Genetic variation of bioavailable iron and zinc in grain of a maize population

More than one-third of the world's population is afflicted by iron (Fe) and zinc (Zn) deficiencies, since cereal grain as a staple food of the people contains low levels or low bioavailability of Fe and Zn because of phytate. In maize, 80% of grain phosphorus (P) is in the form of phytate, and P could be an indicator of phytate content. The objectives of this study were (1) to estimate genetic variation of Fe and Zn in a maize population including P/Fe and P/Zn molar ratios as quantitative traits; (2) to determine relations among yield, P, Fe, Zn, P/Fe and P/Zn molar ratios; and (3) to define the implications of those on biofortification (breeding) programmes. There were significant genetic variations and workable heritabilities for Fe, Zn, P/Fe and P/Zn estimated in 294 F4 lines of a maize population, but there were no associations among six traits according to both simple correlations and principal component analysis. Weak correlations between P and Fe and between P and Zn indicated feasibility of breeding non low-phytic acid maize genotypes with more appropriate phytate/Fe and phytate/Zn relations. Bioavailability of iron and zinc varied substantially in a maize population justifying utilisation of these unique parameters in biofortification programmes.     

Enhancing the mineral and vitamin content of wheat and maize through plant breeding

More than half of the world's population suffers micronutrient undernourishment. The main sources of vitamins and minerals (iron, zinc, and vitamin A) for low-income rural and urban populations are staple foods of plant origin that often contain low levels or low bioavailability of these micronutrients. Biofortification aims to develop micronutrient-enhanced crop varieties through conventional plant breeding. HarvestPlus, the CGIAR's biofortification initiative, seeks to breed and disseminate crop varieties with enhanced micronutrient content that can improve the nutrition of the “hard to reach” (by fortification or supplementation programmes) rural and urban poor in targeted countries/regions. In attempting to enhance micronutrient levels in maize and wheat through conventional plant breeding, it is important to identify genetic resources with high levels of the targeted micronutrients, to consider the heritability of the targeted traits, to explore the availability of high throughput screening tools and to gain a better understanding of genotype by environment interactions. Biofortified maize and wheat varieties must have the trait combinations which encourage adoption such as high yield potential, disease resistance, and consumer acceptability. When defining breeding strategies and targeting micronutrient levels, researchers need to consider the desired micronutrient increases, food intake and retention and bioavailability as they relate to food processing, anti-nutritional factors and promoters. Finally, ex ante studies are required to quantify the burden of micronutrient deficiency and the potential of biofortification to achieve a significant improvement in human micronutrient status in the deficient target population in order to determine whether a biofortification program is cost-effective.     

Enhancing the mineral and vitamin content of wheat and maize through plant breeding

More than half of the world's population suffers micronutrient undernourishment. The main sources of vitamins and minerals (iron, zinc, and vitamin A) for low-income rural and urban populations are staple foods of plant origin that often contain low levels or low bioavailability of these micronutrients. Biofortification aims to develop micronutrient-enhanced crop varieties through conventional plant breeding. HarvestPlus, the CGIAR's biofortification initiative, seeks to breed and disseminate crop varieties with enhanced micronutrient content that can improve the nutrition of the “hard to reach” (by fortification or supplementation programmes) rural and urban poor in targeted countries/regions. In attempting to enhance micronutrient levels in maize and wheat through conventional plant breeding, it is important to identify genetic resources with high levels of the targeted micronutrients, to consider the heritability of the targeted traits, to explore the availability of high throughput screening tools and to gain a better understanding of genotype by environment interactions. Biofortified maize and wheat varieties must have the trait combinations which encourage adoption such as high yield potential, disease resistance, and consumer acceptability. When defining breeding strategies and targeting micronutrient levels, researchers need to consider the desired micronutrient increases, food intake and retention and bioavailability as they relate to food processing, anti-nutritional factors and promoters. Finally, ex ante studies are required to quantify the burden of micronutrient deficiency and the potential of biofortification to achieve a significant improvement in human micronutrient status in the deficient target population in order to determine whether a biofortification program is cost-effective.     

