Drought stress modify cuticle of tender tea leaf and mature leaf for transpiration barrier enhancement through common and distinct modes

Abstract

Sun 4 & changsong chen 2* cuticle is the major transpiration barrier that restricts non-stomatal water loss and is closely associated with plant drought tolerance. Although multiple efforts have been made, it remains controversial what factors shape up the cuticular transpiration barrier. Previously, we found that the cuticle from the tender tea leaf was mainly constituted by very-long-chain-fatty-acids and their derivatives while alicyclic compounds dominate the mature tea leaf cuticle. the presence of two contrasting cuticle within same branch offered a unique system to investigate this question. In this study, tea seedlings were subjected to water deprivation treatment, cuticle structures and wax compositions from the tender leaf and the mature leaf were extensively measured and compared. We found that cuticle wax coverage, thickness, and osmiophilicity were commonly increased from both leaves. New waxes species were specifically induced by drought; the composition of existing waxes was remodeled; the chain length distributions of alkanes, esters, glycols, and terpenoids were altered in complex manners. Drought treatment significantly reduced leaf water loss rates. Wax biosynthesis-related gene expression analysis revealed dynamic expression patterns dependent on leaf maturity and the severity of drought. these data suggested that drought stress-induced structural and compositional cuticular modifications improve cuticle water barrier property. In addition, we demonstrated that cuticle from the tender leaf and the mature leaf were modified through both common and distinct modes. The cuticle presents on the outer surface of the epidermal cells at the aerial surfaces of vascular plants except the stems of woody plants, it is constituted of cutin and waxes which collectively form a hydrophobic layer. Cutin is insoluble polyester of long-chain hydroxyl fatty acids; waxes are either embedded within the cutin matrix in the form of intracuticular waxes or deposited on the outer surface as an epicuticular film, and are soluble in organic solvents 1,2. Cuticular waxes vary qualitatively and quantitatively among plant species; within same species wax composition also is organ-, tissue-, or even developmental stage-dependent 3-8. Based on cuticular wax composition plants can be broadly divided into two groups: plants containing only very long chain fatty acids (VLCFAs) and their derivatives such as alcohols, alkyl esters, aldehydes, and alkanes in their cuticular waxes, and plants with high percentage of alicyclic compounds (triterpenoids, steroids, or tocopherols) besides VLCFAs 9. Recently, Zhu et al. 3 reported that cuticular waxes from tender tea leaf mainly contain VLCFAs without triterpenoids; in contrast, cuticular waxes from mature tea leaf are dominated by triterpenoids and steroids. Plant cuticle plays multiple functions in the interactions with environment, its principal function is to restrict uncontrolled water loss through non-stomatal pathway 10,11. Studies from diverse plant species have demonstrated

Plasticity of the Cuticular Transpiration Barrier in Response to Water Shortage and Resupply in Camellia sinensis: A Role of Cuticular Waxes

“…After leaf development completion, the absolute amounts and the relative composition of surface compounds are invariable ( Jetter et al, 2000 ). A recent study showed that drought stress modified tea cuticular waxes of the tender and mature tea leaf through some common and unique modes for transpiration barrier reinforcement ( Chen et al, 2020 ). Here, we found that the leaf cuticular transpiration barrier was reversibly modified in Wuniuzao during the WD–RE cycle ( Figure 4 ).…”

“…The plant cuticle is a lipophilic layer coating essentially all aerial organs and acts as an interface between plants and environment. Besides protection from UV radiation, insects, pathogens, and environmental contaminants ( Eigenbrode and Espelie, 1995 ; Krauss et al, 1997 ; Neinhuis and Barthlott, 1997 ; Müller, 2006 ; Zhang et al, 2019 ; Lino et al, 2020 ), the cuticle serves as a primary barrier to restrict non-stomatal water loss and facilitate plants to survive through drought stress ( Riederer and Schreider, 2001 ; Nawrath et al, 2013 ; Chen et al, 2020 ). The cuticle is a composite material chiefly made of cutin, waxes (epicuticular and intracuticular waxes), and polysaccharides ( Guzmán et al, 2014a , b ; Fernández et al, 2017 ).…”

“…Cuticular wax composition can be modified by developmental programs or environmental cues ( Weissflog et al, 2010 ; Buschhaus et al, 2015 ; Zhu et al, 2018 ; Bourgault et al, 2020 ; Chen et al, 2020 ). In response to drought stress, plants undergo diverse wax modifications for transpiration barrier reinforcement ( Aharoni et al, 2004 ; Zhang et al, 2005 ; Bueno et al, 2019 ; Li et al, 2019 ).…”

“…However, crucial aspects of cuticle modification, especially the mechanisms to regulate wax deposition at individual cuticular compartments, remain largely unknown. Recently, tea tree ( Camellia sinensis ) emerged as a good system to study plant cuticle ( Zhu et al, 2018 ; Chen et al, 2020 ). In this study, three germplasms of Camellia sinensis ( Wuniuzao , 0202-10 , and 0306A ) were subjected to water deprivation (WD), then irrigation was resumed for plant recovery.…”

Presentation_1.PPTX

“…The plant cuticle is a lipophilic layer coating essentially all aerial organs and acts as an interface between plants and environment. Besides protection from UV radiation, insects, pathogens, and environmental contaminants (Eigenbrode and Espelie, 1995;Krauss et al, 1997;Neinhuis and Barthlott, 1997;Müller, 2006;Zhang et al, 2019;Lino et al, 2020), the cuticle serves as a primary barrier to restrict non-stomatal water loss and facilitate plants to survive through drought stress (Riederer and Schreider, 2001;Nawrath et al, 2013;Chen et al, 2020). The cuticle is a composite material chiefly made of cutin, waxes (epicuticular and intracuticular waxes), and polysaccharides (Guzmán et al, 2014a,b;Fernández et al, 2017).…”