# The JHAMT1 gene is necessary for wing differentiation in Aphis gossypii

## TL;DR

This study identifies the JHAMT1 gene as crucial for wing development in the cotton aphid, which could help in controlling its spread.

## Contribution

The study reveals JHAMT1 as a key gene in wing differentiation in Aphis gossypii.

## Key findings

- JHAMT1 is significantly upregulated in alate nymphs during critical wing differentiation stages.
- Knockdown of JHAMT1 inhibits wing development in 60.2% of treated alate nymphs.
- JHAMT1 is essential for the formation of wing buds in Aphis gossypii.

## Abstract

Aphis gossypii (cotton–melon aphid) is ranked among the top 10 most destructive agricultural pests worldwide, inflicting substantial damage on a wide range of host plants annually. Wing polyphenism is a key trait that facilitates rapid population expansion and efficient virus transmission. However, the molecular mechanisms underlying wing differentiation in this sap-sucking pest remain poorly understood.

The differentiation dynamics of newborn A. gossypii nymphs into to alate (winged) or apterous (wingless) morphs was characterized, coupled with pairwise morphological comparisons. The second- and third-instar nymphal stages were identified as two critical turning points for wing morph determination. The number of differentially expressed genes between alate and apterous morphs increased during development, peaking at the fourth-instar nymphal stage before declining in adulthood. Notably, compared with that in the apterous morph, upregulated genes in the alate morph at each developmental stage were consistently enriched in the juvenile hormone (JH) biosynthesis signaling pathway. Four JHAMT (juvenile hormone acid methyltransferase)—encoding the rate-limiting enzyme in JH biosynthesis—were identified in the A. gossypii genome. Among these, only JHAMT1 exhibited significantly elevated expression in the second- and third-instar nymphs of the alate morph, corresponding to the critical period of wing differentiation. Knockdown of JHAMT1 via dsJHAMT1 feeding in third-instar alate nymphs resulted in a 79% reduction in transcript level and significantly inhibited normal wing differentiation in 60.2% of the treated individuals. Notably, wing buds of these affected nymphs failed to develop and eventually disappeared in adulthood, demonstrating that JHAMT1 is indispensable for wing morph formation in A. gossypii.

This study clarifies the complete differentiation process of A. gossypii into alate or apterous morphs and confirms that JHAMT1, a key regulatory gene in JH biosynthesis, plays a pivotal role in wing differentiation of the alate morph. Given its essential function in wing development, JHAMT1 holds strong potential as a molecular target for developing strategies to control outbreaks and spread of the cotton aphid.