*4.6. RNA Extraction and qRT-PCR Analysis*

Total RNA was extracted with TRIzol Reagent (Invitrogen, 15596-026, Dalian, China) according to the manufacturer's instructions. For the first-strand cDNA synthesis experiment of miR319, a One Step PrimeScript® miRNA cDNASynthesis Kit (Takara, Dalian, China) was used. For each sample, 4 µg of total RNA was converted to cDNA in a 20-µL reaction system, which contained 10 µL of <sup>2</sup><sup>×</sup> miRNA reaction buffer mix, 2 <sup>µ</sup>L of 0.1% BSA, and 2 <sup>µ</sup>L of miRNA PrimeScript®RT Enzyme Mix. qRT-PCR was performed using SYBR® Premix Ex TaqTM II (Takara) and undertaken with a 7500 Fast Real-Time PCR system (Applied Biosystems Inc., Foster City, CA, USA). The specific miR319 and TCP genes primers used are given in Table S2. The reactions were incubated in a 96-well plate at 95 ◦C at 30 s, followed by 40 cycles of 95 ◦C at 15 s and 60 ◦C at 30 s. The 25-µL reaction solutions contained 12.5 <sup>µ</sup>L of SYBR®*Premix* Ex TaqTMII (2×), 1 <sup>µ</sup>L of PCR forward primer (10 <sup>µ</sup>M), 1 <sup>µ</sup>L of PCR reverse primer (10 µM) and 2 µL of five fold diluted cDNA template. All reactions were performed with three replicates. Relative expression levels were calculated by the comparative threshold cycle (2−∆∆<sup>T</sup> ) method.

**Supplementary Materials:** Supplementary materials can be found at http://www.mdpi.com/1422-0067/19/11/ 3655/s1.

**Author Contributions:** Z.Y. and W.Y. conceived and designed the experiments; Z.Y., W.Z., Y.L., J.W. and H.L. performed the experiments; Z.Y. and X.F. analyzed the data; Z.Y. and Y.L. wrote the paper. Y.L. and X.F. reviewed and edited the manuscript. All authors read and approved the manuscript.

**Funding:** This work was supported by the National Natural Science Foundation of China (31201247), Young Elite Scientists Sponsorship Program by CAST (2016QNRC001), and State Key Laboratory of Crop Biology Open Fund (2015KF12).

**Conflicts of Interest:** The authors declare no conflict of interest.
