New horizons for building pyrenoid-based CO2-concentrating mechanisms in plants to improve yields

Many photosynthetic species have evolved CO(2)-concentrating mechanisms (CCMs) to improve the efficiency of CO(2) assimilation by Rubisco and reduce the negative impacts of photorespiration. However, the majority of plants (i.e. C3 plants) lack an active CCM. Thus, engineering a functional heterologous CCM into important C3 crops, such as rice (Oryza sativa) and wheat (Triticum aestivum), has become a key strategic ambition to enhance yield potential. Here, we review recent advances in our understanding of the pyrenoid-based CCM in the model green alga Chlamydomonas reinhardtii and engineering progress in C3 plants. We also discuss recent modeling work that has provided insights into the potential advantages of Rubisco condensation within the pyrenoid and the energetic costs of the Chlamydomonas CCM, which, together, will help to better guide future engineering approaches. Key findings include the potential benefits of Rubisco condensation for carboxylation efficiency and the need for a diffusional barrier around the pyrenoid matrix. We discuss a minimal set of components for the CCM to function and that active bicarbonate import into the chloroplast stroma may not be necessary for a functional pyrenoid-based CCM in planta. Thus, the roadmap for building a pyrenoid-based CCM into plant chloroplasts to enhance the efficiency of photosynthesis now appears clearer with new challenges and opportunities

Ecology of charophytes – permanent pioneers and ecosystem engineers

For almost a century, charophytes have been regarded as a group that is confined to low-nutrient-clear water conditions. In light of recent research, this generalisation of the ecological niche dimensions of charophytes has changed and now includes more facets of ecological existence. In this review, the current knowledge with respect to species-specificity as well as temporal aspects – ontogenetic and successional ones – of the ecological requirements of charophytes are presented and discussed. This review identifies new directions for ecological research on charophytes as well as knowledge gaps to be filled, not just for reasons of academic curiosity, but also for applied purposes such as lake restoration, bioremediation and bioindication of water quality and water regime

Comparative study of the oospore morphology of two populations of a rare species Chara baueri A. Braun in Cedynia (Poland) and Batzlow (Germany)

Morphological features of oospores of Chara baueri A. Braun, one of the rarest charophyte species worldwide, were studied based on 100 oospores collected from a small and temporarily dried mid-field pond near Cedynia, Western Poland. This is the first Polish and fifth presently known locality of this species. For comparison 67 oospores from a German population (similar pond localized near Batzlow, Germany) were also measured. So far, data on morphology of C. baueri oospores as well as the species ecology are limited. The only more detailed study of oospores for this species was earlier performed on 15 oospores from Kazakhstan. Largest polar axis (LPA, length), largest equatorial diameter (LED, width), isopolarity index (ISI = LPA/LED × 100), number of ridges, width of fossa, distance from apical pole to LED (AND) and anisipolarity index (ANI = AND/LPA × 100) were measured. The comparative analysis revealed that the oospores from Poland are generally bigger and more prolate than the Ger­man ones. The differences for most of studied parameters were statistically significant. The finding is discussed in the context of habitat differentiation of both studied sites. Moreover, the results obtained of oospore measurements for both populations differs from most of the data known so far from the literature

The physico-chemical diversity of pit lakes of the Muskau Arch (Western Poland) in the context of their evolution and genesis

In the vegetation seasons 2016–2017, a survey of 30 pit lakes localized in the eastern part of the Muskau Arch (Western Poland) was carried out. The aim of the study was to characterize the habitat conditions of the selected lakes, based on the physico-chemical water characteristics. We hypothesized that the age and genesis of pit lakes are the main factors responsible for their hydro-chemical diversity. Therefore, in each of the lakes 27 physico-chemical parameters and chlorophyll a were measured in the water surface, in the peak of the vegetation season (July–August). Additionally, they were described in terms of genesis, origin and age. The results showed that the investigated lakes display a high diversity of habitat conditions reflected in varied physico-chemical water properties (significant lake-to-lake differences). The parameters mostly responsible for the differences were: Secchi depth (transparency), pH, EC, colour, hardness, TP, TN, TC, Ca2+, Mg2+, Fe, Al, Mn, S and Chl a. The comparison of the type of excavated aggregate showed significant differences for four parameters only. Much greater differences were found for the genesis of lakes (mining method) – 15 of the 28 analysed parameters significantly differentiated the lakes. Further analysis showed that half of the studied parameters were significantly correlated with the age of the pit lakes. Our results suggest that in addition to natural changes, secondary human-caused transformations (mostly neutralization and fertilization of the water) were among the key factors responsible for the differentiation of the lakes

Nitella opaca [Bruzelius] Agardh [Characeae] w Wielkopolsce

This paper presents historical and new localities of Nitella opaca, a rare charophyte species whose distribution in the light of published data and herbarium material was restricted to a few localities in the Wielkopolska region. The basic information on the species ecology and detailed characteristics of phytocoenotic interrelation are provided. So far, the occurrence of Nitelletum opacae in the Wielkopolska region has not been reported