Search Results (146)

Chlorophyll biosynthesis is essential for photosynthesis and plant development. Disruptions in this pathway often manifest as pigment-deficient phenotypes. This study characterizes the morphological, anatomical, and physiological consequences of a chlorophyll-deficient rice mutant (yellow seedling, YS) caused by a loss-of-function mutation in the OsCHLI gene, which encodes the ATPase subunit of magnesium chelatase. Comparative analyses between YSs and wild-type green seedlings (GSs) revealed that YSs exhibited severe growth retardation, altered mesophyll structure, reduced xylem and bulliform cell areas, and higher stomatal and papillae density. These phenotypes were strongly light-dependent, indicating that OsCHLI plays a crucial role in light-mediated chloroplast development and growth. Transcriptome analysis further revealed global down-regulation of photosynthesis-, TCA cycle-, and cell wall-related genes, alongside selective up-regulation of redox-related pathways. These results suggest that chlorophyll deficiency induces systemic metabolic reprogramming, prioritizing stress responses over growth. This study highlights the multifaceted role of OsCHLI in plastid maturation, retrograde signaling, and developmental regulation, providing new insights for improving photosynthetic efficiency and stress resilience in rice. Full article

Manganese (Mn) excess and low pH often coexist in some citrus orchard soils. Little information is known about the underlying mechanism by which raising pH reduces Mn toxicity in citrus plants. ‘Sour pummelo’ (Citrus grandis (L.) Osbeck) seedlings were treated with 2 (Mn2) or 500 (Mn500) μM Mn at a pH of 3 (P3) or 5 (P5) for 25 weeks. Raising pH mitigated Mn500-induced increases in Mn, iron, copper, and zinc concentrations in roots, stems, and leaves, as well as nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, copper, iron, and zinc distributions in roots, but it mitigated Mn500-induced decreases in nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, and boron concentrations in roots, stems, and leaves, as well as nutrient imbalance. Raising pH mitigated Mn500-induced necrotic spots on old leaves, yellowing of young leaves, decreases in seedling growth, leaf chlorophyll concentration, and CO₂ assimilation (A_CO2), increase in root dry weight (DW)/shoot DW, and alterations of leaf chlorophyll a fluorescence (OJIP) transients and related indexes. Further analysis indicated that raising pH ameliorated Mn500-induced impairment of nutrient homeostasis, leaf thylakoid structure by iron deficiency and competition of Mn with magnesium, and photosynthetic electron transport chain (PETC), thereby reducing Mn500-induced declines in A_CO2 and subsequent seedling growth. These results validated the hypothesis that raising pH reduced Mn toxicity in ‘Sour pummelo’ seedlings by (a) reducing Mn uptake, (b) efficient maintenance of nutrient homeostasis under Mn stress, (c) reducing Mn excess-induced impairment of thylakoid structure and PEPC and inhibition of chlorophyll biosynthesis, and (d) increasing A_CO2 and subsequent seedling growth under Mn excess. Full article

The Citrus tristeza virus (CTV), a member of the Closterovirus genus, is considered a serious threat to citrus trees grafted onto sour orange (SO) rootstock. In the Mediterranean area, the most prevalent CTV strains are VT and T30. The VT strain includes both mild and severe isolates, some of them associated with seedling yellows (SY) syndrome. Mild CTV-VT isolates that do not induce SY symptoms (no-SY) show minor variations in their Orf1a, p23, and p33 genes, with a single nucleotide polymorphism at position 161 of the p23 gene. These isolates can repress superinfection with homologous severe isolates. The aim of this study was to investigate the mechanism of cross-protection by means of biological indexing, real-time RT-PCR high-resolution melting (HRM), and p23 gene amplicon sequencing. Four no-SY CTV-VT isolates were inoculated onto SO seedlings and Hamlin sweet orange trees grafted on SO. These plants were later challenged with two homologous CTV-VT SY isolates and remained asymptomatic. The biological evaluation of the infection process in superinfected plants was investigated via inoculation of the bark on SO seedlings that were also asymptomatic. A parallel HRM analysis of midvein RNA extracts revealed that the melting temperature (Tm) of the no-SY isolates was statistically lower than that of the SY isolates. The Tm values of RNAs extracts from superinfected plants were not statistically different from those of the no-SY isolates. This suggests that the SY isolates failed to establish infection or replicate in plants pre-inoculated with no-SY isolates. This blockage of replication resembles superinfection exclusion, with attractive perspectives to prevent SY damage in field applications. Full article

