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<jats:p>Accurate estimation of fractional vegetation cover (FVC) is essential for crop growth monitoring. Currently, satellite remote sensing monitoring remains one of the most effective methods for the estimation of crop FVC. However, due to the significant difference in scale between the coarse resolution of satellite images and the scale of measurable data on the ground, there are significant uncertainties and errors in estimating crop FVC. Here, we adopt a Strategy of Upscaling-Downscaling operations for unmanned aerial systems (UAS) and satellite data collected during 2 growing seasons of winter wheat, respectively, using backpropagation neural networks (BPNN) as support to fully bridge this scale gap using highly accurate the UAS-derived FVC (FVC<jats:sub>UAS</jats:sub>) to obtain wheat accurate FVC. Through validation with an independent dataset, the BPNN model predicted FVC with an RMSE of 0.059, which is 11.9% to 25.3% lower than commonly used Long Short-Term Memory (LSTM), Random Forest Regression (RFR), and traditional Normalized Difference Vegetation Index-based method (NDVI-based) models. Moreover, all those models achieved improved estimation accuracy with the Strategy of Upscaling-Downscaling, as compared to only upscaling UAS data. Our results demonstrate that: (1) establishing a nonlinear relationship between FVC<jats:sub>UAS</jats:sub> and satellite data enables accurate estimation of FVC over larger regions, with the strong support of machine learning capabilities. (2) Employing the Strategy of Upscaling-Downscaling is an effective strategy that can improve the accuracy of FVC estimation, in the collaborative use of UAS and satellite data, especially in the boundary area of the wheat field. This has significant implications for accurate FVC estimation for winter wheat, providing a reference for the estimation of other surface parameters and the collaborative application of multisource data.</jats:p>

<jats:sec><jats:title>Introduction</jats:title><jats:p>Trans-grafting could be a strategy to transfer virus resistance from a transgenic rootstock to a wild type scion. However contradictory results have been obtained in herbaceous and woody plants. This work was intended to determine if the resistance to sharka could be transferred from transgenic plum rootstocks to wild-type apricot scions grafted onto them.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>To this end, we conducted grafting experiments of wild- type apricots onto plum plants transformed with a construction codifying a hairpin RNA designed to silence the PPV virus and studied if the resistance was transmitted from the rootstock to the scion.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Our data support that the RNA-silencing-based PPV resistance can be transmitted from PPV-resistant plum rootstocks to non-transgenic apricot scions and that its efficiency is augmented after successive growth cycles. PPV resistance conferred by the rootstocks was robust, already occurring within the same growing cycle and maintained in successive evaluation cycles. The RNA silencing mechanism reduces the relative accumulation of the virus progressively eliminating the virus from the wild type scions grafted on the transgenic resistant PPV plants. There was a preferential accumulation of the 24nt siRNAs in the scions grafted onto resistant rootstocks that was not found in the scions grafted on the susceptible rootstock. This matched with a significantly lower relative accumulation of hpRNA in the resistant rootstocks compared with the susceptible or the tolerant ones.</jats:p></jats:sec><jats:sec><jats:title>Discussion</jats:title><jats:p>Using transgenic rootstocks should mitigate public concerns about transgenes dispersion and eating transgenic food and allow conferring virus resistance to recalcitrant to transformation cultivars or species.</jats:p></jats:sec>

