Characteristics of fine particulate matter (PM2.5) at Jinsha Site Museum, Chengdu, China.

Air pollution is a serious threat to ancient sites and cultural relicts. In this study, we collected indoor and outdoor PM2.5 samples and individual particles at the Exhibition Hall of Jinsha Site Museum in June 2020, and then the chemical components, sources, morphology, and mixing state of the fine particulate matter were analyzed. Our results show that the indoor and outdoor PM2.5 concentrations at the Exhibition Hall were 33.3±6.6 and 39.4±11.4 µg m-3, respectively. Although the indoor and outdoor concentrations of OC and EC were close, the proportion of secondary organic carbon in OC outdoor (33%) was higher than that indoor (27%). The PM2.5 was alkaline both indoors and outdoors, and the outdoor alkalinity was stronger than the indoor alkalinity. SNA (SO42-, NO3-, and NH4+) was the dominant component in the water-soluble inorganic ions; Na+, Mg2+, and Ca2+ were well correlated (R2> 0.9), and Cl- and K+ were also highly correlated (R2> 0.8). Enrichment factor analysis showed that Cu (indoor) and Cd were the main anthropogenic elements and that Cd was heavily enriched. Principal components analysis showed that the main sources of PM2.5 at Jinsha Site Museum were motor vehicles, dust, secondary sources, and combustion sources. The individual particles were classified as organic matter, S-rich, soot, mineral, and fly ash/metal particles, and most of these particles were internally mixed with each other. At last, we proposed pollution control measures to improve the air quality of museums and the preservation of cultural relicts.

Genome-wide identification of ABA receptor PYL family and expression analysis of PYLs in response to ABA and osmotic stress in Gossypium.

Abscisic acid (ABA) receptor pyrabactin resistance1/PYR1-like/regulatory components of ABA receptor (PYR1/PYL/RCAR) (named PYLs for simplicity) are core regulators of ABA signaling, and have been well studied in Arabidopsis and rice. However, knowledge is limited about the PYL family regarding genome organization, gene structure, phylogenesis, gene expression and protein interaction with downstream targets in Gossypium. A comprehensive analysis of the Gossypium PYL family was carried out, and 21, 20, 40 and 39 PYL genes were identified in the genomes from the diploid progenitor G. arboretum, G. raimondii and the tetraploid G. hirsutum and G. barbadense, respectively. Characterization of the physical properties, chromosomal locations, structures and phylogeny of these family members revealed that Gossypium PYLs were quite conservative among the surveyed cotton species. Segmental duplication might be the main force promoting the expansion of PYLs, and the majority of the PYLs underwent evolution under purifying selection in Gossypium. Additionally, the expression profiles of GhPYL genes were specific in tissues. Transcriptions of many GhPYL genes were inhibited by ABA treatments and induced by osmotic stress. A number of GhPYLs can interact with GhABI1A or GhABID in the presence and/or absence of ABA by the yeast-two hybrid method in cotton.

NADK2 positively modulates abscisic acid-induced stomatal closure by affecting accumulation of H2O2, Ca2+ and nitric oxide in Arabidopsis guard cells.

NAD kinase2 (NADK2) plays key roles in chloroplastic NADP biosynthesis, stress adaptation and modulation of cellular metabolisms in Arabidopsis. However, it is unknown whether and how NADK2 affects abscisic acid (ABA)-mediated stomatal movement. Here, we detected that null mutant nadk2 was more sensitive to drought stress than WT, and NADK2 gene was active in guard cells. Furthermore, NADK2 mutation impaired ABA-induced stomatal closure and ABA inhibition of light-promoted stomatal opening. NADK2 disruption also impaired ABA-stimulated accumulation of H2O2, Ca2+ and nitric oxide (NO) in guard cells, but did not affect the stomatal closure evoked by exogenous H2O2, Ca2+ or NO. Expression analysis revealed that ABA-promoted increases in transcripts of AtrbohD, AtrbohF and NIA1 were markedly arrested in guard cells of nadk2 compared with those of WT. Besides, genetic evidence indicated that NADK2 acted synergistically with OST1 and ABI1 during ABA-induced stomatal closure. Together, these results suggest that NADK2 is an essential positive regulator, and functions upstream of H2O2 in guard cell ABA signaling. It stimulates stomatal closure mainly through increasing the generation of H2O2, Ca2+ and NO in guard cells in Arabidopsis.