两种遗传背景下小麦Wx近等基因系面粉及面制品色泽研究

为探索不同Wx基因型对面粉及面制品色泽的影响及色泽改良途径,为糯小麦的育种改良提供理论依据,利用‘扬01-2’和‘扬麦17’2种遗传背景下的8种Wx基因型的近等基因系为材料,对8种基因型面粉、面片色泽及色泽主要影响因素多酚氧化酶(PPO)活性进行研究。结果表明,在面粉色泽上,2个背景下8种基因型间总体上无显著差异,其中以aaBBDD和aabbdd 2种基因型面粉色泽略好;在面片色泽及面条感官评价上,2个遗传背景下均以AAbbdd基因型色泽较好,aabbdd基因型色泽较差。面粉多酚氧化酶活性(PPO)检测结果显示,在2个遗传背景下,全缺失型aabbdd均极端高于其它基因型,其原因需深入研究。糯小麦育种需重视对低PPO活性材料的筛选。     

不同棉花基因型种子萌发响应铜胁迫的差异

在铜污染耕地种植棉花对提高耕地利用效率和棉农收入具有重要意义,但铜胁迫对棉花种子萌发的影响仍不清楚。以7个陆地棉品种（系）为试验材料,设置0、10、100和2 000μmol/L 4个Cu²⁺浓度处理进行发芽试验,记录10d后棉花种子的发芽率和幼苗的鲜重、根长和芽长。以幼苗鲜重、根长和芽长为指标,采用耐性指数和隶属函数对不同品种（系）种子的耐受性进行综合评价。结果表明,在Cu²⁺浓度10~2 000μmol/L范围内随着浓度的升高,幼苗鲜重、根长和芽长所受抑制增强,且根长的受抑制程度高于芽长。在中低浓度下（10~100μmol/L）能将不同基因型种子萌发对铜胁迫的耐受性较好地区分开来,鄂抗棉10号的耐性指数和隶属函数平均值均居首位,而SGK321均居末位。研究结果初步表明,鄂抗棉10号为铜胁迫钝感基因型,而SGK321为敏感基因型。     

山西小麦品种(系)多酚氧化酶基因的等位变异分布

为了明确山西小麦品种（系）多酚氧化酶(PPO)基因的等位变异分布,选育PPO活性低的小麦品种。利用PPO基因的功能性标记PPO16、PPO18 和PPO 29 对121 份山西小麦品种（系）进行分析。结果表明：Ppo-A1a 和Ppo-A1b 基因型的品种（系）分别为56 份和65 份,频率分别为46.3%和53.7%;Ppo-D1a和Ppo-D1b 基因型的品种（系）分别为50 份和71 份,频率分别为41.3%和58.7%;两基因组合类型Ppo-A1a/Ppo-D1a、Ppo-A1a/Ppo-D1b、Ppo-A1b/Ppo-D1a 和Ppo-A1b/Ppo-D1b 的小麦品种（品系）分别有43 份、50 份、37 份和56 份,分布频率分别为35.5%、41.3%、30.6%和46.3%。本研究在山西小麦品种（系）中检测出37 份低PPO活性基因Ppo-A1b/Ppo-D1a 组合类型的品种（系）,为常规育种获得低PPO活性的小麦品种提供依据。     

莴笋多酚氧化酶的酶学特性研究

采用分光光度法测定莴笋多酚氧化酶(PPO)活性,考察底物特异性、pH值、温度、热稳定性、底物浓度、金属离子及抑制剂对PPO酶活特性的影响,研究莴笋PPO酶学特性。结果表明,莴笋PPO的最适底物为邻苯二酚,最适pH值5.0,最适温度25℃;90℃热处理60 s莴笋PPO酶活基本完全丧失;莴笋PPO最适底物浓度为0.10 mol/L,PPO酶促褐变反应动力学符合米氏方程,相应的动力学参数Km=0.667 mol/L,Vmax=826.4 OD/min;Mg2+、Ca2+、Mn2+、Zn2+对PPO酶活有一定的的抑制作用,Cu2+和Fe3+对PPO酶活有一定的促进作用;五种抑制剂对抑制莴笋PPO酶活力均具有一定的作用,且抑制作用随抑制剂浓度的增大而加强,试验范围内抑制作用由强到弱依次为:抗坏血酸L-半胱氨酸Na HSO3柠檬酸EDTA,抗坏血酸对莴笋PPO酶活的抑制效果最佳。     

