Effects Of Growth Regulators On Endogenous Hormones And PIN Gene Of 'Korla Fragrant Pear' Sepal Development

Affected by some factors such as genetic characteristics and environment,the sepals of pear fruit are falling off or persistent,while the persistent sepals of pear fruit affect the appearance quality of pear fruit and reduce its commodity value and market competitiveness.Many studies have found that endogenous hormones play an overall regulatory role in the growth and development of pear fruits,and the loss of plant organs is closely related to the changes in the types and concentrations of endogenous hormones.However,there are few studies on the mechanism of endogenous hormones and sepal shedding during fruit development.In this study,the 'Kurla fragrant pear' was used as the test material to study the effects of auxin and auxin inhibitor on the development of the sepals of fragrant pear fruits;And the effects of auxin inhibitors on the development of young fruit vascular bundles;and the expression characteristics of the related auxin transporter PIN gene in the 'Korla fragrant pear' decalyx fruit and the persistent calyx fruit were studied.The main results were as follows:(1)Using 'Korla fragrant pear'(referred to as fragrant pear)as the test material,IAA,TIBA treatment and clear water were sprayed on the'fragrant pear' short fruit branch,and the first and fourth parts of'fragrant pear' were measured by high performance liquid chromatography(HPLC)technology The auxin(IAA),gibberellin(GA3),and abscisic acid(ABA)contents of the flowers or young fruit calyx tube,carcass,and fruit stalk during the shedding period of sequenced fruit were analyzed.Change and its relationship with sepal shedding.The results showed that in the same treatment,the deciduous rate of the fourth-order fruit of Xiangli young fruit was significantly higher than that of the first-order fruit;in the same order,the detached rate of TIBA-treated fruit>clean water treatment>IAA treatment.'Korla fragrant pear' fruit sepal shedding is closely related to endogenous hormones.There are significant differences in the distribution of endogenous hormones in young calyx fruit of different treatments,lower endogenous IAA and GA3 levels and higher endogenous ABA The level is conducive to shedding of fruit sepals.At the same time,it was found that the IAA and TIBA treatments affected the changes in the contents of IAA,GA3 and ABA in the carcass and fruit stalk parts of theof 'Korla fragrant pear',and the changes in the contents of IAA,GA3 and ABA had a certain effect on the shedding of the pear calyx tube.(2)Using bioinformatics analysis methods and qRT-PCR technology to conduct PIN gene family analysis and gene expression analysis.The results showed that 15 PIN genes were screened and identified from the pear gene pool,forming a PIN gene family,named after PbPINs,divided into 5 subgroups,unevenly distributed on 11 chromosomes,containing 1-13 Exons,0-12 introns,the number of conserved motifs is 4-18,and is mainly subject to purification selection during evolution.In this study,the seven genes PbPIN02,PbPIN05,PbPIN09,PbPIN10,PbPIN11,PbPIN12 and PbPIN14 were all expressed in the 1st and 4th order flowers of'Xiangli' or the calyx tube of the young fruit,indicating that these 7 genes fell offthe pear sepal In the process,it plays a certain role in the transport of auxin.Under water treatment and IAA treatment,the expression levels of PbPIN02,PbPIN09 and PbPIN11 all showed similar trends,and the expression level during the critical period of calyx tube shedding on April 11 was significantly higher than that of other genes,indicating that PbPIN02,PbPIN09 and PbPIN11 It is possible that auxin transport plays a major role in the process of'Xiangli' calyx tube shedding.Exogenous IAA and TIBA have different effects on PIN expression.In this study,it was found that spraying IAA would inhibit the expression of PbPIN gene,and spraying TIBA would promote the expression of PbPIN02 and PbPIN09 genes in the fruit.(3)At the flowering stage,the fourthinflorescence of 'Korla fragrant pear' short fruit branches were sprayed with water,IAA and TIBA,and the dynamic changes of the number and area of the vascular bundles of the fruit stalk,equator and calyx tube were compared.The results showed that the number of vascular bundles in the three treatments was 8-12,and the number of vascular bundles in the fruit stalk,equator and calyx tube in the control and IAA treatments was greater than that in the TIBA treatment,while the control vascular bundles The number of tube bundles is not much different from the IAA treatment.The vascular bundle area of the fruit stalk and equator of the control> IAA treatment> TIBA treatment,while the control vascular bundles The number of tube bundles is not much different from the IAA treatment,but both were higher than those of TIBA treatment.The calyx tube shedding rate was negatively correlated with the number of fruit vascular bundles,equator vascular bundles,calyx tube vascular bundles,and calyx tube vascular bundle area,and was significantly related to the number of fruit stalk vascular bundles and calyx tube vascular bundle area sexually negative correlation.Comprehensive comparison,TIBA treatment will inhibit the number and area of calyx vascular bundles,thereby increasing the calyx detachment rate of'Korla fragrant pear'.