Thalamic gray matter volume mediates the association between KIBRA polymorphism and olfactory function among older adults: a population-based study.

The kidney and brain expressed protein (KIBRA) rs17070145 polymorphism is associated with both structure and activation of the olfactory cortex. However, no studies have thus far examined whether KIBRA can be linked with olfactory function and whether brain structure plays any role in the association. We addressed these questions in a population-based cross-sectional study among rural-dwelling older adults. This study included 1087 participants derived from the Multidomain Interventions to Delay Dementia and Disability in Rural China, who underwent the brain MRI scans in August 2018 to October 2020; of these, 1016 took the 16-item Sniffin' Sticks identification test and 634 (62.40%) were defined with olfactory impairment (OI). Data were analyzed using the voxel-based morphometry analysis and general linear, logistic, and structural equation models. The KIBRA rs17070145 C-allele (CC or CT vs. TT genotype) was significantly associated with greater gray matter volume (GMV) mainly in the bilateral orbitofrontal cortex and left thalamus (P < 0.05) and with the multi-adjusted odds ratio of 0.73 (95% confidence interval 0.56-0.95) for OI. The left thalamic GMV could mediate 8.08% of the KIBRA-olfaction association (P < 0.05). These data suggest that the KIBRA rs17070145 C-allele is associated with a reduced likelihood of OI among older adults, partly mediated through left thalamic GMV.

Enhanced Coprime Array Structure and DOA Estimation Algorithm for Coherent Sources.

This paper presents a new enhanced coprime array for direction of arrival (DOA) estimation. Coprime arrays are capable of estimating the DOA using coprime properties and outperforming uniform linear arrays. However, the associated algorithms are not directly applicable for estimating the DOA of coherent sources. To overcome this limitation, we propose an enhanced coprime array in this paper. By increasing the number of array sensors in the coprime array, it is feasible to enlarge the aperture of the array and these additional array sensors can be utilized to achieve spatial smoothing, thus enabling estimation of the DOA for coherent sources. Additionally, applying the spatial smoothing technique to the signal subspace, instead of the conventional spatial smoothing method, can further improve the ability to reduce noise interference and enhance the overall estimation result. Finally, DOA estimation is accomplished using the MUSIC algorithm. The simulation results demonstrate improved performance compared to traditional algorithms, confirming its feasibility.

Multimorbidity, cognitive phenotypes, and Alzheimer's disease plasma biomarkers in older adults: A population-based study.

INTRODUCTION: To examine the burden and clusters of multimorbidity in association with mild cognitive impairment (MCI), dementia, and Alzheimer's disease (AD)-related plasma biomarkers among older adults. METHODS: This population-based study included 5432 participants (age ≥60 years); of these, plasma amyloid beta (Aß), total tau, and neurofilament light chain (NfL) were measured in a subsample (n = 1412). We used hierarchical clustering to generate five multimorbidity clusters from 23 chronic diseases. We diagnosed dementia and MCI following international criteria. Data were analyzed using logistic and linear regression models. RESULTS: The number of chronic diseases was associated with dementia (multivariable-adjusted odds ratio = 1.22; 95% confidence interval [CI] = 1.11 to 1.33), AD (1.13; 1.01 to 1.26), vascular dementia (VaD) (1.44; 1.25 to 1.64), and non-amnestic MCI (1.25; 1.13 to 1.37). Metabolic cluster was associated with VaD and non-amnestic MCI, whereas degenerative ocular cluster was associated with AD (p < 0.05). The number of chronic diseases was associated with increased plasma Aß and NfL (p < 0.05). DISCUSSION: Multimorbidity burden and clusters are differentially associated with subtypes of dementia and MCI and AD-related plasma biomarkers in older adults. HIGHLIGHTS: We used hierarchical clustering to generate five clusters of multimorbidity. The presence and load of multimorbidity were associated with dementia and mild cognitive impairment. Multimorbidity clusters were differentially associated with subtypes of dementia and Alzheimer's disease plasma biomarkers.

Association of Accelerometer-Measured Sedentary Behavior Patterns With Nonalcoholic Fatty Liver Disease Among Older Adults: The MIND-China Study.

