Ultrastructural Mechanisms of Embryo Abortion in Buckwheat (Fagopyrum esculentum) under High Temperature Stress | Chapter 6 | Current Research Progress in Agricultural Sciences Vol. 10

Buckwheat (Fagopyrum esculentum) is grown mainly as a cereal crop and the only non-cereal crop in the cereal group. It is characterized by a high content of digestible proteins, carbohydrates and minerals so it has gained popularity as a pseudocereal health-food grain. Since buckwheat is grown in hot climate countries, the ultrastructural mechanism of embryo abortion which happens a lot in buckwheat under high-temperature stress, was studied at Miyazaki University located in the 31-degree north latitude of Japan, as a first case, using light and transmission electron microscope (TEM), at 1–3 d after pollination (DAP). The plants of buckwheat were cultivated in a controlled phytotron (Koito, Japan) from germination to seed mature at 32°C/23°C, day and night. As a result, the first sign of degeneration appeared at the subcellar level in the embryo sac within 2 DAP. Embryo development is significantly slowed. Almost all abortions are at the proembryonic, 8 to 24-cell stage. Embryo abortion is characterized by the appearance of large vacuoles in the embryo proper. The cytoplasm either is low in density or shows gradual condensation. Various changes occur in the abnormal cytoplasm: the cell walls expand, the ER becomes vesiculate, and osmiophilic deposits accumulate along the cell wall. The central cell degenerates to a greater degree. In particular, the following cases appeared during the endosperm development of early embryo formation. The endosperm is absent or degenerates with either electron-dense condensed cytoplasm or dispersed cytoplasm in the early free-nuclear stage. The membrane system of organelles collapses. Dictyosomes and ER also become highly vesiculated and almost all organelles disperse within the central cell, while ribosome number is sharply decreased. In the aborted embryo sac, nucellar cells show a high degree of degeneration with condensed cytoplasm and vacuolation. As both the nucellus and endosperm are heavily damaged by heat stress of high temperature, this damage leads to the loss of normal endosperm function. Nutrients are not stored or transported to the developing embryo and, thus, embryo abortion is triggered before the embryo becomes autophytic. This topic, from a grain production point of view, is relevant and promising, stress factors affect plant fertilization and subsequently have an impact on seed yield and quality. This manuscript, from a scientific research point of view, provides valuable insights into the mechanisms underlying embryo abortion in F. esculentum under high-temperature stress, a critical issue in plant reproductive biology and crop resilience. The findings contribute to broader research on heat stress tolerance, offering potential implications for breeding strategies aimed at improving reproductive success in temperature-sensitive crops.

 

Author (s) Details

 

Liming Guan
Faculty of Agriculture, University of Miyazaki, Nishi 1–1 Gakuenn Kibanadai, Miyazaki 889–2192, Japan.

Lanzhuang Chen
Faculty of Horticulture, Minami Kyushu University, 11609 Takanabe-cho, Miyazaki, 884–0003, Japan and College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China.

 

Taiji Adachi
Faculty of Agriculture, University of Miyazaki, Nishi 1–1 Gakuenn Kibanadai, Miyazaki 889–2192, Japan.

 

Please see the book here:- https://doi.org/10.9734/bpi/crpas/v10/4651