Grain cadmium and zinc concentrations in wheat as affected by genotypic variation and potassium chloride fertilization

Thirteen bread wheat (Triticum aestivum L.) and two durum wheat (Triticum turgidum L. var. durum) cultivars were grown over six site-years to identify differences in grain Cd and Zn concentrations, as affected by genotypic variation and soil application of potassium chloride (KCl) fertilizer. Application of KCl fertilizer did not consistently affect grain Cd concentration of wheat cultivars, but increased average grain yield and decreased average grain Zn in 4 of 6 site-years. However, soil type and year had significant effects on grain Cd and Zn, indicating a strong environmental effect on grain quality. Grain concentrations of Cd and Zn were generally lower for the clay loam (CL) than the fine sandy loam (FSL) soils. The wheat cultivars showed significant genotypic differences in grain concentrations of Cd and Zn, suggesting the potential of breeding to reduce Cd and increase Zn concentrations in grain. The two durum cultivars contained high concentrations of Cd but not Zn compared to the bread wheat. The interaction between cultivars and site-years was significant for grain Zn, but not for grain Cd, suggesting that grain Cd is a more stable trait than grain Zn across environments. Grain Zn and Cd were not related to each other but they both correlated negatively with grain yield. The lack of relationship between Zn and Cd suggests that breeding for enhanced Zn concentration can be attained without necessarily affecting grain Cd concentration. The negative relationship between Cd and Zn concentration and dry matter yield was likely the result of biological dilution, suggesting that genetic improvement leading to increased yield may concurrently decrease mineral concentration. Results of this study are useful to improve the mineral composition of wheat used for human consumption through the development of cultivars and use of agronomic management practices that increase Zn and/or reduce Cd concentrations in wheat grain.     

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.     

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。     

18个黄淮海地区推广冬小麦品种的遗传多样性分析

为给小麦育种中种质资源的合理使用提供信息参考,利用78对核心SSR引物对参试的18个小麦品种进行了基因组扫描,并通过ntsys 2.11软件对其4个农艺性状、5个品质指标和SSR标记进行了聚类分析。78对引物在18个品种中扩增出268条多态性带,每个引物2~9条,平均3.44条。18个品种可分为2大类群,第Ⅰ类包括13个品种,第Ⅱ类包括5个品种。第II类的农艺和品质指标都比第Ⅰ类高,其中面团稳定时间与第Ⅱ类差异明显,平均为13.2min。聚类结果和品种之间的亲缘关系相吻合。18个品种的遗传相似系数范围为0.55~0.86,平均为0.67。参试小麦品种存在一定的异质性,但差异较小,遗传基础狭窄。     

Effect of drought and elevated temperature on grain zinc and iron concentrations in CIMMYT spring wheat

Abiotic stress caused by increasing temperature and drought is a major limiting factor for wheat productivity around the world. Wheat plays an important role in feeding the world, but climate change threatens its future harvest and nutritional quality. In this study, grain iron (Fe) and zinc (Zn) concentrations of 54 wheat varieties, including CIMMYT derived historic and modern wheat varieties grown in six different environmental conditions, were analyzed. The objective of the study was to evaluate the effect of water and heat stress on the nutritional value of wheat grains with a main emphasis on grain protein content, Zn and Fe concentrations. Significant effects of environment on protein content and grain micronutrients concentration were observed. The protein and Zn concentrations increased in the water and heat stressed environments, whereas Zn and Fe yield per unit area was higher in non-stress conditions. The results suggest that genetic gains in the yield potential of CIMMYT derived wheat varieties have tended to reduce grain Zn, in some instances; however, environmental variability might influence the extent to which this effect manifests itself.     

