Search

Seed germination is a key stage in the life history of plants, which has a crucial effect on plant community structure. Climate change has substantially altered the surface soil temperature and light availability, which can affect seed germination. However, whether the seed germination of different functional groups is affected by the interactions of light and temperature remains unclear. Under laboratory conditions, we examined the effects of low temperature and darkness, as well as their interaction, on the seed germination of 16 species belonging to three plant functional groups (annual and biennials, perennial grasses, and perennial forbs) in a typical steppe, Northern China. We found that low temperature had a significant negative effect on seed germination of all species. Low temperature significantly decreased the final germination percentage and germinative force of the three plant functional groups, and the germination duration of perennial grasses. Darkness significantly decreased the germinative force of perennial forbs and total seeds, and the germination duration of perennial grasses. The interactive effects of light and temperature on the seed final germination percentage and germinative force of perennial grass indicated that darkness strengthened the inhibitory effect of low temperature on the seed germination of the grass functional group. Our study indicate that the seed germination of different plant functional groups varied greatly in response to changing environmental conditions. Our results suggest that future climate change could alter the regeneration and species composition of plant communities through changing seed germination. [ABSTRACT FROM AUTHOR]

Seed germination is a key stage in the life history of plants, which has a crucial effect on plant community structure. Climate change has substantially altered the surface soil temperature and light availability, which can affect seed germination. However, whether the seed germination of different functional groups is affected by the interactions of light and temperature remains unclear. Under laboratory conditions, we examined the effects of low temperature and darkness, as well as their interaction, on the seed germination of 16 species belonging to three plant functional groups (annual and biennials, perennial grasses, and perennial forbs) in a typical steppe, Northern China. We found that low temperature had a significant negative effect on seed germination of all species. Low temperature significantly decreased the final germination percentage and germinative force of the three plant functional groups, and the germination duration of perennial grasses. Darkness significantly decreased the germinative force of perennial forbs and total seeds, and the germination duration of perennial grasses. The interactive effects of light and temperature on the seed final germination percentage and germinative force of perennial grass indicated that darkness strengthened the inhibitory effect of low temperature on the seed germination of the grass functional group. Our study indicate that the seed germination of different plant functional groups varied greatly in response to changing environmental conditions. Our results suggest that future climate change could alter the regeneration and species composition of plant communities through changing seed germination., Competing Interests: The authors declare that they have no competing interests., (© 2022 Liu et al.)

The article presents the result of a study which was done to examine the compensatory growth Phaeodactylum tricornutum, marine diatom after the cells underwent varying extent of darkness and ultraviolet (UV) radiation. As reported, marine phytoplankton P. tricornutum which were obtained from the Institute of Hydrobiology, Jinan University, Guangzhou, China was used in the study and it was found that compensatory growth occured in the recovery stage after meeting darkness and UV radiation.

Troglomorphism-any morphological adaptation enabling life to the constant darkness of caves, such as loss of pigment, reduced eyesight or blindness, over-developed tactile and olfactory organs-has long intrigued biologists. However, inferring the proximate and ultimate mechanisms driving the evolution of troglomorphism (stygomorphism) in freshwater fish requires a sound understanding of the evolutionary relationships between surface and stygomorphic lineages. We use Restriction Site Associated DNA Sequencing (RADseq) to better understand the evolution of the Sinocyclocheilus fishes of China. With a remarkable array of derived stygomorphic traits, they comprise the largest cavefish diversification in the world, emerging as a multi-species model system to study evolutionary novelty. We sequenced a total of 120 individuals throughout the Sinocyclocheilus distribution. The data comprised a total of 646,497 bp per individual, including 4378 loci and 67,983 SNPs shared across a minimum of 114 individuals at a given locus. Phylogenetic analyses using either the concatenated RAD loci (RAxML) or the SNPs under a coalescent model (SVDquartets, SNAPP) showed a high degree of congruence with similar topologies and high node support (>95 for most nodes in the phylogeny). The major clades recovered conform to a pattern previously established using Sanger-based mt-DNA sequences, with a few notable exceptions. We now recognize six major clades in this group, elevating the blind cavefish S. tianlinensis and the micro-eyed S. microphthalmus as two new distinct clades due to their deep divergence from other clades. PCA plots of the SNP data also support the recognition of six major clusters of species congruent with the identified clades in ordination space. A Bayes factor delimitation (BFD) analysis showed support for 21 species, recognizing 19 previously described species and two putative new cryptic ones. Two species whose identities were previously disputed, S. furcodorsalis and S. tianeensis, are supported here as distinct species. In addition, our multi-species calibrated tree in SNAPP suggests that the genus Sinocyclocheilus originated around 10.16 Mya, with most speciation events occurring in the last 2 Mya, likely favored by the uplift of the Qinghai-Tibetan Plateau and cave occupation induced by climate-driven aridification during this period. These results provide a firm basis for future comparative studies on the evolution of Sinocyclocheilus and its adaptations to cave life., (Copyright © 2022. Published by Elsevier Inc.)

