外源苯丙氨酸对水稻幼苗主根根尖生长的调节效应

Regulating effect of exogenous phenylalanine on the growth of main primary tips in rice seedlings

本实验采用外源苯丙氨酸(Phe)与苯丙氨酸解氨酶(PAL)的专一性抑制剂2-氨基茚满-2-膦酸(AIP)对水稻幼苗进行处理,通过比较不同处理间主根的生长指标、根尖木质素含量、根尖细胞PAL活性、根尖细胞OsCAD1表达水平及CAD活性,以及根尖导管出现位置,研究外源Phe对水稻幼苗主根根尖生长的调节作用。结果发现,外源Phe抑制幼苗主根和根尖的长度,并提高根尖的木质素含量、OsCAD1表达水平、CAD活性及PAL活性,而AIP则逆转Phe的作用效应。这表明,外源Phe通过上调木质素合成关键基因表达水平及其酶活水平,提高了木质素合成效率,从而缩短导管出现位置到根尖前端的距离和抑制根尖伸长,最终延缓水稻幼苗主根生长。

In this experiment,rice seedlings were treated with exogenous phenylalanine(Phe)and 2-aminoindan-2-phosphonic acid(AIP),a specific inhibitor of phenylalanine ammonialyase(PAL).By comparing the growth indexes of primary roots,lignin content,and PAL activity in root tips,OsCAD1 expression level and CAD activity of root tip cells,and the location of root tip vessels among different treatments,to explore the regulatory effect of exogenous Phe on the growth of primary root tips in rice seedlings.All these results confirmed that exogenous Phe inhibited the length of primary roots and root tips of seedlings,with the improvement of the lignin content,OsCAD1 expression level,CAD activity and PAL activity of root tips,while AlP reversed the impact of Phe.In conclusion,this results indicated that the exogenous Phe enhanced lignin synthesis efficiency by upregulating the expression level of key gene and its enzyme activity in the synthesis of lignin.Thus,it leads to a reduction in the distance between the position of the vessels and the front end of the root tips,inhibiting root tip elongation,and eventually,delaying primary roots growth in rice seedlings.