| The growth type of peach mainly refers to the growth habits of the trees,including height,branch angle,the germination and extension of branches,the density of branches,growth rhythm,etc,which is closely related to production traits,determines the peach tree structure,affects the tree group illumination and photosynthesis,overall yield and fruit quality China is the origin of peach and has abundant germplasm resources.According to the literature,six growth types of peach with obvious difference in tree structure were observed.The exploration of different growth types of peach resources lays the foundation for the cultivation of new varieties suitable for different needs and different tree species.To investigate the structure of different growth types of peach trees provides theoretical basis for understanding the formation mechanism of peach growth patterns and peach breeding,what’s more,it also play important roles in promoting the production of peach trees and enhancing the competitiveness.In this study,the structure of six growth types of peach,dynamic changes of three related traits related to branching angle in growing peach and spatio temporal expression of LAZY1 gene that regulated branch angle were analyzed.The main results are as follows:1.The average angle of the leaves in six grow types of peach ranged from 62.76° to 73.50° and showed no obvious difference among each other.However,the branch angle exhibited significant difference among six growth types of peach.For the basal angle of 1st order branches,weeping type was maximum(93.92°)while dwarf type was minimum(36.75°),the other four growth type were medium.However,the lumbar angle and top angle of 1st order branches showed the similar change rules in the six growth types of peach which displayed the maximum level in weeping type and the medium level in open type,and exhibited no significant difference among four other growth types.2.The characteristics of leaf structure in six growth types of peach were also investigated.The average leaf length of upright type which was maximum(11.01 cm),while its average petiole length was minimum(2.41 cm).The average leaf length and leaf width of compact type peach was 16.2 cm and 4.57 cm resceptively,and possessed the maximum average leaf area(47.28 cm2).There was no significant difference among the other four growth habits of the leaves characteristics.All the leaf veins of six growth habits of peach was eucamptodromous venation pinnate.The number of secondary veins of upright type was highest while the weeping type had the least secondary veins.The open type had the maximum angle while the dwarf type had the minimum angle.3.Correlation analysis of leaf vein structures and tree structures in six growth habits of peach was performed.The results indicated that there was a negative correlation between the numbers of secondary vein and the top angle of 1st order branches in open type,dwarf type and compact type,especially in open type which correlation coefficient reached a significant level(-0.970).In another hand,there was a positive correlation between the numbers of secondary vein and the top angle of 1st order branches in the uprigh type,weepintg type and broom type.In the open type,dwarf type and compact type,the angle of secondary vein had a negative correlation with the top angle of 1st order branches and only in the compact type their correlation coefficient reached a significant level(0.953).There was a negative correlation between angle of secondary vein and the top angle of 1st order branches among the other three growth types.The differences of leaf secondary veins angle and the numbers of secondary veins of peach veins could reflect the changes of different growth types of peach tree structure in a certain extent.It could be a morphological marker for early selection of different growth types of peach.4.The growth amount of three growth types of peach was detected.The result showed that the three growth types of peach exhibited a similar characteristic throughout the whole growing season,and there were two growth peaks in the whole growth period.The plant height,shoot length and plant height increase amount presented the highest level in‘Sahonglongzhu’ and the lowest level in‘Okubao’.5.The basal angle,lumbar angle and top angle of three growth types of peach shoots in the whole growth process were investigated.The result showed that the average basal angle of ‘Okubao’ gradually increased to 84.67 °,while the average basal angle of‘Honghuashabtao’and ‘Sahonglongzhu’ gradually decreased to 28.33° and 17.67°,respectively.For lumber angle,it firstly increased and then decreased to 65.5° in‘Okubao’,whereas it decreased in the whole growth process in ‘Honghuashabtao’and ‘Sahonglongzhu’ and finally reached 18° and 8°,respectively.The top angle of three growth types of peach showed a similar trend with the lumbar angle.All the basal angle,lumbar angle and top angle of each period were biggest in ‘Okubao’and were smallest in ‘Sahonglongzhu’.The key period of each angle change of three growth types of peach was different from each other.6.The expression pattern of LAZY1 in different tissues was investigated with Quantitative real-time RT-PCR.The results showed that LAZY1 exhibited similar expression pattern among the 3 growth types of peach.Specifically,LAZY1 presented the hightest expression levle in branches,followed by the phloem of branch junction and leaves,while the lowest expression level was detected in the xylem of branch junction.The expression of LAZY1 in the‘Sahonglongzhu’ maintained a relatively low level in each tissue and period.However,the expression level of LAZY1 in the ‘Okubao’was lower than ’Sahonglongzhu’.The expression pattern of LAZY1 in different period was also detected with q PCR.The result showed that the expression level of LAZY1 in‘Okubao’only slightly changed in different period.Furthermore,at the early stages of growth the expression of LAZY1 was more active in leaf and branch junction,while at the late stages of growth the expression of LAZY1 was more active in the branches.The expression level of LAZY1 in‘Honghuashantao’ changes greatly in different periods,especially in the branch and branch junction and the highest expression level was presented in July 14 th.LAZY1 remained a low m RNA level and exhibited no obvious change throughout the growing season in ‘Honghuashantao’.The expression of LAZY1 in leaf,branch junction and branch all exhibited a negative correlation with branch angle at different periods although the correlation coefficient was low. |
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