Histological And Cytological Changes And Gene Analysis Of Adventitious Shoot Regeneration Of Populus Euphratica Oliver In Vitro

Plant regeneration is an important strategy for their survival under complex conditions.It can be classified into three main categories: tissue repair,de novo organogenesis and somatic embryogenesis.The process of adventitious shoot formed from the explants or wounds is termed de novo shoot organogenesis and its mechanisms have been studied for many decades.However,the dynamics of cellular events and how important genes directing this shooting process are not yet clear.P.euphratia is an important species in the desert region of China.The study of its regeneration mechanism has important significance.Here we evaluated the shoot regeneration capacity of P.euphratia leaf explants and selected three samples which have strong regeneration ability and three samples which have limited regeneration ability.Then we analyzed the morphological and histological images,the hormone changes and different gene expression patterns during the process of adventitious shoot regeneration of the two groups.The main results are as follows:1.The process of in vitro adventitious shoot regeneration from P.euphratia leaves can be divided into three stages: regenerative competent cell proliferation,shoot progenitor formation,and shoot outgrowth.2.During the adventitious shoot regeneration process of the six samples,the proliferation of regenerative competent cells was observed,which showed that callus formation started.After cultured under light,the three samples with strong regeneration ability produced more calli and formed many adventitious shoots,while the three samples with limited regeneration ability produced less calli or produced no callus and finally failed to form adventitious shoots.3.During the three stages,auxin may play a role to promote shoot progenitor formation and cytokinin may play a role to promote regenerative competent cell proliferation.4.The results of RNA-seq showed that the genes largely differently expressed in the stage of shoot progenitor formation between the two groups and were significantly enriched in GO terms of response to sucrose metabolism,starch metabolism and hormonal signaling.This work studied the process of in vitro adventitious shoot regeneration from P.euphratia leaves and we found that the three samples with limited regeneration ability had callus initiation but were defective in callus development and shoot regeneration.A set of genes involved in starch metabolism,sucrose metabolism and hormonal signaling pathways differentially expressed and they may demonstrate the differences in the de novo shoot regeneration capacity between the two groups...