (Figure 9).…”

“…Our analysis of gene regulation in multiple plant hormone signal pathways revealed that the growth promoting hormones auxin, gibberellin, brassinosteroid, cytokinine and senescing hormones of abscisic acid and ethylene were all stimulated under shade treatment. This could be a crosstalk from a manner of hormone cascaded signaling network [44,47,50]. The regulation on the hormone DEGs activates downstream regulation to promote growth elongation under shade [45].…”