Doubled Haploids in Tropical Maize: I. Effects of Inducers and Source Germplasm on in vivo Haploid Induction Rates

ABSTRACTArtificial chromosome duplication is one of the most important process in the attainment of doubled haploids in maize. This study aimed to evaluate the induction ability of the inducer line KEMS in a tropical climate and test the efficiency of the R1-Navajo marker by flow cytometry to evaluate two chromosome duplication protocols and analyze the development of the doubled haploids in the field. To accomplish this goal, four genotypes (F1 and F2 generations) were crossed with the haploid inducer line KEMS. The seeds obtained were selected using the R1-Navajo marker and subject to two chromosome duplication protocols. Duplication was confirmed using flow cytometry. The percentages of self-fertilized plants after duplication as well as the quantities of doubled haploid seeds obtained after the self-fertilization processes were analyzed. It was observed that the germplasm influences haploid induction but not the duplication rates of the tested protocols. Protocol 2 was more efficient for the duplication of haploids, in the percentage of self-fertilized plants after duplication, and in the attainment of doubled haploid lines. Moreover, the haploid inducer line KEMS can produce haploids in a tropical climate. Other markers, in addition to the R1-Navajo system, should be used in the selection of haploid seeds.

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Doubled haploid production in maize under Sub-montane Himalayan conditions using R1-nj-based haploid inducer TAILP1

Indian Journal of Genetics and Plant Breeding (The) ◽

10.31742/ijgpb.80.3.4 ◽

2020 ◽

Vol 80 (03) ◽

Author(s):

R. K Khulbe ◽

A. Pattanayak ◽

Lakshmi Kant ◽

G. S. Bisht ◽

M. C. Pant ◽

...

Keyword(s):

Doubled Haploid ◽

Sweet Corn ◽

Haploid Induction ◽

Maize Breeding ◽

Line Production ◽

Haploid Inducer ◽

Breeding Programmes ◽

Source Populations ◽

Developmental Phases

The use of in vivo haploid induction system makes the doubled haploid (DH) technology easier to adopt for the conventional maize breeders. However, despite having played an important role in the initial developmental phases of DH technology, Indian maize research has yet to harvest its benefits. Haploid Inducer Lines (HILs) developed by CIMMYT are being widely used in maize breeding programmes in many countries including India. There, however, is no published information on the efficiency of DH line production using CIMMYT HILs in Indian maize breeding programmes. In the present study, the efficiency of DH production using CIMMYT’s tropically adapted inducer line TAILP1 was investigated with eight source populations including two of sweet corn. The average haploid induction rate (HIR) of TAILP1 was 5.48% with a range of 2.01 to 10.03%. Efficiency of DH production ranged from 0.14 to 1.87% for different source populations with an average of 1.07%. The information generated will be useful for maize breeders intending to use DH technology for accelerated development of completely homozygous lines.

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In Vivo Haploid Induction in Maize: Comparison of Different Testing Regimes for Measuring Haploid Induction Rates

Crop Science ◽

10.2135/cropsci2015.11.0668 ◽

2016 ◽

Vol 56 (3) ◽

pp. 1127-1135 ◽

Cited By ~ 10

Author(s):

Albrecht E. Melchinger ◽

Pedro Correa Brauner ◽

Juliane Böhm ◽

Wolfgang Schipprack

Keyword(s):

Haploid Induction

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Extension of thein vivohaploid induction system from maize to wheat

10.1101/609305 ◽

2019 ◽

Author(s):

Chenxu Liu ◽

Yu Zhong ◽

Xiaolong Qi ◽

Ming Chen ◽

Zongkai Liu ◽

...

Keyword(s):

Pollen Viability ◽

Haploid Induction ◽

Male Sterile ◽

Crop Breeding ◽

Crop Species ◽

Ploidy Levels ◽

New Approach ◽

Knock Out ◽

Haploid Production

AbstractDoubled haploid breeding technology has been one of the most important techniques for accelerating crop breeding. In compare toin vivohaploid induction in maize, which is efficient and background independent, wheat haploid production by interspecific hybridization pollinated with maize is influenced by genetic background and requires rescue of young embryos. Here, we analyzed the homologues of maize haploid induction geneMTL/ZmPLA1/NLDin several crop species systematically, the homologues are highly conserved in sorghum, millet and wheat etc. Since wheat is a very important polyploidy crop, as a proof of concept, we demonstrated that thein vivohaploid induction method could be extended from diploid maize to hexaploid wheat by knocking out the wheat homologues (TaPLAs). Result showed that double knock-out mutation could trigger wheat haploid induction at ~ 2%-3%, accompanied by 30% - 60% seed setting rate. The performance of haploid wheat individual showed shorter plant, narrower leaves and male sterile. Our results also revealed that knockout ofTaPLA-A andTaPLA-D do not affect pollen viability. This study not only confirmed the function of the induction gene and explored a new approach for haploid production in wheat, but also provided an example that thein vivohaploid induction could be applied in more crop species with different ploidy levels. Furthermore, by combining with gene editing, it would be a fast and powerful platform for traits improvement in polyploidy crops breeding.

