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Soft rot of konjac ( Amorphophallus spp.) is a devastating disease caused by the bacterium Pectobacterium carotovorum subsp. carotovorum (Pcc) with serious adverse effects on plantation development, corm quality and crop yield due to the current lack of effective control measures. The main objective of the present study was to elucidate the mechanisms underlying plant resistance to soft rot disease. A combination of transcriptomic and metabolomic analyses demonstrated significant enrichment of differentially expressed genes (DEG) and differentially accumulated metabolites (DAM) associated with plant hormones, phenylpropanoid biosynthesis and, in particular, alkaloid metabolism, in Amorphophallus muelleri following Pcc infection compared with A. konjac , these data implicate alkaloid metabolism as the dominant mechanism underlying disease resistance of A. muelleri. Quantitative real-time polymerase chain reaction analysis further revealed involvement of PAL , CYP73A16 , CCOAOMT1 , RBOHD and CDPK20 genes in the response of konjac to Pcc. Analysis of the bacteriostatic activities of total alkaloid from A. muelleri validated the assumption that alkaloid metabolism positively regulates disease resistance of konjac. Our collective results provide a foundation for further research on the resistance mechanisms of konjac against soft rot disease.

Background and aims Digestive tract cancers, encompassing esophageal, stomach, colorectal cancers, account for about 20% of all cancer cases worldwide. This study seeks to examine the global epidemiological trends of these cancers in adolescents and young adults (AYA) from 1990 to 2021, as well as the related risk factors, to offer valuable insights for the formulation of health policies and the efficient distribution of public health resources. Methods Data from the Global Burden of Disease 2021 (GBD 2021) were utilized to conduct a comprehensive assessment of the global incidence, death, and disability-adjusted life years (DALYs) of digestive tract cancers within the AYA population. The correlation between cancer burden and socioeconomic development was examined by Socio-Demographic Index (SDI) regions. Use comparative risk assessment from GBD to evaluate risk factors for cancer deaths and DALYs. Assess incidence trends with BAPC model. Results The global burden of digestive tract cancer increased at different rates from 1990 to 2021. In 2021, colorectal cancer in AYA accounted for 70,201 incidences, 26,222 deaths, and 1,538,837 DALYs worldwide. In contrast, esophageal and stomach cancer had lower burdens in 8,164 and 42,039 incidences, respectively. While the incidence and death rates of esophageal and stomach cancers have declined, colorectal cancer have shown a significant increase in AYA. The age-standardized incidence rate (ASIR) of colorectal cancer correlates positively with SDI. In AYA, level 2 risk factors for colorectal cancer include alcohol use, dietary risks, high body mass index, high fasting plasma glucose, low physical activity, and tobacco. For esophageal cancer, the risk factors are alcohol use, dietary risks, and tobacco, and for stomach are dietary risks and tobacco. By 2040, the ASIR of the three digestive tract cancers in AYA will all decrease according to the BAPC model prediction. Conclusion The study of digestive tract cancers in AYA serves to identify risk factors within the realm of public health, facilitate the rational allocation of medical resources. Moreover, it can attend to the physical and mental health requirements of AYA individuals and enhance the cognitive framework regarding cancer.

Amorphophallus sp. is an economically important crop for rural revitalization in southwest China. However, Fusarium solani often infects Amorphophallus sp. corms during storage, damaging the corm quality and affecting leaf elongation and flowering in the subsequent crop. In this study, the mechanism of resistance to F. solani was investigated in the leaf bud and flower bud corms of Amorphophallus muelleri through transcriptome and metabolome analyses. A total of 42.52 Gb clean reads and 1,525 metabolites were detected in a total of 12 samples including 3 samples each of disease-free leaf bud corms (LC), leaf bud corms inoculated with F. solani for three days (LD), disease-free flower bud corms (FC), and flower bud corms inoculated with F. solani for three days (FD). Transcriptome, metabolome, and conjoint analyses showed that ‘MAPK signal transduction’, ‘plant-pathogen interaction’, ‘plant hormone signal transduction’, and other secondary metabolite biosynthesis pathways, including ‘phenylpropane biosynthesis’, ‘arachidonic acid metabolism’, ‘stilbene, diarylheptane and gingerolin biosynthesis’, and ‘isoquinoline alkaloids biosynthesis’, among others, were involved in the defense response of A. muelleri to F. solani . Ultimately, the expression of six genes of interest ( AmCDPK20 , AmRBOH , AmWRKY33 , Am4CL , Am POD and AmCYP73A1 ) was validated by real-time fluorescence quantitative polymerase chain reaction, and the results indicated that these genes were involved in the response of A. muelleri to F. solani . Ferulic acid inhibited the growth of F. solani , reducing the harm caused by F. solani to A. muelleri corms to a certain extent. Overall, this study lays a strong foundation for further investigation of the interaction between A. muelleri and F. solani , and provides a list of genes for the future breeding of F. solani -resistant A. muelleri cultivars.

