Transcriptional repressor MdMYB6L is induced by heat stress and plays a negative regulatory role in apple skin colouration in low-altitude regions. Pericarp colour is a critical economic trait in apple, with the red colouration of apple skin in high-altitude regions being significantly more pronounced than that in low-altitude regions. However, the regulatory mechanisms governing anthocyanin accumulation in the apple pericarp in these regions have not been thoroughly explored. In this study, multiple MYB transcription factors were significantly downregulated in ‘Xiangfu’ apple fruit under high-altitude climate conditions compared to that in low-altitude regions. MdMYB6L exhibited an inverse expression pattern compared to MdANS, MdCHS, MdDFR, and MdUFGT. MdMYB6L functions as a nuclear-localised transcriptional repressor induced by heat stress. UV treatment and cold stress decreased its expression, with this effect becoming more pronounced when these stressors were alternated. Stable transformation in ‘Orin’ callus and apple fruit injections of MdMYB6L showed that MdMYB6L was a negative regulator of anthocyanin biosynthesis and inhibited the expression of the above four structural genes. Yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) assays demonstrated that MdMYB6L directly bound to the promoters of these genes, regulating their expression levels. Our findings indicate that MdMYB6L is the key regulator controlling apple skin colouration under the climate conditions of high- and low-altitude regions, providing a highly valuable candidate for application in breeding apple varieties with a higher nutritional value.

Abstract Apple stem grooving virus (ASGV) is one of the most significant pathogens infecting pome and stone fruit trees worldwide. The ASGV-encoded coat protein (CP) functions to encapsulate the viral genomic RNA and is essential for virus infection, while its genetic variation and pathogenicity remain largely unclear. Here, co-variation of the amino acids for ASGV CP and its implication have been analyzed. The results showed that, based on co-variation at amino acid positions 103 and 108, CP variants clustered into three groups, designated as types E103-A108, E103-E108, and Q103-E108. By using a potato virus X-based pathogenicity system, expression of CP (E103-A108)ASGV, CP (E103-E108)ASGV, and CP (Q103-E108)ASGV led to attenuated disease symptoms and lower virus accumulation of potato virus X (PVX). Notably, type CP (Q103-E108)ASGV exhibited lower virulence compared with the other two types. Transient expression assay in Nicotiana benthamiana plants demonstrated that the mutant type CP (Q103-E108)ASGV accumulated in a significantly higher level than the other two types. Especially, in vivo and cell-free degradation assays revealed that the mutation of E103 to Q103 enhances protein stability probably via facilitating its escape from ubiquitin–26S proteasome pathway-mediated degradation. Furthermore, ASGV CP has been demonstrated to possess activity of viral suppressor for RNA silencing (VSR). Taken together, these results provide insights into understanding of the multiple roles in aspects of genetic variation, pathogenicity of heterologous PVX, protein homeostasis, and VSR activity of ASGV CP.

Abstract Aluminum (Al) toxicity induced by soil acidification is a global environmental concern that threatens agricultural production and ecosystem health in acid-soil regions. To advance the breeding of Al-tolerant crops and support ecological restoration, this study aimed to elucidate the molecular mechanism underlying Al tolerance in apple (Malus domestica). Through molecular cloning, genetic transformation, and protein-DNA interaction assays, we identified an Al-responsive MADS-box gene, MdAGL42, and its upstream regulator, the C2H2-type zinc finger transcription factor MdZAT5. Overexpression of MdAGL42 significantly enhanced Al tolerance, while reducing the accumulation of reactive oxygen species (ROS), malondialdehyde (MDA), and Al3+ under Al stress. Furthermore, we demonstrated that MdZAT5 transcriptionally activates both MdAGL42 and MdCSD1 (Cu/Zn superoxide dismutase 1), thereby forming a synergistic regulatory network. Our findings reveal, for the first time, the molecular basis of the MdZAT5-MdAGL42 transcriptional regulatory module in conferring Al tolerance. This study provides crucial genetic resources for molecular breeding of Al-tolerant Rosaceae crops and contributes to strategies for ecological restoration and sustainable agriculture in acidified regions.

