Studies On Reproductive Biology And Distant Hybrid Compatibility Of 12 Genus Viola

The most of genus Viola is a perennial plant,with a few are biennial herbs.The wild resources are abundant of Viola in China,and about 110 species.Many of them have the advantages of peculiar leaves,strong heat and cold resistance and so on,which are rare in the cultivated species of Viola tricolor.Distant hybridization is an important way to cultivate new varieties.It is of great significance to explore the compatibility of distant hybridization in pansy plants for the cultivation of new varieties of V.tricolor with excellent comprehensive characters.In this study,the karyotypes of 6 species of wild pansy were analyzed,and the biological characteristics of reproduction were studied.On this basis,the related combinations were selected and hybridized,and the fluorescence observation method of aniline blue staining was used.The fertilization and embryo development of pansy after hybridization were observed and analyzed by paraffin section method,and the hybrid progenies were identified.results as following:The results of karyotype analysis of 6 wild Viola species were as follows: V.hancockii karyotype formula was 2n=2x=24=10m+14sm;V.uariegataisch karyotype formula was 2n=2x=12=14m+10sm;V.acuminata karyotype formula was 2n=2x=24=20m+2st+2sm;V.dissecta karyotype formula was 2n=2x=24=20m+2st+2sm,V.acuminata karyotype formula was 2n=2x=20=8sm+12m;V.prionantha karyotype formula was 2n=4x=48=36sm+12m;V.philippica karyotype formula was 2n=4x=48=36sm+12m;The index of karyotypic asymmetry was 60.99%~65.57%.According to the ratio of the longest to the shortest chromosome length and the chromosome ratio of the arm ratio greater than 2,the karyotype classification of pansy,V.hancockii,V.uariegataisch,V.acuminata,V.acuminate,V.dissecta Viola philippica were all 2A type.V.prionantha belongs to 3A karyotype.The degree of evolution of six pansy germies is as follows: V.prionantha > V.philippica > V.hancockii > V.uariegataisch > V. acuminata > V.dissecta.The 6 wild corydalis,3 Viola wittrockiana and 3 Viola cornuta stigma of were higher than that of anthers.The stigmability and the time of powder dispersion were overlapped.The results of pollen/ovule ratio,hybrid index and pollination test showed that the breeding system were self-compatible of Viola philippica and Viola prionantha and sometimes needed pollinators.The breeding systems of the other 10 germplasms were facultative outbreeding,and some of them were self-compatible and needed pollinators.The pollen morphology of 12 Viola germplasm was observed by scanning electron microscope.The whole pollen grains of wild pansy were long ellipsoid or ellipsoidal shape,pollen equatorial view is oblong,and the ends are tapered;The polar view is three-lobed or nearly circular,and the pollen surface is smooth and perforated.The pollen whole view,lateral view and polar view of 6 wild pansy plants are basically consistent.The shape of pollen grains of Viola wittrocki and Viola cornuta is rectangular or pentagonal columnar,the pollen equator is rectangular or rhomboid,the polar view is quadrangular or pentagonal columnar,the pollen has 4~5 grooves,and the germination groove is distributed in equal spaced ring.The outer wall is decorated with a wrinkled pattern.The suitable medium for pollen germination of Viola philippica is that sucrose 280 g/ L boric acid 240 mg/ L + GA3 90 mg/ L + Ca(NO3)2 200 mg/L;The suitable medium for pollen germination of Viola wittrockiana is that 240 g/ L sucrose + 260 mg / L boric acid + GA390 mg / L + Ca(NO3)2 200 mg/ L;The suitable combination for pollen germination of V.uariegataisch and V.dissecta is that 285 g/L sucrose+ 250 mg/L boric acid +50 mg/L GA3 +200 mg/L Ca(NO3);Different storage temperatures have different differences in pollen viability,The optimum storage temperature was-80 °C.The effects of three protective enzyme activities on the pollen germination rate of V.uariegataisch and V.dissecta were: SOD>CAT> POD.The results showed that the pollen germination were a less,the pollen tube could not grow smoothly in the pollen tube channel of style was the root cause of hybrid sterility of JB-1-1-2 ×V hancockii,EYO-1-2-1-5 ×V hancockii and EYO-1-2-1-5 ×V.philippica.The results showed that the pollen germination were a less,the pollen tube could not grow smoothly in the pollen tube channel of style,and the lack of nutritional supply of endosperm degenerated and disintegrated embryos was the root cause of hybrid sterility.The results of paraffin section observation showed that the root cause of hybrid sterility of EYO-1-2-1-5×V.philippica.,JB-1-1-2 ×V.uariegataisch,DFM-16-2-2 ×V.dissecta,PXP-BT-D-1-1-4 ×V.philippica,EYO-1-2-1-5×V.hancockii,JB-1-1-2×V.hancockii was the root cause of endosperm degeneration and disintegration,embryo sac hollow and lack of nutritional supply of embryo development.The phenotypic traits of 10 hybrid progeny were identified,it was found that there were more partial maternal heredity in the hybrid progenies,and the preliminary judgment that V.prionantha × E01,V.prionantha ×PXP-BT-D-1-1-4,V hancockii × 08 H,V hancockii × PXP-BT-D-1-1-4,V hancockii × JB-1-1-2,V.uariegataisch × JB-1-1-2 was a real distant hybrid,but it needs to be further verified by means of molecular markers.