| Cauliflower is a variant of cabbage species in crucifer,with flower-ball as edible organs,flower-ball has rich nutrition,it is recognized as one of the most nutritious crops,especially calcium,antioxidant,vitamin A,vitamin K,carotene,riboflavin and iron content is very rich.In addition,it also contains a variety of indole derivatives,has anti-cancer effects.In recent years,the rapid expansion of cultivated area,according to the Food and Agriculture Organization(FAO)statistics,the world’s cauliflower cultivation area are 1165737 hm~2 in 2014.China’s planting area accounted for 41.0%,up to 478252 hm~2,has become the world’s first cauliflower production and consumption.Because of cauliflower as cruciferous plant,with strong heterosis,and the male sterility is the main way to reflect the heterosis.To know more about abortion mechanism and speed up utilization,the deep and systemic studies on morphological,physiological,biochemical and cytological studies were included in the paper using the methods of classical quantity genetics and cell genetics,the thermo-sensitive male sterility and its near isogenic 1ines used as materials.The main conclusions are as follows:(1)In order to promote the use of"two-line hybrid breeding,the thermo sensitive male sterile mutant,GS-19 of the thermo sensitive male sterile line was selected by successive years selfing and field selection to 2004-A19.The male sterile plant grow medium,leaf colour is grey green,plant height is 62 cm,Plant width is 64cm,21 leaves,ball-flower high round,white,tight,single ball weight is 0.8-1.0 kg,strong resistance to disease.(2)In order to make clear the fertile conversion process differences with GS-19 shape feature,using the vernier caliper measurement and the electron microscopy scanning,the results found that the sterile and fertile plants of the flower and anther development are distinct.When the flower buds were larger than 0.5 mm,the abortion occurred,and there was a slight atrophy of the anther wall in the early stage,the surface becomes rough and the cross section is hollow.With the further development of the anther,sterile anthers shriveled into shape,obvious atrophy,empty wall cracking,no pollen grains or individual irregular shape,obvious depression abortive pollen grains.But the anthers of the fertility plants is normal,the outer wall is smooth,inside is still filled with no empty pollen,anther dehiscence phenomenon,flowering stage,the crack can see a large number of full of pollen,the pollen grains were oval,smooth and plump.(3)Based on the GS-19 hybrid F1 and F2 florescence fertility statistical analysis we found that F1 fertility completely normal,fertile and sterile separation ratio of F2was 2.8-2.9:1.X~2 test is x~2=1.4168,less than x~2=3.84,The results showed that there was no significant difference between the number of actual observation and the number of times,and it was considered that the ratio of fertility and sterility was in accordance with the law of segregation ratio of Mendel’s genetic law 3:1which indicated that the thermo sensitive male was controlled by a pair of recessive nuclear genes,its role is not affected by the type of cytoplasm.(4)In order to find the environmental factors of fertility change on the GS-19,the anniversary of the greenhouse planting,self-service thermometer to record the temperature.By fertility statistical analysis,we found that the fertility conversion of the GS-19is closely related with the average daily temperature.The flowering period of GS-19 was from February 10th to December 31st in different sowing dates.From February 10th to March 22nd,GS-19 showed normal fertility,fertility rate reached100%,the average daily temperature was 5.81-15.28℃.From March 23rd to May21st,GS-19 showed partial sterile,fertility rate is 2%-98%,the daily average temperature is 6.75-21.24℃.From May 22nd to October 6th,GS-19 was completely sterile,the fertility rate was 0,the average daily temperature is 13.38-25.50℃.From October 7th to October 21st,GS-19 also showed partial sterile,the fertility rate is 3%-86%,the average temperature is 8.62-16.34℃.From October 22nd to December31st,the fertility of GS-19 was returned to normal,the daily average temperature is4.59-17.86℃.These results show that the fertility conversion depends only on the temperature,irrespective of photoperiod,which belongs to the temperature sensitive male sterility.Fertility change critical temperature is 17.6℃,when the average temperature is lower than 16℃,the fertility is completely normal.When the average temperature is higher than 17.6℃,the fertility is sterile.(5)In order to investigate the role of endogenous hormones on fertility control of the cauliflower thermo-sensitive male sterile line GS-19,taking GS-19 as the material,high performance liquid chromatography(HPLC)was adopted to comparatively analyze the dynamic changes of gibberellin(GA),auxin(IAA),abscisic acid(ABA)and zeatin riboside(ZR)of leaves and buds in different developmental stages of sterile plants and fertile plants.The results showed that the changes of endogenous hormone(GA,IAA,ABA and ZR)of sterile plants and fertile plants both had obvious differences in leaves and buds in different developmental stages.GA and ABA content of buds of sterile plants appeared upward trend in general,GA content was significantly higher than that of fertile plants in sporogenous stage,tetrad stage and pollen maturation stage,was 45.1%,210.4%and 54.5%higher than that of fertile plants respectively,while ABA content was higher than that of fertile plants only in tetrad stage and pollen maturation stage,was 82%and 35.2%higher than that of fertile plants respectively.IAA content of buds of sterile plants decreased at first and then rose,which was significantly higher than that of fertile plants in sporogenous stage and pollen maturation stage,was 52.7%and 82.1%higher than that of fertile plants respectively.But ZR content rose at first and then decreased,which was significantly higher than that of fertile plants in tetrad stage and pollen maturation stage,was 580.9%and 243.9%higher than that fertile plants respectively.Comparing with fertile plants,IAA/ABA of buds of sterile plants appeared a"V"type change,which was minimum in tetrad stage.While GA/ABA and ZR/ABA of which appeared a inverted“V”change,which was maximum in tetrad stage.ABA and ZR were not detected in leaves;GA and ABA content of sterile plants were significantly higher than those of fertile plants.(6)In order to explain the biological process of GS-19 abortion,the squash,paraffin section and transmission electron microscope to observe the cytology biological process of anther abortion.The results found that there was significant difference in sterile and fertile anther development biological process.The anther development of GS-19has differentiation of pollenmother cell,form normal pollen sac,don’t produce pollen grains or produce trace ofpollen grains withoutviability,the developmentof anthersis blocked from pollen mother cell to the tetradstage.The pollen mother cells could not pass the meiosis,with no dyads and tetrads formed in GS-19,insteading of some"pseudo microspores".Which belong to an abortive type of pollen mother cell.The pollen exines of the"pseudo microspores"were abnormal.(7)The cauliflower thermo-sensitive male sterile line GS-19 discovered independently by our research group is used as the test material,using ISSR technique to find the molecular markers that linked to the thermo-sensitive male sterile genes,which speeds up the breeding process of the thermo-sensitive male sterile line.The result shows that with 90 ISSR random primers marking sterile and fertile gene pools,the molecular marker IT13–600 that linked to the thermo-sensitive male sterility is found.And gets a genetic fragment with length is 559bp by clones and sequences that obtained specific fragment.IT13–600 is used to carry out the molecular identification on 30 cauliflower germplasms,combining with conventional breeding technologies,3new germplasms with thermo-sensitive male sterility and genetic stability are created. |
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