In a recent study, RLB (RICE LATERAL BRANCH) gene were demonstrated to control the plant height of rice. A loss-function mutation of the gene led to reduced stature. However, when the authors overexpressed the gene, the transgenic lines also showed reduced plant height. The authors further determined the expression levels of endogenous and transformed RLB copies, and found that both of them were decreased to very low levels.

Question: RLB gene was proofed to positively regulate the plant height of rice, we expected that overexpression of RLB may cause overaccumulation of the RLB gene transcription and increase to some extent, at least not reduce, the plant height. Why overexpression of RLB resulted in reduced transcription for both endogenous and transformed RLB copies and caused the similar phenotype with the mutant? Based on the knowledge we have learned about small RNA biogenesis and functions, please:

1) give the possible explanation of the phenomena;

2) describe the mechanism may cause the above phenomena;