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<jats:p>Planting spacing plays a key role in the root system architecture of the cotton group under local irrigation. This study used the Cellular Automata (CA) theory to establish a root visualization model for the cotton group at two different planting spacing (30 and 15 cm) within a leaching-pond. At a planting spacing of 30 cm, the lateral roots grew almost horizontally toward the irrigation point, and a logarithmic relationship was observed between root length density and soil water suction. However, at a planting spacing of 15 cm, the lateral roots exhibited overlapping growth and mainly competed for resources, and a power function relationship was observed between root length density and soil water suction. The main parameters of the visualization model for each treatment were essentially consistent with the experimental observations, with respective simulation errors were 6.03 and 15.04%. The findings suggest that the correlation between root length density and soil water suction in the cotton plants is a crucial driving force for the model, leading to a more accurate replication of the root structure development pathway. In conclusion, the root system exhibits a certain degree of self-similarity, which extends into the soil.</jats:p>

<jats:sec><jats:title>Introduction</jats:title><jats:p>Soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is an important disease affecting soybean yield in the world. Potential SCN-related QTLs and QTL-by-environment interactions (QEIs) have been used in SCN-resistant breeding.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>In this study, a compressed variance component mixed model, 3VmrMLM, in genome-wide association studies was used to detect QTLs and QEIs for resistance to SCN HG Type 0 and HG Type 1.2.3.5.7 in 156 different soybean cultivars materials.</jats:p></jats:sec><jats:sec><jats:title>Results and discussion</jats:title><jats:p>The results showed that 53 QTLs were detected in single environment analysis; 36 QTLs and 9 QEIs were detected in multi-environment analysis. Based on the statistical screening of the obtained QTLs, we obtained 10 novel QTLs and one QEI which were different from the previous studies. Based on previous studies, we identified 101 known genes around the significant/suggested QTLs and QEIs. Furthermore, used the transcriptome data of SCN-resistant (Dongnong L-10) and SCN-susceptible (Suinong 14) cultivars, 10 candidate genes related to SCN resistance were identified and verified by Quantitative real time polymerase chain reaction (qRT-PCR) analysis. Haplotype difference analysis showed that Glyma.03G005600 was associated with SCN HG Type 0 and HG Type 1.2.3.5.7 resistance and had a haplotype beneficial to multi-SCN-race resistance. These results provide a new idea for accelerating SCN disease resistance breeding.</jats:p></jats:sec>

<jats:p>Soil disinfection using high temperatures <jats:italic>via</jats:italic> steam is a promising approach to manage plant pathogens, pests, and weeds. Soil steaming is a viable option for growers who are moving away from dependence on chemical soil fumigants, especially in plant nursery or high tunnel environments. However, there are few studies that investigate how soil steaming causes substantial disturbance to the soil by killing both target pathogens and other soil biota. Steaming treatments also change the trajectory of the soil microbiome as it reassembles over time. Growers are interested in the health of soils after using steam-disinfection, especially if a virulent pathogen colonizes the soil and then flourishes in a situation where there are very few microbes to suppress its growth. Should recruitment of a virulent pathogen occur in the soil, this could have devasting effects on seed germination, seedling establishment and survival. Beneficial microbes are often used to prevent the colonization of plant pathogens, especially after a soil-steaming event. Here, we experimentally test how soil fungal communities assemble after steaming disinfection. We introduce to steam-treated soil <jats:italic>Fusarium solani</jats:italic>, an important fungal pathogen of soybean and <jats:italic>Trichoderma harzianum</jats:italic>, a known beneficial fungus used for soilborne pathogen suppression. Results show that <jats:italic>F. solani</jats:italic> significantly affects the relative abundance and diversity of the soil fungal microbiome, however, <jats:italic>T. harzianum</jats:italic> does not mitigate the amount of <jats:italic>F. solani</jats:italic> in the steam treated soil. Within the <jats:italic>T. harzianum</jats:italic> microbial addition, the soil fungal communities were similar to the control (steaming only). This result suggests inoculating the soil with <jats:italic>T. harzianum</jats:italic> does not drastically alter the assembly trajectory of the soil fungal microbiome. Other soil amendments such as a combination of <jats:italic>Trichoderma</jats:italic> spp. or other genera could suppress <jats:italic>F. solani</jats:italic> growth and shift soil microbiome composition and function post-steaming, however, more experimental research is needed.</jats:p>

