Transcriptome analysis of Kentucky bluegrass subject to drought and ethephon treatment

Abstract

Kentucky bluegrass (Poa pratensis L.) is an excellent cool-season turfgrass utilized widely in Northern China. However, turf quality of Kentucky bluegrass declines significantly due to drought. Ethephon seeds-soaking treatment has been proved to effectively improve the drought tolerance of Kentucky bluegrass seedlings. In order to investigate the effect of ethephon leaf-spraying method on drought tolerance of Kentucky bluegrass and understand the underlying mechanism, Kentucky bluegrass plants sprayed with and without ethephon are subjected to either drought or well watered treatments. The relative water content and malondialdehyde conent were measured. Meanwhile, samples were sequenced through Illumina. Results showed that ethephon could improve the drought tolerance of Kentucky bluegrass by elevating relative water content and decreasing malondialdehyde content under drought. Transcriptome analysis showed that 58.43% transcripts (254,331 out of 435,250) were detected as unigenes. A total of 9.69% (24,643 out of 254,331) unigenes were identified as differentially expressed genes in one or more of the pairwise comparisons. Differentially expressed genes due to drought stress with or without ethephon pre-treatment showed that ethephon application affected genes associated with plant hormone, signal transduction pathway and plant defense, protein degradation and stabilization, transportation and osmosis, antioxidant system and the glyoxalase pathway, cell wall and cuticular wax, fatty acid unsaturation and photosynthesis. This study provides a theoretical basis for revealing the mechanism for how ethephon regulates drought response and improves drought tolerance of Kentucky bluegrass.

Plant hormone ethylene: A leading edge in conferring drought stress tolerance

“…Ethephon (150 mg L −1 ) seed treatment increased the antioxidant enzymes' activity, as well as reduced MDA content and electrolyte leakage compared to control (Zhang et al, 2018b). Similarly, Zhang et al (2021b) revealed that seed priming with ethylene (200 mg L −1 ) influenced the expression of genes related to signal transduction pathways, protein denaturation and stabilization, transportation, osmosis, and the antioxidant system in kentucky bluegrass. Exogenously‐applied ethylene at a concentration of 1.0 mM has a beneficial effect on maize under drought stress.…”

“…It also facilitates the growth of new adventitious root systems and sustains fundamental metabolism, thereby promoting plant tolerance to drought stress (Zhang et al, 2013). Ethylene acquisition is crucially linked with the varying degrees of drought exposure, which affects every aspect of plant stages (Cui et al, 2015; Zhang et al, 2021b; Chen et al, 2022). Furthermore, increased ethylene production in response to drought stress reduces growth rate, photochemical efficiency, and grain yield by accelerating leaf and flower abscission and senescence (El‐Beltagy & Hall, 1974; Beltrano et al, 1999; Yang et al, 2014a), indicating that ethylene has a biphasic function in plants.…”

“…Drought stress regulates the source‐ sink dynamics and osmotic adjustments by controlling ethylene production primarily in reproductive tissues, including floral, pedicel, calyx and fruit (Jaafar et al, 1999; Nakano et al, 2002). Exogenous application of ethylene (including ethephon) has a positive impact on plants by augmenting their tolerance to drought stress (Xiao‐Le et al, 2014; Roberto et al, 2015; Yu et al, 2017a; Zhang et al, 2021b; Iqbal et al, 2022). This is achieved by regulating cuticular wax production, which plays a crucial role in sustaining water levels and membrane stability necessary for plant growth (Yu et al, 2017a).…”

Effect of ethylene pretreatment on tomato plant responses to salt, drought, and waterlogging stress

“…Similarly, Scarpeci et al (2017) showed that overexpressing AtERF019 in Arabidopsis increased drought tolerance and decreased transpiration rate by reducing stomatal conductance. In a study by Zhang et al (2021), an ethephon (a liquid formulation that releases ethylene gas after spraying) pre‐treatment was administered to Kentucky bluegrass ( Poa pratensis L.), which subsequently led to an osmotic enhancement when exposed to drought stress by promoting antioxidant enzyme activity and the accumulation of proline. Similarly, priming wheat grains with ethylene has been shown to elicit improved drought tolerance by regulating auxin and abscisic acid signaling, ROS scavenging, and osmotic regulation (Yang et al, 2021).…”

Transcriptome Analysis of Native Kentucky Bluegrass (Poa pratensis L.) in Response to Osmotic Stress

“…Some up-regulated DEGs included PYL, JAZ and BSK involved in the hormone signaling transduction of ABA, jasmonic acid (JA) and brassinosteroid (BR) [18]. An RNA-seq approach using three germplasm sources with different drought tolerances identified transcript isoforms exhibiting a shared response of all three germplasm sources to drought stress and transcript isoforms exhibiting a tolerance response, where the more drought-tolerant germplasm sources exhibited higher transcript differences compared to the drought-susceptible cultivar [19].…”