Root Physiological Traits and Transcriptome Analyses Reveal that Root Zone Water Retention Confers Drought Tolerance to Opisthopappus taihangensis

Abstract

Opisthopappus taihangensis (Ling) Shih, as a relative of chrysanthemum, mainly survives on the cracks of steep slopes and cliffs. Due to the harsh environment in which O. taihangensis lives, it has evolved strong adaptive traits to drought stress. The root system first perceives soil water deficiency, triggering a multi-pronged response mechanism to maintain water potential; however, the drought tolerance mechanism of O. taihangensis roots remains unclear. Therefore, roots were selected as materials to explore the physiological and molecular responsive mechanisms. We found that the roots had a stronger water retention capacity than the leaves. This result was attributed to ABA accumulation, which promoted an increased accumulation of proline and trehalose to maintain cell osmotic pressure, activated SOD and POD to scavenge ROS to protect root cell membrane structure and induced suberin depositions to minimize water backflow to dry soil. Transcriptome sequencing analyses further confirmed that O. taihangensis strongly activated genes involved in the ABA signalling pathway, osmolyte metabolism, antioxidant enzyme activity and biosynthesis of suberin monomer. overall, these results not only will provide new insights into the drought response mechanisms of O. taihangensis but also will be helpful for future drought breeding programmes of chrysanthemum. Drought stress is one of the most common abiotic stresses that threatens the healthy growth and development of plants. With the further aggravation of global warming and shortages of fresh water associated with population growth, it is estimated that drought stress will severely reduce the yield and quality of crops and ornamental plants 1. Therefore, further exploration of the physiological and molecular mechanisms is necessary for breeding drought-tolerant plants. Plants have evolved physiological, biochemical and molecular strategies to adapt to arid environments and to prevent cells from water deficiency. Physiological adaptability, including abscisic acid (ABA) content changes, proline accumulation, and superoxide dismutase (SOD) and peroxidase (POD) enzyme activities, are fundamental for plants to withstand drought stress 2-5. Drought-responsive molecular mechanisms have been divided into two terms: those that directly protect plants against drought stress and those that regulate targeted gene expression and signal transduction in plants in response to drought 6. The first term includes genes encoding proteins that function by protecting cell turgor, such as enzymes participating in the biosynthesis of various osmoprotectants 4,7,8. Moreover, late-embryogenesis-abundant proteins, chaperones and antioxidant enzymes directly prevent plants from drought damage. The second term of genes mainly comprises transcription factors, which are activated by signal transduction pathways and regulate functional genes 2,9. Furthermore, protein kinases, protein phosphatases, enzymes related to phospholipid metabolism and ubiquitin ligase play significant roles in the signal trans...

Root plasticity under abiotic stress

“…The benefit of suberin may therefore be root-type specific ( Yıldırım et al, 2018 ; Cuneo et al, 2020 ). Studies comparing wild barley with domesticated cultivars indicate that wild barley has more suberin deposition in the exodermis under drought, similar to other drought-adapted species ( Kreszies et al, 2020 ; Yang et al, 2020 ). Suberin was shown to function in salt exclusion, as a barrier in the endodermis ( Ranathunge and Schreiber, 2011 ; Barberon et al, 2016 ).…”

Characteristics and Expression Analyses of Trehalose-6-Phosphate Synthase Family in Prunus mume Reveal Genes Involved in Trehalose Biosynthesis and Drought Response

“…During the water-deficient period, soil relative water content was measured every two days in order to detect the drought degree, following the oven-drying method [ 31 ]. The relative water content of leaves was computed every two days as described by in Yang [ 32 ]. The fifth to ninth leaves from the top of a branch were harvested every two days with three biological replicates, and the fresh weight (FW) of leaves was rapidly measured.…”

“…The relative expression abundance of TPS genes was detected by setting up a 10 μL PCR reaction buffer. The PCR reaction was amplified as described by Yang [ 32 ]. The expression abundance of PmTPS genes was calculated by the 2 −ΔΔCT method, where PmPP2A was used as the reference [ 56 ].…”

Growth and Nutritional Quality of Lemnaceae Viewed Comparatively in an Ecological and Evolutionary Context

“…While experimental manipulation of the plant microbiome is challenging in terrestrial plants growing in soil, some evidence is available for enhanced plant productivity in the presence of fungal partners of terrestrial plants [118,119]. Inoculation of terrestrial plant roots with arbuscular mycorrhizal fungi increased root volume and activity, triggering photosynthetic upregulation in some systems [118,120].…”

“…Conversely, the elimination of the mycorrhizal system of cucumber resulted in declining photosynthesis rates ( [121]; see also [122]). Transcriptomic analysis of such systems revealed differential gene expression in pathways of photosynthesis, hormone metabolism, carbohydrate metabolism, amino acid metabolism, stress response, signal transduction, and antioxidation [119].…”