<jats:p>The shade avoidance syndrome (SAS) is a collective adaptive response of plants under shade highlighted by characteristic phenotypes such as hypocotyl elongation, which is largely mediated by concerted actions of auxin and GA. We identified ATHB2, a homeodomain-leucine zipper (HD-Zip) domain transcription factor known to be rapidly induced under shade condition, as a positive regulator of GA biosynthesis necessary for the SAS by transactivating the expression of <jats:italic>GA20ox2</jats:italic>, a key gene in the GA biosynthesis pathway. Based on promoter deletion analysis, EMSA and ChIP assay, ATHB2 appears to regulate the <jats:italic>GA20ox2</jats:italic> expression as a direct binding target. We also found that the <jats:italic>GA20ox2</jats:italic> expression is under negative control by TCP13, the effect of which can be suppressed by presence of ATHB2. Considering a rapid induction kinetics of <jats:italic>ATHB2</jats:italic>, this relationship between ATHB2 and TCP13 may allow ATHB2 to play a shade-specific activator for <jats:italic>GA20ox</jats:italic> by derepressing a pre-existing activity of TCP13.</jats:p>

<jats:p>As one of the key enzymes in the biosynthesis of polyamines, S-adenosylmethionine decarboxylase (SAMDC) plays an important role in plant stress resistance. In this study, four <jats:italic>SAMDC</jats:italic> genes <jats:italic>(CsSAMDC1-4)</jats:italic> were identified in cucumber (<jats:italic>Cucumis sativus</jats:italic> L.) and divided into three groups (I, II, and III) by phylogenetic analysis. Motif analysis suggested the existence of many conserved motifs, which is compatible with SAMDC protein classification. Gene structure analysis revealed that <jats:italic>CsSAMDC2</jats:italic> and <jats:italic>CsSAMDC3</jats:italic> in group I have no intron, which showed a similar response to salt stress by gene expression analysis. <jats:italic>CsSAMDC3</jats:italic> responded differently to hormone and stress treatments, and was more susceptible to salt stress. Compared with wild-type (WT) tobacco, the activities of superoxide dismutase, peroxidase, and catalase were increased in <jats:italic>CsSAMDC3</jats:italic>-overexpressing tobacco under salt stress, but the content of electrolyte leakage, malondialdehyde, and hydrogen peroxide were decreased, which alleviated the inhibition of growth induced by salt stress. Under salt stress, overexpression of <jats:italic>CsSAMDC3</jats:italic> in transgenic tobacco plants exhibited salt tolerance, mainly in the form of a significant increase in dry and fresh weight, the maximal quantum yield of PSII photochemistry, the net photosynthetic rate and the content of spermidine and spermine, while the content of putrescine was reduced. In addition, the expression levels of antioxidase-related coding genes (<jats:italic>NtSOD</jats:italic>, <jats:italic>NtPOD</jats:italic>, <jats:italic>NtCAT</jats:italic>) and PAs metabolism-related coding genes (<jats:italic>NtSAMS</jats:italic>, <jats:italic>NtSPDS</jats:italic>, <jats:italic>NtSPMS</jats:italic>, <jats:italic>NtPAO</jats:italic>) in transgentic plants was lower than WT under salt stress, which suggested that overexpression of <jats:italic>CsSAMDC3</jats:italic> affected the expression of these genes. In summary, our results showed that <jats:italic>CsSAMDC3</jats:italic> could be used as a potential candidate gene to improve salt tolerance of cucumber by regulating polyamine and antioxidant metabolism.</jats:p>

<jats:p>Establishing an artificial grassland is a common measure employed to restore heavily degraded alpine grasslands for regional sustainability. The Three-River Headwaters Region in China has significant areas of black-soil-type grassland which is typified by heavy degradation; nearly 35% of the grassland regions in the Three-River Headwaters Region has degraded into this type. There are different plant community types of black-soil-type grasslands, however, it is not clear which restoration measures should be adopted for different kinds of black-soil-type grasslands. Here, we investigate the plant community characteristics and soil physicochemical properties of artificial grasslands, two types of black-soil-type grasslands, and native undegraded grassland in the Three-River Headwaters Region, then analyzed the direct and indirect interactions between the plant and soil properties by partial least squares path models (PLS-PM). Our results revealed that establishing artificial grassland significantly increased aboveground biomass and plant community coverage, and also decreased plant species richness and diversity and soil water content, soil organic carbon and total nitrogen in the 0-10 cm soil layer as compared with black-soil-type grasslands. Plant community diversity had a positive effect on plant community productivity, soil nutrient, and soil water content in native undegraded grassland. These results suggest that more management interventions are needed after establishing an artificial grassland, such as reducing dominant species in two types of black-soil-type grasslands, water regulation in the <jats:italic>A. frigida</jats:italic>-dominated meadow, diversifying plant species (i.e., Gramineae and sedges), and fertilizer addition.</jats:p>

