Outcrossing rate of barley genotypes with different floral characteristics in drought‐stressed environments in Jordan

The flowering characteristics of a highly inbreeding species such as barley might influence the extent of outcrossing that can be expected. Increased outcrossing is a prerequisite to exploit heterosis in inbreeding species, which can lead to considerable yield increase as has been demonstrated for barley grown under marginal conditions. Anther extrusion (AE) in barley has been demonstrated to be a genetically controlled, quantitative trait with intermediate to high heritability. Some authors consider AE and open flowering in barley as identical. The present study was conducted to investigate whether barley genotypes with increased AE exhibit increased outcrossing rates under field conditions in comparison with genotypes showing no AE. Field experiments were conducted in three contrasting environments in Jordan in the 2001/02 growing season using six adapted barley genotypes, three with high AE and three with no AE. Outcrossing rates were investigated employing codominant DNA markers (microsatellites). No significant difference in outcrossing rates was detected between anther‐extruding and non‐extruding barley genotypes. Results indicate that high AE is not a sufficient condition to cause increased outcrossing rates and thus cannot be termed open flowering.     

开花集中度是影响粳稻细胞质雄性不育系异交结实率的重要因素

阐明粳稻细胞质雄性不育系开花习性与异交率之间的关系,是选育高异交率粳稻不育系的重要基础。在对284份滇一型粳稻细胞质雄性不育系的自然异交率检测和部分不育系开花性状观测的基础上,通过相关分析和开花习性的精细比较,发现粳稻不育系间自然异交结实率变化幅度较大,大多数粳稻不育系的自然异交率都比较低,但同时也鉴定出少量高异交率的不育系。相关分析发现颖花的开颖角度与粳稻不育系的自然异交结实率呈显著正相关。通过对三个不育系开花性状的精细观察分析,显示了开花集中度是影响粳稻不育系异交率的重要因素。在粳稻不育系的育种实践中应该加大对不育系开颖角度和开花集中度的选择,以提高粳稻不育系的异交结实率。     

Gain from marker‐based recurrent selection for increased heterozygosity in barley

Barley (Hordeum vulgare L.) is a highly adaptable cereal crop grown under a wide range of agro‐ecological conditions. Various literature reports demonstrate that heterozygosity may enhance the yielding level and stability of barley particularly in stress‐prone environments. The major aim of this study was to investigate whether recurrent selection (RS) for heterozygosity at highly polymorphic codominant molecular marker loci increases outcrossing in a genetically broad‐based population. Four to six SSR marker loci were used for this purpose. Selection was conducted over four cycles. Progress from selection was evaluated in a terminal experiment comprised of population samples from all four RS cycles. All experiments were conducted under greenhouse conditions. The starting population was composed of 201 gene bank accessions (178 lines, 12 landraces and 11 wild barley populations) sampled in West Asia and North Africa. Selection led to a stepwise increase in heterozygosity from 0.23% to 1.50%. Correspondingly, the estimated multilocus outbreeding rate rose from 1.4% to 3.5%. This positive selection response offers new perspectives for improving the productivity of barley in stress‐prone areas.     

百子莲的花部特征与繁育系统观察

 通过观察, 运用杂交指数、花粉、胚珠比、人工授粉和套袋试验等方法, 对上海市引种的处 于半自然状态的百子莲(Agapanthus praecox ssp. orientalis‘BigBlue’) 的开花状态、繁育系统进行了研究。结果表明: 百子莲单花花期一般2～3 d, 花药全部开裂需要3～5 h。开花过程中柱头与花药无明显空间隔离现象, 雄蕊先于雌蕊成熟。杂交指数等于4, 花粉-胚珠比等于25 622, 结合人工套袋和授粉试验的结果, 可以确定该物种的繁育系统属于异交为主, 部分自交亲和, 传粉过程需要传粉者。     