小麦籽粒微量元素含量的研究进展

以禾谷类作物为主食引起的人体摄取必需微量元素(特别是Fe和Zn)不足,已对现代社会和谐发展造成沉重的经济负担和安全隐患。小麦(Triticum aestivumL.)是中国和全球大多数人主要的食物和矿质元素来源。小麦籽粒中Zn、Fe含量普遍较低,已引起国内外学者们的高度关注。本文综述了小麦籽粒微量元素含量器官间、基因型间的差异及其影响因素和相关性状研究进展,介绍了小麦籽粒吸收和富集微量元素的生理与遗传基础,展望了提高小麦籽粒微量元素的研究内容和方向。     

北部冬麦区旱地小麦品种的演变规律

为了给北部冬麦区旱地小麦育种提供参考,利用1986-2015年国家北部冬麦区旱地小麦长治区试点参试品种的试验资料,研究其演变规律,并对产量和主要农艺性状进行相关和通径分析。结果表明,28年间北部冬麦区旱地小麦品种产量呈逐年递增趋势,年平均遗传进展分别为68.163kg·hm~(-2)或1.57%。主要农艺性状演变的总趋势是,有效穗数和千粒重增加,穗粒数略有减少,株高降低,抽穗期和成熟期提前,灌浆期延长,其年平均遗传进展分别为0.18%、0.26%、-0.03%、-0.26%、-0.12%、-0.05%、0.17%。从产量及主要农艺性状变化趋势和变异情况及区域布局、气候条件和育种现状分析,选育抗旱节水性好、高产稳产适应性广的品种是北部冬麦区旱地小麦育种面临的挑战和最终目标。为了适应当前耕作制度、生产条件和气候变化的影响,北部冬麦区旱地品种选育应在加强品种抗旱节水性选择的基础上,通过适当降低株高增强抗倒性来进一步增加穗数,通过选育穗子较大、小穗数适中、结实性好的品种来提高穗粒数,通过选择灌浆期长且灌浆速率高的品种来提高品种的千粒重。     

小麦抗纹枯病种质资源的鉴定与评价

为了筛选小麦纹枯病稳定抗源,在对国内外小麦种质资源初选的基础上,采用人工病麦粒接种法对114份小麦品种纹枯病抗性进行了连续3年的鉴定.结果表明,在参试品种中未发现免疫或高抗纹枯病材料,大部分为中抗材料,共筛选出包括Niavt 14、剑子麦、新麦26在内的37份稳定抗和中抗纹枯病种质.在这些抗病材料中,13份为国内改良品种,7份为国内地方品种,17份为国外引进品种.其中国内改良品种农艺性状较好,可直接用于抗病育种,国内地方品种和国外品种农艺性状较差,需要进一步改良后用于抗病育种.     

2004-2022年甘肃省审定小麦品种情况分析与展望

为了给甘肃省高产优质小麦新品种的选育提供参考依据，对以甘肃省2004-2022年审定的284个小麦品种的基本情况和抗条锈病性进行了分析，并统计了生育期、株高和产量水平。结果表明，甘肃省近19年审定的小麦品种数量呈现波动上升趋势，育种单位主力为省内科研院所，联合育种呈现波动上升趋势，表明科研工作者对小麦品种选育具有较高的积极性；通过高使用频率直接亲本统计分析，发现甘肃省审定的小麦品种亲本配置组合主要来自主栽品种和人工创制的种质资源，并发现5个高使用频率直接亲本，表明近19年甘肃省审定品种遗传基础较窄；育成品种主要采用的育种方式为杂交育种，且育种方式趋于单一，表明今后要加强创新育种方式；审定的小麦品种以冬小麦为主，其中80.2%集中在陇东泾河上游川塬山地冬小麦区和陇南渭河上游河谷山地冬小麦区，而审定的春小麦97.9%则集中在河西内陆河灌溉春小麦区和陇中干旱川山春小麦区；小麦抗病性方面，审定品种对条锈病的抗性水平相对较好，但年际间波动较大；春小麦生育期年平均增加0.15 d，而冬小麦生育期年平均减少0.46 d；株高年平均降低1.10 cm，平均产量呈逐年上升趋势，年均增长47.25 kg·hm^-2，其中2012年产量最高，为8 136.2 kg·hm^-2；千粒重、穗粒数和有效穗数均呈现逐渐上升趋势，但穗粒数变化不大，年均增加0.08粒，千粒重年均增加2.71 g，有效穗数年平均增加1.29个。综上，在后续的育种工作中，可结合不同育种方式，更进一步选育出高产、优质和高抗的小麦新品种。     