Insecticides are mainly used to control aphids as they are potatoes’ main vectors of viruses. This study analysed the flight activity of Myzus persicae, Phorodon humuli, and Aphis nasturtii from a suction trap over 22 years (2002–2024). We also analysed the flight activity of seven aphid species, vectors of viruses from the yellow water trap over 6 years (2019–2024). The number of catches of aphids in the suction trap was higher in 2014–2024 than in 2002–2013: for M. persicae, 4.2-fold, P. humuli 2.1-fold, and A. nastrurtii, 1.9-fold. A statistically significant correlation between mean temperature per year and total capture of M. persicae per year in the suction trap was found. The analysis showed no relationship between the abundance of M. persicae and P. humuli from the suction trap in spring and the abundance in the yellow water trap in the potato field. The dominant aphid species in the yellow water trap were M. persicae, Brevicoryne brassicae, and Aphis fabae. Regression analysis showed no direct relationship between aphid abundance in the yellow water trap over the period of 2019–2024 and seedling recruitment. Potato aphid control options are discussed concerning the flight activity and specific life cycles of each aphid species. Full article

In vitro micropropagation is used to rapidly shorten the breeding process of crops, such as kale, an internationally widespread winter vegetable. The aim of this study is to develop optimised micropropagation protocols for three kale varieties. First, it was determined which seed surface disinfection method resulted in the highest germination rate and the lowest infection rate. Secondly, it was investigated which of several existing Brassica protocols and one modified protocol from the literature provided the highest regeneration efficiency of kale explant types (cotyledons, hypocotyl, root, and intact seedlings as the control) after eight weeks of cultivation. Germination was highest and fastest after disinfection with 10% NaClO for 10 min for “Frostara” and at 5% for 2.5 min for “Schatteburg”. The infection rate and speed were lowest in treatments with 10% NaClO. The regeneration efficiency and number of newly formed leaves, roots, shoots, and stems varied between media, explant type, and kale variety. Most new leaves and shoots were formed when hypocotyls were used as explant type. Roots regenerated mostly more roots than shoots, stems, and leaves. A higher ratio of auxin to cytokinin in the culture medium partially increased leaf regeneration. The addition of AgNO₃ increased shoot regeneration and reduced yellowing and leaf drop. Phenotypic anomalies occurred less frequently in media with lower hormone concentrations. All tested protocols are suitable for kale micropropagation, but regeneration was highly dependent on the medium for different varieties and explant types. Therefore, this study builds a basis for future micropropagation of kale and the development of variety-specific protocols for maximum commercial success. Full article

The large yellow croaker (Larimichthys crocea) is one of China’s most economically important marine fish species, with its cage culture production leading the nation for many years. However, the rapid expansion of aquaculture has brought challenges such as germplasm degradation, reduced disease resistance, inconsistent product quality, and low adoption of improved strains, which have hindered the sustainable development of the industry. The primary objective of this review is to summarize the current practices and challenges in seedling selection for L. crocea. The secondary objectives include discussing the influence of genetic, physiological, and environmental factors on growth performance and proposing future research directions for sustainable breeding programs. This review covers key topics including morphological screening, growth performance evaluation, genetic diversity conservation, disease resistance improvement, and adaptation to environmental stress. It also explores the application of modern technologies such as marker-assisted selection, intelligent monitoring, environmental control, precision feeding, and disease prevention. Moreover, it highlights core issues in current breeding practices, such as over-reliance on single-trait selection and insufficient integration of environmental adaptability and disease resistance. Finally, future trends are discussed, emphasizing the integration of genomic tools with artificial intelligence to promote intelligent, precise, and sustainable breeding approaches. These insights aim to enhance aquaculture productivity while supporting long-term ecological balance and industry sustainability. Full article