Zinc (Zn) is an essential plant micronutrient, but excessive soil Zn causes toxicity, inhibiting growth and reducing crop yields. Elucidating plant adaptation mechanisms to Zn stress is critical for improving performance in Zn-rich environments. While multiple genes/proteins regulating plant Zn homeostasis are known, proteins with unknown domains (e.g., the DUF506 family) remain functionally unclear. This study explored the role of MdDUF506 in apple (Malus domestica) responses to Zn stress. Results showed that MdDUF506 overexpression altered the expression of heavy metal stress-related genes. Under Zn stress, MdDUF506-overexpressing apple plants had 32% lower hydrogen peroxide (H2O2) and 21% lower superoxide anion (O2 -) content than wild-type (WT) plants. This reduction in reactive oxygen species (ROS) improved growth and significantly enhanced Zn tolerance in both apple plants and their callus. Additionally, upregulated CAT, POD, and SOD in MdDUF506-overexpressing plants may increase ROS-clearing enzyme activity, aiding adaptation to adverse environments. In summary, MdDUF506 may positively regulate apple Zn stress responses by modulating ROS-related gene expression, and its overexpression confers excellent Zn tolerance. This study clarifies DUF506 family function and provides a potential target for improving Zn stress resistance in woody fruit crops.

Nitrogen (N) is the most important nutrient for plant growth and development. However, the mechanisms by which the form and supply of N regulate the growth and N utilization of cherry rootstock are unclear at present. We investigated the effects of different N supply levels and N forms on the growth, N uptake, assimilation and distribution, and photosynthetic N use efficiency (PNUE) of Gisela 6 cherry rootstock seedlings. The results showed that a high N level and a single supply of either nitrate N or ammonium N hindered N uptake and assimilation, increased photosynthetic limitation, reduced PNUE and 15N use efficiency, and inhibited cherry rootstock growth. Further experiments showed that a mixed supply of nitrate N and ammonium N maintained high transcription levels of nitrate and ammonium transporters as well as N metabolism enzyme activities, thereby increasing the net inflow rates of NO3− and NH4+ into roots and the soluble protein content of leaves. In addition, a mixed N supply reduced oxidative damage to leaves by maintaining an appropriate nitrate/ammonium ratio, increased the proportion of leaf N allocated to photosynthetic N, decreased leaf cell wall thickness, and enhanced stomatal conductance, mesophyll conductance, and the maximum carboxylation efficiency. This resulted in reduced leaf photosynthetic limitation, increased leaf net photosynthetic rate and PNUE, and ultimately enhanced the growth of Gisela 6 cherry rootstock seedlings. Our results provide a basis for optimizing N management strategies in cherry cultivation.

Yanjinyu is a mid ripe apple variety bred through a cross between Honglu and Guanghui made in 2008 in Yantai Agricultural Science Research Institute of Shandong Province, China. It was initially selected due to its bright yellow surface and good quality of the fruit. After six years of continuous observation, it was finally selected in 2020 and registered as a non major crop variety by the Ministry of Agriculture and Rural Affairs in 2024. The Yanjinyu tree was vigrous, with a wide open posture, high bud burst rate, and moderate branching ability. One year old branches were gray brown in color. The leaves were dark green. The leaf edge was sharply serrated. The flower bud was red, the petal was oblong and separated in relative positions. In Yantai area, the initial flowering period of Yanjinyu was mid April, the peak flowering period was from 17 to 19, April, and the fruit development period was about 130 days. The fruit was elliptical in shape. The fruit shape index was 0.95, and the average single fruit weight was 211.2 g; The fruit surface was smooth and rust free with bright yellow color. The flesh was light yellow, crispy, juicyand, aromatic. The aftertaste was sweet; The peel hardness of the fruit was 9.8 kg·cm-2, the soluble solids content was 14.8%, the titratable acid content was 0.22%, and the vitamin C content was 3.1 mg·100 g-1. The quality was excellent. Yanjinyu was susceptible to branch ring spot disease and rot disease, moderately resistant to apple glomerella leaf spot and rust diseases, highly resistant to winter cold, and moderately resistant to frost during flowering period. The shelf life of the fruit was 10-15 days. The fruits could be stored in cold store for 2 months. The variety could be suitable for free bagging cultivation. Intensive cultivation with dwarf rootstock should be recommended.

The photosynthetic nitrogen (N) use efficiency (PNUE) of apple leaves varies under different calcium (Ca) levels, but the underlying physiological mechanism remains unclear. This study systematically elucidated the synergistic regulatory mechanisms of Ca levels on N uptake, allocation, and photosynthetic performance in apple rootstock by integrating a leaf photosynthetic N allocation model, photosynthetic limiting factor analysis, and microstructural observations. Ca stress (low Ca: 0.1 mM Ca2+; high Ca: 15 mM Ca2+) significantly suppressed nitrate transporter gene (NRT) expression and reduced the net NO3− influx rate of root surfaces, thereby hindering N uptake and translocation to shoots. Low Ca treatment increased stomatal and biochemical limitations by inducing stomatal closure and reducing the maximum carboxylation rate (Vₘₐₓ). By contrast, high Ca treatment increased mesophyll conductance limitation by increasing cell wall thickness, leaf thickness, and leaf Ca oxalate content, and by decreasing Ca and N availability. Both low and high Ca treatments disrupted leaf N allocation, characterized by increased proportions of non-protein and storage N and decreased allocation to photosynthetic N components, such as carboxylate system N and electron transport N. Together, these changes reduced the leaf PNUE. By contrast, optimal Ca treatment (5 mM Ca2+) significantly improved the leaf net photosynthetic rate and PNUE by optimising photosynthetic N allocation, improving leaf structural integrity and reducing starch grain accumulation. This study provides a theoretical basis for precise Ca management in apple orchards.