INTRODUCTION: The relationships between sedentary behavior patterns and nonalcoholic fatty liver disease (NAFLD) in older adults are not well investigated. METHODS: This population-based study included 1,899 rural-dwelling adults (aged 60 years or older). We assessed sedentary parameters with ActiGraph and defined NAFLD using ultrasonography. RESULTS: Long total and prolonged sedentary time were associated with increased likelihoods of NAFLD, whereas engaging more breaks per sedentary hour and reallocating sedentary time to light-intensity physical activity were associated with reduced likelihoods of NAFLD (P linear <0.05). DISCUSSION: Shorter sedentary time, engaging more frequent breaks in sedentary behavior, and replacing sedentary time with physical activity are associated with reduced likelihoods of NAFLD in older adults.

Secondary Amine-Mediated Domino Reaction for the Synthesis of Substituted Quinolines from Dicyanoalkenes and Enynals.

Substituted quinolines, tricyclic and tetracyclic molecules with a quinoline moiety are synthesized by a domino reaction from dicyanoalkenes and 3-aryl-pent-2-en-4-ynals in one pot. We established two methods: one is catalyzed by chiral diphenylprolinol silyl ether, and the other is catalyzed by di(2-ethyl)hexylamine, in combination with p-nitrophenol. A wide variety of dicyanoalkenes can be employed. As the catalysts are secondary amines, and water is the only by-product, this is an environmentally benign synthetic method for the preparation of substituted quinolines.

Objectively-measured movement behaviors, systemic low-grade inflammation, and plasma neurofilament light chain in older adults: a population-based study.

BACKGROUND: Evidence has linked self-reported sedentary behavior (SB) and physical activity (PA) with cognitive impairment; however, the underlying mechanisms are poorly understood. We examined the associations of the accelerometer-measured movement behaviors with plasma neurofilament light chain (NfL) among older adults and the role of systemic low-grade inflammation in the associations. RESULTS: This population-based study included 1,029 dementia-free older adults (age ≥ 60 years, range 60-88 years; 59.48% women) who undertook the ActiGraph substudy (March 2018-December 2020) in MIND-China. There were nonlinear relationships of daily SB and PA time with plasma NfL concentration, such that more daily SB time or less time spent in daily light-intensity physical activity (LPA) and moderate-to-vigorous-intensity physical activity (MVPA) was significantly associated with increased plasma NfL only when SB time ≥ 8.00 h/day or LPA time < 5.00 h/day or MVPA time < 2.00 h/day. Furthermore, more daily SB time or less daily LPA and MVPA time was significantly associated with higher serum low-grade inflammation score, a composite measure generated from serum IL-6, IL-8, TNF-α, and ICAM-1 (P < 0.05). Finally, low-grade inflammation score accounted for 14.5% to 17.8% of the associations between movement behaviors and plasma NfL. CONCLUSIONS: More daily SB and less PA time are associated with neurodegeneration and systemic low-grade inflammation in older adults. The association of movement behaviors with neurodegeneration is partially mediated by low-grade inflammation.

Genome-wide identification and characterization of AINTEGUMENTA-LIKE (AIL) family genes in apple (Malus domestica Borkh.).

AINTEGUMENTA-LIKE (AIL) genes play a key role in various growth and developmental processes in plants. Thus far, the genome-wide identification of AIL genes has been reported for some plant species. However, genome-wide identification of AIL genes has not been conducted in apple (Malus domestica Borkh.). The current study focused on a comprehensive analysis of the AIL genes in the apple genome (i.e., MdAIL genes). In total, 27 MdAIL genes in the apple genome were identified and then divided into four groups according to phylogenetic analysis. The chromosomal locations, gene and protein structures, and physicochemical characteristics of MdAIL genes were analyzed. Synteny analysis revealed that segmental duplication events played a major role in the expansion of the AIL gene family in apple. The analysis of cis-regulatory elements in MdAIL promoter regions indicated that most of the MdAIL genes are involved in embryo development and seed germination. Moreover, the analysis of tissue-specific expression patterns and transcript levels in adventitious bud regeneration indicated that MdAIL genes play an extensive regulatory role in apple growth and development, especially in the regulation of germination and adventitious bud regeneration from in vitro leaves of apple. In conclusion, this is the first genome-wide analysis of the AIL genes in apple. The current results may help in better understanding the evolution and function of MdAIL genes and thus facilitate further research on plant growth and development.

