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.

Effects of exogenous paclobutrazol and sampling time on the efficiency of in vitro embryo rescue in the breeding of new seedless grape varieties

Embryo rescue technology plays an important role in seedless grape breeding.However,the efficiency of embryo rescue,including the embryo formation,germination,and seedling rates,is closely related to the parental genotypes,degree of abortion,growth medium,and plant growth regulators.In this study,we investigated the effects of different concentrations of paclobutrazol(PAC),a plant growth regulator,and embryo collection times on the embryo formation,germination,and seedling rates for different hybrid combinations of grape breeding varieties used for their aroma and cold-resistance traits.The results showed that the different PAC concentrations had varying impacts on the development of ovules and embryos from the different grape varieties.The embryo formation rates of the‘Sultanina Rose’בBeibinghong’and‘Kunxiang Seedless’בTaishan-2’crosses were the highest under the 5.1μmol L^(-1)PAC treatment.The 1.0μmol L^(-1)PAC treatment was optimal for the germination and seedling development of the‘Sultanina Rose’בBeibinghong’embryos,whereas the 0.2μmol L^(-1)PAC treatment induced the highest germination rate for the‘Sultanina Rose’בKunxiang Seedless’cross.The optimal sampling times for each cross varied as 39 d after pollination(DAP)for the‘Flame Seedless’בMuscat Hamburg’cross,46 DAP for the‘Kunxiang Seedless’בBeibinghong’cross,and 41 DAP for the‘Ruby Seedless’בBeibinghong’and‘Fantasy Seedless’בShuangyou’crosses.Moreover,the medium modified with 0.5 g L^(-1)of indole-3-butyric acid allowed the malformed seedlings to develop into plantlets and achieve larger progenies.This study provides a useful basis for further studies into grape embryo rescue and could improve breeding efforts for new seedless grape varieties.

Pollination Methods and Embryo Rescue Techniques of Hybridization between Lilium Oriental Hybrids

The pollination methods and embryo rescue techniques of hybridization between I.ilium Oriental hybrids were studied in this paper. The results showed that ： （ 1 ） in the combination of ＇ Justina＇ x ＇ Shala＇, pollen tubes were observed to grow downward in styles and target to ovules in ovaries when normal sti^na 13o1- lination method was used; pollen tubes were found to grow directionless to a different degree at stylar cuts and in ovaries when cut-style pollination method was used; the longer the styles were left, the more pollen tubes toward to ovules were observed and more plump seeds were produced; the maximum plump seeds were obtained via normal stigma pollination. （2） Hybridization experiments were performed for the 56 combinations of Lilium Oriental hybrids with normal stigma pollina- tion, and one combination generated no plump ovule and three combinations generated fewer than 10 plump ovules while the other 52 combinations generated plenty of plump ovules, which preliminarily indicated that normal stigma pollination method could be used as an universal pollination technique for hybridization between Lilium Oriental hybrids. The experiment results of different embryo rescue techniques showed that using cut-ovule inoculation about 70 d after pollination had a fas- ter germination speed and a higher germination rate of hybrid embryo than normal ovule inoculation, and embryo rescue efficiency of the former method was obviously higher than ＂embryo isolated inoculation＂ on 40 d after pollination. The research suggested that ＂cut-ovule inoculation＂ about 70 d after pollination could be regarded as an universal embryo rescue technique for hybridization between Lilium Oriental hybrids.

Embryo culture is an efficient way to conserve a medicinally important endangered forest tree species Strychnos potatorum

The present study reports a protocol for germination of Strychnos potatorum （ver. Tel. Chilla） using zygotic embryo culture as an embryo rescue method. A 100% germination rate was obtained by culturing the embryos on full-strength Murashige and Skoog＇s medium （MS） containing 20 g/L sucrose in comparison to McCown and Lloyd＇s Woody Plant Medium （WPM）. Germination rates decreased when the sucrose concentration was lower or higher than 20 g·L-1 . WPM/MS medium containing glucose at levels 30, 20, 15 g·L-1 showed a smaller percentage of germination and at quarter strength, WPM/MS medium with glucose did not respond. Multiple shoot formation was found at 1.0 2.0 mg/L BAP; 3.0 mg/L Kn; 2.0 mg/L TDZ on MS medium with 20 g·L-1 sucrose. Germination rates improved when the embryos were placed upright （vertically） in the medium. The in vitro germinated seedlings were acclimatized in a walk-in-chamber and maintained in the green house with the survival rate of 65% 75%. These plants were transferred to the field and were found to be phenotypically normal, healthy and similar to donor plants. This protocol will be useful to overcome seed dormancy and for rapid multiplication and conservation of S. potatorum using zygotic embryo culture.