春小麦和苜蓿根际溶磷菌筛选及其溶磷能力测定

对春小麦(Triticum aestivum)和苜蓿(Medicago sativa)根际和非根际土壤中溶磷菌进行分离得到溶磷菌株368株,小麦和苜蓿根际溶磷菌数量分布为:根际土(RS)>远离根际土(NRS)>根表(RP)>根内(HP)。利用溶磷圈法初步筛选出66株具有较高溶磷能力的菌株,经钼蓝比色法测定其溶磷量,获得12株溶磷量大于100 mg/L的高效溶磷菌,且发现溶磷能力与pH值没有显著相关性。     

我国北部冬麦区小麦区域试验重复次数和试点数量的优化设计

农作物品种区域试验重复次数和试点数量的合理配置有利于提高试验的成本效率和品种选择效率。本研究分析了2010—2019年期间北部冬麦区小麦品种区域试验的重复次数和试点数量设置的合理性,依据小麦品种试验的信噪比和遗传力水平随重复次数和试点数量的变化规律,提出了重复次数和试点数量的优化设计方案。结果表明:(1)北部冬麦区小麦单点试验的遗传力平均达到0.87,需要的重复次数平均值仅为1.4,说明3次重复可以充分保证试验精确度的需求。(2)北部冬麦区水地组和旱地组小麦区域试验达到0.75的遗传力水平时,需要的试点数量分别为11个和13个,目前有效试点数量分别约为11个和8个,分别达到0.75和0.60的遗传力水平。(3)小麦品种区域试验结果对品种的审定和应用十分重要,而每年都可能有少数试验点因为各种异常情况而报废,为保证试验结果的可靠性,可按H=0.75的水平需求安排试验点数量和重复次数,即重复次数可保持当前的3次;水地组的试点数量可保持在11个左右;旱地组可将试点增加到13个;如要将遗传力提高到0.80的水平,则需约16个试点。     

Genome-wide association study for spot blotch resistance in Afghan wheat germplasm

Spot blotch (SB), caused by Bipolaris sorokiniana, is a devastating disease of wheat globally, especially in South Asia and South America. Understanding the genetics of resistance to SB is important for developing breeding strategies to improve resistance. A panel of 301 genotypes from Afghanistan was phenotyped over two crop seasons using a mixture of virulent B. sorokiniana isolates and genotyped using DArTSeq to obtain genome-wide markers. Fifty genotypes (16.6%) showed disease scores less than the resistant control. Principal component analysis using the genotypic data clustered the genotypes into five different groups. Among models used for genome-wide association mapping, the multilocus mixed model, and fixed and random model circulating probability unification algorithms were most effective in identifying significant marker-trait associations (MTA). Twenty-five MTAs at p ≤ .001 were identified on chromosomes 1A, 1B, 1D, 2B, 2D, 3A, 3B, 4A, 5A, 5B, 6A, 7A, and 7D, indicating the quantitative nature of resistance to SB. Phenotypic variation explained by these markers ranged from 2.0% to 17.7%, and genomic regions on the chromosomes 1D, 2D, 3A, 3B, 4A, 5A, and 5B coincided with loci identified in previous studies. Three single nucleotide polymorphism (SNP) markers on chromosomes 1B (SNP 1113207) and 5A (SNPs 5411867 and 998276) were significant in both crop seasons as well as in the combined analysis across seasons. Marker 5411867 is close to Vrn-A1, shown to be associated with SB in previous studies. Furthermore, among known SB resistance genes, Sb2 on chromosome 5B was predicted to be significant in this panel.     

