Special issue in honour of Prof. Reto J. Strasser - Efficacy of botanical pesticide for rotifer extermination during the cultivation of Nannochloropsis oculata probed by chlorophyll a fluorescence transient

Abstract

Nannochloropsis is widely used in aquaculture as a feed source. However, large-scale cultivation of Nannochloropsis usually fails due to rotifer contamination. In order to identify an effective technique for reducing rotifer contamination, the effect of Brachionus plicatilis contamination on photosynthetic characteristics in Nannochloropsis oculata and the efficacy of the celangulin (CA):toosendanin (TSN) (1:9) combination for rotifer extermination were investigated using chlorophyll a fluorescence transient. B. plicatilis could directly devour microalgal cells and sharply reduced N. oculata density to very low levels. B. plicatilis also inhibited activities of PSII reaction centers, both acceptor and donor side, thereby damaging the photosynthetic performance of surviving N. oculata cells. However, the CA:TSN (1:9) combination could completely eliminate B. plicatilis, thereby preventing rotifers from devouring microalgae cells and protecting the photosynthetic performance of the surviving algal cells against rotifers damage. Therefore, the binary combination of CA:TSN (1:9), is considered to be a good candidate of botanical pesticide for controlling rotifer contamination.

24-epibrassinolide improved chilled tomato photosyntheticperformance by stabilizing electron transport chain and function of photosystem II

“…These results suggested that excess radiation energy could not be consumed through photochemical quenching and thermal dissipation, which may lead to photoinactivation of PS II, and even photodamage. In fact, we also observed that RC/ CS was decreased by 87.0 % in chilled tomato (Table 4), which suggested that chilling stress led to the inactivation of PS II reaction centers and decreased the density of active PS II reaction centers (Zhang et al 2020c). In our present study, there was higher Y(II), qP, Y(NPQ), and NPQ, and lower Y(NO) in LTBR plants than in LT ones (Table 3).…”

Upregulation of the mitochondrial alternative oxidase pathway improves PSII function and photosynthetic electron transport in tomato seedlings under chilling stress

“…In this study, chilling decreased Y(II) and qP by 39.3 and 18.0%, respectively (Table 1), which suggested that chilling decreased the utilization of absorbed light energy in chloroplasts by the closure of PSII. The decrease in RC/CS under chilling stress (Table 2) further indicated that chilling led to the inactivation of PSII reaction centres and decreased the density of active PSII reaction centres (Zhang et al 2020). We observed that the inhibition of AOX pathway activity caused significant decreases in Y(II), qP, and RC/CS in tomato seedlings under both normal temperature and chilling conditions (Tables 1, 2).…”

Biological Contamination: A Serious Constraint in Large Scale Microalgae Biomass Production

“…These insecticides attack the animals' digestive system, causing death owing to cellular damage in the midgut. Zhang et al [54] found the elevation in photosynthetic performance of Nannochloropsis cells while using the combination of celangulin and toosendanin at 1:9 ratio, which could be due to the elimination of Brachionus plicatilis (rotifer) breeding. As a result, plant-derived insecticides have the potential and feasibility to intervene in biological contaminations in microalgae and cyanobacteria mass cultures.…”