As soil acidification occurs due to industrial and agricultural production processes, it can induce the release of rhizotoxic aluminium ions (Al3+) into the soil, ultimately causing aluminium (Al) stress. Excessive Al content in soil exhibits significant phytotoxicity, inhibiting the growth of roots and stems. In this study, we conducted an investigation into the Al stress tolerance of two apple rootstocks, namely 'YZ3' and 'YZ6', and discovered that 'YZ3' exhibited a superior ability to alleviate the inhibitory effects of Al stress on plant growth. By comparing the transcriptomes of two rootstocks, a differentially expressed gene, MdDUF506, containing an unknown functional (DUF) domain, was identified. Overexpression of MdDUF506 in apple and calli enhances the ability to scavenge reactive oxygen species (ROS), subsequently mitigating the oxidative damage induced by Al stress on plant growth and development. Furthermore, MdDUF506 regulates Al stress tolerance by modulating the expression of genes related to Al stress (MdSTOP1, MdRSL1, MdRSL4, MdGL2, and MdRAE1). MdDUF506 interacts with MdCNR8, positively regulating Al stress tolerance. Taken together, these discoveries offer crucial candidate genes for targeted breeding as well as fresh insights into resistance to Al stress.

The red flesh coloration of apples is a result of a biochemical pathway involved in the biosynthesis of anthocyanins and anthocyanidins. Based on apple genome analysis, a high number of regulatory genes, mainly transcription factors such as MYB, which are components of regulatory complex MYB-bHLH-WD40, and several structural genes (PAL, 4CL, CHS, CHI, F3H, DFR, ANS, UFGT) involved in anthocyanin biosynthesis, have been identified. In this study, we investigated novel genes related to the red-flesh apple phenotype. These genes could be deemed molecular markers for the early selection of new apple cultivars. Based on a comparative transcriptome analysis of apples with different fruit-flesh coloration, we successfully identified and characterized ten potential genes from the plant hormone transduction pathway of auxin (GH3); cytokinins (B-ARR); gibberellins (DELLA); abscisic acid (SnRK2 and ABF); brassinosteroids (BRI1, BZR1 and TCH4); jasmonic acid (MYC2); and salicylic acid (NPR1). An analysis of expression profiles was performed in immature and ripe fruits of red-fleshed cultivars. We have uncovered genes mediating the regulation of abscisic acid, salicylic acid, cytokinin, and jasmonic acid signaling and described their role in anthocyanin biosynthesis, accumulation, and degradation. The presented results underline the relationship between genes from the hormone signal transduction pathway and UFGT genes, which are directly responsible for anthocyanin color transformation as well as anthocyanin accumulation during apple-fruit ripening.

ABSCISIC ACID-INSENSITIVE5 (ABI5) is a core regulatory factor that mediates the ABA signaling response and leaf senescence. However, the molecular mechanism underlying the synergistic regulation of leaf senescence by ABI5 with interacting partners and the homeostasis of ABI5 in the ABA signaling response remain to be further investigated. In this study, we found that the accelerated effect of MdABI5 on leaf senescence is partly dependent on MdbHLH93, an activator of leaf senescence in apple. MdABI5 directly interacted with MdbHLH93 and improved the transcriptional activation of the senescence-associated gene MdSAG18 by MdbHLH93. MdPUB23, a U-box E3 ubiquitin ligase, physically interacted with MdABI5 and delayed ABA-triggered leaf senescence. Genetic and biochemical analyses suggest that MdPUB23 inhibited MdABI5-promoted leaf premature senescence by targeting MdABI5 for ubiquitin-dependent degradation. In conclusion, our results verify that MdABI5 accelerates leaf senescence through the MdABI5-MdbHLH93-MdSAG18 regulatory module, and MdPUB23 is responsible for the dynamic regulation of ABA-triggered leaf senescence by modulating the homeostasis of MdABI5.

