Histological Mechanism And Cross-compatibility On Distant Hybridization In The Calycanthaceae

The Cross Compatibility is an important basis for the content of the cross-breeding. It willprovide technical support for the expand breeding parents and innivation new germplasmresources. Calycanthaceae was subdivided into9species belongingto3genera. Chimonanthuspraecox is an important fragrant flowers in winter. Calycanthaceae plates were selected to beused as parents for artificial cross. examined germination behavior of pollen grains on thestigmas after pollination and observed embryo development using paraffin section or wholeclearing technology. From pollen tube germination and growth, fertilization, as well as hybridembryo growth and development to reveal Calycanthaceae plates’ compatibility. Investigatedistant hybridization mechanis. lay the foundation for the Calycanthaceae plates distanthybridization.1.Pollen preservation and vitalityIn order to overcome the problem of flowering inconsistent, storage Chimonanthuspraecox’s pollen in-80℃and-196℃. The results showed that pollen can save a certain vitalityafter a moderately dry In both conditions. The pollen viability was11.4%and12.7%after3months when dry2h in silica gel and storage temperature in-80℃and-196℃. Storaged Pollencould meet the need through the latter cross-pollination experiments. But Calycanthus floridusvar. oblongifolius and Sinocalycanthus chinensis’s pollen viability is zero using same method inChimonanthus praecox florescence, the pollen produced in summer may be the main factorsresulting in short life-span.2.Intergeneric cross-compatibilit among CalycanthaceaeThere are no significant barriers in pollen germinate, Pollen tube growth and fertilizationstage. However, the higher proportion of hybrid embryos degradation in early stage result lowseed setting rate. When S. chinensis×C. floridus var. oblongifolius, most of pollen tubes reachedinto embryo sac approximately at36h, reproductive barrier was due to hybrid embryo abortion ordegeneration in the early development stage, when C. floridus var. oblongifolius×S. chinensis,pollen could adhere and further germinate on stigmas and pollen tubes could reach embryo sacs in48h, that was contributing to high percentage of abnormal megagametophyties and hybrid embryoabortion in the early stage caused hybrid barriers. There are no pollen germination in the two crosses(C. praecox×S. chinensis and C. praecox×C.floridus var.oblongifolius), Indicated these cross had low compatibility. however pollen couldadhere and further germinate on stigmas when C. floridus var.oblongifolius×C. praecox. and S.chinensis×C. praecox.indicated a certain compatibility. but the ability to form normal hybridsrequires further study.3.Intergeneric cross-compatibilit among ChimonanthusUsing C. praecox, C. salicifolius and C. nitens as the materials. investigated their crosscompatibility. The results showed that pollen could germinated on the stigma regardlessreciprocal cross, but the rate of germination is less than10%, Cytological observation of thedevelopment process of C. praecox’s embryo and endosperm at the state of nature and afterhybridization by whole clearing technology. The results showed that double fertilization formedin8d of C.praecox×C.salicifolius S.Y. Hu.. globular embryo formed in15d. globular embryowere degenerating in25d. endosperm development was not been observed in the wholeprocess.however endosperm became cellular at25d in natural condition. endosperm growthretardation result the low seed setting rate.