小麦铁锌营养品质研究进展

\"隐性饥饿\",即铁、锌等微量元素缺乏症,已成为困扰我国居民的首要营养不良问题.选育高铁、锌含量、强植酸酶活性或低植酸含量的\"微量营养强化型\"小麦品种对于改善我国西部居民的营养状况具有重要的意义.本文主要介绍小麦铁锌营养品质的遗传改良研究进展,包括铁锌营养品质的相关化学组分(铁、锌、植酸和植酸酶)及改善小麦铁锌营养品质的遗传途径等两方面,并指出了小麦铁锌营养品质的研究方向和工作重点.     

小麦响应逆境胁迫的蛋白质组学研究进展

小麦生长发育过程中会受到多种逆境胁迫的影响,在胁迫条件下,小麦可通过改变自身的蛋白质表达水平对各种胁迫作出响应。蛋白质组学研究能够全面揭示小麦响应胁迫时其细胞内蛋白质的动态变化规律,鉴定差异表达的蛋白质,并发现胁迫响应相关的标志物,是小麦抗逆生物学研究的重要组成部分。本文简要综述了蛋白质组学技术在小麦响应非生物(低温、高温、干旱、盐碱)和生物(病原菌)胁迫上的最新进展,并对其应用前景进行了展望,以期为深入研究小麦响应逆境胁迫的分子机制提供参考信息。     

Variation in mineral micronutrient concentrations in grain of wheat lines of diverse origin

150 lines of bread wheat representing diverse origin and 25 lines of durum, spelt, einkorn and emmer wheat species were analysed for variation in micronutrient concentrations in grain. A subset of 26 bread wheat lines was grown at six sites or seasons to identify genetically determined differences in micronutrient concentrations. Substantial variation among the 175 lines existed in grain Fe, Zn and Se concentrations. Spelt, einkorn and emmer wheats appeared to contain higher Se concentration in grain than bread and durum wheats. Significant differences between bread wheat genotypes were found for grain Fe and Zn, but not Se concentration; the latter was influenced more by the soil supply. Grain Zn, but not Fe, concentration correlated negatively with grain yield, and there was a significant decreasing trend in grain Zn concentration with the date of variety release, suggesting that genetic improvement in yield has resulted in a dilution of Zn concentration in grain. Both grain Zn and Fe concentrations also correlated positively and significantly with grain protein content and P concentration, but the correlations with kernel size, kernel weight or bran yield were weak. The results from this study are useful for developing micronutrient biofortification strategies.     

Wheat ferritins: Improving the iron content of the wheat grain

The characterization of the full complement of wheat ferritins show that the modern hexaploid wheat genome contains two ferritin genes, TaFer1 and TaFer2, each represented by three homeoalleles and placed on chromosome 5 and 4, respectively. The two genes are differentially regulated and expressed. The TaFer1 genes are, except in the endosperm, the most abundantly expressed and regulated by iron and abscisic acid status. The promoter of TaFer1, in contrast to TaFer2, has iron- and ABA-responsive elements, supporting the expression data. The TaFer1 and TaFer2 genes encode two isoforms, probably functional different and acting in heteropolymer structures of ferritin in cereals. Iron biofortification of the wheat grain is possible. Endosperm targeted intragenic overexpressing of the TaFer1-A gene results in a 50–85% higher iron content in the grain.     

小麦类成束阿拉伯半乳糖蛋白编码基因TaFLA的克隆与表达分析

为研究类成束阿拉伯半乳糖蛋白编码基因Fasciclin-Like Arabinogalactan-protein(FLA)在小麦抗逆境胁迫和花药发育中的作用,利用同源克隆法从小麦中获得1个FLA基因,命名为TaFLA,并对其组织表达特性和逆境胁迫表达特性分别进行了分析。序列分析结果表明,TaFLA基因含有1个1 530 bp的完整开放阅读框,编码509个氨基酸;TaFLA蛋白含有预测的N-末端信号肽,两个Fasciclin结构域(氨基酸205-300、371-474)和两个N-糖基化位点(氨基酸369和487)。系统演化分析结果表明,TaFLA基因与二粒小麦处于同一分支,其亲缘关系最近。荧光定量表达分析结果表明,TaFLA基因在小麦根、小穗(除去雄蕊)、减数分裂前和分裂时期的雄蕊中均有表达,其中,小穗(除去雄蕊)中表达量最高;在低温胁迫处理下,TaFLA基因表达上调,而在干旱、高盐和ABA处理下,表达量均有所下降;温敏雄性不育系BS366在不育环境(低温)下,TaFLA基因在雄蕊发育关键时期(二分体时期)大量表达,约为可育环境(高温)下表达量的29倍。     

