New Aspects of Tulip Breeding: Embryo Culture and Polyploid

Abstract

In order to improve bulb productivity and ornamental characteristics in tulips, it is necessary to increase genetic variation by using breeding techniques such as overcoming of interspecific barrier, embryo rescue of abortive embryos and induction of polyploids. To identify interspecific barrier between species, crossing experiments have been studied about fifty years ago and recently embryo rescue technique just has been attempted in Holland. In polyploid breeding, colchicine treatment is a common technique to produce polyploids, whereas nitrous oxide has been applied to zygotes as a polyploidizing agent in various crops. This paper reviews some of the literature and our results regarding to embryo rescue technique and also reports on the usefulness of 2n pollen induced with nitrous gas in tulip breeding.

Analysis of introgression of the Tulipa fosteriana genome into Tulipa gesneriana using GISH and FISH

“…The possibility of transmitting important agricultural traits, such as virus resistance, from T. fosteriana to T. gesneriana during interspeciWc tulip breeding has been suggested previously (Van Eijk et al 1991;Custers et al 1995;Okazaki 2005). We found that interspeciWc breeding in progeny obtained by backcrossing T. gesneriana with the fertile interspeciWc hybrid 'Purissima' expands the genetic variation of garden tulips.…”

Cross compatibility in intraspecific and interspecific hybridization in yam (Dioscorea spp.)

“…Besides, hybrid genotypes acting as a bridge between related incompatible yam species could be developed 19 or to experiment the cut-style pollination technique which had been successful in other crops 18 . The post-zygotic barriers resulting in seedless fruits can be controlled by biotechnology techniques such as the embryo rescue to prevent post-zygotic abortions 17 . Such techniques have been fully developed and implemented by CIRAD-Guadeloupe, France, and could be transferred to other programs to exploit interspecific and interploidy crosses in yam breeding 20 , 21 .…”

“…An attempt with an interspecific cross to introgress desired genetic variants among yam species has been reported 16 . However, such effort is often challenged by pre-zygotic and post-zygotic cross-compatibility barriers in most crops 17 – 19 , including the yams 20 , 21 . Although some yam species cross naturally in controlled and wild environments 22 , efforts are necessary to understand the nature of crossing barriers and devise means that facilitate gene flow among yam species to achieve cross-breeding goals.…”