不同国家小麦种质资源遗传多样性研究

为有效利用国外引进的小麦种质资源,采用多样性指数、变异系数和聚类分析等方法,对来自6个国家的728个小麦品种(系)19个性状的遗传多样性进行了分析.结果表明,智利小麦的穗粒数多,蛋白质含量高,生育期偏长;中国小麦的粒重高,植株偏低;俄罗斯小麦的单株穗数多;墨西哥小麦的面粉吸水率高;荷兰小麦对白粉病的抗性好.中国小麦的6个产量性状和4个品质性状、俄罗斯小麦的植株性状、墨西哥小麦对黄矮病的抗性及澳大利亚小麦对白粉病的抗性变异类型丰富.荷兰小麦的6个产量性状、中国小麦的植株性状和俄罗斯小麦的4个品质性状变异程度最大.聚类分析表明,中国、智利和澳大利亚等3个国家小麦种质资源的变异类型较多,而俄罗斯种质资源变异类型较少;上述6个国家在育种过程中相互利用了彼此的种质资源,但各自的种质资源均具有独特的遗传特点.由此说明,从不同国家引进的小麦种质资源既可以改良中国小麦品种的农艺性状、品质性状和抗病性,也有助于拓宽中国小麦种质资源的遗传基础.     

Genetic diversity for grain nutrients contents in a core collection of finger millet (Eleusine coracana (L.) Gaertn.) germplasm

Finger millet is a promising source of micronutrients and protein besides energy and can contribute to the alleviation of iron (Fe), zinc (Zn) and protein malnutrition affecting women and preschool children in African and south-east Asian countries. The most cost effective approach for mitigating micronutrient and protein malnutrition is to introduce staple crop cultivars selected and/or bred for Fe, Zn and protein dense grain. Breeding finger millet for enhanced grain nutrients is still in its infancy. Analysis, detection and exploitation of the existing variability among the germplasm accessions are the initial steps in breeding micronutrient and protein-dense finger millet cultivars. Evaluation of finger millet core collection for grain nutrients and agronomic traits revealed a substantial genetic variability for grain Fe, Zn, calcium (Ca) and protein contents. The accessions rich in nutrient contents were identified and their agronomic diversity assessed. The accessions rich in Zn content have significantly higher grain yield potential than those rich in Fe and protein content. Grain nutrient-specific accessions and those contrasting for nutrient contents were identified for use in the strategic research and cultivar development in finger millet.     

山西省优质小麦品种系谱分析及品质遗传改良

对山西省几个优质小麦品种进行了系谱追溯，分析了其优质性状及其它主要农艺性状的遗传来源。结果认为，这些优质品种多有国外血统，遗传基础丰富；但优质品种间亲缘关系近，优质源利用单调。在优质育种中应重视不同优质源的利用，尤其异质优质源的结合，在小麦品质性状改良上，既要重视蛋白质含量，也要重视蛋白质质量即优质亚基组成。     

不同小麦品种氮素利用效率特征差异的研究

为了给氮高效优质小麦品种的选育和栽培提供理论依据,采用盆栽试验,研究了郑麦0943、郑麦0856和郑麦7698三个中强筋小麦品种的氮素利用效率特征以及茎叶中氮组分、氮代谢酶活性的差异。结果显示,施氮可显著促进小麦氮素的吸收和累积,不同小麦品种氮素利用效率特征存在明显差异。3个小麦品种中,郑麦0943氮素吸收量最大,氮素吸收效率和氮素利用效率均较高,氮素收获指数也显著高于其他两个品种,且籽粒中氮素来源以后期根系氮素的吸收和转移为主,前期地上部营养体的氮素转移能力也明显强于其他两个品种;不施氮条件下,郑麦0943开花期茎叶中具有较高的营养性氮含量和较低的结构性氮和功能性氮含量,且施氮后功能性氮含量增幅最大,硝酸还原酶和谷氨酰胺合成酶活性也最高;不施氮条件下,郑麦7698氮素干物质生产效率和氮素收获指数均最低,郑麦0856氮素干物质生产效率最高,但氮素收获指数低于郑麦0943。综合而言,郑麦0943的氮肥生产效率最高,而郑麦0856的氮素农学利用效率最高,二者的氮素吸收效率和氮素表观回收率均高于郑麦7698。     

