Low-temperature stress is one of the main environmental factors limiting the growth and development of apple trees early in the growing season. Previous studies have shown that exogenous methyl jasmonate (MeJA) can significantly improve the low-temperature tolerance of Malus baccata roots, but its molecular mechanism has not been clarified. Based on pre-transcriptome sequencing data, a MbMYC2 (a key factor in JA signaling) and a MbTRX (a redox regulator) were identified in the combination treatment of low temperature and MeJA. The gene expressions of MbMYC2 and MbTRX in the roots of Malus baccata were significantly upregulated by the MeJA application in under low-temperature stress. Subcellular localization test confirmed that the MbMYC2 protein was localized in the nucleus. To explore the function of MbMYC2 in Malus baccata roots under low-temperature stress, we obtained transgenic Arabidopsis thaliana lines overexpressing MbMYC2. Phenotypic analysis showed that the leaf survival rate of transgenic Arabidopsis thaliana lines were significantly higher than those of WT plants under low-temperature stress. The results of physiological and biochemical indexes showed that the activities of antioxidant enzymes (SOD, APX, and GR, etc.) and the contents of osmotic regulators (proline, etc.) of transgenic Arabidopsis thaliana lines were significantly increased, and the levels of malondialdehyde (MDA) and reactive oxygen species (H2O2, O2·-) were significantly decreased compared with WT. Under low-temperature stress, the expression levels of stress-responsive marker genes AtDREB2A, AtRD26, AtRD29A, and AtRD29B were significantly up-regulated in transgenic lines. Yeast one-hybrid (Y1H) assay confirmed that MbMYC2 protein can bind directly to MbTRX gene promoter and activated its transcription. GUS activity analysis and LUC analysis and chromatin immunoprecipitation quantitative PCR (ChIP-qPCR) results further confirmed the positive regulation of MbMYC2 on MbTRX transcription. In conclusion, the results of this study suggest that the MbMYC2 protein activates the expression of MbTRX by can bind to its promoter, thereby boosting the activity of antioxidant enzymes. This study provides a theoretical basis for the study of mechanism of JA signal regulating apple low-temperature tolerance.

Low temperature limits the growth and yield of apple trees. Previous experiments have proven that exogenous methyl jasmonate (MeJA) can improve the low-temperature adaptability in Malus baccata Borkh. roots which is widely used as rootstocks in northern China. Whereas the molecular mechanism of MeJA regulating the suboptimal low-temperature adaptability of apple roots remain poorly understood. The purpose of this work was to explore the potential regulating mechanisms of jasmonate signal in M. baccata roots in response to suboptimal low root-zone temperature stress (5 ± 0.5 °C for 2 h) through transcriptome and physiological analysis. Transcriptome bioinformatics analyses demonstrated that 2285 differentially expressed genes (DEGs) were predominantly associated with the jasmonates biosynthesis, hormone signaling pathways, MAPK signaling, and glutathione metabolism. Further investigations highlighted the regulating role of JAs in the low-temperature acclimation of the apple roots. Firstly, MeJA application inhibited the accumulations of reactive oxygen species and malondialdehyde in M. baccata roots through increasing antioxidant enzyme activities under suboptimal low-temperature, together with the increase of endogenous JAs levels. Secondly, the transcriptional levels of several pivotal JAs signaling genes were significantly up-regulated in the MeJA pre-treated roots under suboptimal low-temperature, verified through expression profiling and qRT-PCR analyses. Thirdly, MbMYC2 directly bound to the promoter of MbPOD, encoding a transcription factor involved in the antioxidant system, and enhanced its transcription. In summary, the mechanism of MeJA enhancing the antioxidant adaptability of M. baccata roots under suboptimal low-temperature stress has been preliminarily clarified, which provides new insights for further elaboration of molecular mechanism that are involved in low-temperature adaptability of apple roots.

