Exploration and Innovation of Distant Hybridization Germplasm of Oryza sativa and Spartina alterniflora

[Objective] The aim was to explore salt-resistant Spartina alterniflora and high-yield rice with germplasm resource in order to create new salt-resistant rice species with dual-purpose of food and forage. [Method] From 2009 to 2011, re- searches on distant hybridization of Spartina alterniflora and Oryza Sativa have been conducted with method of distant hybridization breeding. On the other hand, break- through and combination techniques （four selected one） were adopted to find the new rice species, including techniques of planting and selection in seashore, cyto- logical detection and selection, phenotype selection of backcross, and molecular marker assisted selection. [Result] Success rate of distant hybridization from 2009 to 2010 was 1.39%. RAPD molecular identification of 7C14 and rice female parent of Zhongxiang No.l, seed 2 was carried on with distant hybridization of male parent of Spartina altemiflora （H）. The results showed that bands same with Spartina alterni- flora parents were found in RH-1-10K205-7C14xH, RH-2-8K157-7C14xH, and RH-13- 9H5-Zhongxaing No.1 xH. Considering absent situation in rice parents, distant hy- bridization strains above were found with same parental genetic element as Spartina alterniflora. Female parent of rice 7K339, however, was under RAPD molecular identification with male parent of Spartina alterniflora. The result showed that bands same with Spartina alterniflora parents were found in RH-5-10K215, RH-6-8K48, RH- 12-9H9, RH-14-9H8 and RH-16-9H28. Considering absent situation in rice parents, distant hybridization strains above were found with same parental genetic element as Spartina altemiflora. Rest hybrid strains were found variance with Spartina alterniflora parents and rice parents in varying degrees. [Conclusion] New and excellent rice species of dual-purpose solves problem not only about salt-resistant species badly needed in coastal development and treatment of saline and alkaline land, but about fine fodder and roughage for herbivore, as well. What＇s more, this is of scientific significance in recourse utilization, efficiency improvement in agriculture, food security, and cultivation strategy.

Exploration and Innovation of Distant Hybridization Germplasm of Spartina,Soughum bicolor and Oryza sativa

[Objective] This study aimed to explore the germplasm resources of salt-tolerant Spartina,sweet-stalk Soughum bicolor and high-yield Oryza sativa for innovation of new germplasms of salt-tolerant and sweet-stalk Oryza sativa with dual purpose of food and forage in sea beach.[Method] From 2009 to 2012,researches on distant hybridization of Spartina,Soughum bicolor and Oryza sativa had been carried out,and the RAPD molecular identification of obtained distant hybridization materials had been conducted.[Result] Experimental evidences of hybrid seed setting,transplanting and economic characters of hybrid materials were obtained;among the 14 hybrid materials for RAPD analysis,5 materials shared common bands with Spartina and Soughum bicolor parents,which were absent in Oryza sativa parent,indicating that the genetic component of Spartina and Soughum bicolor parents has been integrated into the 5 distant hybrids.[Conclusion] This study has important scientific significance in recourse utilization,agricultural efficiency improvement,food security,and cultivation strategy of China,showing broad application prospects.

The contribution of distant hybridization with decaploid Agropyron elongatum to wheat improvement in China

Wheat is a staple food crop in the world as well as in China. Because of the progress of wheat breeding and other agricultural ＂sci-technologies, the wheat grain yield per unit area has increased more than five folds from 1952 to 2006 in China. The first part of this article briefly reviews the history of wheat breeding in China. Second, the establishment of ＂Triticum aestivum-Agropyron＂ distant hybridization system and its contribution to wheat production and breeding in China are summarized. Finally, the future challenges of wheat breeding are discussed, which include how to increase the utilization efficiencies of water, soil nutrient and light energy through breeding. As an example, our research progress on how to increase light use efficiency in wheat through breeding is introduced and discussed.

Creating New Germplasm by Distant Hybridization in Stone Fruits:Ⅰ.Effects of Different Treatments on Cross Compatibility of Distant Hybridization inStone Fruits

The effects of different treatments on cross compatibility in distant hybridization werestudied in 69 cross combinations among 9 cultivars of stone fruits. The results showedthat the setting percentage in balloon stage was obviously higher than that in earlyblooming stage. The differences of fruit set between positive and reverse crosses weresignificant. Female parent affected cross compatibility more remarkably than male parentin distant hybridization. The appropriate electrostatic field, He-Ne laser combinedtreatment with 60Co γ-ray and He-Ne laser could improve the pollen germination rate invitro effectively, the fruit set percentage was higher than control, while 60Co γ-raytreatment reduced the pollen germination rate in vitro, and the fruit set percentageobtained by distant hybridization was lower than control.