Ginkgo biloba L., the only surviving species of Ginkgoopsida, is a famous relict gymnosperm, it may provide new insight into the evolution of photosynthetic mechanisms. Flavodiiron proteins (FDPs) are conserved in nonflowering plants, but the role of FDPs in gymnosperms has not yet been clarified. In particular, how gymnosperms integrate FDPs and cyclic electron transport (CET) to better adapt to excess light is poorly understood. To elucidate these questions, we measured the P700 signal, chlorophyll fluorescence and electrochromic shift signal under fluctuating and constant light in G. biloba. Within the first seconds after light increased, G. biloba could not build up a sufficient proton gradient (ΔpH). Concomitantly, photo-reduction of O 2 mediated by FDPs contributed to the rapid oxidation of P700 and protected PSI under fluctuating light. Therefore, in G. biloba, FDPs mainly protect PSI under fluctuating light at acceptor side. Under constant high light, the oxidation of PSI and the induction of non-photochemical quenching were attributed to the increase in ΔpH formation, which was mainly caused by the increase in CET rather than linear electron transport. Therefore, under constant light, CET finely regulates the PSI redox state and non-photochemical quenching through ΔpH formation, protecting PSI and PSII against excess light. We conclude that, in G. biloba, FDPs are particularly important under fluctuating light while CET is essential under constant high light. The coordination of FDPs and CET fine-tune photosynthetic apparatus under excess light., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Pinellia ternata is a medicinal herb of Araceae, and its tubers are used as medicines. It is a common Chinese herbal medicine in China and has a large market demand. When exposing to strong light intensity and high temperature during the growth process, P. ternata withers in a phenomenon known as "sprout tumble", which largely limits tuber production. Shade can effectively delay sprout tumble formation and increase its yield, however the relevant regulation mechanism is unclear. DNA methylation, as a self-modifying response to environmental changes, is often involved in the regulation of plant growth and development. In this study, P. ternata grown under natural light and 90% shading were selected as the control group and the experimental group for genomic DNA methylation analysis by using methylate sensitive amplification polymorphism(MSAP). The results showed that a total of 617 loci were detected with 20 pairs of primers, of which 311 were in the natural light group and 306 in the shading group. The methylation sites in the light and shading groups accounted for 58.2% and 71.57%, respectively, and the methylation ratios in the methylation sites were 27.65% and 29.41%, respectively, indicating that shading significantly induced the genome DNA methylation of P. ternata. Compared to the natural light group, shading promoted 32.51% of the genes methylation, while inducing 16.25% gene demethylation. This study reveals the DNA methylation variation of P. ternata under shading conditions, which lays a preliminary theoretical foundation for further analysis of the mechanism of shading regulation of P. ternata growth from epigenetic level.

