Study On Plant Cotyledon Growth And Functional Traits

Life history strategy and plant function traits are hot topics of research on plant population ecology. As an important component of seed and seedling, cotyledon is a vital stage in plant life history. At different development stages, cotyledon may form various ecological adaptive strategies to adapt to the survival environments, including the adaptive strageies pertaining to morphological structure, physiological functions and genetic molecules during the growth and development. Therefore, exploring the mechanisms of plant ecological adaptations through cotyledon morphology and development and life history strategy would provide new insights into plant ecological adaptations. In the present study designed along the life history from cotyledon development in embryos, growth to maturation, the nutrient absorption by seed embryos, the specific water-stop structure of impermeable seed coat, and the conditions for the growth of cotyledon embryos and epigeal germination were analyzed. The contrast structure of the different functional groups of C3 and C4 in cotyledon and true leaf was illustrated through investigating their structural and physilogical traits, and the morphology, functional traits, environmental adaptablity and molecular defense mechanisms were explored. The results from this basic and applied research may play a critical role in elucidating the plant population evolution, community renewal and succession and vegetation recovery.In this study, scanning electron microscopy was employed to observe the channel for nutrient absorption by embryos and permeable seed-coat structures, and the embryo growth and seed dormancy characteristics were analyzed by means of incomplete embryo culture, germination and microscopy. In addition, the structural and physiological traits of cotyledon were measured using an isotope assay, the response of cotyledon functional trains to environments was investigated through determination of morphological and physiological parameters, and the defense function of cotyledon was analyzed using scanning electron microscopy and molecular biological techniques. The results as follows.l.In this experiment, we observed seed stalks of Caragana arborescens Lam. during various periods after flowering. We used anatomy and scanning electron microscopy to analyze the vascular bundle connection between seed stalk and seed coat. The mature seed stalk was mainly constituted by vessel elements, thick-walled cells and some thin-walled cells. A ring was formed by a group of elongated cells on the seed where it connected to the seedstalk. In the center of the ring, the two tiers of sclerenchyma cells created a sizable depression, which helped to attach the seed and assisted its growth. The gap in the ring in the central grain was closed in the early ripened grain, which was related to the duration of plant growth-as the seed matured, the gap opened and enlarged. The seedstalk extended into the seed in two ways: through the seed coat to the embryo, and through the embryo. In the seed stalk, the vessels were intensive and reticular, and the secondary cell walls mainly had reticulate thickening. However, secondary cell walls were thickened by a ring or thread thickening pattern in the seed, and both patterns were utilized for specific seed functions.2.The primary aim of this section was to characterize the structure difference between permeable and impermeable seeds, revealing the water-controlling structure and demonstrating the absorbing process.The general anatomy micropyle and seed coat were described by scanning electron microscopy. Dye tracking experiment was performed to exhibit the pathway of water movement during imbibition. Micropyle opening could be observed in permeable seed coats. Esteosclereid could impede the water uptake and layer of esteosclereid near the embryo was hydrophilic and the other side was hydrophobic.3.Rudimentary spatulate embryo affected the germination characteristics of seeds, and need appropriate germination conditions to germinate. Such as Lonicera caerulea, the seeds belong to morphological and physiological dormancy. The optimal germination temperature 25/15℃ and treatment with 300 ppm GA can promote the embryo growth and development.4.The microstructures of cotyledon and true leaf, cotyledon C3 and C4 structure were observed. We found true leaf structure with Kranz anatomy, cotyledons did not necessarily have the structure such as corn. However, leaves and cotyledons were not Kranz structure, and plants can also have advanced C4 photosynthetic function. Maize δ15N isotope ratio is high, the reaction of the monocot C4 plants to environmental factors of high fitness.5.Functional traits of 5 different buried depth and shading conditions on leaf have the certain influence.17 plants the cotyledons than leaf area with the weakening of light intensity increases, and the relatively low dry matter content and cotyledon thickness is adapted to water heat and soil conditions are relatively good results.6.Through the field investigation and scanning electrton microscopic observation, radish and Chinese cabbage by insect eating, is consistent after stimulated cotyledon defense rules, but their self defense in different ways. Cabbage stimulated secretion of white substance cotyledon, inference was the chemical substance, or secreting chemicals to protect themselves, which belongs to a part of the chemical defense. Radish was eating, cotyledon surface produces a lot of glands, which belongs to the category of morphological defense. The morphology of cotyledon is cotyledon defense to adapt to a reflection of the environmental evolution.7.OsPR1b gene, which is involved in the pathway of plant disease resistance, was detected in cotyledon, and exogenous jasmine acid and ethylene treatment caused a remarkable increase in the expression of OsPR1b gene, which enhances the cotyledon function in fight against diseases.This study systematically, for the first time, investigates the growth and functional traits of cotyledon using modern advanced techniques, and innovative ecological adaptive strategies and basic theory of cotyledon are obtained.