小麦糖转运蛋白基因 TaSWEET6的克隆与表达分析

植物SWEET基因家族是一类糖转运蛋白,参与生殖发育、衰老、逆境响应等多个生理过程。为研究小麦SWEET基因对逆境胁迫的响应及其在花药发育过程中的功能,采用同源克隆的方法从普通六倍体小麦中克隆出TaSWEET6基因(GenBank登录号为KU936097)后对其进行染色体定位、同源蛋白序列比对和系统进化树分析,同时分析TaSWEET6基因于普通六倍体小麦在正常生长情况下及非生物胁迫条件下不同组织器官中和光温敏雄性不育小麦BS366在不同发育时期的花药中的表达模式。序列分析结果表明,TaSWEET6基因包含1个732bp的完整开放阅读框,编码243个氨基酸。跨膜结构分析得知,TaSWEET6蛋白包含2个Mtn3_slv跨膜结构域和1个起连接作用的跨膜-螺旋。系统进化树分析表明,TaSWEET6蛋白与大麦处于同一分支,其亲缘关系最近。中国春缺四体定位表明,TaSWEET6基因位于7D染色体上。表达分析表明,TaSWEET6基因在小麦根、茎、叶、种子、小花(除去雄蕊)、各时期雄蕊中均有表达,小孢子时期雄蕊表达量最高;在低温、干旱、NaCl和ABA胁迫处理下,TaSWEET6基因表达均有上调;光温敏雄性不育系BS366在不育环境(低温短日照)下,TaSWEET6基因在雄蕊发育关键时期(二分体时期)高度表达。说明小麦TaSWET6基因可能参与了多种逆境应答反应,并在小麦雄蕊发育过程中发挥着重要作用。     

植物对铁元素吸收、运输和储存的分子机制

铁是植物生长发育所必需的微量矿物元素之一.随着土壤盐碱化程度加剧,植物缺铁现象愈发普遍,导致作物产量和品质降低,进而影响人们的营养健康.植物在长期的进化过程中,形成了较完善的铁吸收和利用系统.本文对植物铁吸收、运输和储存等方面的研究现状进行了综述,总结了近年来通过生物加强提高植物铁元素含量和环境适应性的研究成果,并对未来可能的研究领域提出了展望.     

小麦SnRK2家族基因鉴定及进化分析

SnRK2是一种植物特异性的丝氨酸/苏氨酸蛋白激酶,在植物生长发育和胁迫耐受信号传递过程中发挥着至关重要的作用。为探索SnRK2在小麦抗逆中的作用,基于最新的小麦基因组信息,采用blastp和hmmer两种方法在普通小麦中共鉴定到30个SnRK2基因家族成员。系统发育分析表明,SnRK2基因在普通小麦及其祖先物种的进化过程中高度保守。利用RNA seq数据分析小麦SnRK2基因在不同组织以及不同胁迫条件下的表达模式,结果表明,小麦SnRK2基因家族成员在不同组织以及不同胁迫条件下表达量均存在差异,且具有显著的组织特异性。通过qRT PCR进一步验证6个小麦SnRK2基因的表达模式,发现不同基因之间的表达量存在明显差异,推测小麦SnRK2基因家族的部分成员出现功能分化。随后,利用已发表的六倍体小麦重测序数据,分析不同小麦群体中SnRK2基因的核苷酸多样性(P_i)和分化指数(F_st),并解析单倍型,推测Ta 5B SnRK2.28基因的AA单倍型为优异等位变异。通过同源建模预测小麦SnRK2蛋白的三维结构,发现小麦SnRK2蛋白结构在进化上高度保守。     

小麦SPL家族基因在非生物胁迫下的表达分析

SQUAMOSA promoter binding protein like(SPL)是一类在植物中广泛存在的转录因子家族,在调控植物生长发育、响应逆境胁迫等方面发挥着重要作用。为解析小麦中SPL家族基因响应非生物胁迫的机理,本研究采用生物信息学的方法在全基因组范围内对小麦SPL基因家族成员进行鉴定,并对鉴定到的SPL基因进行表达模式分析。结果表明,在全基因组范围内共鉴定到56个小麦SPL基因,其中27个是miR156的靶基因;系统进化分析发现,56个小麦SPL基因聚类为7个亚家族。基于转录组数据对表达模式进行分析,发现36个小麦SPL基因与非生物胁迫响应相关,响应缺氮、缺磷、高盐、低温、干旱、高温胁迫以及热旱共胁迫的基因分别有12、16、22、6、13、14和21个,其中TraesCS3D02G425800同时响应7种非生物胁迫。qRT PCR验证结果与转录组数据基本一致。     

