Application of larch miR166a in plant development regulation and control

The invention discloses an application of larch miR166a in plant development regulation and control. The application provided by the invention specifically is the application of nucleic acid molecules shown in any of (1)-(4) in plant development regulation and control, namely (1) RNA molecules shown in sequence 1 in a sequence table; (2) RNA molecules shown in sequence 2 in the sequence table; (3) RNA molecules shown in sequence 3 in the sequence table; (4) DNA molecules shown in 27th-539th of the sequence 3 in the sequence table. Experiments prove that the transgenic plants with overexpressed LaMIR166a genes generate lots of lateral roots and grow well when cultured on a rooting culture medium a17 for 4 months; non-transgenic control plants only elongate main roots, do not generate lateral roots and relatively grow slowly. The result indicates that the overexpressed miR166a is capable of promoting the growth speed of larch tissue culture seedling and the generations of the lateral roots, thus increasing the transplanting survival rate.