# Long-term functional kleptoplasty in benthic foraminifera

## TL;DR

This paper shows that the foraminifera Hauerina diversa can retain functional chloroplasts from algae for over 50 days, even without food, and that these chloroplasts work efficiently under bright light.

## Contribution

The study reveals the long-term stability and efficiency of kleptoplasty in H. diversa, including resistance to photoinhibition and maintenance under starvation.

## Key findings

- Kleptoplasts in H. diversa remain functional for over 50 days without food.
- Kleptoplasts show no photoinhibition under high light intensities.
- Starvation leads to growth inhibition, similar to symbiont-bearing foraminifera.

## Abstract

Foraminifera are highly diverse rhizarian protists, with some lineages having developed the ability to retain chloroplasts from algal prey (kleptoplasty). Recently, we revealed the evolutionary relationship between kleptoplasty and algal symbiosis in the benthic foraminifera Hauerina diversa. In this study, we explored fundamental aspects of host-kleptoplast interactions. The photosynthetic rates of H. diversa show the sequestered kleptoplast activity under a wide range of light intensities with no signs of photoinhibition. This lack of photoinhibition response may be attributed to the loss of key elements responsible for this process during the acquisition of kleptoplasts. Our study demonstrates the stability and notably extended retention of kleptoplasty in H. diversa, evidenced by its plastid retention under conditions of heterotrophic feeding deprivation for 50 days. The host-kleptoplast interactions suggest that H. diversa is highly committed to this partnership and that this kleptoplasty species likely relies on similar kleptoplast/alga maintenance mechanisms as symbiont-bearing foraminifera.

•The kleptoplasts were retained in H. diversa for more than 50 days•The kleptoplasts are efficient under high light with no signs of photoinhibition•Starvation results in growth inhibition, similar to algal-bearing foraminifera•The host is committed to maintaining the kleptoplasts under starvation stress

The kleptoplasts were retained in H. diversa for more than 50 days

The kleptoplasts are efficient under high light with no signs of photoinhibition

Starvation results in growth inhibition, similar to algal-bearing foraminifera

The host is committed to maintaining the kleptoplasts under starvation stress

Aquatic biology; Earth sciences; Marine organism; Microorganism