Potential use of doubled haploid lines for the screening of resistance to yellow rust (Puccinia striiformis) in hexaploid wheat

Doubled haploid lines derived from anther culture of two Iranian spring wheat genotypes‘Ghods’susceptible and‘9106’resistant to yellow rust in Iranian field conditions, and their F₁ hybrids were used in this study. Seedlings of 36 doubled haploid lines, selected out of 96 according to their agronomic traits and the two parental genotypes were inoculated with eight races of yellow rust. The parental genotypes (‘Ghods’and‘9106’) were segregating for some of the races but their doubled haploid lines were either resistant or susceptible to them.‘Ghods’was susceptible to three of the races studied but three doubled haploid lines derived from it were resistant to them. Five selected doubled haploids from the‘9106’genotype and six from F₁ hybrid plants were resistant to all eight races tested. After further investigations in Iranian field conditions it was found that some of these lines can be used as donor genotypes for resistance to yellow rust in wheat breeding programmes. Use of these genotypes should be possible if the French yellow rust races used for selection also represent the dominant races in Iran. It can be concluded that anther culture provides an efficient method for fixing genes of resistance to yellow rust and desirable doubled haploids from F₁ plants can be derived.     

甘蓝型油菜DH群体抗倒伏相关性状遗传分析

为明确油菜抗倒伏性的遗传规律,本文利用抗倒伏性差异显著的2个甘蓝型油菜品系配制杂交组合,构建含280个株系的DH群体,采用作物茎秆强度抗倒测量仪等考种工具对该群体进行连续两年的抗倒伏性鉴定,并利用植物数量性状的主基因 + 多基因混合遗传模型及偏度和峰度分析对抗倒伏性进行遗传分析。结果表明,茎秆抗折力和茎秆抗折强度都受到0对主基因 + 9对微效多基因控制,茎秆抗折力和单株生物量的基因间无互作,茎秆抗折强度的基因间有互补作用,茎秆抗折力和茎秆抗折强度两年的平均遗传率在50%左右,而茎秆直径两年的平均遗传率为69.338 %,单株生物量两年的遗传率分别为52.198%和69.284%,遗传率都较低,性状受环境影响都较大,因此对于茎秆抗折力、茎秆抗折强度、茎秆直径和单株生物量,在育种选择的早期阶段都不宜太严格。同时茎秆抗折强度相比茎秆抗折力更能说明作物的抗倒伏能力,因而在抗倒伏选择育种时应更加关注。     

Refinement of shed-microspore culture protocol to increase normal embryos production in hot pepper (Capsicum annuum L.)

A low percentage of normal-looking embryos (20%) is still a problem in an efficient shed-microspore culture of hot pepper (Capsicum annuum L.) and it is more a serious problem in other androgenesic culture systems of pepper. Therefore, several factors were investigated to refine the protocol in order to increase the percentage of normal-looking embryos. The most important factors which improved the protocol and resulted in a significantly higher percentage of normal-looking embryos produces (>50%), were delayed enrichment of the liquid upper layer medium with 2.5 μM Zeatin and 5 μM IAA, and reduced incubation temperature from 28 °C to 21 °C, both after 3 weeks of culture. Addition of 1% activated charcoal in the solid lower layer of the medium enhanced the total embryo yield only, while an application of abscisic acid and increased osmolality medium had a detrimental effect on embryo production. The use of doubled haploid lines as anther donor plants has clearly decreased the variability and improved the statistical analysis of treatment effects. A higher percentage of normal embryos are produced with this refined protocol, and is therefore more suitable for implementation in the breeding programs of hot pepper.     

辐照花粉授粉及胚挽救时期对苦瓜离体雌核发育的影响

采用辐照花粉授粉结合胚挽救技术,以7个不同基因型苦瓜作花粉供体对MC52进行授粉,系统探讨辐照剂量、胚挽救时期对成苗率的影响及辐照剂量对产胚类型的影响.结果表明:进行苦瓜辐照花粉授粉诱导离体雌核发育的适合辐照剂量为150 Gy,胚最佳抢救时期为授粉后第10天.试验发现辐照剂量在200Gy时也可获得高的坐果率,但大部分种子已成空壳,对于苦瓜辐照花粉授粉诱导雌核发育获得单倍体是没有意义的;对辐照获得的102株苗进行倍性鉴定,虽未得到单倍体植株,但在该试验中仍有较高比例的各种类型胚未发育成植株,还须进一步优化胚的培养条件.     

Plant Regeneration of Irradiated Barley Haploid Calus Derived by Bulbosum Method

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玉米单倍体雌穗育性自然恢复研究

为了对玉米单倍体雌穗育性恢复能力进行系统遗传分析,本研究以22个玉米自交系诱导产生的单倍体为材料对雌穗自然恢复能力进行观察,通过分类比较的方法分析单倍体雌穗平均结实株率、平均结实籽粒数和2个雌穗育性恢复指标自然恢复的遗传特点。结果表明,不同自交系的单倍体雌穗平均结实株率为89.54%,变异范围为73.56%~99.18%;单倍体雌穗平均结实籽粒数为15.4粒,变异范围为2.67~59.82粒。单倍体雌穗结实株率的广义遗传力为0.67,平均结实籽粒数的广义遗传力为0.86。22个自交系材料中,B73的单倍体雌穗育性恢复能力较其他试验材料强,单倍体雌穗平均结实株率为99.18%,平均结实籽粒数为59.82粒,基因型在单倍体雌穗育性自然恢复过程中起主要作用。通过对单倍体雌穗育性恢复与雄穗育性恢复性状进行相关性分析发现单倍体雌穗育性恢复与雄穗育性恢复是2个相对独立的过程。     