Zinc (Zn) is an essential micronutrient required for plants to perform various metabolic functions, and plant responses to Zn deficiency have been extensively studied. However, excessive levels of Zn in soil can induce toxic effects in plants, posing a substantial challenge to global agricultural productivity. Consequently, elucidating the response mechanisms of crop plants to excessive Zn toxicity is currently of great significance. In this study, seedlings of maize inbred line B73 were exposed to excessive Zn treatment, and transcriptomic profiling of the roots was conducted at 0, 2, 6, 12, 24, and 48 h post-treatment. In addition to changes in the expression of genes encoding zinc-regulated, iron-regulated transporter-like protein (ZIP), metal tolerance protein (MTP), and yellow stripe-like (YSL) transporter family members involved in Zn transport, we observed that differentially expressed genes (DEGs) were significantly enriched in the phenylpropanoid–lignin metabolic pathway across all treatment stages, including the early (2 and 6 h), middle (12 and 24 h), and late (48 h) stages of Zn treatment. Among the 11 core structural enzyme-encoding genes involved in monolignols biosynthesis from phenylalanine in this pathway, the expression of eight of them was altered by Zn treatment. Additionally, genes encoding peroxidase (POD), which are responsible for the polymerization of monolignols into lignin, demonstrated extensive changes across all treatment stages, particularly at the late stage. The expression levels of these key enzyme genes were further validated using quantitative real-time PCR. Correspondingly, the activity of POD enzymes and the lignin content both significantly increased in Zn treated roots. These findings suggest that the phenylpropanoid–lignin metabolic pathway plays a crucial role in maize root responses to excessive Zn stress. Full article

Regulating chloroplast gene expression is crucial for maintaining chloroplast function and plant development. Pentatricopeptide repeat (PPR) proteins form a vast protein family that regulates organelle genes and has multiple functions during plant development. Here, we found that two P-type PPR proteins, YS1 (yellow-green seedling 1) and YS2, jointly regulated seedling development in rice. The loss of YS1 and YS2 exhibited the collapsed chloroplast thylakoids and decreased photosynthetic activity, leading to the yellowing and death of rice seedlings. YS1 and YS2 could directly bind to the transcript of the psbH-petB intergenic region to facilitate the splicing of petB intron, thereby affecting the splicing efficiency of petD, which is located downstream of petB in the five-cistronic transcription unit psbB-psbT-psbH-petB-petD. The mutations in YS1 and YS2 led to decreased mature transcripts of petB and petD after splicing, significantly reducing the protein levels of PetB and PetD. This further led to deficiencies in the cytochrome b6/f and photosystem I complexes of the electron transport chain (ETC), ultimately resulting in decreased ETC-produced NADPH and reduced contents of carbohydrates in ys mutants. Moreover, transcriptome sequencing analysis revealed that YS1 and YS2 were vital for chloroplast organization and carbohydrate metabolism, as well as chloroplast RNA processing. In previous studies, the mechanism of petB intron splicing in the five-cistronic transcription unit psbB-psbT-psbH-petB-petD of rice is unclear. Our study revealed that the two highly conserved proteins YS1 and YS2 were functionally redundant and played critical roles in photosynthesis and seedling development through their involvement in petB intron splicing to maintain chloroplast homeostasis in rice. This work broadened the perspective on PPR-mediated chloroplast development and laid a foundation for exploring the biofunctions of duplicated genes in higher plants. Full article

Tomato yellow leaf curl disease (TYLCD) significantly affects tomato yield. The jasmonic acid (JA) pathway is crucial in the defence response of plants; however, its role in plant resistance to TYLCD remains undefined. In production, CCC (chlorocholine chloride) is often used to cultivate strong seedlings to enhance seedling vitality and improve stress resistance. However, the mechanism through which CCC enhances disease resistance in tomatoes remains unclear. In this study, tomato seedlings were exogenously sprayed with 300 mg/L CCC before and after inoculation with tomato yellow leaf curl virus (TYLCV). The results indicated that no significant tomato yellow virus disease phenotype was observed in tomato seedlings after spraying with CCC and subsequent inoculation with the virus. Spraying CCC on seedlings inoculated with the virus and exhibiting typical phenotypes can significantly alleviate the yellowing and curling symptoms of new leaves and improve photosynthesis-related indicators in tomato plants. The detection of virus copy numbers within the plants revealed that the virus copy numbers in plants treated with CCC were significantly lower than those in the control group. Transcriptomic analysis revealed that, after spraying CCC, the key enzyme genes AOS2 and AOC in the JA synthesis pathway in tomatoes were significantly upregulated, whereas the expressions of JAZ2 and MYC2 genes, which negatively regulate JA synthesis, were significantly downregulated. In the stable state, JAZ proteins interact with MYC2 and inhibit its transcriptional activity of MYC2. Tomatoes overexpressing MYC2 and JAZ2 exhibit a significant decrease in TYLCD resistance. These results indicated that exogenous spraying CCC affected the expression of genes such as MYC2 and JAZ2, and then regulated JA pathway, increased the endogenous JA content in plants, and enhanced the disease resistance of tomato plants to TYLCD. This study provides a scientific reference for effectively preventing and controlling TYLCD in tomato production and reducing the influence of TYLCD on tomato yield and quality. Full article