水稻不育系IR 58025A与其改良新不育系制种产量比较研究

利用3个IR58025B改良的新不育系恒达A、福稻A、钧达A,以IR58025A为对照,与恢复系成恢727进行了杂交制种产量比较试验。结果表明,与对照IR58025A相比,不育系恒达A、福稻A、钧达A分别与成恢727配制F1的制种产量极显著增加,平均产量分别为2.85 t/hm~2、2.78 t/hm~2和2.64 t/hm~2;这3个不育系柱头活力强于IR58025A、且柱头外露率和异交结实率较高是制种组合产量显著提高的主要原因。     

水稻光温敏核不育系育性敏感期高温对异交特性的影响

以培矮64S、Y58S、广占63–2S、H638S为材料,R527为恢复系,在育性敏感期利用人工气候室以24、27、30、33、36℃5个温度连续处理6 d,以田间自然温度条件作对照(CK,平均温度29.8℃),研究温度对不育系幼穗生理生化特性和抽穗开花期异交特性的影响。结果表明:培矮64S和Y58S在27℃处理时柱头总外露率最高,分别为86.81%、86.06%,广占63–2S和H638S在24℃处理时柱头总外露率最高,分别76.24%、81.76%;4个不育系的柱头活力系数均在24℃处理时表现最好,分别为1.96、2.12、1.74、1.94;培矮64S、广占63–2S和H638S在24℃处理时异交结实率最高,分别为58.87%、54.22%、50.50%,Y58S在27℃处理时异交结实率最高,为58.96%;33℃处理时,4个不育系的过氧化物酶(POD)活性显著高于对照;36℃处理时,4个不育系丙二醛(MDA)和脯氨酸的含量显著高于对照。综合以上结果,培矮64S育性敏感期以24℃处理较好,Y58S、广占63–2S、H638S育性敏感期以27℃处理较好。     

水稻光温敏核不育系福龙S2的育性观察

以培矮64S为对照,采用分期播种试验,分析水稻光温敏核不育系福龙S2的育性与特征特性表现,结果表明:福龙S2播始历期86~89 d;稳定不育期从7月20日开始;开花习性好,柱头活力强,午前花比率达70%以上;柱头外露率较高,单边外露率高于双边外露率;福龙S2比培矮64S具有更好的异交结实特性。     

Breeding and genomics status in faba bean (Vicia faba)

Faba bean is an important legume crop because of its high‐yield potential and nutrition‐dense grains. There have been significant achievements in faba bean improvement in the last four decades, which led to the doubling of the global yield average. This study reviews the genetic diversity, the breeding methodologies, major achievement on biotic and abiotic traits, and the recent molecular approaches. The high genetic diversity among faba bean accessions has been useful for increasing yield potential of the crop. Substantial increase in yield potential can be gained through the development of cultivars in open pollinated conditions. In the past, many faba bean varieties that are tolerant to abiotic and biotic stresses were released worldwide. The average yield gains varied from 1.65% per year in Syria to 4.17% per year in Ethiopia. The recent advances in molecular technologies will be used to develop more coherent genetic maps, which would also facilitate assembling and ordering genomic scaffolds in a future genome‐sequencing effort and molecular‐breeding approach.     

Genetic effects and plant architecture influences on outcrossing rate in soybean

Outcrossing rate is an important determinant of cytoplasmic male sterile(CMS) breeding and hybrid seed production for heterosis in soybean. Parental lines with a high outcrossing rate were screened for backcross breeding to obtain the high outcrossing rate maintenance B-lines and sterile A-lines. Application in production practices will help to increase hybrid soybean production. In this study, JLCMS82B and JLCMS89B were selected as parents for the construction of outcrossing rate segregation populations, and the progeny-array approach(PAA) and glyphosate resistant gene markers were used to determine outcrossing rates. We found that:(1) The outcrossing rate between JLCMS82B and JLCMS89B was significantly different;(2) the outcrossing rate of the F_2 segregating populations was a quantitative trait, though whether an additive or epistatic effect exists required analysis with a triple test intersection analysis;(3) agronomic traits correlated with outcrossing rate; outcrossing rate was the highest with plant height of about 84 cm, lower number of plant branches, earlier flowering time, larger angle between the branches and the main stem, and with more divergent plant morphology. Correlation analysis between agronomic traits and outcrossing rate can effectively guide the screening of parents with a high outcrossing rate.