The type and content of carbohydrates in konjac corms are an essential factors in determining the quality of konjac; however, the pattern of carbohydrate changes and the mechanism regulating the development of mother and daughter corms in the “relay growth” process of Amorphophallus muelleri remain unclear. This study aimed to investigate changes in corm carbohydrates during the growth cycle of A. muelleri and to compare the carbohydrate composition and the expression of related genes between mother and daughter corms. Integrated metabolome and RNA-seq analyses identified 37 differential metabolites as well as 8074 genes that were differentially expressed between mother and daughter corms, the majority of which were involved in starch and sucrose metabolism. More than 80% of the differential metabolites, including sucrose and starch, tended to accumulate in the mother corms; however, konjac glucomannan (KGM), as one of the most important carbohydrates and its major component of the corm, accumulated in higher amounts in the daughter corms. In addition, the expression of invertase and alpha-amylase that promote the breakdown of sucrose and starch was 351.78- and 15.63-fold higher, respectively, in the daughter corm, whereas that of the starch synthesis gene AkWAXY was only 0.096 times as high as in the mother corms. Furthermore, the level of cellulose synthase-like protein G, which promotes KGM synthesis, was 3.85 times higher in daughter corms compared to mother corms. Thus, we inferred that the daughter and mother corms had two distinct carbohydrate utilization strategies. This study provides insights into temporal changes in carbohydrates during the growth cycle of A. muelleri .

Amorphophallus muelleri has a multileaf growth pattern different from that of other konjacs; however, the hormonal mechanism underlying this phenomenon is not clear. In this study, the levels of hormones closely related to the sprouting of the axillary bud, including five types of cytokinins, indole-3-acetic acid (IAA) and abscisic acid (ABA) were measured. In the second leaf sprouting stage, the content of trans-zeatin riboside (tZR) in corms increased more than 5000-fold over that in the dormancy period. Surprisingly, although the expression of CYP735A1 and CYP735A2 , which synthesize the precursors for tZR was elevated at the second leaf sprouting stage, the expression of IPTs , which have key roles in cytokinin biosynthesis, did not change significantly. In addition, most cytokinin contents in leaves during the same period were significantly lower than those in corms. We speculate that the high cytokinin contents in the corms may not biosynthesized de novo in corms. In addition, the IAA content in the corms also considerably increased during the second leaf sprouting stage. Indole-3-acetaldehyde oxidase ( AO1 ) and auxin efflux carrier PIN1A , presented relatively high expression levels in the same period. In contrast, ABA content, and the expression of NCED1 , a rate-limiting enzyme in ABA biosynthesis, were suppressed at the second leaf sprouting stage. It is worth mentioning that N6-(Δ2-isopentenyl) adenosine (iP)-type cytokinins have a high content in corms in the dormant period that significantly decreases after the first leaf sprouting stage, which is completely different from the trend of tZR. By treating dormant corms with iP, the percentage of multibud plants increased, and the growth performance in terms of bud and root length was significantly higher than those of the control. This implies that iP-type cytokinins tend to play a role in promoting first seedling sprouting. Furthermore, there was a remarkable increase of the IAA content in both corms and roots under iP treatment but an inhibitory effect in buds. We speculate that the increase in the IAA content induced by iP is tissue specific. These results will assist in the understanding of the role of hormones, especially cytokinins, in the multileaf growth type of konjac.

[This corrects the article DOI: 10.3389/fpls.2024.1334996.].