Malus sieversii is considered the ancestor of the modern cultivated apple, with a high value for apple tolerance breeding. Despite studies on the temperature adaptability of M. sieversii carried out at a physiological response and the genome level, information on the proteome changes of M. sieversii during dormancy is limited, especially about the M. sieversii subtypes. In this study, a DIA-based approach was employed to screen and identify differential proteins involved in three overwintering periods of flower buds in two M. sieversii subtypes (Malus sieversii f. luteolus, GL; Malus sieversii f. aromaticus, HC) with different overwintering adaptabilities. The proteomic analysis revealed that the number of the down-regulated differential expression proteins (DEPs) was obviously higher than that of the up-regulated DEPs in the HC vs. GL groups, especially at the dormancy stage and dormancy-release stage. Through functional classification of those DEPs, the majority of the DEPs in the HC vs. GL groups were associated with protein processing in the endoplasmic reticulum, oxidative phosphorylation, starch and sucrose metabolism and ribosomes. Through WGCNA analysis, tricarboxylic acid cycle and pyruvate metabolism were highly correlated with the overwintering stages; oxidative phosphorylation and starch and sucrose metabolism were highly correlated with the Malus sieversii subtypes. This result suggests that the down-regulation of DEPs, which are predominantly enriched in these pathways, could potentially contribute to the lower cold tolerance observed in HC during overwintering stage.

Methyl jasmonate (MeJA) has been documented to mitigate the oxidative stress caused by abiotic triggers. In this study, we investigated the mechanism through which exogenous MeJA alleviates oxidative damage in the roots of Malus baccata under a suboptimal low root-zone temperature. A suboptimal low root-zone temperature promoted increases in the activity and transcription of allene oxide synthase (AOS) and jasmonic acid carboxyl methyltransferase (JMT), elevated the levels of endogenous jasmonic acid (JA), MeJA and jasmonate isoleucine (JA-Ile), and induced the accumulation of malondialdehyde (MDA) and reactive oxygen species (ROS). The addition of exogenous MeJA further increased the JA (1 h, 12-24 h), MeJA (1-24 h), and JA-Ile (1-6 h) contents and enhanced the activities and transcription of lipoxygenase (LOX) and JMT. The upregulated expression of JASMONATE ZIM-DOMAIN (JAZ) and MdMYC2 indicated that suboptimal low root-zone temperature could activate JA signalling in roots, and exogenous MeJA could further strengthen JA signalling under lowtemperature stress. Exogenous MeJA alleviated oxidative damage to stressed roots by enhancing ascorbate-glutathione (AsA-GSH) cycle activity. In addition, pre-treatment with phenidone (an inhibitor of lipoxygenase) exerted the opposite effects to those induced by exogenous MeJA treatment. These findings indicated that exogenous MeJA enhanced antioxidant systems and detoxified ROS by regulating JA signalling and thereby protected M. baccata roots from damage caused by suboptimal low root-zone temperature stress.

Hanfu apple is the main cultivar grown in the cool areas of Northeast, Northwest, and North China. Here, we proposed a chromosome-level Hanfu genome assembly using PacBio, Illumina and Hi-C sequencing data. The total contig length was 628.99 Mb, with scaffold and contig N50 sizes of 36.18 Mb and 1.25 Mb, respectively. The Hanfu genome had a total of 39,617 genes, of which we predicted the function for 38,816. Evolutionary analysis showed that Hanfu may have undergone a γ-event, a recent whole-genome duplication. A comparative analysis was conducted on the genomes of Hanfu and homozygous triploid HFTH1, which were cultured using the anthers of diploid Hanfu apples. Three variants were identified, including 2,155,184 single nucleotide polymorphisms (SNPs), 413,108 insertions/deletions (indels), and 7,587 structural variants (SVs).This high-quality genome will provide a reference for the genetic improvement of apples and the breeding of more varieties with high resistance and high quality.

