Common reed accumulates starch in its stem by metabolic adaptation under Cd stress conditions

Abstract

In a previous study, we reported that the common reed accumulates water-soluble Cd complexed with an α-glucan-like molecule, and that the synthesis of this molecule is induced in the stem of the common reed under Cd stress. We studied the metabolic background to ensure α-glucan accumulation under the Cd stress conditions that generally inhibit photosynthesis. We found that the common reed maintained an adequate CO2 assimilation rate, tended to allocate more assimilated 11C to the stem, and accumulated starch granules in its stem under Cd stress conditions. AGPase activity, which is the rate-limiting enzyme for starch synthesis, increased in the stem of common reed grown in the presence of Cd. Starch accumulation in the stem of common reed was not obvious under other excess metal conditions. Common reed may preferentially allocate assimilated carbon as the carbon source for the formation of Cd and α-glucan complexes in its stem followed by prevention of Cd transfer to leaves acting as the photosynthetic organ. These responses may allow the common reed to grow even under severe Cd stress conditions.

The Effect of Cadmium on the Activity of Stress-Related Enzymes and the Ultrastructure of Pea Roots

“…Interestingly, Barcelo et al [25] did not observe starch grains in the plastids of six-day-old Phaseolus vulgaris root after 15 days of 5 µg/mL CdCl 2 supplementation. However, similar to our results, Higuchi et al [47] observed starch accumulation under Cd stress, but in the stem of common reed. Moreover, since the export and allocation of carbon was not disturbed by Cd, these authors suggested that it might be an adaptive response, rather than a result of damage under excess Cd conditions [47,48].…”

“…However, similar to our results, Higuchi et al [47] observed starch accumulation under Cd stress, but in the stem of common reed. Moreover, since the export and allocation of carbon was not disturbed by Cd, these authors suggested that it might be an adaptive response, rather than a result of damage under excess Cd conditions [47,48]. Another feature we observed in the Cd-stressed root cells was oil bodies.…”

Similarities and Differences of Photosynthesis Establishment Related mRNAs and Novel lncRNAs in Early Seedlings (Coleoptile/Cotyledon vs. True Leaf) of Rice and Arabidopsis

“…The main DEGs were chloroplast development and the carbon cycle pathway in early rice growth and development. Sucrose and starch contents due to alterations of the allocation pattern of photosynthetic fixed carbon (Higuchi et al, 2015;Pilkington et al, 2015). Temporary starch exists in cells with photosynthetic capacity, synthesized in the chloroplast during the day, and degraded at night to provide carbon for non-photosynthetic metabolism (Lunn, 2007).…”

Improvement of cadmium tolerance and accumulation of Phragmites spp. Tabarka by ethyl methane sulfonate mutagenesis

“…In general, reed (Phragmites spp.) is widely known as highly tolerant plant to a variety of environmental stresses such as heavy metals (Higuchi et al 2015). In particular, this plant species accumulates Cd dominantly in roots rather than shoots (Ali et al 2004;Stoltz and Greger 2002).…”