In our latest post, Shanwen Sun, a doctoral student at Universität Bayreuth, discusses his new paper, Drought survival is positively associated with high turgor loss points in temperate perennial grassland species

About the paper

What’s your paper about?

The paper originally assessed the relationship between turgor loss point (i.e., the leaf water potential at which the turgor pressure of leaf cells equals zero) and whole-plant survival under drought, and the potential mechanism that may underlie it if any relationship exists in temperate grassland species.

Two anonymous reviewers recommended to test the role of turgor loss point in determining species distribution along soil moisture gradients. I was reluctant to do that in the beginning with the concern that the test and its corresponding discussion may alter the focus of the paper. But in the end, the integration is good and extends the paper to a broader topic. 

What is the background behind your paper?

Turgor loss point has long been suggested as an important trait of plants’ adaptation for drought stress. Megan Bartlett and others have published a series of significant papers to validate its importance and found that a low turgor loss point can promote plants’ drought resistance and allow plants to occupy dry habitats by enabling plants to close stomata later under drought. But their findings were constrained to woody species, so we decided to test the role of turgor loss point for drought resistance in grassland species.

How did you come up with the idea for it?

The work is within the framework of my Ph.D. research, in which we assessed the importance of various traits that have been known or hypothesized to be important for drought resistance in grassland species. This manuscript is the first chapter of my thesis and I will look to 37 more traits in the future.

What are the key messages of your article?

First, high rather than low turgor loss point is positively related to high whole-plant survival under drought in temperate grassland species. The trend is opposite to the one found in woody species.

Second, the potential mechanism that may underneath the positive relation between turgor loss point and whole-plant survival under drought is that high turgor loss points can allow plants to respond to water stress earlier by closing stomata to save water and maintain high water potentials under drought.

Third, turgor loss point is not related to species distribution along soil moisture gradients, suggesting that the relations between species drought resistance and species distribution is complicated or weak.

How is your paper new or different from other work in this area?

Unlike previous studies that linked turgor loss point to leaf mortality or species distribution in herbaceous species, we directly related turgor loss point to whole-plant survival under drought. The later may alter species distribution and the composition and diversity of grassland communities, and thus is more theoretically and practically important.

Two anonymous reviewers recommended to test the role of turgor loss point in determining species distribution along soil moisture gradients. I was reluctant to do that in the beginning with the concern that the test and its corresponding discussion may alter the focus of the paper. But in the end, the integration is good and extends the paper to a broader topic.

Does this article raise any new research questions?

Turgor loss point accounted a fraction of variation in whole-plant survival under drought in temperate grassland species. What else contributes to high survival under drought and how it or they coordinate with high turgor loss point are still open to test.

About the research

What is the broader impact of your paper?

I have seen many papers, including highly cited papers that directly used traits as proxies of species performance under environmental stress and tried to understand the role of environmental stress in determining species distribution patterns, and population and community dynamics. However, the opposite relations between turgor loss point and drought resistance in grassland species and woody species, found in our paper, suggest that the relations between traits and performance need to be directly established in different plant life forms, before using traits as proxies or to make predictions for consequences of climate change.

When R outputted the positive relation, my first thought was ‘is my code wrong?’

Where you surprised by anything when working on it?

I actually expected that the negative relation between turgor loss point and drought resistance as in woody species would occur in temperate grassland species as well. So, when R outputted the positive relation, my first thought was ‘is my code wrong?’

What would you like to do next?

The ‘osmometer’ method allows researchers to assess turgor loss point in various species. The next thing I would do is to assess the role of turgor loss point in promoting drought resistance in other grasslands and other life forms.

About the Author

What are you currently working on?

I am currently trying to explore the mechanisms of plants stress resistance at molecular level using modern bioinformatic tools.

What is the best part of being ecologist?

The field work was actually the part that I like the best as an ecologist. After the labor work, all went to the restaurant, grabbed some bottles of beer, and talked and laughed loudly.

A piece of advice for other ecologists

Be aware of the difference when looking for the consistency.

You can read the paper here and the plain language summary here.