新疆野苹果作为苹果砧木利用的研究进展

新疆野苹果是我国重要的野生果树资源,在栽培苹果起源研究和砧木利用方面有重要价值。本文在收集整理近年来有关新疆野苹果大量文献的基础上,从苹果砧木利用角度,就新疆野苹果对主要生物逆境、非生物逆境的抗性以及与主栽品种的嫁接亲和性进行了综述,以期为相关研究提供参考。     

陕西不同区域苹果林土壤水分动态和水分生产力模拟

基于WinEPIC和偏最小二乘回归模型对1981—2016年陕西不同区域成龄苹果林的水分生产力影响因子和土壤水分动态进行比较.结果表明: 研究期间,陕北丘陵沟壑区、渭北残塬区和关中平原区成龄苹果林年均产量分别为16.94、22.62和25.70 t·hm^-2,年均蒸散量分别为511.2、614.9和889.88 mm,水分生产力分别为3.81、3.82和3.24 kg·m^-3.在陕北区和渭北区,林地水分胁迫最严重,年均胁迫天数分别为54.89、28.38 d,关中区的N素胁迫较为剧烈,年均胁迫天数为25.87 d.陕北区和渭北区影响苹果林产量的最大因子是降水量,其标准化回归系数分别为0.274和0.235,但施N量对产量也有较大影响,回归系数分别达0.224和0.232;关中区的最大影响因子为施N量,回归系数为0.335,其次是供水量和施P量,回归系数分别为0.154和0.147.陕北区和渭北区影响苹果林水分生产力的最大因子是降水量,其标准化回归系数分别0.238和0.194;关中区最主要的影响因子为施N量和供水量,回归系数分别为0.182和0.178.在模拟期间,陕北区、渭北区和关中区苹果林地的过耗水总量分别为1152.17、1342.95和1372.42 mm,2~15 m土层土壤有效含水量下降速率分别为63.44、57.08、51.41 mm·a^-1,深层土壤干层出现时间分别为8、13和17年后,干层稳定至11 m深的时间分别为18、21和26年,干燥化严重.不同区域苹果林的管理重心应参考水分生产力的主导因子确定.     

Agrilus mali Matsumara (Coleoptera: Buprestidae), a new invasive pest of wild apple in western China: DNA barcoding and life cycle

Agrilus mali Matsumara (Coleoptera: Buprestidae) is a wood‐boring beetle distributed to eastern China that occasionally injures apple species. However, this wood‐boring beetle is new to the wild apple forests (Malus sieversii) of the Tianshan Mountains (western China) and has caused extensive tree mortality. The development of a biological control program for these wild apple forests is a high priority that requires exploration of the life cycle, DNA barcoding and taxonomic status of A. mali. In this study, to determine the diversity of invasive beetles, a fragment of the mitochondrial cytochrome oxidase gene was analyzed. Based on the results, beetles from Gongliu and Xinyuan counties of Xinjiang were identical but differed from those in the apple nursery of Gongliu by a single‐nucleotide substitution. We summarize the taxonomic status, relationships, and genetic distances of A. mali among other Agrilus species using the Tajima‐Nei model in maximum likelihood phylogeny. Analysis revealed that A. mali was closely related to Agrilus mendax and both belong to the Sinuatiagrulus subgenus. The life cycle of A. mali was investigated based on a monthly regular inspection in the wild apple forests of Tianshan. Similar to congeneric species, hosts are injured by larvae of A. mali feeding on phloem tissue, resulting in serpentine galleries constructed between bark and xylem that prevent nutrient transport and leading to tree mortality. Future studies will focus on plant physiological responses to the invasive beetles and include surveys of natural enemies for a potential classical biological control program.     

粗毛栓菌诱变菌株SAH-12漆酶的分离纯化及酶学性质研究

粗毛栓菌Trametes gallica诱变菌株SAH-12是通过紫外诱变选育所得的漆酶高产菌株,Active-PAGE分析表明SAH-12在高氮低碳无机盐培养液(LM3)中至少分泌3种漆酶同工酶(Lac1、Lac2、Lac3)。采用硫酸铵盐析、透析和Sephadex-G75分子筛层析从其培养液中分离纯化得到电泳纯的Lac1,纯化倍数6.54,酶活性回收59.7%。Lac1经SDS-PAGE验证为一条带,其表观分子量为61.5kDa。Lac1为一种糖蛋白,含糖量11.6%,等电点pI4.40,催化氧化底物ABTS的最适反应温度为60℃,最适pH为2.6,Km值为25μmol/L。Lac1在40℃(pH4.0)以下和pH1.5～5.0(28℃)范围内稳定。金属离子Fe2+、Ag+、Hg2+和Cr3+与抑制剂DTT、SDS、EDTA和DMSO对Lac1有抑制作用,其中Fe2+和DTT完全抑制酶活,而Cu2+对酶有明显激活作用,Mn2+、Zn2+对酶活影响不大。Lac1不仅可使一些合成染料明显脱色,而且对苹果汁多酚祛除也有较好效果。40℃用该酶(1U/mL)处理苹果汁5h,其多酚含量可降低40%。     

