玉米光敏色素A1与A2在各种光处理下的转录表达特性

摘要

光敏色素是一类红光/远红光受体，它们在植物体内有非活性形式的红光吸收型(Pr)和活性形式远红光吸收型(Pfr)2种状态，通常其活性形式负责调控植物的种子萌发、株高、开花时间和避荫性等生长发育过程。在禾本科中，光敏色素只有 PHYA、PHYB 和 PHYC 三个基因亚家族，古四倍体化造成的玉米光敏色素基因有6个成员，即PHYA1、PHYA2、PHYB1、PHYB2、PHYC1和PHYC2。光敏色素A参与抑制下胚轴的伸长、促进张开子叶和花青素的积累、阻断持续远红光条件下的变绿。为了评价ZmPHYA1和ZmPHYA2对光的响应能力及其功能差异，本研究采用实时定量PCR技术分析玉米自交系B73和Mo17中ZmPHYA1和ZmPHYA2对不同光照处理响应的表达模式。结果表明玉米光敏色素A主要在叶片和花丝中表达，并且ZmPHYA1转录丰度是ZmPHYA2的2~8倍；玉米自交系B73和Mo17中胚轴在黑暗、远红光和蓝光条件下较红光和白光下更长。ZmPHYA1和ZmPHYA2的转录水平在持续远红光和蓝光条件下均较高；并且均较迅速响应黑暗到远红光和蓝光光质转换，但是前者的丰度显著高于后者， ZmPHYA1在远红光下更重要，而ZmPHYA2在蓝光下更重要。ZmPHYA1和ZmPHYA2同样响应于黑暗到红光和白光的转换，并且ZmPHYA1和ZmPHYA2表达模式基本一致。ZmPHYA1和ZmPHYA2的表达均能响应长日照和短日照处理，但是ZmPHYA1转录丰度高于ZmPHYA2的2~5倍。以上结果表明， ZmPHYA1和ZmPHYA2的转录能有效地响应各种光处理，可能ZmPHYA1在作物改良上比ZmPHYA2更有效。本研究为进一步了解ZmPHYA1和ZmPHYA2基因功能以及评价二者的光反应能力提供了理论基础。%Plant phytochromes are a family of red/far-red light photoreceptors, which have two forms in plant: inactive red light ab-sorbing form (Pr) and active far-red light absorbing form (Pfr). During plant growth and developmental processes, phytochromes play pivotal roles in regulations of seed germination, plant height, flowering time, and shade-avoidance. In the grasses, three subfamilies are present:PHYA,PHYB andPHYC. In maize, an ancient genome duplication has increased the family member to six:PHYA1, PHYA2,PHYB1,PHYB2,PHYC1, andPHYC2. Phytochrome A facilitates the inhibition of hypocotyl elongation, opening of the api-cal hook, expansion of cotyledons, accumulation of anthocyanin and blocking of greening by continuous FR (FRc) light. In order to evaluate the light response capability and difference of transcription abundance betweenZmPHYA1 andZmPHYA2, we employed quantitative real-time PCR (qRT-PCR) assay to investigate the expression patterns ofZmPHYA1 andZmPHYA2 in the inbred line B73 and Mo17 with different light treatments. The results indicated that both ZmPHYA1 andZmPHYA2 had a high expression level in leaf and silk, and the transcription abundance ofZmPHYA1 was 2–8 times higher than that ofZmPHYA2. Inbred lines of both B73 and Mo17 possessed longer mesocotyls in dark, far-red and blue light conditions than in red or white light conditions. BothZmPHYA1 and ZmPHYA2 had a high expression level in far-red and blue lights and rapidly responded to dark-to-far-red and dark-to-blue transitions. ZmPHYA1 was more important under far-red light, so wasZmPHYA2 in blue light. Both of the genes could rapidly respond to transi-tions from dark to red or white light with similar expression pattern. The both genes also respond to long-day or short-day treatments, however the transcription abundance ofZmPHYA1was 2–5 times higher than that ofZmPHYA2during the treatments. All the results suggested that the transcription of bothZmPHYA1 andZmPHYA2 could rapidly responded to different light treatments;ZmPHYA1 might be more effective thanZmPHYA2 in crop improvement. Our results provide a theoretical basis for the function study and evaluation of light response ability for bothZmPHYA1 andZmPHYA2.