玉米生物诱导孤雌生殖单倍体影响因素研究进展

玉米单倍体育种技术能显著缩短育种周期,提高育种效率,在现代商业化育种中占有重要的地位。规模化高效单倍体的产生是单倍体育种技术应用的前提条件。总结了父本诱导系、母本的遗传背景、诱导的环境、授粉方式等影响玉米生物诱导孤雌生殖单倍体产生的因素,通过文献综合分析得出了获得大量的孤雌生殖单倍体除了选择合适的高频率孤雌生殖诱导系外,同时要考虑其他诱导因素的影响。并就高效生产孤雌生殖单倍体的未来研究及发展方向进行了讨论,以期促进单倍育种技术的规模化应用。     

孤雌生殖诱导玉米单倍体育种技术研究

玉米单倍体育种技术可以有效地缩短育种进程,快速获得大量纯合系。孤雌生殖诱导是获得玉米单倍体的主要方法之一,该项技术在国外各大育种公司已被广泛使用,但在国内仍处于研究探索阶段。本文从诱导系的选择与繁殖、基础材料的组配、杂交诱导、单倍体籽粒的挑选、单倍体植株的种植、加倍以及双单系的繁殖等方面综述了孤雌生殖诱导系（简称诱导系）产生玉米单倍体育种技术的基本流程,同时展望了单倍体育种的应用前景。     

玉米单倍体DH系特点及应用研究进展

利用单倍体诱导系选育技术能显著加快育种进程,高效单倍体诱导材料的培育及单倍体DH系应用是玉米单倍体育种的重要基础.本文就玉米单倍体DH系的特性及应用加以阐述,并对今后玉米单倍体DH系研究进行了展望.     

玉米单倍体诱导系Stock6及其在玉米育种中的应用

玉米单倍体育种可缩短育种周期、提高育种效率,利用玉米单倍体诱导系诱导玉米单倍体简单易行,单倍体筛选方便。简述了玉米单倍体诱导系Stork6的发现、改良及在玉米育种中的应用。     

“七大农作物育种”重点专项建立玉米单倍体育种体系

<正>自交系是玉米杂种优势利用的基础,以生物诱导为基础的玉米单倍体育种(DH育种)技术可以快速育成品系,加快育种进程,其在国内外种业上的规模化应用已经促进了玉米选系技术的变革,成为现代三大玉米育种关键技术之一。玉米单倍体技术与分子育种及传统育种方法的深度融合还可以有效地改进传统育种模式,在商业化育种流程及育种管理模式创新等方面具有重要作用。     

东北早熟玉米育种方法改良的目标、必要性及主要内容

1改良目标围绕东北玉米种业发展对种质改良及技术需求,重点明确玉米产量及抗性性状基因的调控机制,创新高配合力多抗玉米自交系设计技术;规模化开发育种性状的功能分子标记,实现分子标记辅助育种技术实用化;开发高诱导率的单倍体诱导系和加倍技术,实现双单倍体（DR）育种技术的规模化应用;针对东北极早熟玉米区育种性状改良需求,引进多样性种质,通过表型和基因型评价,发掘优异基因资源,创建有效的种质改良与创新平台。     

单倍体育种技术的应用进展

为了给今后西番莲等热带果树的单倍体育种研究提供理论指导,文章归纳了人工诱导孤雄生殖、人工诱导孤雌生殖、染色体加倍等不同单倍体育种培养技术的技术要点及发展现状,总结了单倍体育种技术在禾谷类作物、花卉、林木和果树育种方面的应用进展。同时指出,单倍体育种技术的发展有利于建立作物品种纯合系,推进遗传学研究,形成新的基因型,加快热带果树的育种进程。     

玉米单倍体鉴定方法研究进展

玉米单倍体鉴定是玉米单倍体育种三大关键技术(杂交诱导、单倍体鉴定、染色体加倍)之一,准确、高效的单倍体鉴定方法不仅可以提高玉米单倍体育种的效率,同时对筛选高诱导率的单倍体诱导系也十分重要。综述了国内外玉米单倍体鉴定方法的演变过程,旨在为玉米单倍体育种工作者把握鉴定方法发展的脉络提供帮助。     

玉米单倍体育种研究

近年来,玉米产业及育种技术发展迅速,而玉米单倍体育种技术是缩短育种进程、提高育种效率的一条快速而有效的途径。就玉米单倍体的获取途径、单倍体诱导的影响因素及单倍体加倍方式等研究进行了综述,对研究中存在的问题进行了探讨,并展望了玉米单倍体育种的应用发展前景。     

重庆玉米DH工程化育种的进展分析

玉米双单倍体(doubled haploid,DH)技术是生物技术与常规育种方法结合产生的一条新的育种途径,能显著加快育种进程。在重庆地区,土壤瘠薄、阴雨寡照、高温干旱等一系列特殊的生态气候因素严重制约重庆玉米DH工程化育种的开展。本综述就重庆玉米DH工程化技术的关键环节进行了探索,包括对诱导系的选择、基础材料的组建、单倍体的诱导、加倍、DH鉴定及应用,总结出一套适宜重庆本地的玉米DH工程化育种体系,提出"目标具体,规模加倍,分圃鉴定,测评应用"的单倍体育种策略,为玉米新型商业化育种体系建立提供参考依据。     