‘嘎拉’苹果及其杂交后代对炭疽叶枯病的抗性机制分析

为解析苹果对炭疽叶枯病的抗性机制,该研究以‘嘎拉’、‘藤牧1号’苹果及其杂交后代等87个苹果品种(系)为试验材料,进行田间调查及人工接种病菌并检测不同品种(系)中病菌生物量,利用SSR分子标记进行基因型鉴定,分析各品种(系)对炭疽叶枯病的抗性差异,利用荧光定量PCR及酶活检测比较分析水杨酸相关基因、抗性酶基因及酶活性水平差异。结果表明：(1)87个苹果品种(系)对苹果炭疽叶枯病的抗性差异明显,‘嘎拉’、‘2 5’、‘19 19’等品种(系)叶片发病严重,表现出对炭疽叶枯病的高感性,‘藤牧1号’、‘40 9’及‘16 16’等品种(系)叶片无病斑或病斑极少,炭疽叶枯病菌含量显著低于感病性品种(系),其抗性显著。(2)SSR标记S0405127和S0304673的基因型鉴定结果与田间表型调查结果相比,准确率分别为93.10%和91.95%,与人工接种结果相比,准确率分别为91.95%和95.40%。(3)SA相关基因的表达模式结果表明,接种炭疽叶枯病菌4 d后,‘藤牧1号’、‘40 9’及‘16 16’等抗性品种(系)中SA合成相关基因MdEDS1、MdPAD4和MdPAL被强烈诱导表达;同时,SA信号转导相关基因MdNPR1、MdPR1、MdPR5的表达显著高于‘嘎拉’等感病品种(系)。(4)接种炭疽叶枯病菌4 d后,‘藤牧1号’、‘40 9’及‘16 16’等抗性品种(系)的MdSOD、MdPOD酶基因表达水平及酶活性显著高于‘嘎拉’、‘2 5’、‘19 19’等感病品种(系)。研究认为,‘藤牧1号’、‘40 9’及‘16 16’等品种(系)通过调控水杨酸合成和信号转导通路及氧化还原相关反应等提高对炭疽叶枯病的抗性,为挖掘抗性基因以及利用优良种质选育抗病品种奠定了基础。     

Potential host fruits for Drosophila suzukii: olfactory and oviposition preferences and suitability for development

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), the spotted wing drosophila, is a pest endemic to Southeast Asia that invaded the Americas and Europe in 2008. In contrast to most of its congeners, D. suzukii possesses a serrated ovipositor that allows it to lay eggs in unwounded commercial fruits, resulting in severe revenue losses for the industry. The purpose of this study was to determine the susceptibility of known host fruits, including cherry, strawberry, blueberry, and grape, and potential host fruits, such as banana and apple, to attack by D. suzukii. Based on the responses to volatile cues offered in a six‐choice olfactometer, the preference of female D. suzukii was ranked in the following order: strawberry = cherry > banana = apple = blueberry = grape, but in no‐choice and choice oviposition tests, the preferences were ranked as follows: cherry > strawberry = blueberry > grape = banana > apple. Furthermore, we reconfirmed that D. suzukii mainly targets rotten fruit for feeding and ripe fruit for oviposition, and females preferred fruits with intensive mechanical damage. Based on developmental parameters, apple was the least suitable host. This study has implications for the control of D. suzukii, especially in mixed fruit orchards, by providing a promising avenue for exploiting behaviour‐based control tools and emphasizing the importance of phenology in host fruit susceptibility.     

Natural variation in cytokinin maintenance improves salt tolerance in apple rootstocks

Plants experiencing salt‐induced stress often reduce cytokinin levels during the early phases of stress‐response. Interestingly, we found that the cytokinin content in the apple rootstock “robusta” was maintained at a high level under salt stress. Through screening genes involved in cytokinin biosynthesis and catabolism, we found that the high expression levels of IPT5b in robusta roots were involved in maintaining the high cytokinin content. We identified a 42 bp deletion in the promoter region of IPT5b, which elevated IPT5b expression levels, and this deletion was linked to salt tolerance in robusta×M.9 segregating population. The 42 bp deletion resulted in the deletion of a Proline Response Element (ProRE), and our results suggest that ProRE negatively regulates IPT5b expression in response to proline. Under salt stress, the robusta cultivar maintains high cytokinin levels as IPT5b expression cannot be inhibited by proline due to the deletion of ProRE, leading to improve salt tolerance.