An Innovative Strategy for Reciprocal Distant Hybridization between Spartina alterniflora and Rice

[Objective] This study aimed to explore germplasm resources of salt toler- ant Spartina alterniflora and high yield rice, and develop an innovative strategy for distant hybridization between S. altemiflora and rice. [Method] Crossing （rice ♀ ）： hot water emasculation and glume-cutting pollination method, heat emasculation and pollen-suction pollination method; reciprocal crossing （S. alterniflora ♀ glume-cutting emasculation and pollination method, continuous emasculation-pollination method, hot water emasculation and continuous emasculation-pollination method. [Result] In crossing groups （rice ♀ × S. alterniflora ♂ ）, compared with hot water emasculation and glume-cutting pollination treatment, the number of seed-bearing combinations, seed number per spike and seedling emergence rate in heat emasculation and pollen-suction pollination treatment were improved by 34.09%, 121.21% and 60.07%, respectively; hybridization efficiency was improved by 6-7 times. In reciprocal cross- ing groups （S. altemiflora ♀× rice ♂ ）, compared with glume-cutting emasculation and pollination treatment, the number of seed-bearing combinations and seed num- ber per spike in continuous emasculation-pollination treatment were improved by 3.14 and 4.21 times, respectively; seedling emergence rate was improved by 68.47%; hybridization efficiency was improved by 7-8 times. [Conclusion] Heat emas- culation and pollen-suction pollination method is suitable for hybridization between rice ♀× S. alterniflora ♂; continuous emasculation-pollination method is suitable for hybridization between S. alterniflora ♀× rice ♂.

Innovation on Distant Hybridization of Saline-tolerant Mud Flat Spartina and Rice Germplasm

To explore saline-tolerant high yield Spartina and rice germplasm resources,innovate upon distant hybridization technology,and develop new saline-tolerant mud flat Spartina germplasm,autonomous patent for invention was used to study distant hybridization of Spartina and rice in 2005- 2016. The study adopted tidal flat planting screening,phenotypic screening,molecular marker assisted selection,to find biological evidences of new germplasm,and also applied crossbreeding,conventional breeding,and molecular breeding,to select new saline-tolerant Spartina and rice varieties. With 12 years of efforts,the team developed 1498 crossbreeding combinations and established pedigree file and seed bank,tested 307 crossbreeding materials(57 hybrid seeds showed parental genetic components of Spartina and Rice); obtained Spartina/ Rice distant hybridization and seed setting,transplanting,hybridization material economic traits,and molecular biological experimental evidences; Rice♀× Spartina ♂ hybridization success rate of 1. 04- 1. 39%; obtained authorization of patent for invention of Distant Hybridization Methods for Spartina and Rice; formulated procedures for high yield cultivation of Spartina-Rice,planted 33. 33 hm2Spartina-Rice in coastal saline and alkaline land,cultivated 10 new saline-tolerant Spartina-Rice varieties,and the rice yield up to 5. 925- 8. 28 t / hm2. Results indicate that Spartina-Rice is saline-tolerant high yield rice germplasm,developed through sexual hybridization,conventional breeding,and molecular breeding technologies,and is optimal crop for saline and alkaline land. Success of Spartina-Rice solves the problem of saline-tolerant crop badly for transformation of saline and alkaline land,the problem of feeds for herbivores,as well as problem of environmental pollution resulted from straw burning. Besides,it is of essential scientific significance for resource utilization,increase of agricultural efficiency,grain security,and farmland strategy,so it has broad application prospect.

