Ghate Tejashree H, Sharma Pooja, Kondhare Kirtikumar R, Hannapel David J, Banerjee Anjan K
Biology Division, Indian Institute of Science Education and Research (IISER), Dr. Homi Bhabha Road, Pune, 411008, Maharashtra, India.
Plant Biology Major, Iowa State University, 253 Horticulture Hall, Ames, IA, 50011-1100, USA.
Plant Mol Biol. 2017 Apr;93(6):563-578. doi: 10.1007/s11103-016-0582-4. Epub 2017 Jan 13.
We demonstrate that RNAs of StBEL11 and StBEL29 are phloem-mobile and function antagonistically to the growth-promoting characteristics of StBEL5 in potato. Both these RNAs appear to inhibit tuber growth by repressing the activity of target genes of StBEL5 in potato. Moreover, upstream sequence driving GUS expression in transgenic potato lines demonstrated that both StBEL11 and -29 promoter activity is robust in leaf veins, petioles, stems, and vascular tissues and induced by short days in leaves and stolons. Steady-state levels of their mRNAs were also enhanced by short-day conditions in selective organs. There are thirteen functional BEL1-like genes in potato that encode for a family of transcription factors (TF) ubiquitous in the plant kingdom. These BEL1 TFs work in tandem with KNOTTED1-types to regulate the expression of numerous target genes involved in hormone metabolism and growth processes. One of the StBELs, StBEL5, functions as a long-distance mRNA signal that is transcribed in leaves and moves into roots and stolons to stimulate growth. The two most closely related StBELs to StBEL5 are StBEL11 and -29. Together these three genes make up more than 70% of all StBEL transcripts present throughout the potato plant. They share a number of common features, suggesting they may be co-functional in tuber development. Upstream sequence driving GUS expression in transgenic potato lines demonstrated that both StBEL11 and -29 promoter activity is robust in leaf veins, petioles, stems, and vascular tissues and induced by short-days in leaves and stolons. Steady-state levels of their mRNAs were also enhanced by short-day conditions in specific organs. Using a transgenic approach and heterografting experiments, we show that both these StBELs inhibit growth in correlation with the long distance transport of their mRNAs from leaves to roots and stolons, whereas suppression lines of these two RNAs exhibited enhanced tuber yields. In summary, our results indicate that the RNAs of StBEL11 and StBEL29 are phloem-mobile and function antagonistically to the growth-promoting characteristics of StBEL5. Both these RNAs appear to inhibit growth in tubers by repressing the activity of target genes of StBEL5.
我们证明，马铃薯中StBEL11和StBEL29的RNA可在韧皮部移动，并且与StBEL5在促进马铃薯生长的特性上发挥拮抗作用。这两种RNA似乎通过抑制马铃薯中StBEL5靶基因的活性来抑制块茎生长。此外，驱动转基因马铃薯品系中GUS表达的上游序列表明，StBEL11和StBEL29的启动子活性在叶脉、叶柄、茎和维管组织中很强，并且在叶片和匍匐茎中受短日照诱导。在特定器官中，短日照条件也会提高它们mRNA的稳态水平。马铃薯中有13个功能性BEL1样基因，它们编码植物界普遍存在的一类转录因子（TF）。这些BEL1转录因子与KNOTTED1类型协同作用，以调节参与激素代谢和生长过程的众多靶基因的表达。其中一个StBEL，即StBEL5，作为一种长距离mRNA信号，在叶片中被转录，然后进入根和匍匐茎以刺激生长。与StBEL5关系最密切的两个StBEL是StBEL11和StBEL29。这三个基因共同构成了整个马铃薯植株中所有StBEL转录本的70%以上。它们具有许多共同特征，表明它们可能在块茎发育中具有协同功能。驱动转基因马铃薯品系中GUS表达的上游序列表明，StBEL11和StBEL29的启动子活性在叶脉、叶柄、茎和维管组织中很强，并且在叶片和匍匐茎中受短日照诱导。在特定器官中，短日照条件也会提高它们mRNA的稳态水平。通过转基因方法和异源嫁接实验，我们表明这两种StBEL都与它们的mRNA从叶片向根和匍匐茎的长距离运输相关地抑制生长，而这两种RNA的抑制品系表现出更高的块茎产量。总之，我们的结果表明，StBEL11和StBEL29的RNA可在韧皮部移动，并且与StBEL5在促进生长的特性上发挥拮抗作用。这两种RNA似乎通过抑制StBEL5靶基因的活性来抑制块茎生长。
