Effects of Low Temperature at Booting Stage on Sucrose Metabolism and Endogenous Hormone Contents in Winter Wheat Spikelet

Abstract

Low spring temperatures often occur during the winter wheat booting stage, when the young ears are very sensitive to cold. In this study, we used two wheat varieties differing in cold sensitivity (sensitive variety Yangmai 18 and tolerant variety Yannong 19) to examine the effect of low temperature on wheat grain number at booting stage. Low temperature stress was simulated in an artificial climate chamber at 4°C for 60 h in 2016 and at 2, 0, or −2°C for 24 h in morphological assays, showing that the development of wheat spikelets was inhibited and floret growth was delayed following low temperature stress. However, an increase in the sucrose content of young panicles was also observed, and the activity of enzymes involved in sucrose metabolism was dynamically altered. Sucrose phosphate synthase activity was enhanced, and sucrose synthase activity significantly increased after treatment at 4 and 2°C, respectively. However, activities of sucrose synthase and invertase decreased with a reduction in temperature. Gene expression assays further revealed downregulation of TaSuS1 expression and upregulation of TaSuS2 , while expression of CWINV was inhibited. Moreover, phytohormone content assays showed an increase in the content of abscisic acid in young wheat ears, but a decrease in the content of auxin and gibberellins. The grain number per spike and 1000-grain weight also showed a downward trend following low temperature stress. Overall, these findings suggest that low temperature at booting induces abscisic acid accumulation in winter wheat, altering the activity of the enzymes involved in sucrose metabolism, which leads to an accumulation of sucrose in the young ears, thereby having a negative effect on wheat production.

Sucrose phosphate synthase (SPS), sucrose synthase (SUS) and their products in the leaves of Miscanthus × giganteus and Zea mays at low temperature

“…SPS and SUS exist in many isoforms which may play various functional roles and be specialized in different tissues and stages of development. In addition, the activity and the localization of these enzymes can be controlled by reversible protein phosphorylation through the calcium-dependent kinases (CPDKs) and regulation mechanisms in individual species are varied (Huber and Huber 1996 ; Toroser and Huber 1997 ; Winter et al 1997 ; Foyer et al 1998 ; Duncan et al 2006 ; Fedosejevs et al 2014 ; Almadanim et al 2017 ).…”

“…SUS isoforms have been found in the different subcellular localizations: in vacuoles (Etxeberria and Gonzalez 2003 ), in plastids (Núñez et al 2008 ), in mitochondria (Subbaiah et al 2006 ), in the cytosol (Baroja-Fernández et al 2009 ) as soluble enzyme and also in a membrane-bound form (Winter et al 1997 ), and in the different areas of the cell wall (Salnikov et al 2003 ; Persia et al 2008 ). The different localization of individual SUS isoforms can promote the membrane-associated or cytosolic sucrose degradation which may result in the further type of carbon utilization path, i.e., cellulose or starch synthesis what can be additionally regulated by various stress factors.…”

“…In the leaves of cold-treated spring and winter wheat, an increase in sucrose amount was noted, but these plants were not capable of adjusting the SPS and SUS activity to stress conditions (Savitch et al 2000 ). Similarly, low temperature caused disorders in the development of wheat spikelets and florets via sucrose over-accumulation as well as changes in enzymes activity and gene expression associated with sucrose metabolism (Zhang et al 2019 ). In the chilling-sensitive accession of Arabidopsis plants, sucrose synthesis is indicated as a metabolic ‘bottleneck’ in response to cold conditions (Nägele et al 2012 ).…”

Comparative analysis of two phytochrome mutants of tomato (Micro-Tom cv.) reveals specific physiological, biochemical, and molecular responses under chilling stress

“…Moreover, low temperature could significantly affect sugar metabolism and endogenous hormone contents in plants [ 12 ]. In general, negative impact of low temperature on MDA, proline, and other low molecular weight molecules has been reported in most plants [ 13 , 14 ]. In plants, low temperature also induce oxidative damage which is caused by generation of free radicals within the cells such as superoxide anion (O2.…”

“…Under normal conditions, ROS production and scavenging processes are in balanced state; however, stress conditions can easily overcome antioxidant defense system which includes both enzymatic and non-enzymatic components [ 16 ]. Enzymatic antioxidants contain enzymes such as superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), glutathione reductase (GR), and glutathione S-transferases (GST), while non-enzymatic antioxidants comprise of proline, glycine betaine, flavonoids, ascorbic acid, glutathione, carotenoids, and tocopherols [ 13 , 16 ]. Another phenomenal response which plants show upon exposure to stress conditions is the accumulation of osmolytes.…”