Regional and temporal differentiation of virulence phenotypes of Puccinia triticina from common wheat in Russia during the period 2001–2018

Leaf rust, caused by the fungus Puccinia triticina, is one of the most damaging rust diseases of wheat in Russia. Populations of P. triticina were monitored in seven regions of Russia from 2001 to 2018, with a total of 5,191 single urediniospore isolates from bread wheat (Triticum aestivum) being analysed. Populations have changed significantly in all regions since 2012, after 2 years of drought (2010–2011). Regional collections of P. triticina were also significantly different between the two periods 2001–2009 and 2012–2018, with changes along two geographic gradients from West Siberia to the north-west and south-west (North Caucasia) of the European part of Russia. All tested isolates were avirulent to resistance gene Lr9 in 2001–2009 but, since 2010, virulence to Lr9 has occurred and annually increased in the Asian part of Russia (Ural and West Siberia) due to deployment of cultivars with the Lr9 gene. Virulence to Lr2a and Lr15 was considerably lower in Dagestan (6%–33%) and all European regions (35%–67%) than in Asian regions (84%–96%). During 2001–2009, virulence on Lr1 was also lower in Dagestan (33%) and the European regions (50%–77%) than in Asia (91%–96%); however, by 2012–2018, nearly all isolates were virulent on Lr1. Remarkable changes were observed in frequencies of P. triticina races defined by their virulence/avirulence to Lr1 and Lr2a genes. We postulate the P. triticina population in Dagestan is specific to that area and pathogen populations in European and Asian parts of Russia are distinct.     

Comparison of growth,survivorship, seed production and shedding of eight weed species in a wheat crop in Western Australia

Development of integrated weed management strategies is dependent on a thorough knowledge of the demography of individual species. The current research established eight winter or summer weed species in a winter annual wheat cropping system at Wongan Hills, Western Australia, and investigated emergence of the first cohort of each species, survivorship, plant size, seed production and seed shedding over three years (2016–2019). The winter weeds Bromus diandrus and Lolium rigidum emerged at the same time as the wheat crop, and the initial cohort of marked plants had 100% survival to seed production in each year. By comparison, other winter weed species like Hordeum leporinum, Rumex hypogaeus, Sonchus oleraceus and Polygonum aviculare frequently emerged later than the crop and had a lower percentage of plants surviving to seed production. However, individual S. oleraceus and P. aviculare plants had the greatest seed production compared to other species. All winter weeds had variable patterns of seed shedding between years, with the exception of L. rigidum. Summer weed species emerged at the same time, but plants in the initial cohort of each species did not always survive to produce seed. The early emergence and high survivorship of B. diandrus indicates high competitive ability, but shedding commenced at a similar time to L. rigidum and harvest weed seed control may be a viable control method for this species.     

Influence of intra-row cruciferous surrogate weed growth on crop yield in organic spring cereals

In Northern Europe, inter-row hoeing has become a popular tactic for controlling weeds in organic cereals. Hoeing is highly effective and can be implemented from crop emergence until stem elongation to maintain a nearly weed-free inter-row zone. However, hoeing has a lesser effect on weeds growing in the intra-row zone, where crop–weed proximity results in heightened competition. In the hoed cereal system, it is investigated whether tall-growing, competitive, cruciferous weeds in the intra-row zone affect crop biomass, yield and thousand kernel weight (TKW). An additive experimental design is employed to enable the fitting of rectangular hyperbolas, describing and quantifying the effects of increasing intra-row surrogate weed density on crop growth parameters. Regressions were studied under the influence of crop (spring barley and spring wheat), row spacing (narrow [12.5 or 15.0 cm] and wide [25.0 cm]) and nitrogen rate (50 and 100 kg NH₄-N/ha). Cruciferous surrogate weeds were found to impact crop yield and quality severely. For example, ten intra-row plants/m² of surrogate weed Sinapis alba reduced grains yields by 7%–14% in spring barley and by 7%–32% in spring wheat with yield losses becoming markedly greater in wheat compared to barley as weed density increases. Compared to wheat, barley limited yield and quality losses and suppressed intra-row weed growth more. Row spacing did not have a consistent effect on crop or weed parameters; in one of six experiments, the 25 cm row spacing reduced yields and increased intra-row weed biomass in wheat. Nitrogen rate did not affect crop or weed parameters. Results warrant the implementation of additional tactics to control intra-row weeds and limit crop losses.     