Phytase activity, phytate, iron, and zinc contents in wheat pearling fractions and their variation across production locations

Pearling is an effective method for evaluating the distribution of chemical components in wheat grain. Twelve pearling fractions (P₁–P₁₂) of wheat grain were obtained using two rice polishers for 10 cultivars (six soft red wheats and four hard white wheats) grown at two locations with different environmental conditions in Jiangsu Province, China. The results show that the effects of cultivar, location, and pearling on wheat flour phytase activity, phytate, iron, and zinc contents were all significant, with pearling having the greatest effect. All the four components showed a diminishing trend as pearling progressed from the outer layers to the inner part of wheat grain. Generally, the P₂ fraction (the outer 4–8% layer of wheat grain) had the highest phytase activity and phytate and iron contents, whereas the P₁ fraction (the outer 0–4% layer) ranked the highest for zinc content. Growing location had a large influence on grain phytase, phytate, and iron, but the differences between locations decreased as pearling level increased.     

小麦苗期对非生物胁迫的响应及叶绿体果糖 1,6 二磷酸醛缩酶基因的表达分析

叶绿体果糖-1,6-二磷酸醛缩酶(Chloroplast Fructose-1,6-bisphosphate aldolase,CpFBA)参与叶绿体(质体)的碳、氮代谢,在光合作用中具有重要功能,并能对植物的非生物胁迫产生积极响应.为了深入研究小麦CpFBA的生物学功能和对外界逆境的响应模式,以矮变1号、返白系、中国春、西农928、西农2000和晋麦47等六个不同生理特性的小麦品种(系)为材料,分析其在低温、NaCl、PEG模拟干旱和ABA处理下最大叶长和主根根长受到的影响,并采用半定量RT-PCR的方法研究小麦幼苗中CpFBA基因表达模式的变化.结果表明,各种外界非生物胁迫均不同程度的抑制了小麦幼苗叶片和根的生长,其中低温和ABA处理的抑制最为显著.在各种处理条件下,小麦幼苗CpFBA均有明显的上调表达,但不同品种间存在差异,表达模式的改变与品种的生理特性之间表现出一定的相关性.     

植物内生菌对大豆促生长和抗胁迫作用的研究进展

植物内生菌是指在其生活史或一段生活史在植物体内并对植物无明显病害的一类微生物。内生菌不仅具有自身特有的生存机制,而且对植物的生长发育具有重要作用。随着分子生物学技术的不断进步,人们将分离的植物内生菌转染于大豆植株,通过对大豆在遭受生物和非生物胁迫下叶片光合参数、酶活性、相关基因表达水平及生物量的测定,来分析植物内生菌对大豆生长的影响。本研究综述了植物内生菌的多样性以及近年来植物内生菌在非生物胁迫下如干旱、盐胁迫、重金属等和生物胁迫下如病虫害对大豆生长发育影响的研究进展,并对内生菌应用的前景进行了展望。     

小麦籽粒矿质元素的基因型差异及对锌强化的响应

为了分析锌强化对不同小麦品种籽粒矿质元素含量的影响,以40个不同小麦品种(系)为材料,在扬花期叶面喷施0.5%的Zn肥,用原子吸收光谱法测定Zn处理与不处理(对照)下不同小麦品种籽粒中6种矿质元素(Zn、Fe、Ca、Mg、Cu、Mn)的含量,并分析这些元素对Zn强化的响应。结果表明,Zn处理后各品种籽粒中Zn含量均比对照有极显著上升,但上升幅度因品种而异。籽粒中Fe、Ca、Mg、Cu、Mn含量对Zn强化的响应因元素种类和品种而异,就品种平均值而言,Mn含量在Zn处理和对照间有极显著差异,Fe、Mg和Cu含量在处理与对照间无显著差异。大部分品种Zn处理后籽粒Ca含量有所下降,Mn则有所增加。对施Zn和对照间被测矿质元素的变幅进行主成分分析,前三个主成分(PC1、PC2、PC3)累积贡献率为0.76,基于前三个主成分对40个品种(系)进行类平均法的聚类分析,将40个品种分为3类:第1类包含有8个品种,Zn处理后籽粒中Ca、Mg、Cu、Fe含量总体呈现降低趋势,而Mn、Zn含量呈增高趋势;第2类包含23个品种,Zn处理后籽粒Ca、Cu含量总体有一定的降低,其余4种元素含量则有一定幅度的提高;第3类共有9个品种,施Zn后Fe含量总体有一定幅度的降低,其余5种元素含量则有一定幅度的增加。来自第2类和第3类中的12个品种在Zn处理后所测定的全部6种元素或者其中大部分元素的含量提高,适宜进行Zn强化,而其余品种Zn强化后部分或全部元素(Zn除外)与对照相比有所下降,不宜作为Zn营养强化的载体品种。     

