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Shifts in the realized niches of exotic species may play an important role in their invasion. Galinsoga quadriradiata has invaded China widely and occupied many climate zones that are different from its native range. We addressed the climatic niche shift of G. quadriradiata and evaluated how this could contribute to its invasion in China. We used the Maxent model to predict the potential distribution of G. quadriradiata using its native and invaded range occurrences and climatic variables. Principal component analysis was conducted to measure climatic niche shifts of G. quadriradiata during its invasion in China. The models revealed only 32.7% niche overlap between the native and invasive populations. The niche similarity of the two populations was significantly low (Schoener's D = 0.093, P < 0.005), suggesting the occurrence of a niche shift. The envelop and center of the realized climatic niche in China has shifted to lower temperature and less precipitation compared to that in its native range. The majority of invaded areas in southern China are in the stabilizing zone, whereas the colonization and adaptation zones are predicted to be at the leading edge of G. quadriradiata invasion in northern China. This suggests that the regional distribution of G. quadriradiata may be in a quasi-equilibrium state, and that the species continues to invade environmentally suitable areas. Alterations in G. quadriradiata 's niche would help to explain why this species is so invasive in China. [ABSTRACT FROM AUTHOR]

Aconitum carmichaelii Debeaux is a traditional Chinese medicinal herb that has been utilized for approximately 2,000 years. However, as cultivation has increased, there have been more reports of A. carmichaelii infections caused by four major pathogenic fungal species, Fusarium oxysporum , F. solani , Mucor circinelloides , and Sclerotium rolfsii , resulting in increased disease incidences and limited production and quality. To detect these infections, we developed a LAMP-based toolbox in this study. The cytochrome c oxidase subunit 1 ( cox1 ) gene, translation elongation factor-1α ( EF-1α ), internal transcribed spacer (ITS) regions of rDNA, and alcohol dehydrogenase 1 ( ADH1 ) gene, respectively, were used to design species-specific LAMP primer sets for F. oxysporum , F. solani , S. rolfsii , and M. circinelloides . The results showed that the LAMP-based toolbox was effective at detecting pathogens in soil and plant materials. We also used this toolbox to investigate pathogen infection in the main planting regions of A. carmichaelii . Before harvesting, F. oxysporum , M. circinelloides , and S. rolfsii were commonly found in the planting fields and in infected A. carmichaelii plants. Therefore, the toolbox we developed will be useful for tracking these infections, as well as for disease control in A. carmichaelii .

China has the largest area of kiwifruit production in the world. Pathogens associated with root diseases of kiwi trees have not been investigated extensively. In this research, three Phytophthora species, Phytophthora cactorum , Phytophthora cinnamomi , and Phytophthora lateralis , which are pathogenic to kiwi trees in the main planting areas of China, were studied. The population densities of these species in 128 soil samples from 32 kiwi orchards in 2017 and 2018 were measured using multiplex real-time quantitative PCR based on the ras-related protein gene Ypt1 . P. cactorum was the most widely distributed of the three species in orchards of the Zhouzhi and Meixian prefectures. We used redundancy analysis to examine soil factors in the kiwi orchards to understand their effects on the population densities of the Phytophthora species. The redundancy analysis indicated that soil temperature and pH were significantly correlated with the abundance of P. cactorum and P. cinnamomi . In addition, two loop-mediated isothermal amplification detection systems for P. cactorum were developed based on the tigA gene. The color-change detection system proved to be accurate, sensitive, and faster than quantitative PCR. The results of this study, along with the loop-mediated isothermal amplification detection systems, will be of great use in the control of Phytophthora diseases for the production of kiwifruits in China.