Improvement of Fiber Quality by Distant Hybridization in the Green Cotton

In order to improve fiber quality of green cotton,a wide hybrid was used between a green fiber cotton and Sea Island cotton.The results show that the hybrid F1 plants were stable,but F2

Creating New Germplasm by Distant Hybridization in Stone Fruits:Ⅱ-Embryo Rescue and Hybrid Identification Between Plum and Apricot

Embryo abortion stage and rescue system of hybrids were studied in the distant hybridizationbetween plum and apricot. Identification of the hybrids was also made. The resultsshowed: (1) Embryo abortion started from three weeks after pollination. (2) The germinationand growth of embryos were different at different growth stages, which could germinateand grow with PF value>0.5, but failed with PF value<0.5. In embryo rescue system ofhybrids, the best germination and differentiation medium was MS+6-BA 2mgL-1+IAA 0.3mgL-1,the rate of germination and differentiation reached up to 80%, bud induction andmultiplication medium was MS+6-BA 1.5mgL-1+IAA 0.3mgL-1, rooting medium was 1/2 MS+IAA0.8mgL-1. Some hybrids were transplanted into the field successfully. (3) Leaf shapeinvestigation and identification by S allele-specific PCR and RAPDs showed that thehybrids were true ones.

The key role of myostatin b in somatic growth in fishes derived from distant hybridization

The basic mechanism of heterosis has not been systematically and completely characterized.In previous studies,we obtained three economically important fishes that exhibit rapid growth,WR(WCC♀×RCC♂),WR-Ⅱ(WR♀×WCC♂),and WR-Ⅲ(WR-Ⅱ♀×4nAU♂),through distant hybridization.However,the mechanism underlying this rapid growth remains unclear.In this study,we found that WR,WR-Ⅱ,and WR-Ⅲshowed muscle hypertrophy and higher muscle protein and fat contents compared with their parent species(RCC and WCC).Candidate genes responsible for this rapid growth were then obtained through an analysis of 12 muscle transcriptomes.Notably,the mRNA level of mstnb(myostatin b),which is a negative regulator of myogenesis,was significantly reduced in WR,WR-Ⅱ,and WR-Ⅲcompared with the parent species.To verify the function of mstnb,a mstnb-deficient mutant RCC line was generated using the CRISPR-Cas9 technique.The average body weight of mstnb-deficient RCC at 12 months of age was significantly increased by 29.57%compared with that in wild-type siblings.Moreover,the area and number of muscle fibers were significantly increased in mstnb-deficient RCC,indicating hypertrophy and hyperplasia.Furthermore,the muscle protein and fat contents were significantly increased in mstnb-deficient RCC.The molecular regulatory mechanism of mstnb was then revealed by transcription profiling,which showed that genes related to myogenesis(myod,myog,and myf5),protein synthesis(PI3K-AKT-mTOR),and lipogenesis(pparγand fabp3)were highly activated in hybrid fishes and mstnb-deficient RCC.This study revealed that low expression or deficiency of mstnb regulates somatic growth by promoting myogenesis,protein synthesis,and lipogenesis in hybrid fishes and mstnb-deficient RCC,which provides evidence for the molecular mechanism of heterosis via distant hybridization.

Research advances in animal distant hybridization

Distant hybridization refers to crosses between two different species or higher-ranking taxa that enables interspecific genome transfer and leads to changes in phenotypes and genotypes of the resulting progeny.If progeny derived from distant hybridization are bisexual and fertile,they can form a hybrid lineage through self-mating,with major implications for evolutionary biology,genetics,and breeding.Here,we review and summarize the published literature,and present our results on fish distant hybridization.Relevant problems involving distant hybridization between orders,families,subfamilies,genera,and species of animals are introduced and discussed,with an additional focus on fish distant hybrid lineages,genetic variation,patterns,and applications.Our review serves as a useful reference for evolutionary biology research and animal genetic breeding.

A comparative study of distant hybridization in plants and animals

Distant hybridization refers to crosses between two different species, genera, or higher-ranking taxa, which can break species limits, increase genetic variation, and combine the biological characteristics of existing species. It is an important way of creating genetic variation, fertile strains, and excellent characteristics in new strains and populations. Combining analyses and summaries from many inter-related documents in plants and animals, both domestic and international, including examples and long-standing research on distant hybridization in fish from our laboratory, we summarize and compare the similarities and differences in plant and animal distant hybridization. In addition, we analyze and review the biological characteristics of their different ploidy progenies and the possible causes of disparity in survival rates. Mechanisms of sterility in animal and plant distant hybrids are also discussed, and research methods for the study of biological characteristics of hybrids, including morphology, cytology,and molecular cytogenetics are presented. This paper aims to provide comprehensive research materials and to systematically compare the general and specific characteristics of plant and animal hybrids with regards to reproduction, genetics, growth traits,and other biological characteristics. It is hoped that this paper will have great theoretical and practical significance for the study of genetic breeding and biological evolution of plant and animal distant hybridization.