宁麦9号与扬麦158株高及其构成因素的遗传解析

宁麦9号与扬麦158是我国长江中下游麦区的主栽品种和骨干亲本,长江中下游麦区近3年来审定品种中80%都是其衍生后代,研究其性状的遗传具重要意义。以宁麦9号与扬麦158为亲本构建的包含282个家系的重组自交系群体为材料,利用Illumina 90k芯片对群体进行基因型分析,建立高密度遗传图谱。连续3个生长季对株高及节间长度、穗长等株高构成因素进行测定,结合遗传图谱对株高及相关性状进行QTL定位,获得14个控制株高及其构成因素的稳定表达位点。通过进一步位置比对,聚焦到6个染色体区段,初步明确了各节间对株高的遗传调控机制。同时,将6个染色体区段中同源性较低的连锁标记转化为适用于高通量筛选的KASP标记,利用101份区域试验材料进行标记效应验证,结果显示聚合Qph-2D与Qph-5A.1两个位点具有较高的选择效率,继续聚合Q2A后,中选材料显著减少,可能降低选择效率;对Q2A与Q5A两个一因多效位点的选择建议以降低株高的等位变异为主;Qd1-5D可作为穗下节间(D1)的选择标记对株高展开优化选择。期望以上结果能为长江中下游麦区的小麦株高遗传改良提供帮助。     

卵穗山羊草和柱穗山羊草与普通小麦属间杂种的产生及其育性比较

分别以卵穗山羊草和柱穗山羊草为母本,以普通小麦为父本杂交,将获得的杂种再进行回交和自交,对其育性进行比较研究.结果表明,不同的种或品种做母本其可交配性表现不同,卵穗山羊草的结实率(14.10%和11.96%),比柱穗山羊草高(2.13%和8.47%).杂种胚产生愈伤组织率和幼胚直接成苗率不同.柱穗山羊草/小麦杂种胚愈伤组织诱导率高于杂种胚.卵穗山羊草/小麦的直接成苗率高于柱穗山羊草/小麦.卵穗山羊草/小麦用小麦回交的结实率为3.71%;柱穗山羊草/小麦用小麦回交未结实.卵穗山羊草/小麦自交也能结实,自交的结实率为0.044%,柱穗山羊草/小麦杂种自交没有结实.卵穗山羊草/小麦杂种的育性较柱穗山羊草/小麦杂种强,卵穗山羊草基因通过杂交向小麦转移比柱穗山羊草更容易.     

A-3中抗条锈新基因YrTp1和YrTp2的分子标记定位分析

【目的】半个多世纪的中国小麦育种史基本是育种家与条锈病的赛跑史。因此，筛选、鉴定、储备和利用新抗源是我国育种和资源研究中的一个长远战略性课题。【方法】利用小麦条锈菌条中31、32号生理小种，对来自小麦与十倍体长穗偃麦草［Thinopyrum ponticum (Host) Liu & Wang］的杂交后代材料A-3进行抗性遗传分析。用荧光SSR分子标记技术，鉴定所携带抗条锈病基因是否为新基因，并对其进行染色体定位研究。【结果】遗传分析表明，A-3对条中31号和32号的抗性由一显一隐2对基因控制。经过对196对微卫星引物的筛选，发现2B染色体短臂上的WMC477-167bp与显性基因紧密连锁，遗传距离为0.4 cM,将该显性基因定位于2BS上；7B染色体短臂上的WMC364-208bp与隐性基因连锁，遗传距离为5.8 cM。图位比较、系谱分析和抗谱分析表明，A-3所含抗条锈基因不同于已知抗条锈基因，暂定名为YrTp1和YrTp2。【结论】可利用A-3中与条锈病抗性紧密连锁的分子标记YrTp1和YrTp2将抗性基因转移到主栽品种中，在小麦育种和生产上发挥作用。