Growth & Development

The economic spectrum of plant carbohydrate storage is blurred

The study implies that the generally overlooked role of storage within the plant economic spectrum represents an important dimension of plant strategy.

Why do plants invest in some traits but not others? The Plant Economic Spectrum proposes that traits are coordinated. Some traits support a live-fast, die young approach to growth, while others support a slow approach to reproduction. Plants can sit somewhere on this spectrum, trading speed against durability. The idea works when you look at leaves, stems and roots. It becomes more difficult when you try connecting aboveground and belowground traits. In new research, Curtis Lubbe and colleagues from the Czech Republic look to see if carbohydrate storage can help make sense of plant economics. They find their results make sense when you connect what happens in the ground with what happens above it.

The reason for investigating carbohydrate storage organs is due to perennation. Perennation is how some plants survive the winter. They store carbohydrates for energy and nutrients in an organ. Potato tubers are an obvious example, but plants can also use other organs like rhizomes. If you’re interested in the plant economic spectrum, then these organs are a bank.

Conceptual structure of trait groups and the relationships between aboveground traits and belowground storage traits. Source: Lubbe et al. 2021.

The scientists examined almost eighty temperate meadow species by examining storage organ turnover traits, storage organ inner structure traits and storage carbohydrate concentrations. The results were surprising.

“The traits of belowground storage organs for 78 species from temperate grasslands were, contrary to expectations, largely independent of one another,” write Lubbe and colleagues. “However, there were correlations of aboveground economic traits with storage organ inner structure, maximum vessel size, and the concentrations of individual types of storage carbohydrate. Although different organ inner structure arrangements did not vary significantly in the concentrations of individual carbohydrate types, they differed in total carbohydrate concentration, indicating an effect of anatomy on carbohydrate storage.”

The diversity of belowground traits did not seem to fall on a fast-slow economic spectrum. This is why the team conclude that there is a need for an expansive view of economic space.

“Although the associations between belowground trait groups within this study are generally weak, we have identified previously unknown links between the aboveground economic spectrum traits and those of storage organ inner structure and storage carbohydrate concentration,” Lubbe and colleagues conclude. “Because our study is the first attempt to broaden the understanding of the plant economic spectrum with the inclusion of storage traits, we hope that it opens our vision to new axes of plant specialization and points out that the economic strategies of plants are not a simple spectrum but rather a complicated economic space that should be further explored in its full complexity.”