Biostimulants play an active role in sustainable crop production. While biostimulants are thought to have long-term effects on plant growth, little research has been conducted to confirm this hypothesis. In this study, we investigated the long-term residual effects of biostimulants applied exclusively during the onion seedling stage on subsequent plant growth. Three onion cultivars (‘Carta Blanca’, ‘Don Victoro’, and ‘Sofire’) were evaluated with the application of nine microbial biostimulants (LALRISE Mycorrhizae, LALRISE Bacillus velezensis, Mighty Mycorrhizae, MycoApply, Spectrum, Spectrum DS, Spectrum Myco, Tribus Original, and Tribus Continuum), one seaweed extract (Kelpak), and two fertilizer types (conventional and organic fertilizer). Plant morphology and biomass were investigated during the early bulb stage of onion growth. Parameters such as plant height, neck diameter, bulb diameter, and the fresh and dry weights of the shoot, bulb, and root were measured. The results indicated significant cultivar-specific effects of microbial biostimulant and fertilizer type, as well as their interactions, on onion early bulb growth. While seaweed extract exhibited minimal residual impact, specific microbial biostimulants, such as Mighty Mycorrhizae and MycoApply, significantly enhanced bulb growth in the red onion ‘Sofire’. Tribus Continuum was found to increase bulb growth of the yellow onion ‘Don Victoro’. Positive effects of microbial biostimulants on onion growth were also observed with LALRISE Bacillus velezensis, Spectrum Myco, Spectrum, and LALRISE Mycorrizae. Furthermore, microbial biostimulants demonstrated more significant positive effects on onion growth when applied in conjunction with organic fertilizer. In conclusion, microbial biostimulants exhibited long-term positive effects on onion plant growth even when applied solely during the seedling stage prior to transplanting. However, these effects were significantly influenced by onion cultivar and fertilizer type, with the greatest benefits observed when combined with organic fertilizer. We recommend MycoApply and Mighty Mycorrhizae for growers seeking to enhance onion productivity, particularly in organic cultivation, as the two products enhanced bulb and leaf growth in ‘Sofire’ and ‘Don Victoro’. Full article

In an effort to enhance wheat’s resilience against rust diseases, our research explores the genetic underpinnings of resistance in a diverse collection of winter bread wheat accessions. Leaf rust (Puccinia triticina), yellow rust (Puccinia striiformis f. sp. tritici), and stem rust (Puccinia graminis f. sp. tritici) are significant threats to global wheat production. By leveraging host genetic resistance, we can improve disease management strategies. Our study evaluated 55 wheat accessions, including germplasm from Kazakhstan, from Uzbekistan, from Russia, from Kyrgyzstan, France, and CIMMYT under field conditions in southern Kazakhstan from 2022 to 2024. The results showed a robust resistance profile: 49.1% of accessions exhibited high to moderate resistance to leaf rust, 12.7% to yellow rust, and 30.9% to stem rust. Notably, ten accessions demonstrated resistance to multiple rust species, while seven showed resistance to two rusts. Twenty accessions were selected for further seedling resistance and molecular analysis. Three accessions proved resistant to six isolates of P. triticina, two to four isolates of P. striiformis, and four to five isolates of P. graminis. Although no genotypes were found to be universally resistant to all rust species at the seedling stage, two accessions—Bezostaya 100 (Russia) and KIZ 90 (Kazakhstan)—displayed consistent resistance to leaf and stem rust in both seedling and field evaluations. Molecular analysis revealed the presence of key resistance genes, including Lr1, Lr3, Lr26, Lr34, Yr9, Yr18, Sr31, Sr57, and the 1AL.1RS translocation. This work provides valuable insights into the genetic landscape of wheat rust resistance and contributes to the development of new wheat cultivars that can withstand these diseases, enhancing global food security. Full article

