Study On The Exogenous DNA Directly Introduced Into Sorghum

Exogenous DNA of tropical sorghum with characters of tall plant height, more juice in haulm, high sugar content, diseases resistance, high biomass and long growth duration, was introduced directly into local sorghum varieties through pollen tube pathway, in order to study the feasibility of this technique used in sorghum breading.Stigma was cut when the receptor had been self-pollinated about 60 min, and dripped foreign DNA on the nick. Many characters could be variable, not only quantitative characters, but also qualitative ones, including agronomic characters, fertility, diseases resistance, sugar content, and kernel quality characters. The transferred frequencies of every variable characters were different. The regularity of segregation of qualitative characters in D2 was not accord with Mendel's regularity of segregation.The determination of quality characters indicated that, 4 transferred progenies'starch content was higher than their receptors, accounting for 6.9 %. 3 transferred progenies' amylopectin content was higher than their receptors, accounting for 5.1%, 8 transferred progenies' tannin content was lower than their receptors, accounting for 11.4%. Some transferred progenies' contents were both higher and lower than their receptors and donors.15 transferred progenies' sugar content was higher than their receptors, accounting for 7.9%. Of the 15 transferred progenies, 8 transferred progenies' sugar content was higher than their receptors and donors. These progenies can't be obtained in conventional breeding.27 transferred progenies' diseases resistance was increased because of the DNA transferring, accounting for 9.1%. In which 5 transferred progenies' diseases resistance increased 2 grade, and 3 transferred progenies' diseases resistance increased 3 grade. The disease resistant of receptor was increased significantly.When the transferred progenies were used in cross breading, some of the sterile lines, maintenance lines and restoring lines' fertility was changed. Meanwhile, variant characters of their transferred progenies could be appeared in filial generation. This indicated that the variant characters after transference were hereditable.To check the variant progenies, POD and ES isoenzymes were analysed in transferred progenies. The results indicated that the transferred progenies' bands of isoenzyme were different from their receptors. The donor's bands of isoenzyme appeared in the transferred progenies in various extends. The activity of isoenzymes was decreased and the bands of isoenzymes were lost. This proved that the DNA fragment of donor had entered to the receptor, and participate in DNA synthesis of receptor. This conformed to the transferredprogenies' crazy segregation phenomenon.The transferred progenies were checked with RAPD. The specific bands were obtained in progenies' amplification primers, and the bands didn't exist in receptor. They inserted into receptor through pollen tube, and affected the expressing of genes in receptors.Variant progenies were obtained by exogenous DNA introduction. And these progenies couldn't be obtained in conventional breeding. It realized the transference of inheritable matter between varieties of distant geography, and made the inheritable types abundant. The results indicated that it was possible to use this technique to create new germplasm and improve attributes by using the pollen tube passage to introduce exogenous DNA. This method can be used as a complementary method of conventional breeding.