Anosmia, mild cognitive impairment, and biomarkers of brain aging in older adults.

Olfactory impairment is a potential marker for prodromal dementia, but the underlying mechanisms are poorly understood. This population-based study included 4214 dementia-free participants (age ≥65 years). Olfaction was assessed using the 16-item Sniffin' Sticks identification test. In the subsamples, we measured plasma amyloid beta (Aß)40, Aß42, total tau, and neurofilament light chain (NfL; n = 1054); and quantified hippocampal, entorhinal cortex, and white matter hyperintensity (WMH) volumes, and Alzheimer's disease (AD)-signature cortical thickness (n = 917). Data were analyzed with logistic and linear regression models. In the total sample, mild cognitive impairment (MCI) was diagnosed in 1102 persons (26.2%; amnestic MCI, n = 931; non-amnestic MCI, n = 171). Olfactory impairment was significantly associated with increased likelihoods of MCI, amnestic MCI, and non-amnestic MCI. In the subsamples, anosmia was significantly associated with higher plasma total tau and NfL concentrations, smaller hippocampal and entorhinal cortex volumes, and greater WMH volume, and marginally with lower AD-signature cortical thickness. These results suggest that cerebral neurodegenerative and microvascular lesions are common neuropathologies linking anosmia with MCI in older adults.

Nonalcoholic fatty liver disease, serum cytokines, and dementia among rural-dwelling older adults in China: A population-based study.

BACKGROUND AND PURPOSE: Little is known about whether nonalcoholic fatty liver disease (NAFLD) is associated with dementia or the role of serum proinflammatory cytokines in the association. We aimed to investigate the interrelationships of NAFLD, serum cytokines, and dementia among rural-dwelling older adults. METHODS: This population-based cross-sectional study included 5129 participants (aged ≥60 years; 61.79% women) who were living in rural communities and examined in March 2018-September 2018. NAFLD was defined through transabdominal ultrasound examination in the absence of hepatitis B or excessive alcohol consumption. Serum cytokines were measured in a subsample (n = 1686). Dementia, Alzheimer disease (AD), and vascular dementia (VaD) were diagnosed following international criteria. Data were analyzed with logistic regression and mediation models. RESULTS: Of the 5129 participants, 455 (8.87%) were detected with moderate-to-severe NAFLD, and 292 (5.69%) were diagnosed with dementia (188 with AD and 96 with VaD). The multivariable adjusted odds ratios associated with moderate-to-severe (vs. no-to-mild) NAFLD were 2.22 (95% confidence interval [CI] = 1.41-3.49) for all-cause dementia, 1.88 (95% CI = 1.01-3.50) for AD, and 2.62 (95% CI = 1.33-5.17) for VaD. In the cytokine subsample, controlling for multiple potential confounders, moderate-to-severe NAFLD was significantly associated with higher levels of serum monocyte chemotactic protein-1, interleukin-17A, interleukin-6 (IL-6), interleukin-8, and tumor necrosis factor-α (P < 0.05). The mediation analysis showed that IL-6 mediated 12.56% of the association between NAFLD and VaD. CONCLUSIONS: Moderate-to-severe nonalcoholic fatty liver disease is associated with dementia and AD, especially with VaD, among rural-dwelling Chinese older adults, in which the association with VaD is partly mediated by serum inflammatory cytokines.

Depth-based sparse bundle adjustment.