GABA (γ-aminobutyric acid) is found in plants and accumulates rapidly under stresses. However, the contributions of glutamic acid and a (Glu)-derived pathway and polyamines (PAs) catabolism pathway on GABA accumulation and the regulatory effects of exogenous putrescine (Put) on a GABA shunt under suboptimal low root-zone temperatures remain unknown. Our results showed that suboptimal low root-zone temperatures (treatment L) significantly increased GABA contents and GABA transaminase (GABA-T) activities. The contribution rate of the PAs catabolism pathway increased from 20.60% to 43.31%. Treatment L induced oxidative stress in Malus baccata Borkh. roots. Exogenous Put increased the contents of endogenous Put, spermine (Spm), and spermidine (Spd), promoted the transformation of PAs, increased the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and decreased the contents of hydrogen peroxide (H2O2), superoxide anion (O2∙−), and malondialdehyde (MDA). Meanwhile, contrasting results were observed after aminoguanidine (AG, an inhibitor of diamine oxidase) application. These findings revealed that the Glu-derived pathway is the main route of GABA synthesis. The contribution rate of the Pas catabolism pathway increased gradually with the extension of treatment time, and the treatment of exogenous Put significantly improved the tolerance of Malus baccata Borkh. Roots to suboptimal low temperature by regulating the transformation of Pas, GABA shunt, and the antioxidant system.

Malus baccata (L.) Borkh. is one of the most widely used rootstocks in the apple-producing region of Northern China. However, in the early growing season, apple roots are often subjected to suboptimal low root-zone temperatures. The regulatory effects of exogenous γ-aminobutyric acid (GABA) on both the γ-aminobutyric acid shunt (GABA shunt) and the respiratory activity of roots under suboptimal low root-zone temperatures remain unknown. To explore the physiological basis for GABA alleviation of low-temperature stress in M. baccata Borkh. roots, the following treatments were examined: suboptimal low root-zone temperature (potted parts of the seedlings were maintained at 5 ± 0.5 °C; L); suboptimal low root-zone temperature + GABA (LG); and suboptimal low root-zone temperature + vigabatrin (VGB; LV), which is a specific active inhibitor of γ-aminobutyric acid transaminase (GABA-T). Each treatment was matched with a control (18 °C/8 °C day/night; CK) for comparison. Our results showed that the L treatment reduced the root vitality, increased malondialdehyde (MDA) content, promoted the accumulation of GABA, activated the GABA shunt, and inhibited the total root respiration rate (VTotal) by decreasing the respiratory rates of Embden–Meyerhof pathway (VEMP) and tricarboxylic acid cycle (VTCAC). The LG treatment significantly increased the content of endogenous GABA, accelerated the metabolism of the GABA shunt, enhanced root respiratory activity by increasing VTotal, VEMP, VTCAC, and increased the cytochrome pathway respiratory rate (VCP), thus alleviating the damage of low root-zone temperature stress. Meanwhile, contrasting results were observed in the LV treatment. These findings revealed that exogenous GABA improved the tolerance of apple rootstocks to suboptimal low temperatures in early spring by regulating the GABA shunt and root respiratory activity.

课程目标达成度评价,是专业认证背景下课程教学效果的一个重要指标.文章以沈阳农业大学园艺专业果树栽培学基础为例课程,结合工程教育专业认证要求,根据课程目标及特点设计教学内容及考核方式,建立毕业要求与课程目标之间的支撑关系,丰富评价方式,建立相应的课程目标达成度评价体系;应用该评价体系对课程的实际教学效果进行评价,了解学生对课程内容及各项课程目标的掌握程度和教学中存在的不足,为后续课程教学的持续改进指明方向.

孔雀是沈阳农业大学从海棠品种绚丽实生苗中选育的品种.树姿直立,幼嫩叶片红褐色,被茸毛,成熟叶片绿色.花量极大,花蕾为红色.平均花芽率为83.0％,花序坐果率为100.0％.果实长圆锥形,萼片聚拢宿存,幼果为深红色,成熟后为亮红色,果面光滑,具有独特的观赏价值.

In the early growing season in northern China, suboptimal low root-zone temperatures is a common abiotic stress that impairs root function and leaf development in fruit trees. In this study, we investigate the physiological role of leaves in jasmonate metabolism and the capacity of scavenging reactive oxygen species in Malus baccata (L.) Borkh. roots under suboptimal low root-zone temperatures. In the presence of intact leaves, suboptimal low root-zone temperatures significantly increased allene oxide synthase (AOS), jasmonate-resistant 1 (JAR), and jasmonic acid carboxyl methyltransferase (JMT) activities and transcription in jasmonate biosynthesis. Meanwhile, elevated endogenous jasmonic acid (JA), methyl jasmonate (MeJA), and jasmonate-isoleucine (JA-Ile) contents were also observed, as were significantly decreased glutathione reductase and dehydroascorbate reductase activities and AsA/DHA and GSH/GSSG ratios. Conversely, leaf removal substantially reduced AOS, JMT, and JAR activities and transcription at most time points and JA (6–24 h), MeJA (1–24 h), and JA-Ile (1–24 h) levels in roots, affecting key enzymes in the AsA–GSH cycle and the AsA/DHA and GSH/GSSG ratios in response to low-temperature treatment, as a result of a significant increase in malondialdehyde content. Thus, leaves are crucial for jasmonate metabolism in roots under suboptimal low root-zone temperatures, with leaf removal exacerbating root oxidative stress by altering JA signaling and AsA–GSH cycle activity.

