MicroRNA319 (miR319) plays an important role in leaf development. Although leaf discs are frequently used for plant transformation, little is known about the function of miR319 in shoot regeneration from leaf explants. To investigate the role of miR319 in de novo shoot organogenesis from leaf explants, the MIR319 gene was overexpressed in petunia (Petunia × hybrida), under the control of the 35S promoter. Petunia leaves overexpressing miR319 (miR319-OX) showed several morphological abnormalities, such as rounded, uneven, and curled leaf blade, larger leaf size, and smaller and rounded abaxial surface cells, which were differences compared to wild-type (WT) leaves. Additionally, miR319-OX leaf explants demonstrated enhanced shoot organogenesis on a growth medium containing 6-benzylaminopurine (BA) at shoot-inducing concentrations, and cytokinin-independent shoot regeneration on hormone-free medium compared with WT explants. Quantitative real-time PCR (qRT-PCR) analysis indicated that the expression of petunia NO APICAL MERISTEM (PhNAM) and SHOOT MERISTEMLESS (PhSTM) genes was markedly increased in miR319-OX explants compared with WT explants under shoot induction conditions, whereas the expression of petunia cytokinin-responsive type-A response regulator genes, PhRR2 and PhRR3, showed no differences in expression between WT and miR319-OX leaf explants. These results suggest that miR319 regulates the formation of shoot meristems from leaf explants in petunia during in vitro culture.

MicroRNA319（miR319）在叶片发育中起重要作用。尽管叶盘通常用于植物转化，但对miR319在从叶外植体再生芽中的功能了解甚少。为了研究miR319在叶片外植体从头芽器官发生中的作用，在矮牵牛中过量表达了MIR319基因（矮牵牛 × 杂种），由35S启动子控制。过表达miR319（miR319-OX）的矮牵牛叶片表现出几种形态异常，例如圆形，不均匀和卷曲的叶片，较大的叶片尺寸以及较小且圆形的背面表面细胞，与野生型（WT）叶片相比有差异。此外，与WT外植体相比，miR319-OX叶外植体在含有6-苄基氨基嘌呤（BA）的生长培养基上，以芽诱导浓度显示出增强的芽器官发生，并且在无激素培养基上不依赖细胞分裂素的芽再生。实时定量PCR（qRT-PCR）分析表明矮牵牛NO APICAL MERISTEM（PhNAM）和SHOOT MERISTEMSLES（PhSTM）在芽诱导条件下，miR319-OX外植体的基因显着高于WT外植体，而矮牵牛细胞分裂素应答A型应答调节基因PhRR2和PhRR3的表达在WT和miR319-OX叶之间的表达没有差异外植体。这些结果表明，miR319在体外培养过程中调节了矮牵牛叶片外植体芽分生组织的形成。