To investigate the effect of nitrogen application and soil microbial activity on the decomposition process of stalk material in stalk composite pipes (SCPs) under subsurface irrigation with stalk composite pipes (SSI), in this study, a field experiment was conducted with two fertilization strategies—banding fertilization and SCP fertigation—at three nitrogen doses (126, 168, and 210 kg/ha), and the Biolog Ecoplate™ was employed to determine soil microbial activity. The results showed that under banding fertilization, the soil microbial activity at 20 cm subsoil and at the SCP wall increased with the increase in nitrogen dosage, ranging from 37.6% to 54.3% and from 21.5% to 23.7%, respectively. Under SCP fertigation, the soil microbial activity at 20 cm subsoil first showed a 58% surge, followed by a 3.9% decrease, with no significant variation in soil microbial activity at the SCP wall. Forty-five days later, the crude fiber content in the SCP wall under SCP fertigation was 17.6–26.3% lower than that under banding fertilization. Based on the comprehensive analysis of the soil microbial activity, SCP fertigation combined with high nitrogen application can accelerate the decay rate of straw in SCPs. This research can provide a reference for formulating irrigation and fertilization regimes for SSI.

Amorphophallus muelleri, a naturally occurring variant of the commercially valuable Amorphophallus species grown in Southeast Asia, stands out for its desirable traits: high konjac glucomannan (KGM) content, apomictic properties, and strong disease resistance. However, the mechanisms governing KGM maturation and biosynthesis within A. muelleri seeds remain poorly understood. Accordingly, wide-targeted metabolomics and RNA-seq were used in the present study to analyze differentially accumulated metabolites (DAMs) and differentially expressed genes (DEGs). Importantly, we sought to identify changes during A. muelleri seed maturation and KGM biosynthesis. Our findings indicated that DAMs associated with amino acids and secondary metabolites were elevated in mature seeds. Moreover, the expression of several genes was also upregulated, including those involved in flavonoid biosynthesis and plant hormone signal transduction pathways, specifically TPS5 , TPS6 , C4H ( CYP73A12 ), and key genes encoding auxin and abscisic acid (ABA) synthesis ( IAA10 , ARF11 , SAPK7 ). Our findings suggest that these genes play positive roles in regulating seed maturation. Additionally, seven genes encoding key enzymes involved in KGM biosynthesis were upregulated during the first two stages of seed maturation compared to the third stage of seed ripening. This indicates a potential correlation between KGM content and the expression of these genes at the post-transcript level. Finally, a strong correlation was identified between key DAMs and DEGs. Collectively, these results provide valuable insights for researchers seeking to understand the molecular mechanisms underlying A . muelleri seed maturation and KGM synthesis.

Sporobolus alterniflorus (S. alterniflorus) is a widespread invasive plant that poses significant threats to coastal wetland ecosystems and local economies worldwide. However, most existing management methods for S. alterniflorus are costly and provide only temporary relief due to reoccurrences and reinvasion. Additionally, limited attention has been paid to examining the application of invasion mechanisms in the design of management measures, hindering the development of effective strategies. In this paper, we reviewed the literature on the mechanisms and management of S. alterniflorus invasion. We identified the key factors enabling invasion mechanisms, analyzed how they are targeted in current control methods, and pointed out their implications for future research. We recommend that the invasion mechanisms of S. alterniflorus should be comprehensively considered during the design of management measures. Furthermore, future research on invasion mechanisms could focus on the joint effects and the relative roles of individual factors in successful invasion, the impact of S. alterniflorus invasion on the coupled human and natural systems, and the systematic review of studies at different scales.

Absolute phononic band gaps can be substantially improved in two-dimensional lattices by using a symmetry reduction approach. In this paper, the propagation of elastic waves in a two-dimensional hybrid triangular lattice structure consisting of stainless steel cylinders in air is investigated theoretically. The band structure is calculated with the plane wave expansion (PWE) method. The hybrid triangular Bravais lattice is formed by two kinds of triangular lattices. Different from ordinary triangular lattices, the band gap opens at low frequency (between the first and the second bands) regime because of lifting the bands degeneracy at high symmetry points of the Brillouin zone. The location and width of the band gaps can be tuned by the position of the additional rods.