以“寒富”苹果为试材,采用气相色谱等方法,比较研究了辽宁省不同气候特征区域对“寒富”苹果果实品质的影响,根据温度和降雨等气候因子在辽宁省划分为干凉区、冷凉区、温凉区、温和区和湿润区.结果 表明:温和区的果实平均单果质量最高,湿润区次之,干凉区最低;温凉区的果实硬度最高,冷凉区次之,干凉区最低;冷凉区的果实可溶性固形物含量最高,干凉区次之,温和区最低;干凉区的果实可溶性糖含量最高,冷凉区次之,温凉区最低;湿润区的果实有机酸含量最高,温凉区最低.在“寒富”苹果果实中共检测到7类、56种香气成分.其中,干凉区果实香气成分数量为56种,温凉区为54种,冷凉区为51种,温和区为46种,湿润区为42种.由香气成分种类判断,“寒富”苹果果实香气属酯香型.地区间果实品质指标差异明显,且气候对果实品质各项指标的影响不同.

对辽宁省抚顺地区120个‘寒富’苹果园进行了调查.结果 表明,抚顺地区‘寒富’苹果园立地条件差,果园基础设施差,砧穗组合以寒富/GM256/山定子为主,人均管理面积为1.07 hm2,管理水平不高,树形不规范,不施基肥的果园占63％.常用的杀菌剂依次是多菌灵、代森锰锌、甲基硫菌灵,最常用的杀虫剂为高效氯氰菊酯,其次是吡虫啉.

‘花束’是从‘绚丽’(Radiant)实生后代中选育出的观赏海棠新品种.树姿直立,树势中等;成枝力强,1年生枝紫褐色;幼叶黄绿色,有红褐色晕,成熟叶绿色;花蕾暗红色,花深粉色,单花在萼片处聚拢,整个花序呈束状;果实扁圆形,果实底色浅红色,果面盖色红色,全面着色,成熟后落果轻,观赏价值高.

以当年生山定子实生苗为试材,采用温室盆栽土培试验,模拟根区亚低温(5℃)条件,设置亚低温(L)、亚低温+外源7氨基丁酸(LG)和亚低温+氨己烯酸(LV)处理,分别于处理后0、12、24、48、96和144 h后剪取白色幼嫩根系,测定山定子根系内源γ-氨基丁酸(GABA)含量、渗透调节物质含量、活性氧含量和抗氧化酶活性等指标,研究根区亚低温下GABA对山定子根系抗氧化系统的调节效应.结果显示:(1)根区亚低温下,山定子根系内源GABA含量略高于对照,渗透调节物质也不同程度积累,超氧阴离子(O2·)含量、过氧化氢(H2O2)含量显著升高,膜脂过氧化程度加深.(2)外源施加GABA进一步促进了内源GABA的积累,明显增加根系中可溶性糖、可溶性蛋白和脯氨酸(Pro)等渗透调节物质含量,显著提高根系的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)等酶活性,最终使得山定子根系中H2O2等的含量降低,膜脂过氧化程度缓解.(3)GABA专一性抑制剂VGB处理后的效果与外源GABA处理结果相反.研究表明,GABA代谢对山定子根系抵御亚低温胁迫引发的氧化胁迫有积极作用,外源GABA具有通过诱导内源GABA代谢提高根系抗氧化能力的生理效应.

