Study On Interspecific Hybridization Between Rap-radish Addtion Line And Brassica Rapa

To breed resistant varieties is an important way to control nematode in vegetable cutivating.In terms of short of nematode resistance sources in Cruciferae Brassica,rape-radish addition line do,Brassica rapa A3 and A1 and F₁ hybrid dA1 between do and A1 were used to cross and backcross.Primary materials were obtained by means of sexul hybridization to transfer radish chromosome d carrying nematode-resistance into Brassica rapa.The results were as follows:1.Hybrids F₁ and BC₁ were obtained between rape-radish addition line do and Brassica rapa by sexual hybridizationSexual hybridization between rape-radish addition line do and Brassica rapa by sexual hybridization was easy to success,hybrids F₁ and BC₁ could be obtained only through the auxiliary artificial pollination.Compatible index of reciprocal cross between addition line do and flowering chinese cabbage A3 respectively Reached1.79 and 1.73,with the average of grain number per silique about two,and compatible index of backcross between F₁ hybrids dA1 and chinese cabbage A1 was 0.28,with the average of grain number per silique less than one.Hybrids from obverse cross do×A3 and back cross dA1×A1 were relatively full,with germination rate more than 85%,but hybrids from inverse cross A3×do was not well,only about half of them germinated.2.Identification of hybrids F₁ and BC₁Seeds from obverse cross do×A3 were all true hybrids with radish chorosome d,few seeds from inverse cross A3×do were not true hybrids,and seven hybrids among forty six backcross seeds had chorosome d identified by RAPD markers and SSR markers.The growth of hybrids F₁ were normal,with characters leaned to the addition line do,and could produce pollen.The growth of BC₁ were also normal,and their characters began to segregate obviously, with some leaned to A1and some leaned to the addition line do.Cellular relative DNA contents of true hybrids lied between their parents.However,true hybrids were not entirely consistent with each other; some hybrids from A3×do had higher level.Cellular relative DNA contents of BC₁ hybrids were not consistent with each other,most of them lied between A1 and dA1 except some neaby dA1.3.Determination of hybrids F₁ and BC₁The large pollen was viable,being deep red stained by acetic acid,but the majority of small pollen had not viability,showing pink or colorless.The pollen viability of parents was more than 90 percent, with little of small pollen,while hybrids F₁ and BC₁ had more small pollen and pollen viability was significantly lower than their parents.There were differences in pollen viability of hybrids from reciprocal crosses between do and A3,in which pollen viability of hybrids from obverse cross was consistent with each other,up to about 40%,except pollen viability of some hybrids from inverse cross was higher,about 65%.The pollen viability of BC₁ changed in the vicinity of 40%,only about 26%, obviously lower than dA1.