The Relationship Between The Characteristic Of The Branch And Leaf In Eucalyptus Spp.and Resistance To Leptocybe Invasa

In the long-term process,plants and plant hoppers cooperative coevolution,plants stop and resistance to attract insects through the type of composition defense and induced defense.Plants’quality characteristics and physiological indexes are changing,to reduce the degree of victim.Eucalyptus spp.is one of the fast-growing tree species widely distribution.Since 2007,Leptocybe invasa invade China,the growth of Eucalyptus spp.is serious damaged.In order to comprehensive prevent and control of Leptocybe invasa,it is important to select insect-resistant strains.In this experiment,research on external characteristics and organizational structure,observe the different structure among Eucalyptus spp.,analyze the correlation and the pest resistance relations.The primary conclusions are as follows:1.Though measure the external characteristics of Eucalyptus spp.,and the change between damage and undamage leaves,the results showed that:①in undamaged leaves the moisture content of high resistance strain is significantly less than mid-resistance and high susceptible strain,the bulk density of high resistance strain is highly significant bigger than mid-resistance and high susceptible strain,which indicated that the higher moisture content and bigger bulk density,the more likely to be damaged.The moisture content and thickness of petioles are positive correlation with insect resistance,but the greater bulk density,the weaker resistance strain.Wax content of leaf in different strains is nothing to do with insect resistance,petioles’ Wax content of high resistance strain is highly significant more than mid-resistance and high susceptible strain,which indicated that wax content can protect Eucalyptus spp.from Leptocybe invasa in a way.②Damaged strains,no matter mid-resistance or high susceptible strain,the moisture content has obvious differences between damage and undamaged leaves,the bulk density of damage leaves are significantly bigger than undamaged leaves.It is known that the moisture content decreased and density increased in damaged leaves when strains were suffer injured.Thickness of petioles are evident larger in damaged leaves.In damaged mid-resistance strain,petioles’ Wax content obviously decreased,a little bit in leaves.The high susceptible strain is not achieved the level of significant in leaves’ wax content,the wax content of petioles in high susceptible strain E.urophylla× E.tereticornis DH201-2 present clearly decrease.2.Though the paraffin section method of Eucalyptus spp.leaves,explore the relationship between organizational structure and insect resistance.The experiment results showed that:there exist significant differences among three strains,cuticle thickness,the thickness of the lower epidermis,the thickness of the main vein are positively correlation with insect resistance.When strains were damaged by the pest,cuticle thickness,the thickness of the upper epidermis,the thickness of the lower epidermis,the thickness of the main vein and blade didn’t show obvious change at all.In the high susceptible strain E.grandis QG8,cuticle thickness and the thickness of the main vein become thinner,meanwhile,the thickness of the upper epidermis trended seriously thinner.Compare with damage and undamaged leaves,E.urophylla× E.tereticornis DH201-2 appear thinner cuticle thickness,the thickness of the lower epidermis and the thickness of the main vein is also flimsier in damaged leaves.From the biological microstructure point of view,cells arranged orderly and closely in undamaged leaves.The high susceptible strain which was damaged shows that,the main vein deformation,and the structure become loose.But the main vein didn’t have significant change in mid-resistance strain.3.Apply electronic scanning microscope to view the thickness of the lower epidermis of Eucalyptus spp.leaves,can found that,the length of stomatal is negative correlation with insect resistance,there is a close relationship between the value of grey and insect resistance.Mid-resistance strain was damaged by pest,the length of stomatal will become longe,however,the trend of high susceptible strain is slowly smaller.When leaves were parasitized,the density of stomatal is obvious reduced in E.dunnii,there is a little change in E.grandis QG8 and E.urophylla× E.tereticornis DH201-2.The height of waxy accumulation were reduced after damaged by the pest.High resistance strain and high susceptible strain were closely coverd wax,wax of mid-resistance strain present flimsy.The main vein cells are long and thin in high resistance strain,on the contrary,main vein formed by thick and short cells in high susceptible strain.In damaged high susceptible strain,wax around stomatal shows molten,cover the part of stomatal area.The main vein cells change short,the boundaries of leaf margin is not clear.Wax spread outward,increase the porosity of naked,the main vein cells mix together,the boundaries of leaf have sediment.