小麦品种面粉粘度性状的品质分析

研究了2个地区21个小麦品种面粉的快速粘度仪参数。结果表明,不同地区不同品种对淀粉快速粘度仪参数均有一定的影响。峰值粘度主要受基因型与环境互作的影响,衰减度相对受基因型的影响较大,其他性状受环境影响比较大。而弱筋小麦品种的淀粉糊化特性指标的环境变异明显高于强筋、中筋品种,说明弱筋小麦淀粉糊化特性受环境影响的程度较大。     

硅对铬、铜胁迫下小麦幼苗生理生化指标的影响

为了明确外源硅对小麦铬、铜毒害的缓解效应,以普通小麦品种京冬8号为材料,采用水培试验,研究硅（Na2SiO3）对K2Cr2O7（0．6 mmol／L）、CuSO4（0．8 mmol／L）胁迫下小麦幼苗生理生化指标的影响。结果表明：在铬、铜胁迫下,小麦幼苗可溶性糖含量、丙二醛（ MDA）含量、超氧化物歧化酶SOD和过氧化物酶POD活性显著升高,叶绿素含量显著降低;外源硅能显著降低铬、铜胁迫下小麦幼苗的可溶性糖含量、MDA含量以及SOD和POD活性,Na2 SiO3浓度为1．5 mmol／L时,效果最明显;外源硅能显著提高铬、铜胁迫下小麦幼苗的叶绿素含量,Na2 SiO3浓度为1．0 mmol／L时,效果最明显。适当浓度的外源硅能在一定程度上减轻重金属铬、铜胁迫对小麦幼苗的伤害。     

海盐苦卤对番茄早疫病菌的抑制及其对番茄叶片防御酶系的影响

采用菌丝生长速率法测定了海盐苦卤对番茄早疫病菌的抑制,通过测定PAL、CAT和PPO的变化,研究了海盐苦卤对番茄叶片防御酶系（苯丙氨酸解氨酶PAL、过氧化氢酶CAT和多酚氧化酶PPO）的影响。结果表明：随着海盐苦卤浓度的降低,其对番茄早疫病菌作用表现为：抑制-促进-抑制,并在浓度为0.0050%具有最佳抑制效果,抑制率为42.3%;此外,浓度为0.050%的海盐苦卤处理能够提高番茄叶片PAL、CAT和PPO的活性。     

人工合成六倍体小麦与普通小麦杂交后代衍生群体的PPO基因分析

四倍体小麦与节节麦杂交培育的人工合成六倍体小麦已广泛应用于国内外小麦品种改良。以引自CIMMYT的Syn768、Syn769、Syn780和Syn786人工合成六倍体小麦分别与中国四川成都平原主栽普通小麦品种杂交、回交的BC2F2：6后代群体中选育的113份优良高代系和川麦38、川麦42、川麦43和川麦47育成品种为材料,采用SSR特异引物Xgwm312标记位点的PAGE凝胶电泳对其PPO基因型进行了研究。结果表明,Xgwm312位点的标记具有多态性,其PCR扩增产物可产生198bp、216bp、232bp和240bp四种等位基因变异片段。在所检测的117份后代衍生群体材料中,65份材料具有198bp片段的等位基因,占全部材料的55．56％;13份含216bp片段的等位基因,其频率为11．11％,35份材料具有232bp片段的等位基因,分布频率为29．91％;只有4份材料含有240bp片段的等位基因,仅占全部材料的3．42％。从每个人工合成六倍体小麦亲本材料所形成的后代衍生群体来看,基因等位变异片段分布频率各不相同。说明PPO基因在小麦杂交后代材料中基因型的表现存在着随机性,与亲本的基因型状况关系极大,并且在后代材料中出现了亲本都没有的240bp等位基因变异片段的材料。通过研究人工合成六倍体小麦与普通小麦杂交后代的PPO基因型,有助于提高分子标记育种效率,也有助于PPO基因型的多态性研究,并为人工合成六倍体小麦在我国小麦品种改良和分子标记育种中的应用提供依据和方法。     

栽培措施及环境对小麦籽粒品质的影响

小麦籽粒品质既受品种本身的遗传特性的影响,也受环境条件的影响。小麦籽粒品质特性是品种基因型和环境条件的综合表现。研究和了解栽培措施及环境对品质的影响,可以进行合理的品种布局和优质高产栽培技术措施的制定,有利于大面积地推广专用优质小麦品种。     

外源钙对海水胁迫下小麦种子萌发及幼苗生长的缓解作用

以合春6号小麦为材料,研究了不同浓度海水对小麦种子萌发及幼苗生长的影响,以及Ca2+对海水胁迫的缓解作用.结果表明:低浓度海水不影响小麦种子萌发,海水浓度高于55％显著抑制小麦种子萌发.海水胁迫显著降低了小麦的根数、根长、胚芽鞘长、苗高.海水浓度为25％时根系活力最强.用4.0 g/L的Ca( NO3)2浸种能缓解海水对小麦的胁迫作用.     

