In nature, plants are under attack by a range of pathogens. To cope with these pathogens, a sophisticated immune system has evolved in plants, including plant cell surface localized pattern recognition receptor (PRR)-initiated pattern-triggered immunity (PTI) and intracellular nucleotide-binding and leucine-rich repeat receptor (NLR)-activated effector-triggered immunity (ETI). In recent years, increasing evidence has demonstrated that organelles, such as the chloroplast, play crucial roles in the complete activation of plant immunity. Therefore, in this review, we focus on the chloroplast and summarize its role in regulating the activation of immune events, including calcium (Ca²⁺) influx, reactive oxygen species (ROS) accumulation, phytohormone biosynthesis, and the expression of defense-related genes. Moreover, information exchange between the chloroplast and the nucleus is highly important during plant immunity. We also highlight the importance of chloroplast-nucleus communication via stromules in plant immunity. This review reveals the function of the chloroplast in maintaining the trade-off between plant growth and immunity and expands our understanding of the complete activation of plant immunity involving chloroplasts.

Paris polyphylla var. yunnanensis is a traditional Chinese medicinal plant, in which polyphyllin as the main medicinal component is an important secondary metabolite with bioactivity. Arbuscular mycorrhizal fungi (AMF) have multiple positive effects on plants, while it is not clear whether AMF increase the content of medicinal components in medicinal plants. In this study, a total of nine AMF treatments were laid to analyze the mycorrhizal effect on polyphyllin accumulation and PpHMGR and PpSE expression of P. polyphylla var. yunnanensis. AMF increased the content of polyphyllin in the cultivated variety with low relation to the increase of inoculation intensity. Polyphyllin I, II, and VII were identified and partly improved by AMF inoculation, dependent on AMF treatments and culture environments. Similarly, the PpHMGR and PpSE expression was induced by mycorrhization, dependent on AMF species, whilst the induction was more obvious in PpSE than in PpHMGR after mycorrhization. It concluded that the symbiotic relationship between P. polyphylla var. yunnanensis and AMF increased polyphyllin content level in the plant, which was associated with the up-regulation of PpSE transcripts.

Crotalaria albida (C. albida) is a traditional Chinese medicinal plant that belongs to Fabaceae family. In this study, the complete chloroplast genome sequence of C. albida was sequenced. The genome is 152,743 bp in length and includes two inverted repeat regions of 25,535 bp. It was predicted to contain 127 genes in the chloroplast genome, among which 82 were protein-coding genes, 37 were tRNA genes, and 8 were rRNA genes. The maximum likelihood phylogenetic analysis based on 24 complete chloroplast genome sequences showed that C. albida was closely related to Ormosia semicastrata, Ormosia emarginata, and Ormosia xylocarpa.

Pepper is an important and widely cultivated economic vegetable in the world (Yin et al., 2021). In June 2021, approximately 25% to 33.3% of the pepper plants had rot disease symptoms in Zhuanghang...

Lonicera japonica Thunb., belonging to Caprifoliaceae, is a widely cultivated traditional Chinese medicinal plant with high economic value. In May of 2024, symptoms of a root rot disease were observed on L. japonica in commercial plantings in Longju Town, Baitu Town, and Gaoliang Town in Wanzhou District (30°23'50″N, 107°52'22″E), Chongqing City (southwestern China). Aboveground parts of infected plants were entirely necrotic and displayed weakened lignification of roots with incidence rate of 45 to 70%. To identify the pathogen, root tissues from 17 diseased plants were collected, surface disinfected in 75% ethanol for 30 seconds, immersed in 5% NaClO for 1 minute, rinsed three times with sterile water, dried on sterile absorbent paper, placed on potato dextrose agar (PDA), and incubated at 28°C in the dark. After 5 days, 95% of the samples developed similar-appearing colonies. A single isolate, B1-V1, was selected for morphological and molecular characterization. After 15 days of incubation at 28℃ on PDA, colonies of B1-V1 reached a diameter of 80 mm; white mycelium grew slightly above the surface of the plate, was velvety in texture, and produced a yellow pigment. Hyaline, septate hyphae produced verticillate conidia that were branched like broomsticks, and conidiophores were transparent and elliptical with a single conidiophore measuring (2.31 - 4.75) × (5.33 - 8.75) μm (n = 32). The morphology was consistent with a previous description of Clonostachys rosea (Wang et al. 2024). The internal transcribed spacer region (ITS), β-tubulin gene (TUB2) and second subunit of RNA polymerase II gene (RPB2) were amplified by primers ITS1/ITS4 (Wang et al. 2024), T1/βt2b (Wang et al. 2024). and RPB2F/RPB2R (Long et al. 2021), respectively. The corresponding sequences from B1-V1 were submitted to GenBank under accession numbers PV368674 (ITS), PV390661 (TUB2), and PV390662 (RPB2). According to a BLAST search, the pathogen displayed the highest sequence similarity to strains GY12 (ITS: OR789466.1, identities: 545/545 bp), JABY1 (TUB2: OP868694.1, identities: 601/617bp) and HZL-6-8 (RPB2: PP486409.1, identities: 896/900bp). A phylogenetic tree was constructed based on concatenated ITS-TUB2-RPB2 sequences using Maximum Parsimony methods by MEGA7 software, revealing that the isolate was most closely related to C. rosea strain TMB (ITS: 491/498bp, TUB2: 311/455bp, RPB2:753/753bp). To confirm pathogenicity, both cuttings derived from branches of two-year-old plants of L. japonica Thunb. and one-year-old plants (n = 6 per group) were surface-sterilized with 75% ethanol. Roots were wounded with a sterile needle and soaked in a 4 × 10⁷ conidia/mL suspension of isolate B1-V1 for 20 days. After inoculation, symptoms including leaf wilting, yellowing, and rot browning and rot were observed, and the number of new roots significantly decreased. Colonies re-isolated from symptomatic roots were morphologically consistent with the original inoculum, thus fulfilling Koch's postulates (Wang et al, 2024). To our knowledge, this is the first report of C. rosea causing root rot in L. japonica Thunb. and provides an essential basis for root rot disease management on this crop in the future.