Research and Breeding Application Progress of the Technique of Producing Double Haploid of Wheat by Wide Hybridization between Wheat and Maize

The technique of producing doublehaploid of wheat by distant hybridization between wheat and maize has characterized with better inducing effect, shorter in- ducing period, easy operation, and so on. At present, it is the most efficient and has great potential of application in breeding of wheat. This article reviewed princi- ple and production process of the technique, research situation of the three key in- dicators of the technology（embryo rate, seedling rate and success rate of doubling）in recent years, and application of the technology in breeding, genetics, germplasm improvement of wheat. At last, both the achievements and the direction of further improvement and development of the technology in our program were discussed.

Research on the Distant Hybrids of Wheat Obtained via Low-Energy Ion-Beam Implantation

The whole DNA of soybean was implanted into four varieties of wheat of Zhongyu 5, Huaiyin 9628, Wenyou 1, Jimai 5 respectively via ion-beam mediation. There were 5 plants obtained whose protein content was higher than 18.5 %, the highest one was 21.44 %. There were 3 plants obtained whose protein content was lower than 11.5%, the lowest one was 10.96%. We can see that the whole DNA of soybean transformed into wheat via ion beam implantation can induce the increase in wheat protein content dramatically. The result also shows that the transformation efficiency of different gene types of wheat receptor varies greatly that the implanting time has a certain effect on the efficiency of transformation.

Development of New Restorer Materials with Ogu CMS in Brassica napus

[Objective] Ogura cytoplasmic male sterility （Ogu CMS） is an ideal pollina- tion control system for heterosis utilization in Brassica napus. However, fertility-restor- ing （Rf） gene only exists in radish chromosome and is closely linked with glucosino- late gene, making it hardly to be applied directly in production. Thus, the key to apply Ogu CMS in Brassica napus is to introduce the Rf genes and to break its linkage with glucosinolate gene. [Me^od] To overcome the interspecific reproductive barrier, grafting was conducted by using Raphanobrassica （2n=-58） as donor materi- als of Rf genes. The obtained interspecific hybrids were analyzed from the agronom- ic traits, seed-setting rate and fertility restoration rate for screening fertility-restoring materials. [Results] By elaborative selection, a homozygous Ogu CMS fertility-restor- ing B. napus material named CLR650 was selected out, whose somatic chromosome numbers were found to be 2n=38-40. Some abnormal phenomena like anaphase bridges and lagging chromosomes in meiosis were observed, but the abnormalities did not affect the formation of normal pollens. It can restore the male fertility in both progenies of self-pollination and testcross by 100%. Molecular analysis showed that CLR650 harbors Ogu CMS fertility-restoring gene, which is obviously different from that of Ogu CMS restore line Rl13 and RHH1 by detecting the molecular markers closely linked with radish restorer gene （Rf0）. [Conclusion] The CLR650 could be a new restorer for the Ogu CMS in B. napus.

Genetic Analysis on Chromosome of Hybrid F_1 between Elymus canadensis and Elymus sibiricus

Morphologic and cytological characteristics of hybrid F1 between E. canadensis and E. sibidcus were studied. The results showed that hybrid F1 were obviously exceeded parents in plant growth vigor, and spike type of F1 was between parents. The karyotype formula of hybrid F1 which was true hybrid was 2n =4x=16M ＋ 10m ＋2st. At meiotic anaphase, chromosome lagging behaviors were frequently observed. The frequency of lagging chromosomes of F1 was 87.37%. At meiotic metaphase, there were many univalents and multivalents, and the rod bivalent formed greatly.