<jats:p>Drought stress is one of the major limitations to the growth and yield productivity of cereal crops. It severely impairs the early growing and grain -filling stages of wheat. Therefore, cost- effective and eco-friendly approaches for alleviating drought stress in cereal crops are in high demand. Polyamines, such as putrescine, have a significant effect on improving crop yield under drought- stress conditions. Therefore, the current study was executed with the aim of exploring the significance of putrescine in alleviating drought stress and improving yield- related traits in wheat. Two distinct wheat cultivars (Fakhar-e-Bhakkar and Anaj-2017) were treated with the foliar application of different concentrations (control, 0.5, 1.0, and 1.5 PPM) of putrescine (put) under two moisture conditions (well- watered and terminal drought stress). The results demonstrate that the imposition of terminal drought stress significantly reduces different physiological and yield- related traits of both wheat cultivars. The reduction of relative water content (RWC%), membrane stability index (MSI), leaf area, tillers per plant, biomass yield, number of spikelets per spike, 100-grain weight, grain yield per plant, and straw yield was greater in Anaj-2017 than in Fakhar-e-Bhakkar cultivar. The results further explain that the foliar application of increased concentrations of putrescine from 0.0 to 1.0 PPM gradually improved physiological and yield traits, whereas these traits declined with the application of putrescine at the highest dose (1.5 PPM). The exogenous application of 1.0 PPM putrescine improved the relative water content (19.76%), specific leaf area (41.47%), and leaf area ratio (35.84%) compared with the controlled treatment. A higher grain yield (28.0 g plant<jats:sup>-1</jats:sup>) and 100-grain weight (3.8 g) were obtained with the foliar application of 1.0 PPM putrescine compared with controlled treatments. The findings of this study confirm the protective role of putrescine against terminal drought stress. It is therefore recommended to use putrescine at a concentration of 1.0 PPM, which could help alleviate terminal drought stress and attain better wheat yield.</jats:p>

<jats:p>Epidemics of leaf rust (caused by the fungal pathogen <jats:italic>Puccinia triticina</jats:italic> Erikss., <jats:italic>Pt</jats:italic>) raise concerns regarding sustainability of wheat production. Deployment of resistant cultivars is the most effective and economic strategy for combating this disease. Ofanto is a durum wheat cultivar that exhibits high resistance to <jats:italic>Pt</jats:italic> race PHT throughout its entire growing period. In the present study, we identified a leaf rust resistance gene in Ofanto and temporarily designated it as <jats:italic>LrOft</jats:italic>. <jats:italic>LrOft</jats:italic> was mapped to a 2.5 cM genetic interval in chromosome arm 6BL between Indel markers <jats:italic>6B6941</jats:italic> and <jats:italic>6B50L24</jats:italic>. During introgression of <jats:italic>LrOft</jats:italic> from Ofanto to common wheat it was observed that F<jats:sub>1</jats:sub> plants of Ofanto crossed with Shi4185 exhibited leaf rust resistance whereas the F<jats:sub>1</jats:sub> of Ofanto crossed with ND4503 was susceptible. In order to map the presumed suppressor locus, a Shi4185/ND4503//Ofanto three-way pentaploid population was generated and <jats:italic>SuLrOft</jats:italic> was mapped on chromosome arm 2AS. <jats:italic>SuLrOft</jats:italic> was mapped within a 2.6 cM genetic interval flanked by <jats:italic>2AS50L14</jats:italic> and <jats:italic>2AS50L6</jats:italic>. Fine mapping using 2,268 plants of the three-way cross narrowed the suppressor locus to a 68.2-kbp physical interval according to IWGSC RefSeq v1.1. Sequence analysis of genes in the physical interval revealed that <jats:italic>TraesCS2A02G110800</jats:italic> encoding an RPP-13-like protein with an NB-ARC domain was a potential candidate for <jats:italic>SuLrOft</jats:italic>.</jats:p>

