Ovary Abortion Induced by Combined Waterlogging and Shading Stress at the Flowering Stage Involves Amino Acids and Flavonoid Metabolism in Maize

Abstract

Maize (Zea mays L.) crops on the North China Plain are often subject to continuous overcast rain at the flowering stage. This causes waterlogging and shading stresses simultaneously and leads to huge yield losses, but the causes of these yield losses remain largely unknown. To explore the factors contributing to yield loss caused by combined waterlogging and shading stress at the flowering stage, we performed phenotypic, physiological, and quasi-targeted metabolomics analyses of maize plants subjected to waterlogging, shading, and combined waterlogging and shading (WS) treatments. Analyses of phenotypic and physiological indexes showed that, compared with waterlogging or shading alone, WS resulted in lower source strength, more severe inhibition of ovary and silk growth at the ear tip, a reduced number of emerged silks, and a higher rate of ovary abortion. Changes in carbon content and enzyme activity could not explain the ovary abortion in our study. Metabolomic analyses showed that the events occurred in ovaries and silks were closely related to abortion, WS forced the ovary to allocate more resources to the synthesis of amino acids involved in the stress response, inhibited the energy metabolism, glutathione metabolism and methionine salvage pathway, and overaccumulation of H2O2. In silks, WS led to lower accumulation levels of specific flavonoid metabolites with antioxidant capacity, and to over accumulation of H2O2. Thus, compared with each single stress, WS more seriously disrupted the normal metabolic process, and resulted more serious oxidative stress in ovaries and silks. Amino acids involved in the stress response in ovaries and specific flavonoid metabolites with antioxidant capacity in silks play important roles during ovary abortion. These results identify novel traits for selection in breeding programs and targets for genome editing to increase maize yield under WS stress.

Exogenous abscisic acid (ABA) improves the filling process of maize grains at different ear positions by promoting starch accumulation and regulating hormone levels under high planting density

“…Soil application of Zn improved maize yield mainly by increasing IG number and weight, but had no such effect on SG [ 13 ]. Improper cropping techniques or ecological stressors can hinder the development of IG or even cause it to fail compared to SG in maize [ 17 , 18 ]. These results imply that IG in maize may be more susceptible to environmental and agronomic changes than SG.…”

“…This distinction is similar in wheat [ 15 ] and rice [ 16 ]. Inadequate cultivation practices or adverse stresses can further amplify this developmental difference between IG and SG, or even result in IG abortion, ultimately adversely affecting maize yield [ 17 , 18 ]. Consequently, a great deal of research has gone into finding efficient agronomic techniques to improve IG filling and hence increase crop yield.…”

Utilizing transcriptomics and metabolomics to unravel key genes and metabolites of maize seedlings in response to drought stress

“…The biosynthesis and degradation of these amino acids are related to glycolysis/gluconeogenesis or the TCA cycle. ZmCS1 (citrate synthase 1, 100280203) is a key gene involved in the TCA cycle and has been reported the associated with phenylpropanoid hydroxycitric acids, avonoids and benzoxazinoids [10].…”

“…Metabolite pro ling studies have revealed that drought stress triggers the production of a diverse range of metabolites in maize. In response to drought, maize undergoes various adaptive reactions, including the synthesis of sugars and free amino acids to regulate osmotic pressure, the activation of anti-oxidative enzymes such as superoxide dismutase (SOD) and catalase (CAT) [8], and the production of antioxidants like glutathione stransferase (GSH-S) [9] and avonoids [10] to counteract reactive oxygen species (ROS) or regulate stomatal opening and closing via ABA hormone signaling [11]. The metabolic pathways of redox homeostasis, osmoregulation, and membrane remodelling play crucial roles in maize drought resistance mechanisms [12].…”

A multi-omic resource of wheat seed tissues for nutrient deposition and improvement for human health

“…To capture the metabolomic changes during wheat seed development, quasi-targeted metabolomics was employed to analyze the wheat samples under a contract with Novogene Co., Ltd. (Beijing, China). The metabolomic method was established by Novogene and reported previously 53 – 55 . The method is described in detail as below.…”