The Preliminary Study On Genes Expression And And Endogenous Hormones Quantitation Analysis Related To IAA And ABA During Fruitlet Abscission In Litchi

Litchi(Litchi chinensis Sonn.) belongs to Sapindaceae family, litchi genus,there is a serious problem that heavy physiological drop of fruitlet leading to low production and the limitation of litchi industry development. In this study, nine ‘Feizixiao'litchi trees that were similar in growth were chosen as the experimental materials. Girdling plus defoliation, dipping in 20 mg/L 2,4-D solution after girdling plus defoliation and dipping in 250 mg/L ethephon solution were tested on the fruit-bearing shoots at 25 d after anthesis. Using q RT-PCR(quantitative real-time polymerase chain reaction), the express features of 23 genes related to IAA(indoleacetic acid) and ABA(abscisic acid) under the different treatments were analyzed, as a result, 12 genes were regarded as genes associated with abscission. And in this study, 22 genes associated with abscission including 10 genes identified before were used to Phylogenetic Analysis. Apart from this, the fruitlet of‘Feizixiao' were chosen as the experimental materials for the preliminary study of IAA and ABA quantitation detect by GC-MS(Gas Chromatograph-Mass Spectrometer-computer).The main results are showed as follows:(1) Field experiments showed that the effect of girdling plus defoliation and dipping in ethephon to fruit-bearing shoots of ‘Feizixiao' litchi at 25 d after anthesis on abscission in the young fruit was very significant. While dip in 2,4-D after girdling plus defoliation can significantly inhibit the fruitlet abscission that was induced by girdling plus defoliation.(2) The relative expression results under the different treatments of 23 genes showed that 12 genes were closely associated with fruitlet abscission in litchi. These 12 genes including Lc TIR, Lc ARP1, Lc ARP2, Lc Aux/IAA1, Lc Aux/IAA3, Lc Aux/IAA5, Lc GH3.2,Lc PIN2, Lc PIN4, Lc SAUR, Lc NCED and Lc SDR.(3) The 22 genes related to IAA and ABA were used to Phylogenetic Analysis with other species. Some reports revealed 13 genes' homologous genes were associated with fruitlet abscission, which included Lc ARF3, Lc ARP2, Lc Aux/IAA1, Lc Aux/IAA3,Lc Aux/IAA7, Lc Aux/IAA8, Lc GH3.2, Lc GH3.5, Lc PIN5, Lc SAUR2, Lc SAUR3, Lc SAUR4 and Lc NCED. But the other 9 genes like Lc TIR, Lc ARP1, Lc Aux/IAA5, Lc Aux/IAA6,Lc Aux/IAA9, Lc PIN2, Lc PIN4, Lc SDR and Lc MCSU had no literatures about abscission reported.(5) Quantitation of IAA and ABA by GC-MS was preliminary studied. The results showed that an efficient, stable and accurate pre-treatment method had not be established and step “concentration” led to a huge loss easily. The process of exploring provided reference for the future research.