Adams Patricia, Nelson Don E, Yamada Shigehiro, Chmara Wendy, Jensen Richard G, Bohnert Hans J, Griffiths Howard
Department of Biochemistry, The University of Arizona, Biosciences West, Tucson, AZ 85721, USA.
Plant Genetics and Breeding Laboratory, Japan Tobacco Inc., Iwata, Japan.
New Phytol. 1998 Feb;138(2):171-190. doi: 10.1046/j.1469-8137.1998.00111.x.
This review describes the life cycle of Mesembryantheum crystallinum L. (the common ice plant, Aizoaceae, Caryophyllales), a halophyte with a developmentally programmed switch from C photosynthesis to Crassulacean acid metabolism (CAM) which is accelerated by salinity and drought. Since there has been controversy regarding the interplay between genes and environmental stimuli during the development of M. crystallinum, it is timely to summarize the life cycle for a defined set of conditions. We seek to establish the framework whereby five stages of development can be described in terms of morphology, physiology, and molecular biology. Stages 1 and 2, representing germination and growth of a juvenile form, show a determinate pattern of growth. Although specific genes for salt tolerance can be induced at these stages, stress early in development prevents progression to the mature form (stages 3-5) in which the plants advance to mature growth, flowering, and seed development. Growth in stage 3 is indeterminate in the absence of stress, but development and flowering are accelerated by environmental stresses, and CAM is constitutively expressed. Depending on the severity of the stress, plants start to flower (stage 4) and then die from the roots, ultimately with only seed capsules remaining viable, with salt sequestered into large epidermal bladder cells (stage 5). We highlight responses to salinity leading to compartmentation of ions and compatible solutes, turgor maintenance, and CAM. Finally, the molecular genetics of the ice plant are characterized, emphasizing selected genes and their products. We conclude with an analysis of the multiple stages of growth as an ecological adaptation to progressive stress. The initial determinate and inflexible juvenile phase provides a critical mass of plant material which supports the indeterminate, mature phase. Depending on the degree of stress, the mature form is then propelled towards flowering and seedset. CONTENTS Summary 171 I. Introduction 172 II. Standardizing methodology 173 III. Growth and development 175 IV. Effects of salt stress on developmental physiology 176 V. Ionic composition of cells during development 179 VI. Water transport within the plant 179 VII. The switch from C to Crassulacean Acid Metabolism 181 VIII. Stress and plant-growth regulators 182 IX. Molecular biology 183 X. Genetics, ploidy and mutants 184 XI. Conclusions and future directions 185 Acknowledgements 187 References 187.
本综述描述了冰叶日中花（Mesembryantheum crystallinum L.，番杏科，石竹目，常见的冰菜）的生命周期，它是一种盐生植物，具有从C3光合作用向景天酸代谢（CAM）的发育程序性转变，盐度和干旱会加速这种转变。由于在冰叶日中花发育过程中，基因与环境刺激之间的相互作用一直存在争议，因此及时总结在特定条件下的生命周期是很有必要的。我们试图建立一个框架，以便从形态学、生理学和分子生物学方面描述五个发育阶段。第1阶段和第2阶段分别代表幼苗的萌发和生长，呈现出一种确定的生长模式。尽管在这些阶段可以诱导出特定的耐盐基因，但发育早期的胁迫会阻止其向成熟形态（第3 - 5阶段）发展，在成熟形态中，植物会进入成熟生长、开花和种子发育阶段。在没有胁迫的情况下，第3阶段的生长是不确定的，但环境胁迫会加速发育和开花，并且CAM是组成型表达的。根据胁迫的严重程度，植物开始开花（第4阶段），然后从根部死亡，最终只有种荚保持存活，盐分被隔离在大型表皮泡状细胞中（第5阶段）。我们重点介绍了对盐度的响应，包括离子和相容性溶质的区室化、膨压维持以及CAM。最后，对冰菜的分子遗传学进行了表征，重点介绍了一些选定的基因及其产物。我们通过分析生长的多个阶段，得出其作为对渐进性胁迫的生态适应的结论。最初确定且不灵活的幼年期提供了足够数量的植物材料，以支持不确定的成年期。根据胁迫程度，成年形态随后会被推动进入开花和结实阶段。目录摘要171 一、引言172 二、标准化方法173 三、生长与发育175 四、盐胁迫对发育生理学的影响176 五、发育过程中细胞的离子组成179 六、植物体内的水分运输179 七、从C3到景天酸代谢的转变181 八、胁迫与植物生长调节剂182 九、分子生物学183 十、遗传学、倍性与突变体184 十一、结论与未来方向185 致谢187 参考文献187