Land leeches in the family Haemadipsidae are mostly from the humid tropical rainforest habitats and habitually take blood from the body of human and other animals. In the present study, we report a new species, Sinospelaeobdella wulingensis sp. n., from caves in the northern subtropical Wuling Mountains of central-south China that feeds blood exclusively on cave-dwelling bats. Based on morphological characteristics, COI gene sequence divergence, and phylogenetic analysis, a new genus Sinospelaeobdella gen. n. is established for the new species, to which a previously described species Haemadipsa cavatuses Yang et al., 2009 is transferred as S. cavatuses comb. n. We also provided extended discussion on phylogenetic relationship within the "Tritetrabdellinae" clade uncovered in a previous study, DNA taxonomy, morphological and behavioral adaptions, biogeography, and possible involvement of Sinospelaeobdella gen. n. in bat transmitted diseases of public concerns.

Premise of Study: The plant size-trait relationship is a fundamental dimension in the spectrum of plant form and function. However, it remains unclear whether the trait scaling relationship within species is modified by tree size. Investigating size-dependent trait covariations within species is crucial for understanding the ontogenetic constraints on the intraspecific economic spectrum and, more broadly, the structure and causes of intraspecific trait variations., Methods: We measured eight morphological, stoichiometric, and hydraulic traits for 604 individual plants of a shade-tolerant evergreen tree species, Litsea elongata, in a subtropical evergreen forest of eastern China. Individual trait values were regressed against tree basal diameter to evaluate size-dependent trait variations. Standardized major axis regression was employed to examine trait scaling relationships and to test whether there was a common slope and elevation in the trait scaling relationship across size classes., Key Results: Small trees tended to have larger, thinner leaves and longer, slenderer stems than larger trees, which indicates an acquisitive economic strategy in juvenile trees. Leaf nitrogen concentrations increased with plant size, which was likely due to a high ratio of structural to photosynthetic nitrogen in the evergreen leaves of large trees. Bivariate trait scaling was minimally modified by tree size, although the elevation of some relationships differed between size classes., Conclusions: Our results suggest that there are common economic and biophysical constraints on intraspecific trait covariation, independent of tree size. Small and large trees tend to be located at opposite ends of an intraspecific plant economic spectrum., (© 2018 Botanical Society of America.)

Study Objectives: To examine the influence of maternal sleep quality and nocturnal sleep duration on risk of gestational diabetes mellitus (GDM) in a multiethnic Asian population., Methods: A cohort of 686 women (376 Chinese, 186 Malay, and 124 Indian) with a singleton pregnancy attended a clinic visit at 26-28 weeks of gestation as part of the Growing Up in Singapore Towards healthy Outcomes mother-offspring cohort study. Self-reported sleep quality and sleep duration were assessed using the Pittsburgh Sleep Quality Index (PSQI). GDM was diagnosed based on a 75-g oral glucose tolerance test administered after an overnight fast (1999 WHO criteria). Multiple logistic regression was used to model separately the associations of poor sleep quality (PSQI score > 5) and short nocturnal sleep duration (<6 h) with GDM, adjusting for age, ethnicity, maternal education, body mass index, previous history of GDM, and anxiety (State-Trait Anxiety Inventory score)., Results: In the cohort 296 women (43.1%) had poor sleep quality and 77 women (11.2%) were categorized as short sleepers; 131 women (19.1%) were diagnosed with GDM. Poor sleep quality and short nocturnal sleep duration were independently associated with increased risk of GDM (poor sleep, adjusted odds ratio [OR] = 1.75, 95% confidence interval [CI] 1.11 to 2.76; short sleep, adjusted OR = 1.96, 95% CI 1.05 to 3.66)., Conclusions: During pregnancy, Asian women with poor sleep quality or short nocturnal sleep duration exhibited abnormal glucose regulation. Treating sleep problems and improving sleep behavior in pregnancy could potentially reduce the risk and burden of GDM., (© Sleep Research Society 2016. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.)

