PJB-2017-852
ANATOMICAL STRUCTURES EVOLVED BY REAUMURIA SOONGORICA IN ALASHAN DESERT
Ruixiang Liu
Abstract
Reaumuria soongorica endemic to Alashan desert, Inner Mongolia, China plays a vital role in maintaining environmental sustainability and is able to tolerate extreme arid and saline soil environment. It evolved with unique anatomical structures in the process of adaptation to desert environment. In order to understand the relationship between the anatomical structures and its abiotic stress tolerances, this study was designed to to examine leaf, stem, and root anatomical structures of wild type R. soongorica from ‘Luanjingtan’, ‘Changliushui’, and ‘Wuliji’ within Alashan desert using paraffin section and scanning electron microscopy analysis. Extreme arid and saline soil profiles of three sampling sites were revealed by low soil moisture content and high salt content with negative soil water potential. Extreme arid and saline soil conditions enabled R. soongorica to have more leaf mesophyll cells and in return with more stem cortex cell shrinkage and cellular osmotic adjustment compounds using paraffin section method. Thick leaf epicuticle and small mesophyll cell size were also found which is involved in preventing leaf water loss. Low leaf stomata density (213.68 ± 71.72 mm-2), high amount of salt glands (24.5±0.5 mm-2), and abundant salt crystals on leaf and stem surface as well as xylem vessels were found using scanning electron microscopy analysis. Specialized multicellular salt gland was structurally formed by five to seven specialized epidermal cells as an ‘opened flower’ shape to secret extra salt out of leaf. In summary, arid and saline soil in Alashan desert enabled R. soongorica to form succulent leaf with thick cuticles, subsidized stomata with low density, and salt glands to decrease leaf transpiration and reduce salt toxicity to maintain active growth.
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