Background The calcium (Ca2+)-dependent phospholipid binding protein annexin gene family, which is known to be related to membrane lipid and cytoskeletal components, is involved in a diverse range of biological functions. However, in cassava (Manihot esculenta Crantz), no studies focusing on the roles of annexin genes in response to abiotic stresses, calcium, and hormones have been informed. Results 12 annexin genes were found and assigned to eight chromosomes in the cassava genome. All of the MeAnns contain a typical annexin domain with four 70-amino acid repeats. The MeAnns are classi�ed into six groups in the phylogenetic tree. In their promoter regions, MeAnns possess at least 3 hormone response-related cis-elements and 1 abiotic stress response-related cis-acting element. MeAnn1, MeAnn2 and MeAnn5 exhibit very high levels of expression in each tested organs or tissues. By contrast, MeAnn12 exhibits very low levels in all the tested organs or tissues. qRT-PCR analysis indicates that both MeAnn5 and MeAnn9 have signi�cantly high expression in leaves after cold, drought, and salt treatments and are highly responsive to CaCl2, GA and JA treatments. MeAnn2 and MeAnn10 are signi�cantly downregulated in leaves by cold, drought and salt stress and negatively respond to CaCl2, GA and JA. The expression patterns of MeAnns under cold, drought, and salt stress are irregular in shoots. In roots, MeAnn1 and MeAnn9 are downregulated by cold, CaCl2 and JA treatments, while their other gene expression patterns are irregular. Conclutions In this study, we identi�ed annexin genes in cassava and our expression pro�ling analysis demonstrated that cassava annexin genes responded to multiple stresses. Our results laid the foundation for further study of the function of cassava anesxin genes and provided an entry point for understanding the response mechanism of cassava to abiotic stress.

Background The calcium (Ca2+)-dependent phospholipid binding protein annexin gene family, which is known to be related to membrane lipid and cytoskeletal components, is involved in a diverse range of biological functions. However, in cassava (Manihot esculenta Crantz), no studies focusing on the roles of annexin genes in response to abiotic stresses, calcium, and hormones have been informed. Results 12 annexin genes were found and assigned to eight chromosomes in the cassava genome. All of the MeAnns contain a typical annexin domain with four 70-amino acid repeats. The MeAnns are classified into six groups in the phylogenetic tree. In their promoter regions, MeAnns possess at least 3 hormone response-related cis-elements and 1 abiotic stress response-related cis-acting element. MeAnn1, MeAnn2 and MeAnn5 exhibit very high levels of expression in each tested organs or tissues. By contrast, MeAnn12 exhibits very low levels in all the tested organs or tissues. qRT-PCR analysis indicates that both MeAnn5 and MeAnn9 have significantly high expression in leaves after cold, drought, and salt treatments and are highly responsive to CaCl2, GA and JA treatments. MeAnn2 and MeAnn10 are significantly downregulated in leaves by cold, drought and salt stress and negatively respond to CaCl2, GA and JA. The expression patterns of MeAnns under cold, drought, and salt stress are irregular in shoots. In roots, MeAnn1 and MeAnn9 are downregulated by cold, CaCl2 and JA treatments, while their other gene expression patterns are irregular. Conclutions In this study, we identified annexin genes in cassava and our expression profiling analysis demonstrated that cassava annexin genes responded to multiple stresses. Our results laid the foundation for further study of the function of cassava anesxin genes and provided an entry point for understanding the response mechanism of cassava to abiotic stress.

Plant annexin belongs to class D annexin family,which is a calcium and phospholipid binding protein in plants.Plant annexin accounts for about 0.1％ of the total protein content in plant,and it has high homology with animal annexin in molecular weight,amino acid sequence and the ability to binding Ca2+ and phospholipid.The subcellular localization of plant annexin is diverse,which is associated with cytoplasmic Ca2+ concentration,cell pH,plant tissue and the external environment.The expression of plant annexin is tissue-specific and is regulated by the levels of various biological and non-biological factors after transcription and translation.Plant annexin has many biological functions such as combining with F-actin,participating in calcium ion channel formation,membrane dynamics function,and ATPase/GTPase and peroxidase activity,and plays an important role in plant growth and adversity stress response.In this paper,we summarized the gene evolution,protein structure,subcellular localization,expression regulation and biological function of plant annexin,aiming to provide a reference for further study on function and utilization of plant annexin.

A full-length galactinol synthase gene sequence of cassava has been cloned into the high expression vector pGEX-6p-1, and named as MeGolS5-pGEX. The GST-MeGolS5 fusion protein was expressed induced by IPTG. The expression conditions such as IPTG concentration, bacterium concentration, induction time and temperature were optimized. The results showed that the expression level of GST-MeGolS5 was increased by accompanying with the induction time. In the condition of 37℃, OD600 is 0.4 and cultured 4 hours, GST-MeGolS5 fusion protein reached the highest expression. 0.2 mmol/L concentration of IPTG can induce GST-MeGolS5 expression effectively in Escherichia coli expression system. The aim of this research was to analyze the function and drought tolerance mechanism of MeGolS5 gene.

以华南8号木薯为材料,采用RT-PCR技术,克隆得到1个具有完整阅读框的木薯膜联蛋白基因,命名为MeAnn1 (Gen Bank序列号为:KM975562),该基因CDS序列长度为951 bp,编码317个氨基酸.生物信息学分析发现,其理化性质、蛋白保守结构域及多个蛋白功能位点与已报道的植物膜联蛋白一致.进化树分析表明,木薯MeAnn1与PtrAnn6、AtAnn1、AtAnn2、AtAnn6和AnrBj1具有较近的亲缘关系,具有59.9％～84％的序列相似性.细胞定位结果表明MeAnn1蛋白主要定位于细胞质和细胞核中.实时荧光定量PCR分析表明,木薯膜联蛋白基因MeAnn1的表达受多种非生物胁迫的诱导,其中低温胁迫下基因表达量上调幅度最大,为对照表达量的24倍;但对H2O2胁迫不敏感.本研究结果有助于进一步研究MeAnn1基因的功能及木薯抗逆的分子机理.

Stearoyl-acyl-carrier protein desaturase is one of the key enzymes that irreversibly catalyze the biosynthesis of fatty acids, and has an influence on the proportion of saturated and unsaturated fatty acids. In this research,MeSACPDhas been cloned from cassava, with 1197 nucleotides and 398 amino acids, respectively. It has high homologous with the stearoyl-acyl-carrier protein desaturase inRicinus communis. The 3D structure ofMeSACPDshow a conserve motif related to Fe ion binding. We suppose the motif may be the active center and the substrate binding site area of stearoyl-acyl-carrier protein desaturase.