茎瘤芥HP家族基因鉴定及表达模式

Genome-wide identification and expression pattern analysis of histidine phosphotransfer genes in Brassica juncea var. tumida

茎瘤芥是制作“涪陵榨菜”的原料,具有很大的经济价值.细胞分裂素在调控植物生长发育及响应逆境胁迫过程中发挥着重要作用,组氨酸磷酸转移酶(histidine phosphotransfer protein,HP)是细胞分裂素信号转导通路中的关键成员之一,目前对茎瘤芥HP家族基因的鉴定和功能研究尚未见报道.在茎瘤芥基因组中鉴定出14个HP家族基因,分别定位在茎瘤芥10条染色体上.系统进化分析结果表明这些基因可聚类为6个分支,蛋白分析结果表明它们均含有磷酸化结构域Hpt及保守的磷酸化位点.基因组织表达模式检测结果表明BjHP2E、BjHP2F和BjHP5AF在茎瘤芥根中的表达水平较高,BjHP3A在叶中表达水平较高,BjHP4在茎和种荚中表达水平较高.此外,BjHP2C和BjHP2F在根中的表达水平受根肿菌侵染的显著诱导.本研究表明,不同的茎瘤芥HP家族成员可能在调控茎瘤芥生长发育及响应根肿菌侵染过程中发挥多方面功能;该结果有助于进一步研究茎瘤芥HP基因在调控植物生长发育和响应逆境胁迫中的功能,为培育优质的茎瘤芥品种提供基因资源.

Tuber mustard(Brassica juncea var. tumida) is the raw material of “Fuling pickle”, which has great economic value. Cytokinins play pleiotropic roles in the regulation of plant growth and development, as well as in plant responses to stresses. Histidine phosphotransfer(HP) proteins are key components of the cytokinin signaling pathway. However, there are no reports on the function of these genes in tuber mustard to date. Here,14 HPs were identified in the genome of tuber mustard, and they were located on 10 of 18 chromosomes. The HP proteins were grouped into six clades in the phylogenetic tree, and all of them contained one HP secondary domain and a conserved phosphorylation amino acid site. According to qRT-PCR results, BjHP2E, BjHP2F, and BjHP5AF were highly expressed in the plant roots, BjHP3A in the leaves, and BjHP4 in the stems and pods. In addition, BjHP2C and BjHP2F expression was significantly induced by Plasmodiophora brassicae treatment.Our results indicate that BjHP genes play pleiotropic roles in the regulation of plant growth and responses to abiotic stress in tuber mustard. These results are helpful for further studies on the function of HPt genes and for breeding new varieties of this crop.