An improved in vitro technique for isolated microspore culture of barley

A detailed procedure for isolated microspore culture of barley is presented along with examples of response across genotypes. Over 30 genotypes, including winter and spring growth habit and 2-row and 6-row genotypes, have shown an essentially genotype independent response, averaging about 10,000 embryos per 5 cm petri culture plate. The regeneration frequency, checked on samples of 500 embryos per plate ranged from 36 to 97% with most genotypes being in the range of 70 to 90%. About 70 to 80% of the plants regenerated have been completely fertile doubled haploids, thus eliminating the need to double the chromosome number of plants. Many little details are critical to success of the microspore procedure and while it saves much time compared to anther culture, greater attention to details and cleanliness is essential. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of thidiazuron on microspore embryogenesis and plantlet regeneration in Chinese flowering cabbage (Brassica rapa. var. parachinenis)

Traditional breeding methods require more than 6 years to obtain homozygous inbred lines, while isolated microspore culture (IMC) is an effective way to cultivate double haploid homozygous lines in only 2 years. However, low embryogenesis induction frequency in Chinese flowering cabbage remains a key obstacle to the practical application of this technique. Thidiazuron was added at different concentrations to NLN‐13 medium to estimate its effects on microspore embryogenesis and plantlet regeneration. Results showed that three genotypes responded positively. Optimum thidiazuron concentrations produced embryo yields of up to 14.67 embryos per bud and increased microspore embryogenesis frequency with up to 100% survival. Plantlet regeneration rates were up to 81.67%, and the treatment groups showed lower callus formation. We obtained up to 552 diploid plants from the tested genotypes, and the percentage of doubled haploid at different TDZ concentrations showed slight differences, and doubled haploid rates in the three genotypes were above 70%. They showed a high uniformity and can be directly used for hybrid breeding. This method accelerates microspore application in Chinese flowering cabbage hybrid breeding.     

Agro-morphological characterization of ovary culture-derived plants of rice (Oryza sativa L.)

Plants derived from unpollinated ovary culture of ten rice genotypes showed significant variability in agro-morphological characteristics. The ovary-derived plant (H1) populations were completely haploid, doubled haploid or haploid-doubled haploid mixture. Haploids had very drastic reduction in plant height, panicle length, grain length, breadth and number and spikelet fertility (0.0%–2.1%). Doubled haploids from the hybrid of UPRI 95–121 × UPRI 95–165 were normal with fertility ranging between 69.6% and 97.7%. A genetic segregation in ratio of 1:1 was observed for five pigmentation characters in the H1 population derived from hybrid UPRI 95–122 × UPRI 95–165. Plant height showed the largest coefficient of variability (28.5%) followed by the number of spikelets per panicle (24.2%), number of grains per panicle (22.0%), percent seed set (9.2%) and panicle length (9.0%). The range of variation in the H1 population from fully fertile hybrid PMS 2A (CMS) × IR 31802 (restorer) was similar to its corresponding F2 population for plant height, spikelet fertility and number of grains/panicle. A single clone of plants from the cultivar BG 1321 exhibited complete male sterility but normal female fertility when pollinated with other varieties. Ovary-derived plants from the CMS lines PMS 2A and IR 58025A showed stable male sterility and those from thermosensitive genetic male sterile line UPRI 95–140 showed thermosensitive genetic male sterility. These lines have potential in the hybrid breeding program and are being currently exploited. This revised version was published online in July 2006 with corrections to the Cover Date.     

普通小麦（浙农林12×CASL7AS）DH系株高的分析

小麦株高与植株倒伏密切相关,影响小麦产量。为挖掘小麦株高QTL位点和候选基因,从遗传和分子水平上解释株高分子机理,本研究将野生二粒小麦染色体臂置换系CASL7AS为母本,课题组自选株系浙农林12（简称ZNL12）为父本,杂交F₁经过花培得到178个DH群体。通过4年2个种植点株高数据,利用55K SNP芯片构建高密度遗传图谱,对小麦株高性状进行QTL分析。该遗传连锁图谱包含3 655个SNP标记,长度为4 738.45 cM,标记间平均遗传距离为1.30 cM,覆盖了小麦21条染色体。其中,A、B、D染色体组分别含有标记1 466、1 492和697个。QTL分析共检测出53个QTL位点,分布于1A、3A、5A、7A、1B、3B、4B、5B、7B、2D、4D、6D和7D染色体上,可解释2.80%~38.50%表型变异。其中,稳定主效 QTL有2个,分别为QPh.zafu.4B-1和QPh.zafu.4D-1,其贡献率分别为25.18%~38.50%和20.67%。经细胞生物学分析,基因型为（0,2）矮秆植株胚芽鞘的表皮细胞长度显著短于基因型为（2,0）的高秆植株,基因型为（0,0）、（2,2）中间型的植株胚芽鞘表皮细胞长度无显著差异,由此推测小麦株高的变异由细胞长度因素决定。QPh.zafu.4B-1候选基因Rht-B1b基因编码区矮秆株系,第904核苷酸处发生碱基“C-T”的突变,形成终止密码子(CAG-TAG);而QPh.zafu.4D-1候选基因Rht-D1b基因编码区矮秆株系,第781核苷酸处碱基突变“G-T”,编码氨基酸中缬氨酸变为天冬氨酸。结果为小麦株高候选基因的筛选和QTL定位提供了优异的遗传位点和候选基因,未来可用于小麦抗倒伏相关的分子标记辅助育种。