Doubled Haploid Production in Crop Plants

The interest of fruit breeders in haploids and doubled haploids (DH), lies in the possibility of shortening the time needed to produce homozygous lines compared to conventional breeding. Haplo-diploidization through gametic embryogenesis allows single-step development of complete homozygous lines from heterozygous parents. In a conventional breeding programme, a pure line is developed after several generations of selfing. With fruit crops, characterized by a long reproductive cycle, a high degree of heterozygosity, large size, and, sometimes, self-incompatibility, there is no way to obtain haploidization through conventional methods. This paper reviews the current status of research on doubled haploid production in the main fruit crops: Citrus, Malus domestica, Pyrus communis, Pyrus pyrifolia, Prunus persica, Prunus avium, Prunus domestica, Prunus armeniaca, Vitis vinifera, Actinidia deliciosa, Olea europaea, Morus alba, Actinidia deliziosa, [Musa balbisiana (BB)], Carica papaya, Annona squamosa, Feijoa sellowiana, Opuntia ficus-indica, Eriobotrya japonica.

Doubled haploid production in fruit crops

Forty-four protocols of doubled haploid production (DH) are presented in this Manual. They are related to at least 33 plant species, not counting protocols on production of DH from interspecific hybrids. The protocols provide procedures for production of DH in such major crops as wheat, maize, barley, rapeseed or potato and also in other crop species where this technology is more advanced, or in other words, where a relatively high frequency of doubled haploids was obtained. However, there have been several approaches to develop doubled haploids in many crops or plant species. We are presenting below the list of publications related to DH production in 226 additional plant species. This list does not include protocols of plant species published in Chapter 2 of this Manual. This means that efforts have been undertaken to develop doubled haploids in more than 250 plant species as the presented list was built on the basis of our own collection of related publications and as a result of searching in publicly available databases. It was impossible to cite all published information. We limited references to those which carried protocols or more recent information on DH production. In the cited papers, presented protocols did not always lead to the regeneration of haploid or doubled haploid plants. However, even negative results can be very helpful for someone who is initiating this work. We hope that publication of this list will help in further application of DH technology in crop improvement and basic research.

Published doubled haploid protocols in plant species

Haploids and Doubled Haploids in Fruit Trees

http://www.iitg.ac.in/rakhi_chaturvedi/pdf/books/j27.pdf

In vitro androgenesis in tree species: an update and prospect for further research.

Anthers of Morus indica L., with microspores at the uninucleate stage were cultured; and the influence of temperature and kinetin pretreatment on induction of androgenic calluses was examined. The effects of various pretreatments revealed that 24 h cold pretreatment increased the percentage of cultures inducing callus. First microspore division was observed after 16 to 20 days of culture. Th anthers split and developed embryogenic calluses on MB medium supplemented with NAA (0.5 mg l−1 and BA (1.0 mg l−1)) using 8% sucrose. Rhizogenesis was induced on medium supplemented with NAA and BA (each 0.5 mg l−1) with reduced myo-inositol (75 mg l−1). Cytological study of induced roots confirmed the haploid nature of calluses. Different type of embryos were initiated upon transfer of calluses to medium supplemented with NAA, BA (each 0.5 mg l−1), 2,4-d (1.0 mg l−1) and PVP (600 mg l−1). These embryoids further developed roots on removal of 2,4-d from the medium and developed precociously without developing cotyledons and formed elongated shoots.

R. K. Datra

Papers

Induction of haploid callus and embryogenesis in in vitro cultured anthers of mulberry (Morus indica)