It is demonstrated in this paper that due to error model inconsistency, a certain degree of accuracy loss would be incurred to the estimated parameters when the traditional bundle adjustment method is directly applied to the scenario where a fraction of observations is implicitly error free (e.g., the reference image points in commonly used least squares matching refinement). To this end, a depth-based object point model and corresponding depth-based sparse bundle adjustment method are proposed in this paper, in which the position of an object point is represented by its 1D depth relative to its reference image. A corresponding projection model is derived, the sparse block structures of normal equations are studied depending on whether there are shared image parameters to be optimized or not, and corresponding sparse solutions of the normal equations and parameter covariance matrices are derived. Compared with the traditional sparse bundle adjustment method, simulated experiments demonstrate that our method matches the error model of the target scenario, and thus can avoid further accuracy loss. Moreover, both simulated and real data experiments demonstrate that our method can effectively improve computational efficiency.

Red cell distribution width, anemia, and lower-extremity physical function among rural-dwelling older adults.

BACKGROUND: Elevated red cell distribution width (RDW) has been associated with degenerative conditions in aging. AIMS: We aimed to evaluate the associations of RDW and anemia with lower-extremity physical function among rural-dwelling older adults. METHODS: This population-based cross-sectional study included 5093 rural residents (age ≥ 60 years, 57.3% women) who participated in the MIND-China Study in Shandong. Data were collected via face-to-face interviews, clinical examinations, and laboratory tests. RDW was categorized according to quartiles and the lower-extremity physical function was assessed using the Short Physical Performance Battery (SPPB), RESULTS: Multiple linear regression analyses suggested that the fourth quartile of RDW (vs. first quartile) was associated with lower SPPB summary score (ß-coefficient - 0.38; 95% CI - 0.58 to - 0.18) and lower scores in balance test (- 0.09; - 0.17 to - 0.01), chair stand test (- 0.17; - 0.27 to - 0.07), and walking speed test (- 0.12; - 0.19 to - 0.05). Anemia was associated with a multiple-adjusted ß-coefficient of - 0.34 (- 0.52 to - 0.16) for SPPB summary score. Stratified analysis by anemia showed that there was a linear association between RDW and SPPB in individuals without anemia but a J-shaped association in individuals with anemia. DISCUSSION: This large-scale population-based study revealed the associations of high RDW and anemia with poor lower-extremity physical function among rural-dwelling Chinese older adults. These findings suggest that an elevated RDW might be a biochemical marker for poor lower-extremity physical function among older adults. CONCLUSIONS: Anemia and an elevated RDW are associated with poor performance in lower-extremity physical function among rural-dwelling Chinese older adults.

Risk factors for inferior vena cava filter thrombosis in traumatic fracture patients with deep venous thrombosis of lower extremity: A single-center experience.

OBJECTIVE: To explore the risk factors for inferior vena cava filter (IVCF) thrombus in orthopedic trauma patients who underwent filter placement with ongoing anticoagulation in clinical settings. METHODS: We retrospectively analyzed clinical data from fracture patients with lower extremity acute deep vein thrombosis (DVT) implanted with an IVCF admitted to Tianjin Hospital from January 2017 to December 2019. Potential risk factors, such as gender, age, diabetes, hypertension, fracture sites, thrombus location, free-floating thrombus, filter type, Injury Severity Score (ISS), and postoperative D-dimer values, were analyzed by the Chi-square test, t-test, logistic regression, and receiver operating characteristic (ROC) curve analysis. RESULTS: A total of 662 patients were included in our study, and filter-related thrombosis was present in 67 (10.1%) patients. No significant differences were observed in age, gender, hypertension, diabetes, fracture site, free-floating thrombus, filter type, indwelling time, and postoperative D-dimer level. Thrombus location and ISS were significantly different (p < 0.05). Popliteal DVT (P-DVT) (odds ratio [OR]: 2.130, p = 0.018) and ISS (OR: 1.135, p = 0.000) were associated with filter thrombus. Patients with P-DVT were prone to a small filter thrombus (OR: 3.231, p = 0.037). From the ROC curve analysis, the diagnostic value of ISS was 24.5 and 26.5 for patients with filter and massive filter thrombus, respectively. CONCLUSION: Thrombus location and ISS were independent risk factors for filter thrombus in patients with traumatic fractures. P-DVT had a higher potential to result in a small filter thrombus and an ISS value >26.5, which was considered a significant massive filter thrombus predictor.