One strain of algicidal bacterium, named as S088, was isolated from the intestine of healthy sea cucumbers (Stichopus horrens) in the South China Sea. Based on the analysis of its biochemical characteristics and 16S rDNA gene sequence, S088 was identified as Bowmanella denitrificans. Importantly, the algicidal activity of S088 on Chlorella vulgaris was characterized in this study. The initial densities of bacterial and algal cell showed strong influence on the removal rates of chlorophyll a. When the strain S088 was cultured under a complete darkness condition at 30 °C, its algicidal activity reached the highest level. Furthermore, it was found that the filtered supernatant from bacterial cultures had full algicidal activity, suggesting that the secreted compounds from S088 are involved in the observed algicidal action of S088. Moreover, the algicidal compounds were heat tolerant and had no cytotoxicity against fish cells, indicating that S088 would have a promising application as a safe probiotics for S. horrens. Finally, this is the first report about the algicidal activities in B. denitrificans.

The death and subsequent decomposition of algal blooms is capable of depleting dissolved O2 to anaerobic levels, and this can de-inactivate hydrogenases. Inspired by this fact, a simple method for efficient H2 production from algal bloom biomass was developed. Direct transfer of Taihu Lake Microcystis spp. blooms into dark conditions resulted in H2 evolution, and yield was much greater than compared to Microcystis spp. cultured in the laboratory and reported previously in the literature. Further, efficient H2 production was inhibited significantly by light, which was most likely due to reduced O2 content and the stimulation of hydrogenase activity. Therefore, a simple approach for efficient H2 production from Taihu Lake Microcystis spp. blooms is presented. Furthermore, a post-treatment strategy for dealing with large quantities of refloated algal blooms is proposed., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Porphyra yezoensis, a representative species of intertidal macro-algae, is able to withstand periodic desiccation at low tide but is submerged in seawater at high tide. In this study, changes in photosynthetic electron flow in P. yezoensis during desiccation and re-hydration were investigated. The results suggested that the cyclic electron flow around photosystem I (PSI) increased significantly during desiccation, continued to operate at times of severe desiccation, and showed greater tolerance to desiccation than the electron flow around PSII. In addition, PSI activity in desiccated blades recovered faster than PSII activity during re-hydration. Even though linear electron flow was suppressed by DCMU [3-(3',4'-dichlorophenyl)-1,1-dimethylurea], cyclic electron flow could still be restored. This process was insensitive to antimycin A and could be suppressed by dibromothymoquinone (DBMIB). The prolonged dark treatment of blades reduced the speed in which the cyclic electron flow around PSI recovered, suggesting that stromal reductants, including NAD(P)H, played an important role in the donation of electrons to PSI and were the main cause of the rapid recovery of cyclic electron flow in desiccated blades during re-hydration. These results suggested that cyclic electron flow in P. yezoensis played a significant physiological role during desiccation and re-hydration and may be one of the most important factors allowing P. yezoensis blades to adapt to intertidal environments.

Taking the Gramineae species Elytrigia intermedia, Avena sativa, Bromus inermis, Elymus sibiricus, Leymus tianschanicus, Elymus dahuricus, Festuca elata, Agropyron cristatum, and Puccinellia distans at the edge of Cele Oasis in southern Taklimakan Desert as test objects, this paper monitored their fast chlorophyll fluorescence kinetics after 20 minutes adaptation in darkness, compared their photosystem II (PS II) characteristics, and analyzed their adaptability to the local environment. Among the nine Gramineae species, L. tianschanicus and E. dahuricus had markedly higher values of maximum fluorescence yield (F(m)), maximum photochemical efficiency of PS II (F(v)/F(m)), and active reaction centers per cross-section (RC/CS0), but lower values of minimum fluorescence yield (F0), absorption flux per reaction center (ABC/RC), maximal trapping flux per reaction center (TR0/RC), flux of dissipated excitation energy per reaction center (DI0/RC), and initial slope of fluorescence intensity (M0), as compared to F. elata, A. cristatum, and P. distans, whereas E. intermedia, A. sativa, B. inermis, and E. sibiricus had a medium level of the values. These results suggested that all the test pasture species were suffered from the severe environmental conditions of Cele Oasis to some extent, as indicated by the inactivation of PS II reaction center and the depression of electron transport chain. L. tianschanicus and E. dahuricus were least impacted, while F. elata, A. cristatum, and P. distans were most impacted.