JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2023, Vol. 47 ›› Issue (6): 150-158.doi: 10.12302/j.issn.1000-2006.202206042

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Study on development characteristics and dynamic changes of starch granules in the fruit of Chimonobambusa utilis

WU Hongyu1,2(), LIN Shuyan1,*(), DING Yulong1, ZHANG Yu1,2, YANG Lu1,2, QIN Min1,2, CAI Ou1,2   

  1. 1. Co-Innovation Center for Sustainable Forestry in Southern China, Bamboo Research Institute, Nanjing Forestry University, Nanjing 210037, China
    2. College of Life Science, Nanjing Forestry University, Nanjing 210037, China
  • Received:2022-06-22 Revised:2022-11-06 Online:2023-11-30 Published:2023-11-23

Abstract:

【Objective】Bamboo plants have a long flowering and fruiting cycle, making it tough to notice bamboo flowering. This study aimed to elucidate the developmental characteristics of the embryo, endosperm and pericarp of Chimonobambusa utilis during fruit development, thereby supplementing the development process of bamboo berry-like caryopses, and revealing the dynamics of starch granules during fruit development.【Method】The fruits of C. utilis at different developmental stages were selected as samples, and their developmental process was studied by appearance observation and paraffin sectioning. Dynamic changes in the distribution of starch granules in cells during fruit growth were assessed by paraffin sectioning, PAS(schiff periodic acid shiff) staining, and scanning electron microscopy. The internal endosperm morphology was used to determine whether C. utilis was mature. 【Result】Non-synchronized development of the embryo and endosperm in C. utilis fruits and endosperm development occurs earlier than embryo development. When mitosis begins in the zygote, the embryo sac contains numerous free nuclei in the endosperm. Development of C. utilis goes through a two-cell proembryo, multicellular proembryo, pear-shaped proembryo, differentiated embryo, and mature embryo stages, which can be divided further into three stages: proembryonic, embryo differentiation, and embryo maturation. The pericarp comprises epidermal and inner parenchyma cells and its thickness gradually increases with the longitudinal elongation of the fruit. The seed coat develops from the integument and is tightly combined with the pericarp. The fruits of C. utilis were characterized post-ripening. The middle portion of the embryonic sac was hollow after harvesting. After 6-10 days, the fruit matured, and the endosperm cells gradually filled the entire embryo sac and turned into storage tissue. The number of starch granules varied dynamically in the endosperm cells, with a change from low to high, while they persisted throughout the development of the pericarp and were distributed in the parenchyma cells. 【Conclusion】C. utilis fruits, including the pericarp, seed coat, endosperm, and embryo, are of the berry-like caryopsis type. Embryo and endosperm development are not synchronous, and embryo development is divided into three stages. The development of endosperms is of the nuclear type. The fruit has a post-ripening period of approximately seven days after picking, and starch granules are distributed in the parenchyma cells of the pericarp and mature endosperm cells.

Key words: Chimonobambusa utilis, berry-like caryopsis, development structure, dynamic distribution of starch granules

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