<jats:sec><jats:title>Introduction</jats:title><jats:p>C<jats:sub>4</jats:sub> photosynthesis is an adaptation that has independently evolved at least 66 times in angiosperms. C<jats:sub>4</jats:sub> plants, unlike their C<jats:sub>3</jats:sub> ancestral, have a carbon concentrating mechanism which suppresses photorespiration, often resulting in faster photosynthetic rates, higher yields, and enhanced water use efficiency. Moreover, the presence of C<jats:sub>4</jats:sub> photosynthesis greatly alters the relation between CO<jats:sub>2</jats:sub> assimilation and stomatal conductance. Previous papers have suggested that the adjustment involves a decrease in stomatal density. Here, we tested if C<jats:sub>4</jats:sub> species also have differing stomatal responses to environmental cues, to accommodate the modified CO<jats:sub>2</jats:sub> assimilation patterns compared to C<jats:sub>3</jats:sub> species.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>To test this hypothesis, stomatal responses to blue and red-light were analysed in three phylogenetically linked pairs of C3 and C4 species from the Cleomaceae (Gynandropsis and Tarenaya), Flaveria, and Alloteropsis, that use either C3 or C4 photosynthesis.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The results showed strongly decreased stomatal sensitivity to blue light in C<jats:sub>4</jats:sub> dicots, compared to their C<jats:sub>3</jats:sub> counterparts, which exhibited significant blue light responses. In contrast, in C<jats:sub>3</jats:sub> and C<jats:sub>4</jats:sub> subspecies of the monocot <jats:italic>A. semialata</jats:italic>, the blue light response was observed regardless of photosynthetic type. Further, the quantitative red-light response varied across species, but the presence or absence of a significant stomatal red-light response was not directly associated with differences in photosynthetic pathway. Interestingly, stomatal density and morphology patterns observed across the three comparisons were also not consistent with patterns commonly asserted for C<jats:sub>3</jats:sub> and C<jats:sub>4</jats:sub> species.</jats:p></jats:sec><jats:sec><jats:title>Discussion</jats:title><jats:p>The strongly diminished blue-light sensitivity of stomatal responses in C<jats:sub>4</jats:sub> species across two of the comparisons suggests a common C<jats:sub>4</jats:sub> feature that may have functional implications. Altogether, the strong prevalence of species-specific effects clearly emphasizes the importance of phylogenetic controls in comparisons between C<jats:sub>3</jats:sub> and C<jats:sub>4</jats:sub> photosynthetic pathways.</jats:p></jats:sec>

<jats:p>Cotton fiber quality-related traits, such as fiber length, fiber strength, and fiber elongation, are affected by complex mechanisms controlled by multiple genes. Determining the QTN-by-QTN interactions (QQIs) associated with fiber quality-related traits is therefore essential for accelerating the genetic enhancement of cotton breeding. In this study, a natural population of 1,245 upland cotton varieties with 1,122,352 SNPs was used for detecting the main-effect QTNs and QQIs using the 3V multi-locus random-SNP-effect mixed linear model (3VmrMLM) method. A total of 171 significant main-effect QTNs and 42 QQIs were detected, of which 22 were both main-effect QTNs and QQIs. Of the detected 42 QQIs, a total of 13 significant loci and 5 candidate genes were reported in previous studies. Among the three interaction types, the AD interaction type has a preference for the trait of FE. Additionally, the QQIs have a substantial impact on the enhancement predictability for fiber quality-related traits. The study of QQIs is crucial for elucidating the genetic mechanism of cotton fiber quality and enhancing breeding efficiency.</jats:p>

<jats:p>Shape is a primary determinant of consumer preference for many horticultural crops and it is also associated with many aspects of marketing, harvest mechanics, and postharvest handling. Perceptions of quality and preference often map to specific shapes of fruits, tubers, leaves, flowers, roots, and other plant organs. As a result, humans have greatly expanded the palette of shapes available for horticultural crops, in many cases creating a series of market classes where particular shapes predominate. Crop wild relatives possess organs shaped by natural selection, while domesticated species possess organs shaped by human desires. Selection for visually-pleasing shapes in vegetable crops resulted from a number of opportunistic factors, including modification of supernumerary cambia, allelic variation at loci that control fundamental processes such as cell division, cell elongation, transposon-mediated variation, and partitioning of photosynthate. Genes that control cell division patterning may be universal shape regulators in horticultural crops, influencing the form of fruits, tubers, and grains in disparate species. Crop wild relatives are often considered less relevant for modern breeding efforts when it comes to characteristics such as shape, however this view may be unnecessarily limiting. Useful allelic variation in wild species may not have been examined or exploited with respect to shape modifications, and newly emergent information on key genes and proteins may provide additional opportunities to regulate the form and contour of vegetable crops.</jats:p>

