Effect of Heat Stress on Seed Protein Composition and Ultrastructure of Protein Storage Vacuoles in the Cotyledonary Parenchyma Cells of Soybean Genotypes That Are Either Tolerant or Sensitive to Elevated Temperatures

Abstract

<jats:p>High growth temperatures negatively affect soybean (Glycine max (L.) Merr) yields and seed quality. Soybean plants, heat stressed during seed development, produce seed that exhibit wrinkling, discoloration, poor seed germination, and have an increased potential for incidence of pathogen infection and an overall decrease in economic value. Soybean breeders have identified a heat stress tolerant exotic landrace genotype, which has been used in traditional hybridization to generate experimental genotypes, with improved seed yield and heat tolerance. Here, we have investigated the seed protein composition and ultrastructure of cotyledonary parenchyma cells of soybean genotypes that are either susceptible or tolerant to high growth temperatures. Biochemical analyses of seed proteins isolated from heat-tolerant and heat-sensitive genotypes produced under 28/22 °C (control), 36/24 °C (moderate), and 42/26 °C (extreme) day/night temperatures revealed that the accumulation in soybean seeds of lipoxygenase, the β-subunit of β-conglycinin, sucrose binding protein and Bowman-Birk protease inhibitor were negatively impacted by extreme heat stress in both genotypes, but these effects were less pronounced in the heat-tolerant genotype. Western blot analysis showed elevated accumulation of heat shock proteins (HSP70 and HSP17.6) in both lines in response to elevated temperatures during seed fill. Transmission electron microscopy showed that heat stress caused dramatic structural changes in the storage parenchyma cells. Extreme heat stress disrupted the structure and the membrane integrity of protein storage vacuoles, organelles that accumulate seed storage proteins. The detachment of the plasma membrane from the cell wall (plasmolysis) was commonly observed in the cells of the sensitive line. In contrast, these structural changes were less pronounced in the tolerant genotype, even under extreme heat stress, cells, for the most part, retained their structural integrity. The results of our study demonstrate the contrasting effects of heat stress on the seed protein composition and ultrastructural alterations that contribute to the tolerant genotype’s ability to tolerate high temperatures during seed development.</jats:p>

Morphological, physiological and biochemical changes in Magnolia zenii Cheng seed during development

“…Knowledge of the physiological and morphological changes that occur during seed development is important for successful seed breeding and seedling production (Song & Choi, 2019 ). In the present study, there was an increased accumulation of starch and protein in the cells in the early developmental (Krishnan et al, 2020 ) up to 135 DAF, when the protein content began to reduce. At this stage, the embryo was fully developed and had acquired germination status.…”

Proteome-Wide Analysis of Heat-Stress in Pinus radiata Somatic Embryos Reveals a Combined Response of Sugar Metabolism and Translational Regulation Mechanisms

“…HSPs are up-regulated under supra-optimal high temperatures ( Yuan et al, 2019 ; Jiang et al, 2020 ) and prevent proteins from being denatured by assisting in protein folding and processing. In that way, proteins can maintain a proper stability and function under unfavorable conditions ( Hasanuzzaman et al, 2013 ; Krishnan et al, 2020 ).…”

Confocal Fluorescence Microscopy Investigation for the Existence of Subdomains within Protein Storage Vacuoles in Soybean Cotyledons

“…Soybean seeds were cut into small pieces (2–4 mm cubes) and fixed for 4 h in 2.5% glutaraldehyde in 100 mM cacodylic buffer, pH 7.2. They were processed and embedded in Spurr’s low-viscosity media as described earlier [ 37 ].…”