Study On Floral Organogenesis And Effect Of Exogenous 6-BA On Sex Differentiation Of Eurya Obtusifolia

Eurya Thunb was a dominant species in the shrub layer of evergreen broad-leaved forest.It was traditionally considered as a strictly dioecious plant,but there was a sexual variation of Eurya obtusifolia at Jinyun mountain in Chongqing.There were three sexes:female plant,male plant and sex variant plant.At present,the research of Eurya obtusifolia was limited to the study of flower morphology and pollination characteristics,ITS and trnL-F sequencing,the physiological and biochemical studies of leaves in the critical period of flower bud differentiation,without discussing the differentiation of flower organs and exogenous hormones.The typical female flower buds,male flower buds and bisexual flower buds of Eucalyptus obtusifolia were used as experimental materials.By observing the morphology and structure of flower buds at different stages of differentiation,aimed to master the whole process of flower bud differentiation in different sexes and its morphological characteristics in each differentiation period,Identify the critical period of flower bud sex differentiation.The effects of 6-BA on the number,proportion,changes of stamens and pistils and endogenous hormone content of different sex flowers of Euphorbia obtusifolia were studied by applying 50,100,150,200 mg·L^-11 6-BA solution to its flower buds and peripheral leaves,to study the effect of 6-BA on the sex differentiation of different sex plants of Euphorbia obtusifolia,and to provide theoretical basis for elucidating the sex differentiation mechanism.Conclusions were as follows:?1?The flower buds of Eucalyptus obtusifolia were 1⁴,which were born in the axilla of new branches and biennial branches.In early August,the flower buds entered the differentiation stage,and the differentiation and development of pistils and stamens are basically completed in mid-late December.In February-March of the next year,the flower buds of Eucalyptus obtusifolia entered the initial flowering stage,which lasts about 120 days.The initiation time of the differentiation of sex-variant flower buds lags15²0 days for females and 10 days for males?2?The process of flower bud differentiation can be divided into 5 periods:Stage of bract differentiation,Sepals stage of differentiation,Stage of petal differentiation,Stage of stamen and pistil differentiation,Stage of stamen and pistil formation.In the process of flower bud development,the primordia of both male and hermaphroditic flower buds appeared at the same time.After a period of time,the primordia of stamens in male flowers developed normally while the primordia of pistil stopped developing.Only pistil primordium was seen in female flower bud,but not stamen primordium.At the stage of pistil and stamen differentiation,the center of female flower bud healed and enlarged,the middle depression formed ovary and the top healed and extended upward to form style.In the male flower bud,the upper part of the stamen primordium bulges to form anther and the lower part forms short filaments.At the mature stage of pistil and stamen,the floral organs continue to grow and develop gradually.The external morphology?color,aspect ratio,etc.?of flower buds changed with the development of differentiation.The key period of sex differentiation was the female-stamen differentiation.?3?In the three sex plants of Eucalyptus obtusifolia treated with different concentrations of 6-BA:?1?the female plants treated with 150 and 200 mg·L^-11 6-BA showed sex variation flowers,all of which had different degrees of stamens,accounting for 11%and 2.9%of the total,respectively.The number of ovules of the female plants treated with different concentrations of 6-BA was smaller than that of the control group,and the number of ovules was the least and the width of ovary was the smallest in150mg·L^-11 treatment,which decreased by 38.41%and 17.34%respectively.?2?There were no female flowers and sex-variant flowers in male plants treated with different concentrations,and the maximum number of stamens,filament length and anther length were found in male plants treated with 150 mg·L^-1,respectively.The other 6-BA treatments at the concentration level had obvious promoting effects on male flowers,and there were significant differences in filament length and anther length between the control group and the control group.?3?6-BA treatment significantly increased the number and proportion of sex-variant flowers and male flowers in the sex-variant plants,but there was no significant difference in the number of ovules and ovary width in the sex-variant flowers.?4?After treatment with 6-BA,in the various stages of flower bud differentiation,the ZR content of the three sex plants in the treatment group was always higher than that of the control,and the treatment group of 150 mg·L^-11 was the most obvious.The content of IAA in the various stages of flower bud differentiation in the treated female plants was unstable,the content of the sex variant strain IAA was decreased,and the content of IAA in the male plants was relatively increased.The content of ABA in the leaves of female,male and sex mutants treated in the stamen and male stage?SSPD?to the stamen and mature stage?SSPF?was lower than that of the control group;The GA₃content in the leaves of the treated female and male mutants during the petal differentiation stage?SPD?to the stamen-differentiation stage?SSPD?increased,while the effect on the GA₃ content in the leaves of the male plants was relatively small;In terms of hormone balance,the ratio of IAA/ABA and GA₃/IAA in the leaves of male and female mutant plants was increased by treatment,and the ratio of ABA/GA₃ and IAA/ZR was decreased,and the leaves of the treated female plants were reduced.The ratio of IAA/ABA,ABA/GA₃,ABA/ZR in each differentiation period increases the ratio of GA₃/IAA.It indicated that exogenous 6-BA increased the accumulation of ZR and GA₃ in flower bud differentiation and GA₃/IAA in female and sex mutants,and decreased the ratio of IAA/ABA,ABA/GA₃ and ABA/ZR in female plants.And the development of gender-variant flowers.?5?Three sex plants of Eucalyptus obtusifolia treated with different concentration gradient 6-BA:?1?The content of soluble sugar in the leaves of 100,150 and 200 mg·L^-16-BA treated females from petal differentiation stage?SPD?to pistil and stamen maturation stage?SSPF?was significantly lower than that of the control group.?2?Male plants treated with 100,150 and 200 mg·L^-11 showed the same trend as the control group,and the soluble sugar content increased significantly at different differentiation stages.?3?Among the sex variants,the content of 150 mg·L^-11 treatment group was significantly higher than that of control group from sepal differentiation stage?SSD?to pistil and stamen differentiation stage?SSPD?.Thus,150 mg·L^-11 treatment promoted the accumulation of soluble sugar content in male and sex variant plants,and inhibited the soluble sugar content in female plants.?6?The total change trend of soluble protein content in leaves of three sexes of Eucalyptus obtusifolia treated with 6-BA of different concentration gradient was similar between the control group and the treatment group.The total change trend of soluble protein content in leaves of Eucalyptus obtusifolia treated with 6-BA increased first and then decreased,reaching its peak at the stage of pistil and stamen differentiation?SSPD?.?1?The content of soluble protein in female plants treated with 6-BA was lower than that in control group at different differentiation stages.?2?The content of soluble sugar in male plants treated with 150 mg·L^-11 was higher than that in control group at different differentiation stages.?3?The content of soluble protein in the leaves of each treatment group was significantly lower than that of the control group.Therefore,a certain concentration of 6-BA can promote the accumulation of soluble protein content in male plants,and inhibit the production of soluble protein content in female and sex variant plants.