MicroRNA156: A Potential Graft-Transmissible MicroRNA That Modulates Plant Architecture and Tuberization in Solanum tuberosum ssp. andigena        

Abstract

MicroRNA156 (miR156) functions in maintaining the juvenile phase in plants. However, the mobility of this microRNA has not been demonstrated. So far, only three microRNAs, miR399, miR395, and miR172, have been shown to be mobile. We demonstrate here that miR156 is a potential graft-transmissible signal that affects plant architecture and tuberization in potato (Solanum tuberosum). Under tuber-noninductive (long-day) conditions, miR156 shows higher abundance in leaves and stems, whereas an increase in abundance of miR156 has been observed in stolons under tuber-inductive (short-day) conditions, indicative of a photoperiodic control. Detection of miR156 in phloem cells of wild-type plants and mobility assays in heterografts suggest that miR156 is a graft-transmissible signal. This movement was correlated with changes in leaf morphology and longer trichomes in leaves. Overexpression of miR156 in potato caused a drastic phenotype resulting in altered plant architecture and reduced tuber yield. miR156 overexpression plants also exhibited altered levels of cytokinin and strigolactone along with increased levels of LONELY GUY1 and StCyclin D3.1 transcripts as compared with wild-type plants. RNA ligase-mediated rapid amplification of complementary DNA ends analysis validated SQUAMOSA PROMOTER BINDING-LIKE3 (StSPL3), StSPL6, StSPL9, StSPL13, and StLIGULELESS1 as targets of miR156. Gel-shift assays indicate the regulation of miR172 by miR156 through StSPL9. miR156-resistant SPL9 overexpression lines exhibited increased miR172 levels under a short-day photoperiod, supporting miR172 regulation via the miR156-SPL9 module. Overall, our results strongly suggest that miR156 is a phloem-mobile signal regulating potato development.

Small Genetic Circuits and MicroRNAs: Big Players in Polymerase II Transcriptional Control in Plants

“…EMSA has been broadly used for characterization of core promoter elements in both animals (Morachis et al, 2010;reviewed in Roy and Singer, 2015) and plants (Achard et al, 2003), including characterization of miRNA core promoters (reviewed in Xie et al, 2010). Using gel-shift assays, Bhogale et al (2014) identified binding sites for the SQUAMOSA PROMOTER BINDING-LIKE9 (SPL9) TF in the potato (Solanum tuberosum) miR172 promoter. Predictably, these binding sites contained a GTAC motif resembling SPL9 binding sites in the promoters of protein coding genes.…”

The Multiple Signals That Control Tuber Formation

“…Because of the transport capacity of the tuber signal, the search for the activating signal has focused on primary products like microRNAs, fulllength mRNAs, and less abundant proteins that move through the sieve element system of the plant (Table I). Two important microRNAs, miR172 and miR156, have been implicated in potato development, but their exact mechanistic connection to tuber formation has not been established conclusively (Martin et al, 2009;Bhogale et al, 2014).…”

Achievements and prospects of applying high-throughput sequencing techniques to potato genetics and breeding

“…Для секвенирования используют как экспериментальные подходы, связанные с высокопроизводительным секвени рованием (Zhang et al, 2013), так и биоинформатические подходы для предсказания структуры микроРНК по уже известным последовательностям (Zhang et al, 2009). Ис следования направлены на изучение микроРНК, которые регулируют экспрессию конкретных генов (Chi et al, 2015), участвующих в формировании стрессового ответа на засуху (Zhang et al, 2014) и играющих роль в процессе клубнеобразования (Martin et al, 2009;Bhogale et al, 2014;Lakhotia et al, 2014).…”