Bacillus thuringiensis (Bt) is widely recognized as the most important microbial pesticide controlling various insect pests and diseases due to its insecticidal crystal proteins (ICPs) and antimicrobial metabolites. The current study investigates the biocontrol potential of B. thuringiensis GBAC46 against the fungal pathogen Fusarium verticillioides and the insect pest Spodoptera frugiperda through multiple mechanisms. Phenotypic experiments revealed that GBAC46 effectively inhibited F. verticillioides growth by inducing reactive oxygen species (ROS) accumulation and showed enhanced larvicidal activity against second instar S. frugiperda larvae. Pot experiments showed that feeding by S. frugiperda enhanced F. verticillioides infection in maize. The Bt strain GBAC46 effectively controlled both pests and diseases in greenhouse maize seedlings. Applying the Bt strain GBAC46 reduced feeding damage from S. frugiperda, decreased leaf yellowing and wilting caused by F. verticillioides, and improved growth indicators such as plant height, fresh weight, and dry weight. RT-qPCR results revealed that the Bt strain GBAC46 induced key defense genes in maize involved in activating salicylic acid, jasmonic acid, and ethylene pathways. The overall study demonstrated and confirmed the GBAC46 strain as a promising microbial agent for disease and pest management. Full article

The devastating tristeza epidemic swept through South American citrus groves in the 1930s and subsequently spread to most citrus-growing regions worldwide, causing varying degrees of damage and prompting significant changes in citrus cultivation practices. The causal agent of the disease, citrus tristeza virus (CTV), belongs to the genus Closterovirus in the family Closteroviridae. CTV virions are approximately two microns long and possess the largest known positive-strand RNA genome in plants, spanning 19.3 kb. The history of tristeza disease and CTV’s molecular biology and taxonomic relationships have been extensively reviewed in the scientific literature. This paper primarily focuses on the author’s personal experiences with tristeza disease and its causal agent over the past six decades. The journey began during a period when biological indexing was the primary diagnostic tool. It later progressed through the isolation of purified CTV particles, which served as a practical diagnostic tool for CTV suppression efforts in Israel during the 1970s. However, biological indexing was first replaced by electron microscopy, followed by ELISA procedures; both were eventually abandoned after it was discovered that many ELISA-positive infections were caused by symptomless CTV isolates, even on trees grafted onto sour orange rootstocks. In retrospect, my work on CTV can be categorized into three main phases. It began with the biological phase, inherited from earlier generations of citrus virologists, followed by the isolation and partial characterization of CTV virions, and culminated in the genomic era. While we live in an age of remarkable biotechnological achievements, my recommendation for future CTV research is to integrate both biological and genomic approaches rather than viewing them as mutually exclusive. This is particularly important for economically significant pathogens such as CTV, which should be studied continuously as both biological agents and molecular pathogens. Full article

Salt stress, as a significant adverse consequence of global climate change, severely restricts the yield and quality of watermelon. In this study, salt-tolerant cultivar T23 and salt-sensitive cultivar B2 were subjected to a 200 mM NaCl treatment (0 h, 6 h, 24 h, 48 h, and 168 h) at the three-leaf stage, and the adaptation mechanisms of the watermelon roots to salt stress were systematically investigated at the phenotypic, physiological, and gene transcription levels. Phenotypic observations revealed that salt stress inhibited seedling growth, caused leaf curling, and induced root yellowing, with the damage being significantly more severe in B2 than in T23. Compared with B2, the activities of superoxide dismutase (SOD) were increased by −7.13%, 169.15%, 34.95%, 84.87%, and 39.87% under NaCl treatment at 0 h, 6 h, 24 h, 48 h, and 168 h, respectively. Compared to the 0 h NaCl treatment, the proline content in B2 increased by 4.25%, 14.39%, and 110.00% at 24 h, 48 h, and 168 h of NaCl treatment, respectively, while T23 showed increases of 93.74%, 177.55%, and 380.56% at the corresponding time points. The provided physiological data demonstrate that T23 exhibits superior antioxidant and osmoregulatory abilities relative to B2. The transcriptome analysis identified differentially expressed genes (DEGs) between the two cultivars under salt stress, with T23 showing the highest number of DEGs at 6 h, while B2 exhibited a significant increase in DEGs at 168 h. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that metabolic pathways such as plant hormone signal transduction, terpenoid biosynthesis, mitogen-activated protein kinase (MAPK) signaling pathways, transporter activity, and transcription regulator activity play important roles in the salt stress response. Furthermore, yeast overexpression experiments preliminarily validated the critical roles of the tonoplast dicarboxylate transporter gene ClCG01G010280 and the NAC transcription factor gene ClCG05G024110 in salt stress tolerance. This study provides new molecular insights into the salt tolerance mechanism of watermelon and offers potential genetic resources for breeding salt-tolerant varieties. Full article