The Emergence of Hybrid Seeds and Polyembryony in Some Citrus Cultigens

An experiment was conducted and through distant hybridization a new promising forms of citruses were obtained. Namely, after hybridization of lemon Georgian and broad-leaved mandarin unshiu （mother components） with early-ripening trifoliata and a hybrid of citrus ichangensis--＂Caucasus＂ （father components） a wide range of nucellar seedlings were obtained. It should be noted that nucellar seedlings of hybrid nature are practically closer to distant hybrids of sexual origin that are sharply inclined to the side of the mother component and produce good quality fruit. Unfortunately, such hybrids are either very rare or cannot be obtained at all. While, in the case of the study, through using new combinations in hybridization, the possibility of getting nucellar seedlings of the hybrid nature is much bigger. Distant hybridization turned out to be particularly interesting because of the polyembryony of citrus plants. Due to this, it gives opportunity to get new promising forms not only from the egg cell but from nucellar cells as well.

Inter-specific and Inter-generic Hybridization Compatibility of Eriobotrya Species (Loquat) and Related Genera

We studied the cross-compatibility among 91 inter-specific combinations and 21 inter-generic combinations in 7 Eriobotrya plants and 2 related genera(Raphiolepis indica Lindl. and Photinia serrulata Lindl.) using emasculation, bagging, and artificial pollination. Our results showed that28 of the 91 inter-specific combinations set no fruit, which means nearly 30% of the combinations were incompatible. In the remaining 63 combinations, most showed partial cross-compatibility, and a few showed complete cross compatibility. Eriobotrya plants were incompatible with plants from their related genera(R. indica Lindl. and P. serrulata Lindl.). Backcrossing produced 5 compatible combinations, which could set fruits and produce F1 progeny but only after embryo rescue. Fruit setting ratios varied among various species used as male or female parents.E. prinoides Rehd. & Wils., common loquat(E. japonica) and Eriobotrya × daduheensis, used as female parents resulted in an average fruitsetting ratio of 36.2%–58.2%. E. deflexa Nakai and its two forms, and E. elliptica Lindl. as female parents resulted in 2.9%–16.3% average fruitsetting ratio; however, the fruit set ratio was higher(22.4%–43.1%) if they were used as male parents. Failure of E. deflexa f. koshunensis Nakai × E.prinoides Rehd. & Wils. hybrids to set fruit could be attributed to sporophytic incompatibility.

Polyploid organisms

Polyploids are organisms with three or more complete chromosome sets. Polyploidization is widespread in plants and animals, and is an important mechanism of speciation. Genome sequencing and related molecular systematics and bioinformatics studies on plants and animals in recent years support the view that species have been shaped by whole genome duplication during evolution. The stability of polyploids depends on rapid genome recombination and changes in gene expression after formation. The formation of polyploids and subsequent diploidization are important aspects in long-term evolution. Polyploids can be formed in various ways. Among them, hybrid organisms formed by distant hybridization could produce unreduced gametes and thus generate offspring with doubled chromosomes, which is a fast, efficient method of polyploidization. The formation of fertile polyploids not only promoted the interflow of genetic materials among species and enriched the species diversity, but also laid the foundation for polyploidy breeding. The study of polyploids has both important theoretical significance and valuable applications. The production and application of polyploidy breeding have brought remarkable economic and social benefits.

An improved hybrid bream derived from a hybrid lineage of Megalobrama amblycephala(♀)×Culter alburnus(♂)

Distant hybridization is an important technique in fish genetic breeding.In this study,based on the establishment of an allodiploid fish lineage(BT,2n=48,F_(1)–F_(6))derived from distant hybridization between female Megalobrama amblycephala(BSB,2n=48)and male Culter alburnus(TC,2n=48),and the backcross progeny(BTB,2n=48)derived by backcrossing female F_(1) of BT to male BSB,an improved hybrid bream(BTBB,2n=48)was obtained by backcrossing BTB(♀)to BSB(♂).Moreover,the morphological and genetic characteristics of BTBB individuals were investigated;BTBB was similar to BSB in appearance but had a higher body height than BSB.The study results regarding chromosome numbers and DNA content indicated that BTBB is a diploid hybrid fish.The 5S rDNA and Hox gene of BTBB were inherited from the original parents.Gonadal development in BTBB was normal.On the other hand,BTBB had a faster growth rate,higher muscle protein level,and lower muscle carbohydrate level than BSB.Hence,bisexual fertile BTBB is promoted and can be applied as a high-quality fish,and it can also be used as a new fish germplasm resource to develop high-quality fish further.Thus,this study is of great significance for fish genetic breeding.