小麦-滨麦2D/2Ns异代换系DM2411的分子细胞遗传学鉴定

为进一步挖掘利用滨麦优异基因,并丰富小麦遗传种质资源,利用形态学、细胞遗传学、基因组原位杂交(Genomic in situ hybridization,GISH)、EST-STS分子标记、SSR分子标记等技术,对从八倍体小滨麦M842-16和硬粒小麦D4286杂交F_7代材料中筛选出的1个遗传稳定的小滨麦异代换系DM2411进行了鉴定。细胞遗传学观察表明,DM2411的染色体主要构型为2n=42=21Ⅱ,遗传稳定。根尖体细胞和花粉母细胞的原位杂交研究表明,DM2411含有1对滨麦Ns基因组。SSR分析表明,DM2411可能缺失了小麦2D染色体。EST分析表明,DM2411可能含有滨麦2Ns染色体。形态学调查表明,DM2411的株高极显著降低。     

高砷煤矿污染土壤的小麦砷累积研究

为了解砷污染土壤对小麦品质的影响及食用砷污染土壤种植的小麦对人群健康的影响,以贵州省兴仁县交乐高砷煤矿区砷污染农田的土壤-小麦系统为研究对象,采用氢化物发生-原子荧光光度法测定土壤和小麦砷含量,并对砷污染土壤及小麦中砷分布特征进行研究。结果表明,受污染农田土壤(区域Ⅰ、区域Ⅱ)的砷含量显著高于周边未受污染农田(区域Ⅲ),区域Ⅰ土壤pH值最低(4.57),土壤砷含量分别是区域Ⅱ、区域Ⅲ的1.94和2.13倍,土壤砷含量与土壤pH值呈显著负相关关系;区域Ⅰ小麦样品不同器官的砷含量为1.37mg·kg~(-1)(根)、0.74mg·kg~(-1)(茎叶)、0.85mg·kg~(-1)(籽粒);受试样品中,67%的小麦籽粒砷含量高于GB2762-2012中规定的小麦砷含量限值(0.5mg·kg~(-1))。采用USEPA推荐健康风险评价模型对当地居民以小麦为砷摄入途径的健康风险评价结果显示,区域Ⅰ、区域Ⅱ小麦的HQ值分别为2.82和1.19,区域Ⅲ为0.97。受试土壤砷污染已对小麦品质产生影响,食用矿区附近砷污染农田种植的小麦可能对居民健康有影响。     

PEG胁迫对不同小麦品种幼苗抗旱生理指标的影响

为给小麦抗旱育种的早期筛选工作提供理论依据,以济麦262(抗旱型)、烟农19(中间型)和临麦2号(水分敏感型)为材料,采用PEG模拟干旱胁迫,探究干旱胁迫对不同小麦品种幼苗生物量、含水量、根系形态特征、抗氧化酶活性和叶绿素荧光参数的影响。结果表明,PEG胁迫下,三个品种中济麦262的生物量最大,地下部含水量显著高于临麦2号和烟农19;其根系的总长、总投影面积、总面积和总体积最大,且受抑制程度最低;其抗氧化酶活性在一定程度上明显增强,尤其是叶片和根系过氧化物酶、根系超氧化物歧化酶及叶片过氧化氢酶活性增强幅度显著高于临麦2号和烟农19;其叶片光化学荧光淬灭系数(qP)和PSⅡ的实际光化学效率与CK相比均呈下降的趋势,其中qP下降程度最低,荧光非光化学淬灭显著增强且高于其他两个品种。综上所述,在PEG胁迫下抗旱品种的生长受抑制程度最小,清除氧自由基能力较强,光能利用率高。     

小麦雄性不育系AL18A育性恢复基因的QTL定位

为加快AL型杂交小麦的发展,以不育系AL18A、恢复系99AR144-1及二者杂交F2代群体为材料,选用SSR标记和分离群体分组分析法进行育性恢复基因的QTL定位。结果表明,育性恢复由主效和微效基因共同控制,采用复合区间作图法分析,在1B染色体上检测到了1个主效恢复基因QTLqRf-1B-1,在5AL染色体上检测到了1个微效QTLqRf-5A-1。qRf-1B-1位于SSR标记Xbarc8与Xgwm413之间,与两标记的遗传距离分别为0.85cM和2.00cM,LOD值为14.06,加性效应为18.87,可解释22.43%的表型变异;qRf-5A-1位于SSR标记Xgwm595与Xgwm410之间,与两标记的遗传距离分别为10.00cM和0.10cM,LOD值为3.18,加性效应为12.32,可解释5.44%的表型变异。     

小麦旗叶大小及穗部相关性状的QTL定位

为了发掘更多控制小麦旗叶大小及穗部相关性状的QTL,以兰考906和小偃81创制的133个F6~F7重组自交系为试验材料,在6个环境下利用SSR标记对旗叶大小及穗部相关性状进行QTL定位。结果表明,有202对SSR标记被用于构建遗传连锁图谱,图谱覆盖小麦21条染色体,全长1 678.93cM,标记间平均距离8.30cM。采用完备区间作图法共检测到30个QTL,分布在1B、2A、3D、4A、4B、4D、5D、6A、6B、6D和7D染色体上。其中,旗叶宽QTL有7个,穗长QTL有9个,小穗数QTL有5个,穗粒数QTL有5个,小穗着生密度QTL有4个,不同环境下单个QTL可解释的表型变异率为4.94%~23.14%,有14个QTL的表型贡献率大于10%,有8个QTL可在2个或2个以上环境中被检测到。其中,Qflw-4A在3个环境中被检测到,贡献率为10.13%~20.77%,是控制旗叶宽的稳定主效QTL;Qsl-4D.2在4个环境中被检测到,贡献率为12.58%~23.14%,是控制穗长的稳定主效QTL;Qker-5D在2个环境中被检测到,贡献率为11.44%~14.32%,是控制穗粒数的稳定主效QTL。这3个稳定主效QTL可作为改良叶宽和增加穗粒数的功能QTL作进一步研究。     

