Function Research Of Flavonoid Biosynthesis In Style Regulating Pollen Tube Growth

Pollen tube elongation and guidance are important parts of plant sexual reproduction. The pollen grain adheres to the stigma and begins to germinate, then, pollen tube grows and penetrates the ovule. It is important to identify the metabolic pathway in psitil involved in pollen tube growth and guidance for success of double fertilization. In this study, we first analayse take advantage of the differentially expressed data in maize silk and Arabidopsis pistil after pollination by the genome-scale enzyme correlation network models(GECN). We identified the enriched metabolic pathway, which may be involved in psitil-pollen interaction in maize and Arabidopsis. Flavonols are present in a wide variety of higher plants. Flavonols can prevent ultraviolet irradiation, regulate auxin polar transport, and regulate the plants-microorganisms interations by inducing the generation of nodule. In this study, we researched functions of flavonoid metabolic pathway in pistil using two strategies: amiRNA technique to knockdown the exprssions of the genes involeved in the flavonoid pathway and appling flavonoids in vitro. The main results are as follows:(1) Fourty metabolic pathways were enriched in the RNA-seq data of pistil after pollination in maize and Arabidopsis,which involved in 88 co-enzymes. For example: Glutamic acid degradation pathway may cause the unordered growth of pollen tube by influrecing the GABA concentration gradient. Starch degradation pathway may affect the pollen tube growth by providing the energy.(2) UF3 GT, UGT75C1, ANS and LAR gene respectively encode anthocyanidin 3-O glucosyltransferase, anthocyanidin 5-O glucosyltransferase, leucocyanidin oxygenase, and leucoanthocyanidin reductase, all of which are involved in flavonoids metabolic pathway. The pollen tube growth were delayed in the amiRNA transgenic plants. Further analysis showed the flavonoids concent was reduced in the pistils of amiRNA transgenic plants than of wild type plant. It suggested that flavonoid can affect pollen tube growthing in vivo.(3) The pollen gernination rate and pollen tube growth rate can be improved when the certain concentration of flavonoids/anthocyanin was added in vitro, which suggest lavonoid/anthocyanin can affect pollen tube growthing in vitro.In total, flavonoid can affect pollen tube growth in vitro and in vivo.