‘741杨’赤霉素氧化酶基因PthGA2ox19调节植株生长发育

Gibberellin oxidase gene PthGA2ox19 in hybrid ‘Poplar 741’ regulates plant growth and development

摘要:

赤霉素2-氧化酶(gibberellin 2-oxidase, GA2ox)是植物体内调控赤霉素(gibberellic acid, GAs)代谢的关键酶，鉴定杨树GA2ox基因并解析其在调控植株生长发育中的功能，能够为选育杨树新品种提供技术支持。本研究通过生物信息学方法对‘741杨’ GA2ox基因进行鉴定和分析，共鉴定出34个GA2ox基因，分布在‘741杨’的7对染色体上。利用实时荧光定量PCR (quantitative real-time PCR, qRT-PCR)技术分析PthGA2ox19的组织表达模式和GA3诱导的表达模式，发现PthGA2ox19在茎中高表达并且在GA3诱导下表达水平显著提高。构建PthGA2ox19过表达载体，并使用农杆菌转化法转化杨树，发现转基因株系PthGA2ox19的表达水平相较于野生型植株显著提高，表型显示为株高变矮、茎秆变细、节间缩短、叶片变小等。通过石蜡切片及显微镜观察分析转基因植株维管组织发育情况，维管组织发育分析表明转基因植株的维管束发育畸形、导管口径减小、木质部和韧皮部厚度变薄。本研究鉴定出了34个‘741杨’ GA2ox基因，其中PthGA2ox19的过表达抑制了杨树的生长和维管组织的发育，表明杨树GA2ox参与了植株生长发育的调控，本研究结果为杨树株型育种提供了新的途径。

Abstract:

Gibberellin 2-oxidase (GA2ox) is a key enzyme regulating the metabolism of gibberellic acid (GAs) in plants. Identifying GA2ox genes in poplar and analyzing their functions in regulating plant growth and development can provide technical support for breeding new poplar varieties. In this study, bioinformatics methods were used to identify and analyze GA2ox genes in hybrid ‘Poplar 741’. A total of 34 GA2ox genes were identified, which were distributed on 7 pairs of chromosomes of hybrid ‘Poplar 741’. The tissue expression pattern and GA3-induced expression pattern of PthGA2ox19 were analyzed by quantitative real-time PCR (qRT-PCR). It was found that PthGA2ox19 was highly expressed in stems and its expression level was significantly increased under GA3 induction. The overexpression vector of PthGA2ox19 was constructed and transformed into poplar by Agrobacterium transformation method. It was found that the expression level of PthGA2ox19 in transgenic lines was significantly higher than that in wild-type plants, and the phenotypes showed shorter plant height, thinner stem, shorter internodes and smaller leaves. The development of vascular tissues in transgenic plants was analyzed by paraffin section and microscope observation. The analysis of vascular tissue development showed that the vascular bundles of transgenic plants developed abnormally, the diameter of vessels decreased, and the thickness of xylem and phloem became thinner. In this study, 34 GA2ox genes of hybrid ‘Poplar 741’ were identified. The overexpression of PthGA2ox19 inhibited the growth and vascular tissue development of poplar, indicating that poplar GA2ox is involved in the regulation of plant growth and development, which can provide a new way for poplar plant type breeding.