以蓬莱地区神富1号苹果为试材,在不同时期增施矿源腐殖酸钾和硝酸铵钙,探索其对苹果果实着色、品质和产量的影响.结果表明,增施矿源腐殖酸钾提高了苹果果实可溶性固形物、还原糖、Vc和总黄酮含量,促进了果皮着色和果皮花青苷的积累,提高了果树产量,能有效防控果实苦痘病.

优良品种是产业发展的基础,1871年传教士将西洋苹果(大苹果)引入我国,开启我国大苹果种植的新纪元,烟台也被称为我国现代苹果的发源地.在150余年现代苹果发展历史中,每一次产业升级都是由品种更新换代所带动.烟台农业科研及推广机构、果业企业持续进行苹果品种更新,引进、选育、推广特色苹果新品种,在新品种带动产业发展、果农致富、城市影响力提升等方面做出了诸多的探索,切实带动了烟台苹果产业的发展,提升了烟台苹果产业的社会影响力,连续十四年稳居中国果品区域公用品牌价值榜首位.

烟台市农业科学研究院与保加利亚农业研究所联合开展黄绿色苹果新品种选育研究,从Prima、Florina、Sumerred等品种的杂交组合中筛选出8个黄绿色新品系,以MM106自根砧繁育苗木进行鉴定评价.结果表明:8个优系的初花期最早在4月13日,最晚在4月25日.其中优选3号、4号、5号为早熟品种,优选6号、8号为中熟品种,优选1号、2号、7号属于中晚熟品种.从果实品质分析结果表明,优选5号的平均单果重最大,为227 g,优选2号的最小,为113 g;优选2号的果形指数最高,为0.89,优选6号的最低,为0.80;优选8号的果肉硬度最大,为10.3 kg/cm2,优选6号的果肉硬度最小,为5.8 kg/cm2.优选7号的果实可溶性固形物和总糖含量均为最高分别是17.5％和8.9％,可滴定酸含量最低,为0.12％,糖酸比高达74.2,优选5号的可溶性固形物和总糖含量均为最低,分别为13.1％和7.0％,优选6号的可滴定酸含量最高,为0.53％,糖酸比最低,仅为14.9;优选1号的平均单株产量最高,为33.0 kg/株,优选2号的最低,为16.6 kg/株.

苹果产业是烟台农业优势特色产业,也是果农增收、乡村振兴的支柱产业产业.烟台苹果150余年的发展历史,经历了青香蕉、红香蕉、小国光、普通红富士、烟富系列优系红富士以及目前的红黄绿多样化品种发展,每一代品种的更新,都需要优质的种苗为基础,我市果业科研机构和种苗企业,持续进行种苗繁育技术创新,带动了全市苹果种苗产业的发展,我市繁育的苹果种苗在全国种苗市场占有率达60％以上,成为我国最大的苹果种苗培育基地,获批农业农村部国家区域性苹果苗木繁育基地.本文系统分析了我市苹果种苗繁育发展历史、现状、育苗技术进展,以期为烟台苹果种苗产业可持续发展提供参考.

Based on the survey records of Tang Quansheng, a modern scholar in China, and combined with the modern literature, this article verified the names and pedigree sources of 18 western apple varieties that have been introduced to Yantai by the American missionary, John Livingston Nevius since 1871. The growth potential, branches, leaves, adaptability, resistance, fruit and storage tolerance of the trees were briefly described, and the characteristics of these western apple varieties were basically reflected. The reasons for the successful introduction and the protection of apple germplasm resources, to some extent, were analyzed.

烟香翠为晚熟黄绿色苹果新品种,是2003年从韩国引进的中熟苹果品种红露的实生后代,果实生育期为162～168 d.该品种果实近圆形,果个较轻,平均单果质量118.3 g,成熟时果皮呈黄绿色,表面光滑,果肉黄白色,去皮硬度9.0 kg·cm-2,口感脆甜、肉质细腻,可溶性固形物含量(w,后同)为17.50%,可滴定酸含量为0.28%,可溶性糖含量为13.85%,维生素C含量为23.50 mg∙kg-1.适应性强、丰产性好、适宜免套袋栽培,山东、新疆、云南等苹果适栽区均可栽培,盛果期每公顷产量2.28 t.