Review of doubled haploid production in durum and common wheat through wheat × maize hybridization

Production of doubled haploids (DHs) is an important methodology to speed the process of breeding and development of mapping populations in crops. The procedure for DH production includes two major steps: haploid induction and chromosome doubling. In recent years, wide hybridization between wheat and maize has become a main approach for haploid production in wheat. In this method, the maize chromosomes are completely eliminated during the early development of the hybrid seeds after wheat spikes were pollinated with maize pollen. Numerous wheat cultivars and mapping populations have been developed using wheat–maize hybridization. In this study, we review the procedures of DH production of durum and common wheat via wide hybridization with maize, the factors which affect the efficiency of DH production, and the mechanism of selective elimination of the maize genome during the early development of the hybrid embryos. We also report a highly efficient protocol for DH production in durum and common wheat, which was established based on the optimal conditions for each of the factors that affect the efficiency of DH production.     

Mapping of maternal QTLs for in vivo haploid induction rate in maize (Zea mays L.)

Haploid technology can significantly shorten the time required for inbred line improvement, accelerate the breeding process, and reduce breeding costs. The production of haploids is not only dependent on the genetics of the paternal haploid inducer, but it is also affected by the genetic background of the maternal donor during the process of haploid production. To address the maternal genetic contribution to haploid production, we pollinated a mapping population consisting of 186 F_2:3 family lines derived from a cross between Zheng58 and Chang7-2 with the inducer line CAU5 and selected haploid kernels using R1-nj kernel markers. Two quantitative trait loci (QTLs), qmhir1 and qmhir2, which contribute to the maternal genetics of haploid induction, were detected on chromosomes 1 and 3, respectively. The qmhir1 locus is located between the flanking marker loci umc1292 and bnlg1014, and it explained 14.70 % of the phenotypic variation. The qmhir2 locus is located between marker loci umc1844 and umc2277 and it explained 8.42 % of the phenotypic variation. The genetic effect of both QTLs is partial dominance.     

Classification approaches for sorting maize (Zea mays subsp. mays) haploids using single-kernel near-infrared spectroscopy

Doubled haploids (DHs) are an important breeding tool for creating maize inbred lines. One bottleneck in the DH process is the manual separation of haploids from among the much larger pool of hybrid siblings in a haploid induction cross. Here, we demonstrate the ability of single-kernel near-infrared reflectance spectroscopy (skNIR) to identify haploid kernels. The skNIR is a high-throughput device that acquires an NIR spectrum to predict individual kernel traits. We collected skNIR data from haploid and hybrid kernels in 15 haploid induction crosses and found significant differences in multiple traits such as percent oil, seed weight, or volume, within each cross. The two kernel classes were separated by their NIR profile using Partial Least Squares Linear Discriminant Analysis (PLS-LDA). A general classification model, in which all induction crosses were used in the discrimination model, and a specific model, in which only kernels within a specific induction cross, were compared. Specific models outperformed the general model and were able to enrich a haploid selection pool to above 50% haploids. Applications for the instrument are discussed.     

Discrimination of haploid and diploid maize kernels via multispectral imaging

The use of doubled haploids (DHs) in maize has become ubiquitous in maize breeding programmes as it allows breeders to go from cross to evaluation in as little as 2 years. Two important aspects of the in vivo DH system used in maize are as follows: (i) the identification of haploid progeny and (ii) doubling of the haploid genome to produce fertile inbred lines. This study is focused on the first step. Currently, identification of maize haploid progeny is performed manually using the R1‐nj seed colour marker. This is a labour‐intensive and time‐consuming process; a method for automated sorting of haploids would increase the efficiency of DH line development. In this study, six inbred lines were crossed with the maternal haploid inducer ‘RWS/RWK‐76’ and a sample of seed was sorted manually for each line. Using the VideometerLab 3 system, spectral imaging techniques were applied to discriminate between haploids and hybrids. Using DNA markers to confirm the haploid/diploid state of the tested seed, for the majority of genotypes haploid identification was possible with over 50% accuracy.     

Development of in vivo haploid inducers for tropical maize breeding programs

Lack of adapted haploid inducers currently impedes adoption of the doubled haploid technology in tropical maize breeding programs. Our objective was to generate inducers with improved adaptation to tropical conditions. We developed segregating generations from crosses between temperate inducers having haploid induction rates (HIR) of 8–10 % and tropical CIMMYT maize lines (CML; HIR = 0 %) and evaluated these for HIR and agronomic performance under tropical lowland field conditions. The applied pedigree breeding scheme comprising mass selection on individual F₂ plants for highly heritable and visually scorable traits, followed by family-based selection for HIR and other agronomic characteristics in advanced selfing and backcross (BC) generations seems highly suitable for breeding improved haploid inducers with adaptation to different agroecologies. The most advanced tropical inducer candidates (TIC) combine HIR of up to 10 % with improved pollen production, disease resistance, and plant vigor compared to temperate inducers under tropical conditions. Agronomic characteristics were significantly improved in the BC to CML compared to BC to inducers, while mean HIR of both populations were similar, indicating that backcrossing to the adapted parent was suitable to improve adaptation of new inducers without sacrificing high HIR. When screening random open-pollinated maize accessions, HIR of up to 3 % were observed, suggesting that novel genetic variation may be present in maize accessions that could be exploited to improve HIR in maize. In conclusion, tropical inducer development proceeds well, but evaluation of TIC in multi-environment trials needs to be completed before large-scale dissemination can commence.     