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Haploidy and plant breeding

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1981.0044 ◽

1981 ◽

Vol 292 (1062) ◽

pp. 499-507 ◽

Cited By ~ 27

Keyword(s):

Plant Breeding ◽

Doubled Haploids ◽

Chromosome Complement ◽

Basic Research ◽

Breeding Value ◽

Additive Variance ◽

Ploidy Levels ◽

Breeding Programmes ◽

Dh Lines

A haploid is an organism that looks like a sporophyte, but has the chromosome complement of a reduced gamete. There are several ways in which haploids can occur or be induced in vivo : spontaneously, mostly associated with polyembryony, and through abnormal processes after crosses, like pseudogamy, semigamy, preferential elimination of the chromosomes of one parental species, and androgenesis. In the crops described, haploids are or are near to being used in basic research and plant breeding. The application of haploids in breeding self-pollinated crops is based on their potential for producing fully homozygous lines in one generation, which can be assessed directly in the field. Early generation testing of segregating populations is possible through haploids, because doubled haploids (DH) possess additive variance only. Haploids can also be applied in classical breeding programmes to make these more efficient through improved reliability of selection. The application of haploids in cross-pollinated crops is also based on a rapid production of DH-lines, which can be used as inbred lines for the production of hybrid varieties. By means of haploids all natural barriers to repeated selfing are bypassed. In autotetraploid crops there are two types of haploid. One cycle of haploidization leads to dihaploids; a second cycle produces monohaploids. The significance of dihaploids is in their greatly simplified genetics and breeding and in the possibility of estimation of the breeding value of tetraploid cultivars by assessing their dihaploids. The main drawback of dihaploids is their restriction to two alleles per locus. Also, after doubling, it is impossible to achieve tetra-allelism at many loci, the requirement for maximal performance of autotetraploid cultivars. Tetra-allelism can be obtained when improved dihaploids have a genetically controlled mechanism of forming highly heterozygous restitution gametes with the unreduced number of chromosomes. Monohaploids, after doubling or twice doubling, may lead to fully homozygous diploids and tetraploids. These are important for basic research, but not yet for practical application. Meiotic data of potato homozygotes at three ploidy levels are presented.

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Doubled haploid technology for line development in maize: technical advances and prospects

Theoretical and Applied Genetics ◽

10.1007/s00122-019-03433-x ◽

2019 ◽

Vol 132 (12) ◽

pp. 3227-3243 ◽

Cited By ~ 14

Author(s):

Vijay Chaikam ◽

Willem Molenaar ◽

Albrecht E. Melchinger ◽

Prasanna M. Boddupalli

Keyword(s):

Doubled Haploid ◽

Chromosome Doubling ◽

Production Costs ◽

Great Promise ◽

Success Rates ◽

Haploid Induction ◽

Maize Breeding ◽

Breeding Programs ◽

Line Production

Key Message Increased efficiencies achieved in different steps of DH line production offer greater benefits to maize breeding programs. Abstract Doubled haploid (DH) technology has become an integral part of many commercial maize breeding programs as DH lines offer several economic, logistic and genetic benefits over conventional inbred lines. Further, new advances in DH technology continue to improve the efficiency of DH line development and fuel its increased adoption in breeding programs worldwide. The established method for maize DH production covered in this review involves in vivo induction of maternal haploids by a male haploid inducer genotype, identification of haploids from diploids at the seed or seedling stage, chromosome doubling of haploid (D0) seedlings and finally, selfing of fertile D0 plants. Development of haploid inducers with high haploid induction rates and adaptation to different target environments have facilitated increased adoption of DH technology in the tropics. New marker systems for haploid identification, such as the red root marker and high oil marker, are being increasingly integrated into new haploid inducers and have the potential to make DH technology accessible in germplasm such as some Flint, landrace, or tropical material, where the standard R1-nj marker is inhibited. Automation holds great promise to further reduce the cost and time in haploid identification. Increasing success rates in chromosome doubling protocols and/or reducing environmental and human toxicity of chromosome doubling protocols, including research on genetic improvement in spontaneous chromosome doubling, have the potential to greatly reduce the production costs per DH line.

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