Accelerometer-assessed sedentary behaviour among Chinese rural older adults: Patterns and associations with physical function.

Sedentary behaviour is associated with a range of adverse health conditions. Population-based studies have rarely examined the distribution and associated factors of accelerometer-measured sedentary behaviour patterns in rural-dwelling older adults. This population-based study included 2096 rural-dwelling older adults (age ≥60 years; 59.0% women) derived from baseline participants of the MIND-China Study. Total sedentary time and patterns (e.g., uninterrupted bouts and breaks) were derived from the hip-worn accelerometers for 7 days. Physical function was assessed using the Short Physical Performance Battery test. Data were analysed using general linear models. Overall, participants spent 58.8% of daily waking time in sedentary behaviour, with nearly half of sedentary time being accumulated through sedentary bouts of 30+ minutes. Men spent more total and accumulated sedentary time than women in each sedentary bout duration, while women had more daily 1+ minute sedentary bouts than men (all P < 0.001). Controlling for moderate-to-vigorous physical activity and other confounders, more prolonged sedentary time and fewer breaks were significantly associated with poor physical function, balance, lower limb strength, and walking speed (all P < 0.001). In older adults living in rural communities, prolonged sedentary behaviour and less frequent breaks are associated with poor physical function.

Genome-Wide Identification, Classification, and Expression Analysis of the HD-Zip Transcription Factor Family in Apple (Malus domestica Borkh.).

Homeodomain-leucine zipper (HD-Zip) family genes are considered to play an important role in plant growth and stress tolerance. However, a genome-wide analysis of HD-Zip genes in apples (Malus domestica Borkh.) has not been performed. We detected 48 MdHDZ genes in the apple genome, and categorized them into three subfamilies on the basis of phylogenetic analysis. The chromosomal locations, gene/protein structures, and physiological and biochemical properties of these genes were analyzed. Synteny analysis revealed that segmental duplications were key in the expansion of the apple HD-Zip family. According to an analysis of cis-regulatory elements and tissue-specific expression patterns, MdHDZ genes may be widely involved in the regulation of apple growth and tolerance to environmental stresses. Furthermore, the transcript levels of apple HD-Zip I and II genes were up-regulated in response to fungal treatments. Expression of apple HD-Zip Ⅲ genes was enhanced during adventitious bud regeneration. This suggested possible roles of these genes in regulating the apple response to fungal infection, as well as adventitious bud regeneration. The current results may help us to better understand the evolution and function of apple HD-ZIP genes, and thus facilitate further research on plant resistance to fungal infection and in vitro regeneration.

Protective effect of miR-138-5p inhibition modified human mesenchymal stem cell on ovalbumin-induced allergic rhinitis and asthma syndrome.

The objective of the study is to evaluate the protective effects of human mesenchymal stem cells (hMSCs) modified with miR-138-5p inhibitor against the allergic rhinitis and asthma syndrome (ARAS). MiR-138-5p or negative control was transfected into hMSCs, and fluorescence-activated cell sorting was used to evaluate hMSC surface markers. Quantitative real-time PCR (qRT-PCR) was used to evaluate miR-138-5p, SIRT1, caspase-3, IL-6, IL-1ß and TNF-α levels after TNF-α and IL-6 stimulations. hMSCs with or without miR-138-5p inhibition was intranasally administered into ARAS mice (n = 10 each group), followed by monitoring sneezing and nasal rubbing events to evaluate the allergic symptoms. Histamine, ovalbumin-specific IgE, IgG2a, IgG1 and LTC4 release were monitored in the serum and nasal lavage fluid using enzyme-linked immunosorbent assay. Expression of SIRT1 and HMGB1/TLR4 pathway in nasal mucosa was assessed. After miR-138-5p inhibitor transfection, the hMSC lineage was preserved. Binding between SIRT1 and miR-138-4p was observed, and miR-138-5p inhibition led to upregulation of SIRT1. Inhibition of miR-138-5p led to attenuated inflammatory responses of hMSCs upon TNF-α and IL-6 stimulation, and allergic symptoms in mice, as well as histamine and ovalbumin-specific IgG release. hMSCs with miR-138-5p inhibition showed characteristics of activated SIRT1 and inhibited HMGB1/TLR4 pathway. Inhibition of miR-138-5p in hMSCs enhanced its effects in attenuating inflammatory responses and allergic reaction in the ARAS model, which is presumably regulated by SIRT1 and the HMGB1/TLR4 pathway.