Changes in micro- and macronutrient composition of pearl millet and white sorghum during in field versus laboratory decortication

Traditional decortication of pearl millet and white sorghum by hand pounding or using a mechanical device were performed in Burkina Faso, and compared to abrasive decortication in the laboratory using the same kernel lots. Using some nutrients as histological markers, the decortication characteristics and nutritional composition (iron, zinc, phytates, lipids, ADF fibres and starch) of decorticated grains were measured. Decortication had numerous effects on grain composition but no significant differences were observed between the two traditional methods of decortication. The effects varied according to the type of grain mainly due to the fact that more germ was removed in sorghum than in millet, as the millet germ is more embedded in the endosperm. During abrasive decortication, zinc and lipid losses increased rapidly due to removal of the germ, particularly in sorghum. Phytates were shown to be located mainly in the bran and germ but also in the endosperm in millet. In both sorghum and millet, half the iron was removed when only 10% of grain DM was abraded. The method of decortication, shock or friction vs. abrasion, influenced the fractions removed and thus the chemical composition of the decorticated kernels.     

Double fortification of sorghum (Sorghum bicolor L. Moench) and finger millet (Eleucine coracana L. Gaertn) flours with iron and zinc

Finger millet and sorghum flours were used as vehicles for double fortification with ferrous fumarate, zinc stearate and EDTA. The iron and zinc salts were added at levels that provided 60 mg iron and 50 mg zinc per kg of flour. EDTA was added at levels equimolar to the added iron. The double-fortified finger millet and sorghum flours contained bioaccessible zinc contents of 0.83 and 1.63 mg/100 g, respectively, while the respective bioaccessible iron contents were 2.39 and 2.63 mg/100 g. The exogenous iron and zinc did not mutually interfere with their bioaccessibility. The shelf-life of the fortified flours was also satisfactory up to a period of 60 days, as indicated by the moisture and free fatty acid contents in the fortified flours. Double fortification of the millet flours did not negatively alter the sensory quality of the products prepared from them. The RDA for iron and zinc of Indian children, women and men can be sufficiently met with approximately 4 dumplings or 9 rotis. The use of such qualitatively and quantitatively rich flours can be promoted through welfare programs to reduce and subsequently eradicate iron and zinc deficiency.     

小麦 TaCP3基因的克隆及其参与非生物胁迫的表达分析

半胱氨酸蛋白酶(cysteine protease,CP)是植物中重要的蛋白酶家族之一,广泛参与植物的各种生理过程;TaCP3属于papain-like(木瓜蛋白酶)家族的半胱氨酸蛋白酶,在小麦的生长发育及抗逆中起到重要作用。为研究 TaCP3基因的结构特征,以及在干旱、高盐、低温和高温胁迫下的表达情况,从小麦抗旱品种西农538中克隆了 TaCP3基因,该基因仅含1个1125 bp的开放阅读框,编码374个氨基酸,在蛋白氨基端有一个28个氨基酸残基组成的信号肽,羧基端具有木瓜蛋白酶亚家族的保守结构域。生物信息学分析表明, TaCP3与大麦和山羊草半胱氨酸蛋白酶基因相似性最高。同时,本研究构建了pcold-TF/TaCP3原核表达载体,通过转化大肠杆菌BL21(DE3),成功表达了TaCP3重组蛋白,分子量约为40 kD。qRT-PCR结果表明, TaCP3的表达对干旱、高盐、低温和高温胁迫均有响应,初始都呈先降后升的趋势;且对干旱胁迫有强烈的正向响应。