全日制专业学位硕士是研究生教育中实现实用型专业人才培养的主要模式,而如何培养优秀的专业学位硕士研究生是当前研究生教育改革面临的重要课题.以沈阳农业大学全日制园艺学专业学位硕士研究生为研究对象,借鉴其他学科专业学位人才培养的成功经验,从专业课程设置、导师队伍建设和质量监督评价等环节出发,探索以确保研究生培养质量为核心的内部质量保障结合外部监督评价的双环式保障体系的可行性,为构建高素质专业人才培养体系提供借鉴.

以5年生‘寒富’苹果园行间生草区不同草种为试材,采用田间取样、实验室内测定分析的方法,研究了行间种植6种草后对土壤微生物种群及土壤酶活性的影响,以期明确苹果园生草后土壤微生物及酶活性的变化特征,从而为生草制苹果园的土壤管理提供理论依据.结果表明:生草处理提高了0～30 cm土壤中细菌、真菌、放线菌的数量,而对30～60 cm土层土壤微生物数量影响较小;生草处理提高了0～30 cm土层的过氧化氢酶、转化酶的活性,脲酶活性则整体表现出下降的趋势;生草处理30～60 cm土层的脲酶、转化酶活性有略升高的趋势,但幅度较小.各生草处理间对土壤酶活性的影响差别较大.

为了更好地掌握沈阳地区冬季少雪、持续低温气候对'寒富'苹果花芽的影响程度,以便为春季修剪和花果管理提供参考,作者对沈阳农业大学长期定位试验园的'寒富'花芽越冬受害情况进行了调查分析.结果表明,各树龄植株、各类结果枝的顶花芽均有不同程度的冻害,除了'寒富'/多花海棠砧穗组合外,其他砧穗组合都表现为长枝顶花芽冻害率最高,短枝顶花芽冻害率最低.

“琥珀”是由沈阳农业大学选育的海棠品种,母本为平邑甜茶(Malus hupehensis Rehd.),父本不详.树姿直立,生长势强.一年生枝黄绿色.成熟叶片浓绿色,叶柄基部有2片托叶.花蕾白色,具粉红色晕;花白色,花瓣近圆形、重叠,部分花为6片花瓣,平均花冠大小3.3 cm,花期10～12 d.连续结果能力强,果实近圆形,底色淡黄色,盖色橙红色,果面光滑,有蜡质,成熟后落果轻,观赏性高.适宜于辽宁省庭院、小区、街道、广场绿化.

‘红萼’是由‘绚丽’和‘御紫’经自由开放授粉、实生播种选育而成的观赏海棠新品种.‘红萼’树姿较直立,生长势强.幼叶红褐色,成熟叶片绿色.花蕾红色,花单瓣,椭圆形,粉红色,基部离生.果实近圆形,花萼宿存,萼端有棱状凸起;底色黄白色,全面着鲜红色.在辽宁省沈阳市,‘红萼’物候期与其他观赏海棠栽培品种相近,花期10～12 d.‘红萼’适合在沈阳地区及类似气候区栽植.

Soil temperature is known to affect plant growth and productivity. In this study we found that low root-zone temperature (LRT) inhibited the growth of apple (Malus baccata Borkh.) seedlings. To elucidate the molecular mechanism of LRT response, we performed comparative proteome analysis of the apple roots under LRT for 6 days. Total proteins of roots were extracted and separated by two-dimensional gel electrophoresis (2-DE) and 29 differentially accumulated proteins were successfully identified by MALDI-TOF/TOF mass spectrometry. They were involved in protein transport/processing/degradation (21%), glycometabolism (20%), response to stress (14%), oxidoreductase activity (14%), protein binding (7%), RNA metabolism (7%), amino acid biosynthesis (3%) and others (14%). The results revealed that LRT inhibited glycometabolism and RNA metabolism. The up-regulated proteins which were associated with oxidoreductase activity, protein metabolism and defense response, might be involved in protection mechanisms against LRT stress in the apple seedlings. Subsequently, 8 proteins were selected for the mRNA quantification analysis, and we found 6 of them were consistently regulated between protein and mRNA levels. In addition, the enzyme activities in ascorbate–glutathione (AsA–GSH) cycle were determined, and APX activity was increased and GR activity was decreased under LRT, in consistent with the protein levels. This study provides new insights into the molecular mechanisms of M. baccata in responding to LRT.