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The following points highlight the top ten applications of haploid plants. The applications are: 1. Development of Pure Homozygous Line 2. Use in Hybrid Development 3. Significance in Early Release of Varieties 4. Hybrid Sorting in Haploid Breeding 5. Induction of Mutagenesis 6. Induction of Genetic Variability 7. Generation of Exclusively Male Plants and a few others.
Application # 1. Development of Pure Homozygous Line:
In plant breeding, it is very much essential to get the pure homozygous line which is generally obtained through selfing for 6-7 generations. But by the use of anther/pollen culture it can be reduced to few months or a year. These genetically pure homozygous lines are used for breeding as well as genetic research purpose. This technique is also helpful for breeding of these plants which have more elongated juvenile phase.
Application # 2. Use in Hybrid Development:
As a result of complete homozygosity obtained from diploidisation, the traits are easily understood and can be fixed for further breeding programme for hybrid production.
Application # 3. Significance in Early Release of Varieties:
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As time taken for getting the homozygous line is less so ultimately many new hybrid varieties can be obtained in less time applying this technique. Also the anther culture can be applied to the F1 hybrid plants which may not be stable in many cases but anther/pollen culture can help to get di-haploid plants with less effort which may be of great use.
Application # 4. Hybrid Sorting in Haploid Breeding:
Haploid breeding involves the hybrid sorting and it is considered superior to pedigree and bulk method as the superior haploid plants are selected and hybridized. Haploids derived from anther culture in less time and with less effort give the advantage of selection of different superior gametes to be used for haploid breeding (Fig. 21.5).
Application # 5. Induction of Mutagenesis:
Haploid cell cultures are useful material for induction of mutations and to study the effect of mutation. This method can overcome the masking effect of presence of dominant gene. The screening method for detection of mutational effect is also easier in this technique.
Application # 6. Induction of Genetic Variability:
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The pollen/microspore are easy explant for production of genetically variable types by introducing the different foreign genes through different transformation procedure. These transformed or transgenic haploids can be used further in breeding programme.
Application # 7. Generation of Exclusively Male Plants:
By haploid production of some dioecious male plant, the di-haploid plant containing both Y chromosomes can produce super-male. In case of Asparagus, male plants give more yield than female plants, so if haploids are produced from anthers of male (XY) plants and by chromosome doubling the Y chromosome containing plant will produce super male plant (YY) which can be subsequently vegetatively propagated.
Application # 8. Development of Disease Resistant/Insect Resistant Varieties:
Haploid production can be used for the introduction of disease resistance genes into cultivars. An established cultivar is crossed with a donor disease resistant species and either F1 or F2 anthers are cultured. Haploids are developed and screened for resistance and then diploidized.
Application # 9. Development of Salt Tolerant Varieties:
Salt tolerant breeding lines have been developed in different crop species which have been further integrated in conventional breeding procedure.
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Application # 10. Development of Aneuploids:
Haploids have been used in the production of aneu plaids like monosomies in wheat, trisomies in potato. In tobacco nullisomics were derived from haploids obtained from monosomies which could not produce nullisomics on selfing.