控释氮肥施用策略对稻茬小麦产量和氮肥吸收利用的影响

为探究控释氮肥施用策略对稻茬小麦产量和氮肥吸收利用的影响,在大田条件下,以小麦品种扬麦16和扬麦20为材料,设置不施氮（T1）、常规速效氮肥分次施用（T2,对照）、常规控释氮肥一次性基施（T3）、速效氮肥减量分次施用（T4）、控释氮肥减量一次性基施（T5）、控释+速效氮肥一次性基施（T6）、控释+速效氮肥配合分次施用（T7）共7种氮肥处理,比较分析了不同处理下稻茬小麦产量、叶面积指数（LAI）、叶绿素相对值（SPAD值）、干物质积累量、氮素积累量、根系吸收面积和根系氧化力等性状的差异。结果表明,两个品种的产量均表现为T6>T7>T3>T5>T2>T4>T1。与T2处理相比,两个品种的平均产量在T3、T6和T7处理下分别增加17.9%、30.3%和25.1%,平均氮肥农学效率（AE）分别增加40.0%、84.8%和72.4%,平均氮肥偏生产力（PFP）分别增加22.2%、52.3%和45.6%。与单一施用速效氮肥（T2、T4）或控释氮肥（T3、T5）处理相比,在控释氮肥与速效氮肥配施（T6、T7）处理下两个品种的地上部农艺性状（干物质积累量、LAI和SPAD值）显著改善,氮素积累量、根干重、根冠比、根系氧化力、根系总吸收表面积和活跃吸收表面积均显著增加。因此,控释氮肥配施速效氮肥策略可以同步促进稻茬小麦地上部与地下部生长,最终实现高产与氮肥高效吸收利用。     

部分春性和半冬性小麦品种氮效率差异分析

为了解小麦冬春性与氮素利用的关系,在大田条件下,以江苏省主栽的15个小麦品种为材料,比较了半冬性和春性小麦的氮效率差异。结果表明,相同施氮条件下,半冬性小麦的平均氮肥吸收效率(NUEa)和氮肥生产效率(NGPE)分别比春性小麦高12.19%和9.64%,差异均达显著水平。其中,NUEa和NGPE最高的半冬性小麦品种均为济麦22,春性小麦两个指标最高的品种均为扬麦15。半冬性小麦的平均氮肥表观利用率(NUR)、氮肥农学效率(NAE)、氮素生理效率(NPE)及氮收获指数亦高于春性小麦,但差异均不显著。半冬性或春性类型小麦中各指标都存在氮高效和氮低效的品种,且品种间差异均极显著;不同品种氮效率高或低的机制不同,使得对氮肥的吸收、利用、转运的能力存在差异,生产中应根据不同品种氮效率机制特点采用不同的施肥应对策略。     

黄淮麦区小麦倒春寒危害机理及防控措施研究进展

倒春寒是限制黄淮麦区冬小麦高产稳产的主要因素之一。本文基于当前研究现状,从细胞膜系统、光合作用、呼吸作用、活性氧代谢、渗透调节物质以及内源激素代谢等方面阐述了倒春寒对小麦的危害机理,提出可以采取选育耐寒品种、水肥管理和应用外源化学调控物质等农艺措施防控倒春寒。建议在今后的小麦倒春寒研究中,应充分运用分子生物学等相关技术辅助传统育种,加快耐倒春寒小麦品种的选育;通过植物建模技术、高通量表型平台等作物表型组学相关技术深入研究倒春寒的致灾机理和响应机制,探讨小麦对倒春寒响应的敏感时段、耐性范围以及灾害的防控指标,研发减灾保产的关键栽培技术体系;最后,应综合考虑多重逆境叠加的影响。本文为找到更有效的倒春寒综合防控方法提供了新的思路。