Studies On The Effect Of Energy Metabolism And MiRNA Regulation Mechanism Of Tillering In A Wheat Mutant Dmc

Common wheat(Triticum aestivum L.)is one of the most valuable and widely planted monocot plants in the world.Tillers are special vegetative branches at the base of monocot plants.Tillers not only determine plant architecuure but also influence crop yield.In this study,a dwarf-monoculm wheat mutant(dmc)was used as the experimental material.The differences in tillering development between dmc and Guomai 301 were analyzed by histological and histochemical observation,miRNome analysis and its combination with transcriptome analysis,and determination of physiological indexes such as photosynthesis,carbohydrate and hormone contents etc.The miRNome of dmc and Guomai 301 were studied by RNA-Seq technology,which involved the screening of different expressed miRNAs(DEMs)and the functional annotation of the target gene of DEMs.Finally,the miRNA-mRNA network regulating the wheat tillering of dmc was determined.The main results of this study are as follows:1.Histological observation found the tiller differentiation and development at the main culm base were severely inhibited in dmc.The tillering primordia of dmc appeared later than that of Guomai 301 and could not grow normally.Histochemical observation found the tiller of dmc lacked the characteristics of the typical meristematic tissues and the tiller primordia of the dmc had less protein than that of the guomai 301.2.A total of 454 miRNAs were obtained from the dmc and Guomai 301,among them,91 miRNAs were significantly differentialy expressed(P<0.05).Among the 91 DEMs,17 of the miRNAs were known,while 74 were novel,of which 49 were highly expressed,and 42 were lowly expressed in dmc compared to Guomai 301.The target genes of these DEMs were mainly involved in structural molecule activity,enzyme regulator activity,and nutrient reservoir activity,which were closely related to the phenotype of dmc.3.Under natural conditions,the photosynthesis capacity of dmc was significantly lower than that of Guomai 301 during tillering.The Kyoto Encyclopedia of Genes and Genomes(KEGG)annotation indicated that fourteen significant DEMs were found to target differentially expressed genes(DEGs)involved in carbohydrate metabolism.The sucrose contents in leaves and tiller nodes of dmc were less than those of the Guomai 301 at the three stages.The decreased sucrose contents of dmc may be related to its low photosynthetic capacity and the decreased sucrose transport from leaves to tiller nodes.This was an important cause for the lack of energy in dmc,which in turn affected its tillering.4.Eleven miRNAs were all highly expressed in auxin(IAA)metabolisms,and miR399 was highly expressed in gibberellin biosynthesis in dmc.By comparing the hormone contents of dmc and Guomai 301 at the three-leaf stage,we found that IAA and Zeatin(ZA)were significantly less in dmc than that in Guomai 301,while gibberellin(GA)were significantly more in dmc than that in Guomai 301.Among them,IAA in Guomai 301 was 1.4-fold of that in dmc,ZA in Guomai 301 was 1.2-fold of that in dmc,and GA in dmc was 1.1-fold of that in Guomai 301.It was suggested that miRNAs are involved in the regulation of hormone metabolism and signal transduction of mutant dmc,which in turn affected its tillering.5.In the end,125 pairs of negative miRNA-mRNA interactions were found.40 key DEMs targeted 45 DEGs including the key DEGs encode growth-regulating factors(GRF),auxin response factors(ARF),and other proteins involved in the metabolisms of hormones and carbohydrates,etc.These miRNAs play an essential regulatory roles in tillering.