<jats:sec><jats:title>Introduction</jats:title><jats:p>The Mediterranean basin is home to centuries-old large olive trees; high-vigor cultivars are widespread, with training forms poorly adapted to mechanical harvesting by trunk/branch shakers. The significant quantity of leaves, the considerable tree height, and the presence of multiple dichotomous hanging branches reduce the transmission of vibrations applied by the branch-shaker machines. Thus, re-shaping pruning may improve the performance of this modern mechanical harvesting method by focusing on removing both the hanging branches and those forming dichotomies. The goal of this study was to evaluate the dynamic responses of large-sized olive trees to pruning (or not) through various field tests under different excitation forces. We hypothesized that more rational pruning could significantly increase vibration transmissions.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>To assess the transmission of vibrations, tests were conducted before and after the pruning on representative trees. Tri-axial accelerometers packed in a small titanium housing were used. Trees were assessed before and after the re-shaping pruning. This study reports the first data about the dynamic behavior of centuries-old tree skeletons, in the context of very large-sized olive trees, while taking into account the effects of two different vibrations application modes: a realistic one represented by the system vibration head-tree, originated when the gripper of a shaking machine wrapped and fastened the main branch of the olive trees, and a more speculative one, represented by a single impulse of a short-duration force originated by a hammer.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>After pruning, spectral density increased 10 fold in the tertiary branches of pruned trees (ranging 1.0–10 m s<jats:sup>−2</jats:sup>) compared to that of not-pruned ones (ranging 0.1–1.0 m s<jats:sup>−2</jats:sup>) at frequency &amp;gt;50 Hz under vibration excitation. Moreover, vibrational decay times (120–150 ms) and amplitude (&amp;gt;10<jats:sup>−1</jats:sup> m s<jats:sup>−2</jats:sup>) were higher under single-impulse excitation.</jats:p></jats:sec><jats:sec><jats:title>Discussion</jats:title><jats:p>A more rational pruning applied to ancient large-sized olive trees significantly increased the vibration transmission under both impulse and vibratory excitation forces, without affected their typical “look”. Moreover, these insights are helpful in turn in achieving maximum fruit-removal efficiency. These insights could be applied to various horticultural conditions which would improve the economic sustainability of monumental olive trees, a key portion of the Mediterranean landscape and cultural heritage.</jats:p></jats:sec>

<jats:p>Cotton is widely grown in many countries around the world due to the huge economic value of the total natural fiber. Verticillium wilt, caused by the soil-borne pathogen <jats:italic>Verticillium dahliae</jats:italic>, is the most devastating disease that led to extensive yield losses and fiber quality reduction in cotton crops. Developing resistant cotton varieties through genetic engineering is an effective, economical, and durable strategy to control Verticillium wilt. However, there are few resistance gene resources in the currently planted cotton varieties, which has brought great challenges and difficulties for breeding through genetic engineering. Further revealing the molecular mechanism between <jats:italic>V. dahliae</jats:italic> and cotton interaction is crucial to discovering genes related to disease resistance. In this review, we elaborated on the pathogenic mechanism of <jats:italic>V. dahliae</jats:italic> and the resistance mechanism of cotton to Verticillium wilt. <jats:italic>V. dahliae</jats:italic> has evolved complex mechanisms to achieve pathogenicity in cotton, mainly including five aspects: (1) germination and growth of microsclerotia; (2) infection and successful colonization; (3) adaptation to the nutrient-deficient environment and competition of nutrients; (4) suppression and manipulation of cotton immune responses; (5) rapid reproduction and secretion of toxins. Cotton has evolved multiple physiological and biochemical responses to cope with <jats:italic>V. dahliae</jats:italic> infection, including modification of tissue structures, accumulation of antifungal substances, homeostasis of reactive oxygen species (ROS), induction of Ca<jats:sup>2+</jats:sup> signaling, the mitogen-activated protein kinase (MAPK) cascades, hormone signaling, and PAMPs/effectors-triggered immune response (PTI/ETI). This review will provide an important reference for the breeding of new cotton germplasm resistant to Verticillium wilt through genetic engineering.</jats:p>