<jats:sec><jats:title>Introduction</jats:title><jats:p>The identification and localization of tea picking points is a prerequisite for achieving automatic picking of famous tea. However, due to the similarity in color between tea buds and young leaves and old leaves, it is difficult for the human eye to accurately identify them.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>To address the problem of segmentation, detection, and localization of tea picking points in the complex environment of mechanical picking of famous tea, this paper proposes a new model called the MDY7-3PTB model, which combines the high-precision segmentation capability of DeepLabv3+ and the rapid detection capability of YOLOv7. This model achieves the process of segmentation first, followed by detection and finally localization of tea buds, resulting in accurate identification of the tea bud picking point. This model replaced the DeepLabv3+ feature extraction network with the more lightweight MobileNetV2 network to improve the model computation speed. In addition, multiple attention mechanisms (CBAM) were fused into the feature extraction and ASPP modules to further optimize model performance. Moreover, to address the problem of class imbalance in the dataset, the Focal Loss function was used to correct data imbalance and improve segmentation, detection, and positioning accuracy.</jats:p></jats:sec><jats:sec><jats:title>Results and discussion</jats:title><jats:p>The MDY7-3PTB model achieved a mean intersection over union (mIoU) of 86.61%, a mean pixel accuracy (mPA) of 93.01%, and a mean recall (mRecall) of 91.78% on the tea bud segmentation dataset, which performed better than usual segmentation models such as PSPNet, Unet, and DeeplabV3+. In terms of tea bud picking point recognition and positioning, the model achieved a mean average precision (mAP) of 93.52%, a weighted average of precision and recall (F1 score) of 93.17%, a precision of 97.27%, and a recall of 89.41%. This model showed significant improvements in all aspects compared to existing mainstream YOLO series detection models, with strong versatility and robustness. This method eliminates the influence of the background and directly detects the tea bud picking points with almost no missed detections, providing accurate two-dimensional coordinates for the tea bud picking points, with a positioning precision of 96.41%. This provides a strong theoretical basis for future tea bud picking.</jats:p></jats:sec>

<jats:p>Photosynthetic electron transfer and its regulation processes take place on thylakoid membranes, and the thylakoid of vascular plants exhibits particularly intricate structure consisting of stacked grana and flat stroma lamellae. It is known that several membrane remodeling proteins contribute to maintain the thylakoid structure, and one putative example is FUZZY ONION LIKE (FZL). In this study, we re-evaluated the controversial function of FZL in thylakoid membrane remodeling and in photosynthesis. We investigated the sub-membrane localization of FZL and found that it is enriched on curved grana edges of thylakoid membranes, consistent with the previously proposed model that FZL mediates fusion of grana and stroma lamellae at the interfaces. The mature <jats:italic>fzl</jats:italic> thylakoid morphology characterized with the staggered and less connected grana seems to agree with this model as well. In the photosynthetic analysis, the <jats:italic>fzl</jats:italic> knockout mutants in <jats:italic>Arabidopsis</jats:italic> displayed reduced electron flow, likely resulting in higher oxidative levels of Photosystem I (PSI) and smaller proton motive force (pmf). However, nonphotochemical quenching (NPQ) of chlorophyll fluorescence was excessively enhanced considering the pmf levels in <jats:italic>fzl</jats:italic>, and we found that introducing <jats:italic>kea3-1</jats:italic> mutation, lowering pH in thylakoid lumen, synergistically reinforced the photosynthetic disorder in the <jats:italic>fzl</jats:italic> mutant background. We also showed that state transitions normally occurred in <jats:italic>fzl</jats:italic>, and that they were not involved in the photosynthetic disorders in <jats:italic>fzl</jats:italic>. We discuss the possible mechanisms by which the altered thylakoid morphology in <jats:italic>fzl</jats:italic> leads to the photosynthetic modifications.</jats:p>

<jats:p>The leaf scorching trait at flowering is a crucial thermosensitive phenotype in maize under high temperature stress (HS), yet the genetic basis of this trait remains poorly understood. In this study, we genotyped a 254 RIL-F<jats:sub>2:8</jats:sub> population, derived from the leaf scorch-free parental inbred line Abe2 and the leaf scorching maternal inbred line B73, using the specific-locus amplified fragment sequencing (SLAF-seq) method. A total of 10,112 polymorphic SLAF markers were developed, and a high-density genetic map with a total length of 1,475.88 cM was constructed. The average sequencing depth of the parents was 55.23X, and that of the progeny was 12.53X. Then, we identified a total of 16 QTLs associated with thermotolerant traits at flowering, of which four QTLs of leaf scorching damage (LS) were distributed on chromosomes 1 (<jats:italic>qLS1</jats:italic>), 2 (<jats:italic>qLS2.1</jats:italic>, <jats:italic>qLS2.2</jats:italic>) and 3 (<jats:italic>qLS3</jats:italic>), which could explain 19.73% of phenotypic variation. Combining one <jats:italic>qLS1</jats:italic> locus with QTL-seq results led to the identification of 6 candidate genes. Expression experiments and sequence variation indicated that <jats:italic>Zm00001d033328</jats:italic>, encoding N-acetyl-gamma-glutamyl-phosphate reductase, was the most likely candidate gene controlling thermotolerant traits at flowering. In summary, the high-density genetic map and genetic basis of thermotolerant traits lay a critical foundation for mapping other complex traits and identifying the genes associated with thermotolerant traits in maize.</jats:p>

