The chromoplasts of Or mutants of cauliflower ( Brassica oleracea L. var. botrytis)

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• 作者：D. J. Paolillo ; D. F. Garvin and M. V. Parthasarathy
• 关键词：Key words ; Brassica oleracea ; ; Carotene ; Membranous chromoplast ; Or mutation ; Plastid replication ; Ultrastructure.
• 刊名：Protoplasma
• 出版年：2004
• 出版时间：December 2004
• 年：2004
• 卷：224
• 期：3-4
• 页码：245-253
• 全文大小：353 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Cell Biology
  Plant Sciences
  Zoology
  
• 出版者：Springer Wien
• ISSN：1615-6102

文摘

The Or mutation in cauliflower (Brassica oleracea L. var. botrytis) leads to abnormal accumulations of -carotene in orange chromoplasts, in tissues in which leucoplasts are characteristic of wild-type plants. Or chromoplasts were investigated by light microscopy of fresh materials and electron microscopy of glutaraldehyde- and potassium permanganate-fixed materials. Carotenoid inclusions in Or chromoplasts resemble those found in carrot root chromoplasts in their optical activity and angular shape. Electron microscopy revealed that the inclusions are made up of parallel, membrane-bound compartments. These stacks of membranes are variously rolled and folded into three-dimensional objects. We classify Or chromoplasts as membranous chromoplasts. The Or mutation also limits plastid replication so that a single chromoplast constitutes the plastidome in most of the affected cells. There are one to two chromoplasts in each cell of a shoot apex. The ability of differentiated chromoplasts to divide in the apical meristems of Or mutant plants resembles the ability of proplastids to maintain plastid continuity from cell to cell in meristems of Arabidopsis thaliana mutants in which plastid replication is drastically limited. The findings are used to discuss the number of levels of regulation involved in plastid replication.