Silencing of LIM homeodomain transcription factor 1 alpha (Lmx1a) gene caused larval molting failure and adult reproductive deficiency in Henosepilachna vigintioctopunctata.

Abstract

LIM-HD (homeodomain) protein is essential for the specific differentiation of various cells and tissues due to its conserved HD. Within the LIM subclass, the LIM-HD transcription factor 1 alpha (Lmx1a) remains poorly characterized in insects. This study investigates the expression patterns of HvLmx1a in the 28-spotted lady beetle, Henosepilachna vigintioctopunctata, at both developmental stage and tissue levels. Furthermore, RNA interference (RNAi)-mediated knockdown of HvLmx1a resulted in increased mortality during the early larval stage. Injection of dsHvLmx1a at the beginning of the 4th instar caused a reduction in 20E titer, disrupted normal molting and pupation processes, and led to the emergence of larval-pupal abnormalities. Notably, HvLmx1a expression was significantly down-regulated on d 2 and 4 post-injection, which coincided with a marked inhibition of HvCHS1 and genes associated with 20E and bursicon signaling pathways. Additionally, silencing HvLmx1a induced qualitative changes in male testes and female ovaries, resulting in infertility and increased mortality. Ultimately, these findings suggest that HvLmx1a influences ovarian morphology and development through lipid metabolism. In conclusion, this study provides the first evidence of the diverse physiological roles of Lmx1a in H. vigintioctopunctata and highlight its potential as a target for RNAi-based biological control strategies.