Aconitum carmichaelii is a typical traditional Chinese medicinal herb that has been grown for more than one thousand years in China (Singhuber et al. 2009). Surveys for damping-off of A. carmichaelii were conducted from 2016 to 2018 in three of China's major planting areas (Shaanxi, Sichuan, and Yunnan Province). Damping-off was observed from April to June with disease incidences ranging from 5% to 11% in ten investigated fields. In the early stage of disease development, the roots were fully covered by white mycelia. When the disease was severe, seedlings were stunted, turned yellow, had withered roots, and some eventually died. One fungus was consistently isolated from the diseased roots in the planting areas of Shaanxi Province (33°7'42″N and 107°20'27″E) on PDA medium. It was identified as Mucor circinelloides , based on morphological characteristics (Schipper 1976). Three isolates from different regions were characterized by yellowish colonies composed of tall and short sporangiophores 6-11 µm in width, terminal and globose sporangia, ellipsoidal sporangiospores 5-8 µm in length and 4-5 µm in width, and obovoid columellae. The internal transcribed spacer regions (ITS) and the large subunit (28S) of ribosomal RNA gene from the representative isolate, MC180610 (GenBank accession no. MK087755, MT043749), were also amplified and sequenced using the universal primer sets, ITS1/ITS4 and NL1/NL4, respectively. BLAST analyses of the ITS sequence showed 99.38% identity with the type strain (CBS 195.68) of M. circinelloides (GenBank accession no. NR&#95;126116), and the 28S sequence showed 99.44% identity with the strain (CBS 274.49) of M. circinelloides f. circinelloides (GenBank accession no. MH868051). The pathogenicity of M. circinelloides isolate (MC180610) to A. carmichaelii was examined by inoculating 150 ml of the hypha suspension of M. circinelloides prepared from a 10-day-old potato dextrose broth culture into the soils of healthy potted A. carmichaelii plants. Uninoculated potted A. carmichaelii plants served as controls. There were three replicates for the inoculated and control plants. All the potted A. carmichaelii plants were incubated at 25°C under 12 h light 12 h dark conditions. The symptoms that developed on M. circinelloides inoculated A. carmichaelii plants were similar to those observed in the field; control plants did not show symptoms. The pathogen was reisolated from symptomatic roots onto the PDA medium and morphologically identified as M. circinelloides . M. circinelloides has been reported as a pathogen of papaya ( Carica papaya ), Mandarin fruits ( Citrus reticulata ), and sweet potatoes ( Ipomea batatas ), respectively (Cruz-Lachica et al. 2018; Saito et al. 2016; Oladoye et al. 2016), but it has never been reported on A. carmichaelii before. This is the first report of damping-off caused by M. circinelloides on A. carmichaelii . This pathogen may present a threat to the production of A. carmichaelii in China.

CLE peptides have been implicated in various developmental processes of plants and mediate their responses to environmental stimuli. However, the biological relevance of most CLE genes remains to be functionally characterized. Here, we report that CLE9, which is expressed in stomata, acts as an essential regulator in the induction of stomatal closure. Exogenous application of CLE9 peptides or overexpression of CLE9 effectively led to stomatal closure and enhanced drought tolerance, whereas CLE9 loss-of-function mutants were sensitivity to drought stress. CLE9-induced stomatal closure was impaired in abscisic acid (ABA)-deficient mutants, indicating that ABA is required for CLE9-medaited guard cell signalling. We further deciphered that two guard cell ABA-signalling components, OST1 and SLAC1, were responsible for CLE9-induced stomatal closure. MPK3 and MPK6 were activated by the CLE9 peptide, and CLE9 peptides failed to close stomata in mpk3 and mpk6 mutants. In addition, CLE9 peptides stimulated the induction of hydrogen peroxide (H 2 O 2 ) and nitric oxide (NO) synthesis associated with stomatal closure, which was abolished in the NADPH oxidase-deficient mutants or nitric reductase mutants, respectively. Collectively, our results reveal a novel ABA-dependent function of CLE9 in the regulation of stomatal apertures, thereby suggesting a potential role of CLE9 in the stress acclimatization of plants., (© 2018 John Wiley & Sons Ltd.)