小麦籽粒2A染色体PPO基因新分子标记的开发与应用

参照位于小麦2B染色体上的多酚氧化酶(Polyphenol Oxidase)基因保守区序列(GenBank:AB254804)设计引物,以一组籽粒PPO活性两极端材料为扩增模板进行筛选,并以195份中国微核心种质材料对其有效性验证,旨在开发小麦籽粒PPO基因新分子标记。在设计的引物中,编号为F-4的引物PCR产物在籽粒PPO活性处于两极端的12份小麦品种中表现出规律性极强的多态性,在籽粒PPO活性极高的6个小麦品种扩增出了1条带(a),在籽粒PPO活性极低的6个小麦品种扩增出了3条带(a,b,c)。利用195个微核心种质材料对引物F-4进行有效性验证,其中123个材料扩增出了一条带(a带),其PPO均值为246.22A475U/(min·g·103),剩下的72个材料都扩增出3条带(a,b,c);其PPO活性均值为155.95A475U/(min·g·103);比前者低90.27A475U/(min·g·103),差异显著。在此基础上利用一套中国春缺体将b条带定位于2A染色体上。扩增序列Blast分析发现,b序列与EF070148序列(2Ab)重合区域为99%,相似达99%,基本可以认定为同一序列;a序列与EF070149序列(2Da)重合区域达99%,相似为98%,基本可以认定为同一序列。位于小麦2A染色体上的PPO基因分子标记F-4可以在小麦PPO活性分子育种中加以应用。     

Enzyme activity in wheat breeding lines derived from matings of low polyphenol oxidase parents

Polyphenol oxidase (PPO) in grain plays a major role in time-dependent discoloration of wheat (Triticum aestivum L.) products, especially fresh noodles. Breeding wheat cultivars with low or nil PPO activity can reduce undesirable product darkening. The low PPO line PI 117635 was crossed to two low PPO wheats, IDO580 and ‘IDO377s’, to determine whether matings between wheats with low levels of grain PPO would result in complementation, such that lines with still lower or nil PPO would be generated. Progeny in a population derived from PI 117635/IDO580 displayed no variation in PPO activity. In the F_3:4 populations derived from PI 117635/IDO377s, and the reciprocal IDO377s/PI 117635, normal distributions of low to high PPO activity were observed. Field-grown populations (F_3:5; F_3:6) derived from IDO377s crosses were analyzed for PPO activity and used to determine whether lines with nil PPO activity were generated. Of 239 lines, 154 were verified to have PPO activity that was not significantly different from the low PPO durum (Triticum turgidum var durum) cultivar ‘Ben’. PCR analysis showed that the populations were fixed for a putative low PPO allele at Ppo-A1. Using markers for Ppo-D1, it was found that the average PPO activity of lines with 490 bp PCR fragments from PPO29 was significantly lower than that of lines with 560 bp fragments from STS01. These results disagreed with that predicted from previous reports for markers for Ppo-D1 alleles. Thus, breeders should exercise caution when making selections using markers for alleles at Ppo-D1, as known markers might predict erroneous phenotypes and genotypes in some wheat backgrounds.     

陕西省地方小麦品种多酚氧化酶基因等位变异检测及分布

小麦籽粒中多酚氧化酶(polyphenol oxidase,PPO)基因活性与面条等面制品颜色褐变密切相关,降低籽粒PPO活性是小麦品质改良的重要目标.利用PPO基因的功能标记PPO18和PPO29,对115份陕西省地方冬小麦品种(系)进行2A和2D染色体上PPO等位基因印Ppo-A 1a、Ppo-A1b和Ppo-D1b检测,并分析了品种等位变异的分布特点.结果显示:PPO18在等位基因Ppo-A1a(高PPO)和Ppo-A1b(低PPO)中分别扩增685 bp和876 bp的片段,PP029在Ppo-D1b(高PPO)等位基因中扩增490bp的片段.115份品种(系)中Ppo-A1a、Ppo-A1b6和Ppo-D1b等位基因的频率分别为37.39%、60.00%和45.22%.在陕西省所培育和引进的冬小麦品种(系)中,地方当家品种中最低PPO活性基因分布较多,而引进的冬小麦品种中高PPO活性基因分布较多.     