<jats:p>Salt stress poses a significant challenge to crop productivity, and understanding the genetic basis of salt tolerance is paramount for breeding resilient soybean varieties. In this study, a soybean natural population was evaluated for salt tolerance during the germination stage, focusing on key germination traits, including germination rate (GR), germination energy (GE), and germination index (GI). It was seen that under salt stress, obvious inhibitions were found on these traits, with GR, GE, and GI diminishing by 32% to 54% when compared to normal conditions. These traits displayed a coefficient of variation (31.81% to 50.6%) and a substantial generalized heritability (63.87% to 86.48%). Through GWAS, a total of 1841 significant single-nucleotide polymorphisms (SNPs) were identified to be associated with these traits, distributed across chromosome 2, 5, 6, and 20. Leveraging these significant association loci, 12 candidate genes were identified to be associated with essential functions in coordinating cellular responses, regulating osmotic stress, mitigating oxidative stress, clearing reactive oxygen species (ROS), and facilitating heavy metal ion transport - all of which are pivotal for plant development and stress tolerance. To validate the candidate genes, quantitative real-time polymerase chain reaction (qRT-PCR) analysis was conducted, revealing three highly expressed genes <jats:italic>(Glyma.02G067700</jats:italic>, <jats:italic>Glyma.02G068900</jats:italic>, and <jats:italic>Glyma.02G070000)</jats:italic> that play pivotal roles in plant growth, development, and osmoregulation. In addition, based on these SNPs related with salt tolerance, KASP (Kompetitive Allele-Specific PCR)markers were successfully designed to genotype soybean accessions. These findings provide insight into the genetic base of soybean salt tolerance and candidate genes for enhancing soybean breeding programs in this study.</jats:p>

<jats:sec><jats:title>Introduction</jats:title><jats:p>Leptoids, the food-conducting cells of polytrichaceous mosses, share key structural features with sieve elements in tracheophytes, including an elongated shape with oblique end walls containing modified plasmodesmata or pores. In tracheophytes, callose is instrumental in developing the pores in sieve elements that enable efficient photoassimilate transport. Aside from a few studies using aniline blue fluorescence that yielded confusing results, little is known about callose in moss leptoids.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Callose location and abundance during the development of leptoid cell walls was investigated in the moss <jats:italic>Polytrichum</jats:italic> commune using aniline blue fluorescence and quantitative immunogold labeling (label density) in the transmission electron microscope. To evaluate changes during abiotic stress, callose abundance in leptoids of hydrated plants was compared to plants dried for 14 days under field conditions. A bioinformatic study to assess the evolution of callose within and across bryophytes was conducted using callose synthase (CalS) genes from 46 bryophytes (24 mosses, 15 liverworts, and 7 hornworts) and one representative each of five tracheophyte groups.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Callose abundance increases around plasmodesmata from meristematic cells to end walls in mature leptoids. Controlled drying resulted in a significant increase in label density around plasmodesmata and pores over counts in hydrated plants. Phylogenetic analysis of the CalS protein family recovered main clades (A, B, and C). Different from tracheophytes, where the greatest diversity of homologs is found in clade A, the majority of gene duplication in bryophytes is in clade B. </jats:p></jats:sec><jats:sec><jats:title>Discussion</jats:title><jats:p>This work identifies callose as a crucial cell wall polymer around plasmodesmata from their inception to functioning in leptoids, and during water stress similar to sieve elements of tracheophytes. Among bryophytes, mosses exhibit the greatest number of multiple duplication events, while only two duplications are revealed in hornwort and none in liverworts. The absence in bryophytes of the CalS 7 gene that is essential for sieve pore development in angiosperms, reveals that a different gene is responsible for synthesizing the callose associated with leptoids in mosses.</jats:p></jats:sec>