Genome-wide identification of the histone acetyltransferase gene family in Triticum aestivum.

BACKGROUND: Histone acetylation is a ubiquitous and reversible post-translational modification in eukaryotes and prokaryotes that is co-regulated by histone acetyltransferase (HAT) and histone deacetylase (HDAC). HAT activity is important for the modification of chromatin structure in eukaryotic cells, affecting gene transcription and thereby playing a crucial regulatory role in plant development. Comprehensive analyses of HAT genes have been performed in Arabidopsis thaliana, Oryza sativa, barley, grapes, tomato, litchi and Zea mays, but comparable identification and analyses have not been conducted in wheat (Triticum aestivum). RESULTS: In this study, 31 TaHATs were identified and divided into six groups with conserved gene structures and motif compositions. Phylogenetic analysis was performed to predict functional similarities between Arabidopsis thaliana, Oryza sativa and Triticum aestivum HAT genes. The TaHATs appeared to be regulated by cis-acting elements such as LTR and TC-rich repeats. The qRT-PCR analysis showed that the TaHATs were differentially expressed in multiple tissues. The TaHATs in expression also responded to temperature changes, and were all significantly upregulated after being infected by barley streak mosaic virus (BSMV), Chinese wheat mosaic virus (CWMV) and wheat yellow mosaic virus (WYMV). CONCLUSIONS: These results suggest that TaHATs may have specific roles in the response to viral infection and provide a basis for further study of TaHAT functions in T. aestivum plant immunity.

Sex disparities in cardiovascular health metrics among rural-dwelling older adults in China: a population-based study.

BACKGROUND: Cardiovascular health (CVH) metrics among Chinese older adults are poorly understood. We investigated sex disparities in CVH metrics and their management among rural-dwelling older adults in China. METHODS: This community-based study included 5026 participants (age ≥ 65 years; 57.2% women) in the baseline survey of a multimodal intervention study in rural China. In March-September 2018, data were collected through face-to-face interviews, clinical examinations, and laboratory tests. We defined six CVH metrics (three behavioral factors-smoking, body mass index, and physical activity; three biological factors-blood pressure, total cholesterol, and blood glucose) following the modified American Heart Association's recommendations. We performed descriptive analysis separately for men and women. RESULTS: Of all participants, only 0.8% achieved ideal levels in all six CVH metrics. Men were more likely than women to have ideal levels in all CVH metrics but smoking. Women had higher prevalence of ideal global (9.7% vs. 7.8%) and behavioral (18.3% vs. 9.5%) CVH metrics (p < 0.001), whereas men had higher prevalence of ideal biological CVH metrics (5.4% vs. 3.5%, p < 0.001). The prevalence of ideal global and behavioral CVH metrics increased with age in both women and men (p for trend< 0.001). Women were more likely to be aware of their hypertension and diabetes, and to receive antihypertensive treatment, while men were more likely to achieve the goal of high cholesterol treatment (p < 0.05). CONCLUSIONS: The CVH metrics among older adults living in the rural communities in China are characterized by an extremely low proportion of optimal global CVH metrics and distinct sex differences, alongside poor management of major biological risk factors. TRIAL REGISTRATION: ChiCTR1800017758 (Aug 13, 2018).

Prevalence and associated factors of poor sleep quality among Chinese older adults living in a rural area: a population-based study.

