Mikania micrantha is a fast-growing global invasive weed species that causes severe damage to natural ecosystems and very large economic losses of forest and crop production. It has advantages in photosynthesis, including a similar net photosynthetic rate as C4 plants and a higher carbon fixation capacity. We used a combination of genomics and transcriptomics approaches to study the evolutionary mechanisms and circadian expression patterns of M. micrantha. In M. micrantha, 16 positive selection genes focused on photoreaction and utilization of photoassimilates. In different tissues, 98.1% of the genes associated with photoresponse had high expression in stems, and more than half of the genes of the C4 cycle had higher expression in stems than in leaves. In stomatal opening and closing, 2 genes of carbonic anhydrase (CAs) had higher expression at 18:00 than at 8:00, and the slow anion channel 1 (SLAC1) and high-leaf-temperature 1 kinase (HT1) genes were expressed at low levels at 18:00. In addition, genes associated with photosynthesis had higher expression levels at 7:00 and 17:00. We hypothesized that M. micrantha may undergo photosynthesis in the stem and flower organs and that some stomata of the leaves were opening at night by CO2 signals. In addition, its evolution may attenuate photoinhibition at high light intensities, and enhance more efficient of photosynthesis during low light intensity. And the tissue-specific photosynthetic types and different diurnal pattern of photosynthetic-related genes may contribute to its rapid colonization of new habitats of M. micrantha.

Mikania micrantha is one of the worst invasive species globally and can cause significant negative impacts on agricultural and forestry economics, particularly in Asia and the Pacific region. The rust Puccinia spegazzinii has been used successfully as a biological control agent in several countries to help manage M. micrantha. However, the response mechanisms of M. micrantha to P. spegazzinii infection have never been studied. To investigate the response of M. micrantha to infection by P. spegazzinii, an integrated analysis of metabolomics and transcriptomics was performed. The levels of 74 metabolites, including organic acids, amino acids, and secondary metabolites in M. micrantha infected with P. spegazzinii, were significantly different compared to those in plants that were not infected. After P. spegazzinii infection, the expression of the TCA cycle gene was significantly induced to participate in energy biosynthesis and produce more ATP. The content of most amino acids, such as L-isoleucine, L-tryptophan and L-citrulline, increased. In addition, phytoalexins, such as maackiain, nobiletin, vasicin, arachidonic acid, and JA-Ile, accumulated in M. micrantha. A total of 4978 differentially expressed genes were identified in M. micrantha infected by P. spegazzinii. Many key genes of M. micrantha in the PTI (pattern-triggered immunity) and ETI (effector-triggered immunity) pathways showed significantly higher expression under P. spegazzinii infection. Through these reactions, M. micrantha is able to resist the infection of P. spegazzinii and maintain its growth. These results are helpful for us to understand the changes in metabolites and gene expression in M. micrantha after being infected by P. spegazzinii. Our results can provide a theoretical basis for weakening the defense response of M. micrantha to P. spegazzinii, and for P. spegazzinii as a long-term biological control agent of M. micrantha.

【Objective】Light is one of the important ecological factors for photosynthesis of plants. The capture and utilization of light by photosynthetic pigments affects the growth and development of plants, and then affects their survival and fitness in natural ecosystems. The objective of this study is to clarify the photosynthetic physiological characteristics and response of gene expression of chlorophyll biosynthesis pathway to different light intensities in Mikania micrantha, as well as the relationship between photosynthetic energy and chlorophyll transformation, and to provide physiological and ecological evidences for explaining the “rapid growth” of M. micrantha.【Method】The photosynthetic pigment content of M. micrantha was determined by ethanol extraction under different light intensities (0, 20%, 40% and 100%). The variation pattern of chlorophyll a and b ratio (Chl a/b) was analyzed. The photosynthetic characteristics of M. micrantha were compared with the representative plants of different photosynthetic pathways (C3, C4 and CAM). The contents of ATP and starch in M. micrantha leaves under the above light intensities were determined by micro-method and anthrone colorimetric method. The cDNA library of M. micrantha under different light intensities was established and sequenced. Bioinformatics software including OrthoFinder, Blastp, HISAT2, StringTie, R package were used to analyze the expression pattern of genes involved in chlorophyll synthesis and light-harvesting complex (LHC) in M. micrantha under different light intensities. The expression patterns of genes related to chlorophyll synthesis pathway were identified.【Result】At 100% light intensity, the Chl b and carotenoid contents and Chl a/b in M. micrantha leaves were similar to those in C4 plant (maize). The Chl a/b in M. micrantha and maize leaves was significantly higher than that in C3 (rice and tomato) and CAM (aloe) plants. The contents of Chl a, Chl b and carotenoid in M. micrantha leaves under different light intensities did not change significantly, but Chl a/b significantly increased with increasing light intensity. Between the 40% and 100% light intensity, ATP content in M. micrantha leaves changed slightly, while starch content in M. micrantha leaves increased significantly in 100% light intensity. When the light intensity was 0, starch content decreased sharply and ATP content increased. The gene expression levels of HEMA, CHLH, CRD1 and CAO gene families involved in chlorophyll biosynthesis in M. micrantha were regulated by light induction, and the expression levels of light-harvesting complex (LHC) genes were higher under high light intensity.【Conclusion】Under different light conditions, M. micrantha may regulate the synthesis of Chl a and Chl b, and the mutual transformation of starch and ATP, which lay the foundation for the higher photosynthetic rate and light adaptability of M. micrantha.

桔小实蝇Bactrocera dorsalis(Hendel),是一种难防治的危险性检疫害虫.当前化学防治是控制桔小实蝇的最主要手段,但随着杀虫剂的大量使用,桔小实蝇已经对多种杀虫剂产生了不同程度的抗药性,这加大了桔小实蝇的防治难度.总结了桔小实蝇的化学防治措施、抗药性现状和抗药性机理研究进展,并对抗性治理和未来桔小实蝇的防治趋势进行展望,旨在为桔小实蝇的化学防治及抗药性的研究提供基础参考.

桔小实蝇[Bactrocera dorsalis(Hendel)]是一种重要的果蔬害虫.我国自台湾首次发现以来已有百余年历史,该虫因繁殖力强、危害严重、扩散蔓延迅速等因素备受关注.本文主要对桔小实蝇的发生为害、入侵历史、分布区域、适生区、传播扩散趋势等进行了梳理分析,明确了该虫的传播扩散趋势,并对北方地区的发生定殖风险进行了评估,为桔小实蝇的监测预警、阻截防控等工作奠定基础.