Revisiting rice breeding methods – evaluating the use of rapid generation advance (RGA) for routine rice breeding

Rice production needs to increase in the future in order to meet increasing demands. The development of new improved and higher yielding varieties more quickly will be needed to meet this demand. However, most rice breeding programmes in the world have not changed in several decades. In this article, we revisit the evidence in favour of using rapid generation advance (RGA) as a routine breeding method. We describe preliminary activities at the International Rice Research Institute (IRRI) to re-establish RGA on a large scale as the main breeding method for irrigated rice breeding. We also describe experiences from the early adoption at the Bangladesh Rice Research Institute. Evaluation of RGA breeding lines at IRRI for yield, flowering time and plant height indicated transgressive segregation for all traits. Some RGA lines were also higher yielding than the check varieties. The cost advantages of using RGA compared to the pedigree method were also empirically determined by performing an economic analysis. This indicated that RGA is several times more cost effective and advantages will be realized after 1 year even if facilities need to be built. Based on our experience, and previous independent research empirically testing the RGA method in rice, we recommend that this method should be implemented for routine rice breeding in order to improve breeding efficiency.     

Genetic analysis of resistance to spot blotch disease in wheat (Triticum aestivum L.) in Zambia

Understanding the genetics of resistance to spot blotch disease, caused by Bipolaris sorokiniana (Sacc.) Shoem, is important to design an appropriate breeding strategy to improve the trait. The objective of this study was to determine the gene action and mode of inheritance of resistance to spot blotch in wheat. Eight genotypes with varying resistance to the disease were crossed in a full diallel mating design. Parents and their progenies were evaluated for spot blotch resistance. Data were analyzed using Hayman’s diallel analysis. The results suggested the importance of additive gene effects in controlling the resistance to spot blotch in the materials under study. No epistasis, maternal, or reciprocal effects were detected. Resistance to spot blotch exhibited partial dominance. Therefore, exercising selection for resistance in the early segregating generation should be an effective approach because of the predominance of additive gene effects. The Wr/Vr graph showed that the parents 30SAWSN5 (P3) and Coucal (P4) possessed more dominant genes, which makes them particularly suitable for inclusion in breeding for resistance to spot blotch.     

Genomic prediction for yields,processing and nutritional quality traits in cultivated potato (Solanum tuberosum L.)

Current potato breeding approaches are hampered by several factors including costly seed tubers, tetrasomic inheritance and inbreeding depression. Genomic selection (GS) demonstrated interesting results regardless of the ploidy level, and can be harnessed to circumvent these problems. In this work, three GS models were evaluated using 50,107 informative SilicoDArT markers and 11 traits in two values for cultivation and use (VCU) potato trials. Two key breeding problems modelled included predicting the performance of (i) new and unphenotyped clones (cross‐validation) and (ii) a VCU using another as training set (TS). GS models performed comparably. Cross‐validation accuracy was high for D35, D45, DMW and BVAL, in ascending order. Prediction accuracies of the VCUs were highly correlated, but the best prediction was obtained for the smaller VCU using the bigger as TS. Cross‐validation and VCU prediction accuracies were higher when bigger TSs were used. The findings herein indicate that GS can be attractively integrated in potato breeding, particularly in early clonal generations to predict and select for traits with low heritability which would otherwise require more testing years, environments and resources.     

Comparing mating designs to restore seed production of interspecific hybrids between Trifolium repens (white clover) and Trifolium uniflorum

Interspecific hybrids between Trifolium uniflorum and cultivated white clover (Trifolium repens) have highly useful characteristics for temperate pastoral systems derived from both parent species. However, the early hybrids (F₁ and BC₁) also have unacceptably poor seed production for commerce. This study analysed the basis for the poor seed production and investigated breeding strategies for overcoming the problem. The BC₁F₁ generation produced lower‐than‐expected numbers of heads per plant and seeds per floret. Backcrossing of selected hybrids to white clover corrected these deficiencies and created new variation. Seed numbers were also returned to near target levels by recurrent selection within the BC₁ generation. Thus, it was possible to retain a theoretical average of 25% of T. uniflorum genome and still achieve high seed production per plant. The BC₁F₂ and BC₂F₁ generations produced high seed numbers per plant, along with reasonable variation. Both of these second‐generation hybrid forms have high reproductive potential and should be the focus for the selection of the desired combinations of agronomic and seed production traits.     

麦瘟病研究进展与展望

由Magnaporthe oryzae引起的麦瘟病是一种毁灭性小麦真菌病害,过去仅在南美流行,可造成10%~100%减产。2016年该病害首次在亚洲出现,给世界小麦生产带来重大潜在威胁。本文对麦瘟病病原生物学与病害流行学、小麦抗性材料筛选、麦瘟病的抗病性机制和综合治理等进行评述,并介绍了该领域国际合作研究的成功经验,以期为国内开展类似工作提供借鉴。尽管我国尚无麦瘟病报道,但南方部分地区为潜在适生区,异常气候可能会导致其在大范围流行,因此需高度警惕。建议与国际麦瘟病协作网合作,尽快开展麦瘟病相关研究,建立对此病害的监测预警和防治关键技术储备体系,以保障我国小麦生产安全。