葫芦科植物单倍体离体诱导研究进展

重点对葫芦科植物离体诱导单倍体的研究进行综述,包括花药培养、离体雌核培养、辐射花粉诱导单倍体培养等在育种中的应用,以及供体基因型、培养基、预处理方式、胚囊发育时期等因素对离体诱导再生频率的影响。关于离体培养发育机制的生理生化研究主要集中在离体雌核发育的形态及细胞学过程以及培养早期生理、生化的变化研究。同时总结了葫芦科植物DH育种研究进展,指出葫芦科植物离体诱导单倍体研究中存在的问题并提出思路和建议     

Production of Doubled Haploids by Anther Culture and Wheat X Maize Method in a Wheat Breeding Programme

Utilization of the doubled haploid method of breeding usually shortens the time to cultivar release, and methods of haploid production need evaluation in a breeding programme. Thirty-eight different three-way crosses were tested for anther culture response. On average 5.8 percent of the anthers cultured produced calli. Three crosses were found recalcitrant for callus induction. Overall, the anther culture method produced 0.6 plantlet per 100 anthers cultured. Five crosses with an average of 5.8 and 2.8 percent of anthers producing calli and plantlets, respectively, were compared using anther culture and wheat × maize crosses. Non-responsive genotypes for callus induction and plantlet formation in the anther culture method proved to be good parental material in wheat × maize crosses. The average percentages of embryo formation and plantlet production in wheat × maize crosses were 10.3 and 4.7, respectively. Anther-derived plants were cytologically unstable, whereas all the plants regenerated from wheat × maize crosses were haploids (n = 21 chromosomes). The chromosome numbers of the polyhaploids were doubled with a colchicine treatment. Improvement of the two haploid production methods to facilitate their efficient use in a breeding programme is discussed.     

Genetic,quantitative and microscopic evidence for fusion of haploid nuclei and growth of somatic calli in cultured <Emphasis Type="Italic">ms10</Emphasis><Superscript><Emphasis Type="Italic">35</Emphasis></Superscript> tomato anthers

In plant breeding, androgenic doubled haploids represent powerful tools to save time and resources for pure line generation. While in many species efficient protocols are known, in tomato (Solanum lycopersicum), the knowledge on the induction of androgenesis is still very scarce, and little is known about the particularities of this highly recalcitrant species. The only known method capable of yielding haploid/doubled haploid tomato plants is anther culture. However, this method has important limitations, including low efficiency of haploid induction and a low proportion of spontaneously doubled haploids. To understand these limitations better, we have analyzed the process of callus formation in anthers of tomato lines carrying the ms10 ³⁵ gene for male-sterility, using light and electron microscopy, flow cytometry and genetic analysis with morphological and molecular markers. Our results demonstrate that haploid, doubled haploid and diploid calli occur in tomato anthers, although at different frequencies. Diploid calli derived either from somatic cells or from the fusion of two genetically different haploid nuclei account for more than 90% of the total of calli produced. Somatic calli are derived from the stubs of connective tissue present in the interlocular septa of anthers. This growth is markedly increased in the ms10 ³⁵ mutants, which explains their higher callogenic rates than standard tomato lines. Together, our results reveal serious drawbacks that explain the low efficiency of anther-derived, doubled haploid production in tomato, and stress the need for alternatives towards doubled haploidy.     

Factors affecting oat haploid production following oat × maize hybridization

Doubled haploids (DHs) are becoming increasingly important in crop breeding programmes but methods for producing oat DHs remain inefficient. In this study haploid and DH oat plants were produced using the oat × maize hybridization method. Factors influencing the rate of caryopsis and haploid embryo production including genotype, post‐pollination plant growth regulator application and temperature were investigated. The four growth regulators tested showed significant differences in their capacity to induce caryopsis formation with dicamba producing the highest numbers of caryopses, followed by picloram, 2,4‐dichlorophenoxyacetic acid (2,4‐D) and gibberellic acid (GA₃). No significant differences were observed between these growth regulators for their effect on embryo production. The concentration of dicamba was also important and was found to influence caryopsis but not embryo production, with 50 and 100 mg/l dicamba producing significantly more caryopses than 25 or 5 mg/l. Temperature had a significant impact on both caryopsis and embryo production with the magnitude and direction of response depending on genotype. Rates of haploid embryo production observed were between 0.8% and 6.7% of the pollinated florets. The proportion of haploids, which survived and were successfully doubled with colchicine following transfer to soil was between 72% and 81%.