重金属Pb、Hg污染对3种小麦种子的萌发及抗氧化活性的影响

以水培的方法,研究了重金属Pb、Hg污染对农麦2号、农麦3号和新春23号3种小麦种子的发芽势、发芽率、芽长和抗氧化活性的影响。结果表明:Pb2+污染对3种种子的发芽势、发芽率、芽长以及幼苗的抗氧化活性均表现出抑制作用,且随着Pb2+浓度的增加,抑制作用逐渐增强;Hg+污染对农麦3号种子的发芽势、发芽率以及芽长均表现出抑制作用,浓度越大抑制作用越强,而对农麦2号和新春23号种子,浓度小于50 mg/L时,对发芽势有促进作用,发芽率和芽长影响不显著,浓度大于100 mg/L时,发芽势、发芽率和芽长都受抑制,且浓度越大,抑制作用越强。3种小麦幼苗的抗氧化活性在不同浓度的汞污染下均降低,且浓度越大幼苗的抗氧化活性越低;当Hg+浓度达300 mg/L时,Pb2+浓度达到500 mg/L时,就会严重影响3种小麦种子的萌发情况。     

Chromosome location of genes affecting polyphenol oxidase activity in seeds of common and durum wheat

This study used cytogenetic stocks to investigate the chromosomal location of genes responsible for polyphenol oxidase (PPO) activity in common and durum wheat seeds. Substitution lines of chromosome 2A of hexaploid varieties ‘Cheyenne’, ‘Thatcher’ and ‘Timstein’ in ‘Chinese Spring’ showed significantly higher PPO activity than all other substitution lines of the same variety, with the exception of substitutions of ‘Cheyenne’ chromosome 3A and ‘Thatcher’ chromosome 4B. Substitution lines of chromosome 2A of Triticum turgidum var. dicoccoides and of chromosome 2D of ‘Chinese Spring’ into the tetraploid variety ‘Langdon’ showed a significant increase in PPO activity relative to all other substitution lines in Langdon. The gene(s) responsible for high PPO activity in chromosome 2D from ‘Chinese Spring’ was mapped on the long arm within a deletion that represents 24% of the distal part of the arm. This study shows that genes located in homoeologous group 2 play a major role in the activity of PPO in wheat.     

Effect of germination, seed abrasion and seed size on polyphenol oxidase assay activity in wheat

Polyphenol oxidase (PPO) is one of the major enzymes responsible for browning of wheat food products. Wheat cultivars differ in PPO activity and plant breeders wish to select germplasm and cultivars with low PPO activities. Prior to harvest, seeds may be exposed to conditions conducive to preharvest sprouting and mechanical damage may occur during harvesting and subsequent handling. Sprouting, mechanical damage and seed size may affect PPO assay activity and therefore impinge upon the breeder's ability to accurately select low PPO genotypes. The effects of incipient germination, mechanical abrasion and seed size on PPO assay activity were investigated using the cultivars ‘Klasic’(hard white spring, high PPO), ‘Penawawa’(soft white spring, high PPO) and ‘ID377s’(hard white spring, low PPO). The influence of embryo vs. distal portions of the seed on PPO assay activity was also examined. PPO activity was assayed with constant mixing using L‐3,4‐dihydroxyphenyl alanine (L‐DOPA) substrate at pH 6.5 at room temperature; absorbance of the reaction solution was measured at 475 nm. There was no change in PPO assay activity for seeds imbibed in water for up to 8 h. PPO assay activity increased in seeds imbibed from 8 to 16 h, and then gradually declined with increasing imbibing time. PPO assay activity initially increased as a result of mechanical abrasion but then gradually declined with increasing abrasion time. Large seeds had a higher total PPO assay activity than small seeds, but the difference in activity was not proportional to seed weight. There was only a slight difference in PPO assay activity between half‐seeds with or without the embryo. Overall, PPO assay activity in dry seeds was stable and exposure of seeds to injury and moisture did not make any significant change in PPO assay activity among the cultivars or their relative rankings.     

小麦多酚氧化酶研究进展

小麦面粉和面食品的色度是小麦磨粉品质和面食品的主要评价指标.。特别是面条、馒头、饺子、烙饼等中式食品对白度的要求相当高。.多酚氧化酶(PPO)与小麦面粉及其面食品在加工、贮藏中的褐变直接相关.。同时,多酚氧化酶种类的遗传变异和表达差异也决定小麦籽粒中的PPO总活性高低,从而直接或间接影响面粉的白度。笔者综述了近年来小麦多酚氧化酶生化机理、分布和分子生物学遗传分析以及与品质关系等方面的研究进展,并且根据多酚氧化酶的表达特性,讨论了小麦高白度新品种选育的策略。