The AP2/ERF (APETALA2/Ethylene−Responsive element binding factor) family genes play crucial roles in plant growth and development, and responses to environmental factors; however, this family has not been characterized in Diospyros species. In Diospyros, the diploid Oily persimmon (D. oleifera, 2n = 2x = 30) has been released with complete genome assembly, which makes it possible for genome-wide gene family identification and exploration of molecular function in cultivated persimmon (D. kaki, 2n = 6x = 90). Here, we identified the AP2/ERF family in Oily persimmon for the first time and investigated its classification, main physicochemical properties, structural characteristic, chromosome distribution, gene replication and collinearity, cis-factor binding sites deduction, GO term annotation, and PPI interaction, as well as its expression profiles in different tissue and under the treatment of polyamines. A total of 157 AP2/ERF genes, including four subfamilies (AP2, RAV, Soloist, and ERF), were identified with distribution on all 15 chromosomes. DkAP2/ERF gene expression patterns were extensive and diverse. They were detected expression in every examined tissue, with the highest number of DkAP2/ERF genes expressed in the root. DkAP2/ERF gene expression analysis in adventitious root generation and elongation of polyamines showed their different responses to the action of polyamines, and more pairs of DkAP2/ERF genes with high correlation in gene expression were obtained. In addition, some DkAP2/ERF genes were detected remarkably correlated with genes related to polyamine synthesis and cell metabolism, including S-adenosyl-L-methionine Decarboxyla2 (SAMDC2), D-type cyclin1 (CYCD1), and D-type cyclin2 (CYCD2) genes,. indicating that DkAP2/ERF genes may play a synergistic role in adventitious root development This study was the first to analyze the AP2/ERF gene comprehensively in Diospyros on a genome−wide scale and will provide insights into the application of adventitious root formation in cultivated persimmon.

[目的]苹果花脸病主要由苹果锈果类病毒(apple scar skin viroid,ASSVd)引起,是一种严重危害苹果产量和果实品质的病害,通过分析苹果花脸症状相关基因表达,探索花脸症状形成的潜在机制.[方法]削取无症状且无ASS-Vd侵染的果皮和表现花脸症状的弘前富士苹果果皮,提取果皮总RNA,通过高通量测序并进行转录组数据分析.[结果]利用RT-PCR方法从表现花脸症状的苹果果皮中得到两条ASSVd序列,其基因组长度分别为331 nt和330 nt,与已公布的ASSVd山东烟台苹果分离物SDYT-1(MW302328.1)和SDYT-3(MW315909.1)完全一致.转录组测序结果表明,与无症状果皮相比,表现花脸症状的果皮中共有差异表达基因6938个,其中有3331个基因显著上调,3607个基因显著下调.通过差异表达基因功能注释分析,表明这些差异基因参与到植物激素(茉莉酸、水杨酸和生长素)合成和信号转导、苯丙烷生物合成等代谢途径.此外,转录组数据分析发现与植物防御反应相关转录因子的编码基因,如Md-WRKY18-like、MdWRKY71、MdNAC29、MdWRKY70等在表现花脸症状的苹果果皮中显著上调,而MdERF61等则显著下调.利用实时荧光定量PCR验证了显著差异表达基因变化情况.[结论]转录组分析结果表明,苹果花脸病果实与正常果实差异表达基因主要参与植物激素信号转导和苯丙烷合成途径.此外,植物抗病相关转录因子及防御相关激素信号可能参与调控苹果花脸病的抗病反应.

The GLABROUS1 enhancer-binding protein (GeBP) gene family encodes typical transcription factors containing an atypical leucine zipper motif, and plays a critical role in regulating plant growth and development, as well as multiple abiotic stresses response, but little is known about the role of GeBP transcription factors in apple. In this study, seven GeBP family members were identified in apple by genome-wide analysis, expression response analysis showed that MdGeBPs had different tissue expression patterns and were responsive to a variety of hormonal and abiotic stresses. Subsequently, MdGeBP3 was cloned and transgenic Arabidopsis and apple callus were obtained for further functional characterization. MdGeBP3 protein was localized in the nucleus, and overexpression of MdGeBP3 was more sensitive to cytokinins and less sensitive to ABA. In addition, ectopic expression of MdGeBP3 in Arabidopsis resulted in reduced drought tolerance, promoted adventitious root development and delayed flowering. Overall, these results suggest that MdGeBP3 may play an important role in regulating apple growth and development, as well as abiotic stress responses.

果树产业是烟台农业的传统优势产业,苹果、樱桃、梨、葡萄和桃等在全国具有极高的知名度,在促进农民增收、推动乡村产业振兴方面发挥了重要作用.烟台市年降水量672.5 mm,主要集中在6-9月,占年总降水量的70％,正处在苹果、梨、桃等果树的生长发育期,能充分满足果树生长发育对水份的需求,但这种气候条件也非常利于杂草的生长.在果园生产管理中,除草是一项非常重要且持续时间最长的工作,极大增加了果园管理成本,是烟台果业目前面临的重要难题.