Worldwide, the yellow-fleshed kiwifruit (Actinidia chinensis) is an important crop that possesses great economic significance due to its nutritional, medicinal and ornamental values. The call for the expansion of the kiwifruit industry in South Africa, due to rising local and international market demand, resulted in the introduction of new plant species in sub-mountainous areas, where soil and climate conditions are more suitable for intensive kiwifruit production than in lowland areas. Consequently, a need to develop suitable commercial protocols for mass propagation of A. chinensis emerged. This study introduces an optimized micropropagation protocol for A. chinensis, facilitating seed germination, seedling development and multiple shoot induction. For seed germination, the effect of cold stratification (CS) and gibberellic acid (GA₃) alone and in combination on in vitro germination of A. chinensis seeds was studied. Sterile seeds were stratified at 4 °C for 28 and 42 days. Batches of stratified and non-stratified (control) seeds were germinated on plant growth regulator-free Murashige and Skoog (MS) media and also on sterile filter paper bridges moistened with dH₂O and GA₃ concentrations of 500, 1000, 1500, 2000 and 2500 ppm. Seeds from the control and the CS treatments alone did not germinate on MS medium. However, on filter paper bridges, seeds cold stratified for 28 days yielded only a 20% germination percentage (GP), whereas CS for 42 days did not promote germination. A maximum GP of 64% and a mean germination time (MGT) of 27.52 days were achieved at a 2000 ppm GA₃ concentration. Cold stratification (28 days) followed by GA₃ treatments yielded an optimum GP of 80% and optimum MGT of 18.94 days at GA₃ concentrations of 500 ppm. In contrast, CS (42 days) followed by GA₃ yielded a maximum GP of 72% and MGT of 18.80 days at a GA₃ of 500 ppm. Conclusively, CS alone had little effect on germination, whereas CS (28 and 42 days) followed by GA₃ significantly (p ≤ 0.05) improved GP. Germinated seeds on moist filter paper can produce seedlings when sub-cultured on MS medium for seedling development. For multiple shoot induction, in vitro shoot culture of A. chinensis was carried out using apical and basal shoot explants from the above in vitro-produced seedlings. These explants were cultured on MS supplemented with 2.2 µM and 4.4 µM 6-Benzylaminopurine (BAP) for shoot multiplication. Axillary shoot proliferation was not observed on apical shoot explants after 4 weeks of culture on MS medium with 2.2 µM BAP. In contrast, the basal shoot explants produced 2–3 axillary shoots, tendrils and calluses at the base on the same medium. The highest number (3–4) of multiple shoots was attained from these basal shoot explants after subculture (10–12 weeks) in the same culture medium. In contrast, only elongation and rooting of apical shoot explants, without axillary shoot induction, occurred after the subculture. Regenerated plantlets derived from both apical and basal shoot explants were successfully acclimatised under a controlled environment at 24 ± 2 °C and 16 h photoperiod of 150–200 µmol m⁻² s⁻¹ light intensity. A similar response was observed for both types of explants of A. chinensis when cultured on MS with 4.4 µM BAP, although the higher concentration of BAP affected the morphological appearance of the regenerated plantlets that had shorter stems and smaller and narrower leaves compared to plantlets derived from 2.2 µM BAP. Full article