Tillering Characteristics Of Rice And Correlation Analysis Of Tillering-related Genes Expression

Rice tillering,one of the most important factors that influences spike numbers and further affects grain yield,is controlled by multiple factors such as endogenous physiology,hormones,genes and exogenous environmental factors.In rice production,low position(earlier development)tillers show higher spike yield than high position(later development)tillers.The biomass of the earlier development tiller at low position is comparable to the main stem's at jointing stage and the panicle traits are closer to the main stem's in mature stage.Thus,the earlier development tiller have greater contribution to the formation of plant yield.In this study,we use 12 rice varieties with different tillering characters as materials and observe the tillering dynamics and development related phenotypic traits under hydroponics in seedling stage,analyzing the activity of tiller-related ammonium nitrogen assimilation enzymes and gene expression.The main results were as follows.1.The early tillers of 12 rice varieties basically formed 22 days after sowing.According to the tiller number per plant,we separate 12 rice varieties into 3 types,class A of 2-2.4 tiller numbers:Tianyouhuazhan,Yangliangyouliuhao,YuesiB,Minghui63;class B of 0.5?1.1 tiller numbers:Yliangyou800,Huanghuazhan,Zhongjiazaol7,Basmatis;class C of 0?0.1 tiller numbers and then futher based on leaf age development character,subdividing it into class C1(HR901and Ezao 18)and class C2(Lemont and Star Bonnet).2.The first leaf tiller incidence of different rice varieties has an extremely significant correlation with the activity of the glutamine synthetase(GS)and glutamate synthase(GOGAT)and has a significant correlation with activity of glutamate dehydrogenase(GDH);the second leaf tiller incidence has an extremely significant correlation with activity of GDH;the third leaf tiller incidence has a significant correlation with activity of GOGAT in the leaf in seedling stage.This indicates that ammonium nitrogen assimilation enzymes of different rice varieties have more influence in the the outgrowth of axillary buds in low position and make a little difference in the formation of axillary buds.3.The third leaf tiller incidence of different rice varieties has a significant correlation with the relative expression of ammonium ion transport protein synthetic gene AMT1-1 in the leaf in seedling stage.As a result,the high expression of AMT1-1 prepares a lot of ammonium ions of nitrogen assimilation for the outgrowth of axillary buds.The first leaf tiller incidence of different rice varieties has an extremely significant correlation with the relative expression of GDH4 in the leaf.It indicates that GDH4 shows a major capacity to assimilate ammonium nitrogen at low position tillering in axillary buds initiation period.4.The second and the third leaf tiller incidence of different rice varieties have an extremely significant correlation with the relative expression of auxin synthetic gene YUCCA6 in tiller node in seedling stage.Obviously it states that YUCCA6 is closely related to the earlier tillering in tiller node and it is a key factor of low position tillering in different rice varieties.5.Low position tillering is related to the genes in strigolactones(SLs)synthetic pathway(HTD1,D10)and signaling pathway(D14,D3)and its downstream genes(IPA1,TB1)in tiller node in seedling stage:the second leaf tiller incidence has a significant correlation with the relative expression of D10,D14,IPA1 and TB1,the third leaf tiller incidence has a significant correlation with the relative expression of HTD1?D14?IPA1 and TB1,the second and the third leaf tiller incidence have an extremely significant correlation with the relative expression of D3.During primordium state,genes of SLs signaling pathway and its downstream have begun to impact with low position tillering.