Molecular cloning and expression analysis of seven sucrose synthase genes in bamboo (Bambusa emeiensis): investigation of possible roles in the regulation of cellulose biosynthesis and response to hormones

Yan Huang,Qian Liao,Shanglian Hu,Ying Cao,Gang Xu,Zhijian Long,Xueqin Lu

doi:10.1080/13102818.2017.1412271

Abstract

ABSTRACTSucrose synthase (SUS, EC 2.4.1.13) is a key enzyme involved in sucrose metabolism. In this study, amplification by polymerase chain reaction confirmed that there are at least seven SUS genes (BeSUS1-7) in the Bambusa emeiensis genome. The expression patterns of the BeSUSs genes differed from each other in various bamboo tissues. Among these BeSUSs, BeSUS2 was expressed predominately in the root and BeSUS5 was most abundant in developing shoots, indicating that these two isozymes might play more important physiological roles in root and shoot than the other BeSUSs genes, respectively. In addition, BeSUSs response to abscisic acid (ABA), methyl jasmonate (MeJA) and 2,6-dichlorobenzonitrile treatment (2,6-DCB, an inhibitor of cellulose synthesis) was also investigated in leaves. The results showed that the expression levels of the BeSUS1, 5 and 7 genes were not only conspicuously induced by ABA treatment but also up-regulated by exogenous application of MeJA, indicating that these three isozymes are most likely involved in ABA and MeJA stress responses and are important in meeting the increased glycolytic demand that occurs during these stresses. Moreover, after 2,6-DCB treatment, the cellulose content of leaves was decreased and the transcripts of BeSUS2, 3 and 7 were markedly decreased, while those of BeSUS 5 and 6 were conspicuously induced. The results suggest that the possible roles of BeSUSs genes in the pathway of sucrose metabolism, bamboo resistance to abiotic stresses and the regulation of cellulose biosynthesis may be divergent.

Highlights

Sucrose, as a major photoassimilate, is exported from source tissues to sink tissues in many plants
The results showed that the expression levels of the BeSUS1, 5 and 7 genes were conspicuously induced by abscisic acid (ABA) treatment and up-regulated by exogenous application of methyl jasmonate (MeJA), indicating that these three isozymes are most likely involved in ABA and MeJA stress responses and are important in meeting the increased glycolytic demand that occurs during these stresses
The results suggest that the possible roles of B. emeiensis sucrose synthase (BeSUS) genes in the pathway of sucrose metabolism, bamboo resistance to abiotic stresses and the regulation of cellulose biosynthesis may be divergent

Summary

Introduction

As a major photoassimilate, is exported from source tissues to sink tissues in many plants. The utilization of sucrose requires its cleavage by either sucrose synthase (SUS, EC 2.4.1.13) or invertase (Inv) in the plant cell. SUS is a key enzyme in sucrose metabolism of plants that converts sucrose and uridine diphosphate (UDP) into fructose and UDP-glucose [1]. SUS has been well characterized in various plants and plays an important role in the regulation of carbon partitioning into various pathways, such as starch biosynthesis [2,3], cellulose synthesis and secondary cell-wall formation [1,4,5,6,7,8]. SUS has shown its potential roles in providing substrates for the polysaccharide biosynthesis or energy production necessary to support rapid plant growth [11]. Previous studies showed that bamboo shoots are rich in SUS [12] and it has been observed during bamboo fibre elongation [13], indicating that SUS might be a key enzyme in manipulating the bamboo growth

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Conclusion