Preliminary Study On Shooting Pattern And Mechanism Of Cephalostachyum Pingbianense

Cephalostachyum pingbianense is an excellent edible bamboo species endemic to southern Yunnan Province of China.So far,C.pingbianense is the only bamboo species recorded as producing shoots in four seasons under natural conditions.It is a good bamboo for both shoot and timber.But,at present,research on C.pingbianense germplasm resources is seriously lagging behind,and the bamboo species is still in the natural growth state to be developed.In order to exploit and utilize the bamboo resources,it is urgent to understand its shooting habit and growth law of young bamboo.The research contents of this paper mainly include the following three aspects:?1?Revealing the law of shooting and the law of shoot-young bamboo growth of C.pingbianense.?2?To explore the regulation of plant endogenous hormones on shoot germination and rapid growth of C.pingbianense young shoot.?3?The transcriptome profile of C.pingbianense was analyzed,and the molecular regulation mechanism of shoot germination of C.pingbianense was preliminarily explored at the transcriptome level.The main results are as follows:1.The law of shooting and the law of shoot-young bamboo growth of C.pingbianense:?1?The shooting duration of C.pingbianense lasted for about 9 months?from September to next May?.According to the quantity of bamboo shoots,the shooting duration could be divided into three stages,i.e.,the early stage,the peak stage and late stage.The most shoots occurred in winter while the least occurred in summer.Five clumps?16.67%?produced bamboo shoots in each season,displaying the characteristics of producing bamboo shoot in all the four seasons.?2?The percentage of the degraded shoot increased gradually during the shooting period,and reached the maximum?87.76%?at the late stage.?3?The height growth of young bamboo culms lasted about 130 days,with an average height of 6.36 m.A growth pattern of"slow-fast-slow"was found at the period of the height growth of young bamboo culms,and the growth curve could be described with an equation:H=0.806-0.029t+0.001t²-5.894×10^-6t³?R²=0.980?.?4?The diameter growth of young culms at the ground lasted about 16 days,with an average diameter of 18.50 mm.The diameter growth of young culms also accorded with the pattern of"slow-fast-slow".2.Regulation of plant endogenous hormones on bud germination and rapid growth of shoot of C.pingbianense:?1?The levels of four hormones in different tissues of C.pingbianense were similar,IAA>ABA>ZR>GA₃.?2?Higher ZR content may promote bamboo shoot bud germination,while higher IAA content and IAA/ABA,IAA/ZR ratio may be detrimental to bamboo shoot bud germination.?3?High ZR,GA₃/ABA,ZR/ABA and IAA/ABA in young shoots may contribute to the rapid growth of C.pingbianense.?4?IAA content of bamboo shoots bud increased from low shooting rate season to high shooting rate season,while ABA,ZR and GA₃showed the opposite trend,which may be related to the accumulation of nutrients and growth and development of bamboo shoots bud.3.Exploring molecular regulation mechanisms of bamboo shoot germination of C.pingbianense by transcriptome:?1?Analysis of transcriptome profiles:C.pingbianense obtained 34.1 Gb clean reads by transcriptome analysis,and 89,345 Unigenes were assembled.GO analysis mainly annotates 32 secondary GO entries such as cellular process,cell part,binding,etc.KEGG metabolic pathway analysis is mainly enriched in 21 KEGG metabolic pathways,such as Metabolic pathways,Biosynthesis of secondary metabolites.?2?Molecular mechanisms regulating shoot germination of C.pingbianense:?1?GO enrichment analysis of differentially expressed genes during shoot germination showed that there were more genes enriched in 31 secondary GO items such as cell process,cell part and binding.KEGG metabolic pathways were enriched to 134 metabolic pathways,including Ribosome,Plant hormone signal transduction,Phenylpropanoid biosynthesis and other 15 metabolic pathways with significant differences.?2?Seven genes with significant difference in expression were screened out from Plant hormone signal transduction:IAA23,IAA33,SAUR32,SAUR71,PYL8,PYL4 and PP2C68.It is speculated that they may be involved in the regulation of C.pingbianense shoot germination.?3?Four differentially expressed genes,CCR4,CCR3,4CL1and PAL3,were screened in Phenylpropanoid biosynthesis.It is speculated that they may play an important role in lignin accumulation in young shoots.?4?Starch and sucrose metabolism also contains multiple differentially expressed genes,which may also play an important role in shoot germination.