Dataset Information

Physiological Changes in Mesembryanthemum crystallinum During the C3 to CAM Transition Induced by Salt Stress.

ABSTRACT: Salt stress impedes plant growth and development, and leads to yield loss. Recently, a halophyte species Mesembryanthemum crystallinum has become a model to study plant photosynthetic responses to salt stress. It has an adaptive mechanism of shifting from C3 photosynthesis to crassulacean acid metabolism (CAM) photosynthesis under stresses, which greatly enhances water usage efficiency and stress tolerance. In this study, we focused on investigating the morphological and physiological changes [e.g., leaf area, stomatal movement behavior, gas exchange, leaf succulence, and relative water content (RWC)] of M. crystallinum during the C3 to CAM photosynthetic transition under salt stress. Our results showed that in M. crystallinum seedlings, CAM photosynthesis was initiated after 6 days of salt treatment, the transition takes place within a 3-day period, and plants became mostly CAM in 2 weeks. This result defined the transition period of a facultative CAM plant, laid a foundation for future studies on identifying the molecular switches responsible for the transition from C3 to CAM, and contributed to the ultimate goal of engineering CAM characteristics into C3 crops.

SUBMITTER: Guan Q

PROVIDER: S-EPMC7090145 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Physiological Changes in Mesembryanthemum crystallinum During the C3 to CAM Transition Induced by Salt Stress.

Guan Qijie Q Tan Bowen B Kelley Theresa M TM Tian Jingkui J Chen Sixue S

Frontiers in plant science 20200317

Salt stress impedes plant growth and development, and leads to yield loss. Recently, a halophyte species Mesembryanthemum crystallinum has become a model to study plant photosynthetic responses to salt stress. It has an adaptive mechanism of shifting from C3 photosynthesis to crassulacean acid metabolism (CAM) photosynthesis under stresses, which greatly enhances water usage efficiency and stress tolerance. In this study, we focused on investigating the morphological and physio ...[more]

PMID: 32256510

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Project description:C3 or crassulacean acid metabolism (CAM)-induced Mesembryanthemum crystallinum plants perform nocturnal starch degradation which is linear with time. To analyse the composition of metabolites released by isolated leaf chloroplasts during starch degradation we developed a protocol for the purification of starch-containing plastids. Isolated chloroplasts from C3 or CAM-induced M. crystallinum plants are also able to degrade starch. With respect to the endogenous starch content of isolated plastids the rate of starch degradation in intact leaves. The combined presence of Pi, ATP, and oxaloacetate is identified to be the most positive effector combination to induce starch mobilization. The metabolic flux through the oxidative pentose-phosphate pathway in chloroplasts isolated from CAM-induced M. crystallinum is less than 3.5% compared with other metabolic routes of starch degradation. Here we report that starch-degrading chloroplasts isolated from CAM-induced M. crystallinum plants use exogenously supplied oxaloacetate for the synthesis of malate. The main products of starch degradation exported into the incubation medium by these chloroplasts are glucose 6-phosphate, 3-phosphoglyceric acid, dihydroxyacetone phosphate and glucose. The identification of glucose 6-phosphate as an important metabolite released during starch degradation is in contrast to the observations made on all other types of plastids analysed so far, including chloroplasts isolated from M. crystallinum in the C3 state. Therefore, we analysed the transport properties of isolated chloroplasts from M. crystallinum. Surprisingly, both types of chloroplasts, isolated from either C3 or CAM-induced plants, are able to transport glucose 6-phosphate in counter exchange with endogenous Pi, indicating the presence of a glucose 6-phosphate translocator as recently demonstrated to occur in other types of plastids. The composition of metabolites released and the stimulatory effect of oxaloacetate on the rate of starch degradation are discussed with respect to the acidification observed for CAM leaves during the night.

Dataset Information

Physiological Changes in Mesembryanthemum crystallinum During the C3 to CAM Transition Induced by Salt Stress.

Publications

Physiological Changes in <i>Mesembryanthemum crystallinum</i> During the C<sub>3</sub> to CAM Transition Induced by Salt Stress.

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