Correlation between leaf epicuticular wax composition and structure, physio‐biochemical traits and drought resistance in glaucous and non‐glaucous near‐isogenic lines of rye

Abstract

SUMMARY The objective of this research was to investigate the differences between glaucous and non‐glaucous near‐isogenic lines (NILs) of winter rye (Secale cereale L.) in terms of epicuticular wax layer properties (weight, composition, and crystal morphology), selected physiological and biochemical responses, yield components, above‐ground biomass, and plant height under soil drought stress. An important aspect of this analysis was to examine the correlation between the above characteristics. Two different NIL pairs were tested, each consisting of a typical glaucous line and a non‐glaucous line with a recessive mutation. The drought experiment was conducted twice (2015–2016). Our study showed that wax accumulation during drought was not correlated with higher leaf hydration and glaucousness. Environmental factors had a large impact on the response of the lines to drought in individual years, both in terms of physiological and biochemical reactions, and the composition of epicuticular leaf wax. The analysed pairs displayed significantly different responses to drought. Demonstration of the correlation between the components of rye leaf wax and the physiological and biochemical parameters of rye NILs is a significant achievement of this work. Interestingly, the study showed a correlation between the wax components and the content of photosynthetic pigments and tocopherols, whose biosynthesis, similarly to the biosynthesis of wax precursors, is mainly located in chloroplasts. This suggests a relationship between wax biosynthesis and plant response to various environmental conditions and drought stress.

Variation between glaucous and non-glaucous near-isogenic lines of rye (Secale cereale L.) under drought stress

“…The Arabidopsis study on MYB96 wax biosynthesis transcription factor 26 suggested that during drought it may also be involved in other biosynthesis pathways, including those related to osmoprotectants and antioxidant biosynthesis. Interestingly, a study by Laskoś et al 24 on winter rye suggested a relationship between wax biosynthesis and the response of the plant to various environmental conditions and drought stress demonstrated by the correlation between leaf wax components and physiological and biochemical parameters of NILs, mostly chlorophyll a parameters, photosynthetic pigments and tocopherols. Cuticle thickness, composition, and morphology can change under soil drought stress 17 .…”

“…The tubules can alter the optical properties of the plant surface, causing the structure to be perceived as a bluish glaucous appearance and leading to higher surface reflectance than crystals belonging to the platelet class 33 , 34 . The plant species, organ, and tissue determine the microstructure of epicuticular wax, which undergoes constant changes during ontogenetic development and may be modified by environmental factors 22 , 24 , 31 , 34 , 35 . Regarding essential cereals such as wheat ( Triticum aestivum L.) or barley ( Hordeum vulgare L.), the plant’s glaucousness is indicated as a positive attribute due to higher yield under water stress conditions 22 , 36 , 37 .…”

A WAX INDUCER1/SHINE transcription factor controls cuticular wax in barley

“…While most land plant cuticles share these compounds, exact cuticle composition and structure vary widely depending on tissue, species, developmental stage and environmental conditions, which likely reflect adaptive responses to diverse niches and growth habits (Jetter et al , 2006; Buschhaus and Jetter, 2011; Edwards and Kenrick, 2015; Gosney et al , 2016; Xue et al , 2017; Domínguez et al , 2017). For instance, grasses, including our cereal staples, show cuticular properties which may help these plants to cope with drought-prone environments, and accordingly, influence grain yields (Dodd and Poveda, 2003; Zhang et al , 2013 a ; Guo et al , 2016; Bi et al , 2017; Xue et al , 2017; Laskoś et al , 2021). In particular, the distinctive blue-green glaucous wax bloom on exposed leaf sheaths, stem nodes and internodes, and inflorescences during the reproductive phase of many graminoid crops may provide protection from pests, UV damage and water loss (Tulloch and Hoffman, 1980; Richards et al , 1986; Febrero et al , 1998; González and Ayerbe, 2010; Zhang et al , 2013 a ; Laskoś et al , 2021) and may have been selected accordingly during barley and wheat domestication (Hen-Avivi et al , 2016; Nice et al , 2016).…”

“…For instance, grasses, including our cereal staples, show cuticular properties which may help these plants to cope with drought-prone environments, and accordingly, influence grain yields (Dodd and Poveda, 2003; Zhang et al , 2013 a ; Guo et al , 2016; Bi et al , 2017; Xue et al , 2017; Laskoś et al , 2021). In particular, the distinctive blue-green glaucous wax bloom on exposed leaf sheaths, stem nodes and internodes, and inflorescences during the reproductive phase of many graminoid crops may provide protection from pests, UV damage and water loss (Tulloch and Hoffman, 1980; Richards et al , 1986; Febrero et al , 1998; González and Ayerbe, 2010; Zhang et al , 2013 a ; Laskoś et al , 2021) and may have been selected accordingly during barley and wheat domestication (Hen-Avivi et al , 2016; Nice et al , 2016).…”

Lipidomic, Transcriptomic, and BSA-660K Single Nucleotide Polymorphisms Profiling Reveal Characteristics of the Cuticular Wax in Wheat

“…Glaucousness has been described as “the visual manifestation of waxiness” by Richards et al (1986) . The cuticular wax content of leaves can be an effective selection criterion in the development of drought-tolerant wheat cultivars ( Song et al, 2016 ; Laskoś et al, 2021 ). Therefore, a better understanding in wheat of the chemical constituents of cuticular wax, its biosynthesis, and genetic basis would benefit wheat improvement research.…”