OBJECTIVE: To investigate the prevalence and associated factors of poor sleep quality among community-dwelling elderly population in a rural area of Northern China. METHODS: We conducted a cross-sectional survey in August-December 2014 and recruited 2195 participants who were aged 65 years or older and living in Yanlou Town of Yanggu County in western Shandong Province, China. Data on demographics, health-related behaviors, and clinical conditions were collected through structured interviews. The Pittsburgh Sleep Quality Index (PSQI) was used to assess the sleep quality and patterns. Poor sleep quality was defined as a PSQI score > 7. We employed multiple logistic models to relate poor sleep quality to various factors. RESULTS: The overall prevalence rates of poor sleep quality were 33.8% in the total sample, 39.2% in women and 26.3% in men (P < 0.01). The most common abnormal sleep domains were prolonged sleep latency (39.7%), decreased sleep duration (31.0%), and reduced habitual sleep efficiency (28.8%). Multiple logistic regression analyses revealed that poor sleep quality was significantly associated with female sex (OR = 1.76, 95% CI 1.46-2.12) and clinical comorbidities such as hypertension (OR = 1.28, 95% CI 1.06-1.54), coronary heart disease (OR = 1.60, 95% CI 1.27-2.00), and chronic obstructive pulmonary disease (OR = 1.82, 95% CI 1.34-2.49). CONCLUSIONS: The sleep disorders were highly prevalent among the elderly in rural China. Modifiable risk factors such as cardiometabolic risk factors and disorders were associated with poor sleep quality, which might be potential targets for interventions to improve sleep quality in elderly population.

Major Latex Protein MdMLP423 Negatively Regulates Defense against Fungal Infections in Apple.

Major latex proteins (MLPs) play critical roles in plants defense and stress responses. However, the roles of MLPs from apple (Malus × domestica) have not been clearly identified. In this study, we focused on the biological role of MdMLP423, which had been previously characterized as a potential pathogenesis-related gene. Phylogenetic analysis and conserved domain analysis indicated that MdMLP423 is a protein with a 'Gly-rich loop' (GXGGXG) domain belonging to the Bet v_1 subfamily. Gene expression profiles showed that MdMLP423 is mainly expressed in flowers. In addition, the expression of MdMLP423 was significantly inhibited by Botryosphaeria berengeriana f. sp. piricola (BB) and Alternaria alternata apple pathotype (AAAP) infections. Apple calli overexpressing MdMLP423 had lower expression of resistance-related genes, and were more sensitive to infection with BB and AAAP compared with non-transgenic calli. RNA-seq analysis of MdMLP423-overexpressing calli and non-transgenic calli indicated that MdMLP423 regulated the expression of a number of differentially expressed genes (DEGs) and transcription factors, including genes involved in phytohormone signaling pathways, cell wall reinforcement, and genes encoding the defense-related proteins, AP2-EREBP, WRKY, MYB, NAC, Zinc finger protein, and ABI3. Taken together, our results demonstrate that MdMLP423 negatively regulates apple resistance to BB and AAAP infections by inhibiting the expression of defense- and stress-related genes and transcription factors.

An Integrated Transcriptome and Proteome Analysis Reveals New Insights into Russeting of Bagging and Non-Bagging "Golden Delicious" Apple.

Apple skin russeting naturally occurs in many varieties, particularly in "Golden Delicious" and its pedigree, and is regarded as a non-invasive physiological disorder partly caused by excessive deposition of lignin. However, the understanding of its molecular mechanism is still limited. In this study, we used iTRAQ (isobaric tags for relative and absolute quantitation) and RNA-seq to detect the changes in the expression levels of genes and proteins in three developmental stages of russeting formation, in russeted (non-bagging) and non-russeted (bagging) skin of "Golden Delicious" apple. 2856 differentially expressed genes and 942 differentially expressed proteins in the comparison groups were detected at the transcript level and protein level, respectively. A correlation analysis of the transcriptomics and proteomics data revealed that four genes (MD03G1059200, MD08G1009200, MD17G1092400, and MD17G1225100) involved in lignin biosynthesis are significant changed during apple russeting formation. Additionally, 92 transcription factors, including 4 LIM transcription factors, may be involved in apple russeting formation. Among them, one LIM transcription factor (MD15G1068200) was capable of binding to the PAL-box like (CCACTTGAGTAC) element, which indicated it was potentially involved in lignin biosynthesis. This study will provide further views on the molecular mechanisms controlling apple russeting formation.