Neuropeptide Bursicon and Its Receptor Mediate Seasonal Polyphenism in the Pear Psylla Cacopsylla chinensis

Core Concepts

Neuropeptide Bursicon and its receptor CcBurs-R play a critical role in regulating the transition from summer-form to winter-form in the pear psylla Cacopsylla chinensis by affecting cuticle content and thickness.

Abstract

This study investigated the novel function of neuropeptide Bursicon and its receptor in mediating the seasonal polyphenism of the pear psylla Cacopsylla chinensis.
The authors first identified two Bursicon subunits, CcBurs-α and CcBurs-β, and found that their expression was upregulated by low temperature (10°C) and the temperature receptor CcTRPM. Knockdown of CcBurs-α, CcBurs-β, or their receptor CcBurs-R significantly reduced cuticle pigment content, chitin content, and cuticle thickness, leading to a decreased transition from summer-form to winter-form in C. chinensis.
Further experiments revealed that the Bursicon heterodimer (CcBurs-α+β) could activate CcBurs-R, which acted as the upstream regulator of the chitin biosynthesis pathway. Additionally, the microRNA miR-6012 was found to directly target CcBurs-R and inhibit its expression, contributing to the regulation of Bursicon signaling in the seasonal polyphenism of C. chinensis.
These findings provide novel insights into the neuroendocrine mechanisms underlying insect seasonal polyphenism, highlighting the critical role of Bursicon signaling in mediating the transition from summer-form to winter-form in the pear psylla.

Stats

Low temperature (10°C) significantly increased the mRNA expression of CcBurs-α, CcBurs-β, and CcBurs-R compared to 25°C.
Knockdown of CcBurs-α, CcBurs-β, or CcBurs-R reduced the total cuticle pigment absorbance by 78.8%, 77.6%, and 83.5%, respectively, compared to the control.
Knockdown of CcBurs-α, CcBurs-β, or CcBurs-R decreased the cuticle chitin content by 67%, 68%, and 69%, respectively, compared to the control.
Knockdown of CcBurs-α, CcBurs-β, or CcBurs-R reduced the cuticle thickness by 57.5%, 54.9%, and 60.5%, respectively, compared to the control.
Knockdown of CcBurs-α, CcBurs-β, or CcBurs-R decreased the transition percent from summer-form to winter-form by 69.6%, 69.0%, and 68.1%, respectively, compared to the control.

Quotes

"Bursicon, also known as the tanning hormone, was initially discovered in the 1960s through neck-ligated assays. It serves a highly conserved function in insects by inducing the clerotization and melanization of the new cuticle in larvae and facilitating wing expansion in adults."
"Increasing studies have shown that miRNAs are important in insect polyphenism, such as miR-31, miR-9, and miR-252, as well as hormone signaling, for examples, miR-133 in dopamine synthesis."
"These findings reveal the novel function of neuroendocrine regulatory mechanism underlying seasonal polyphenism and provide critical insights into insect Bursicon and its receptor."

Key Insights Distilled From

The fascinating role of neuropeptide Bursicon and its receptor in shaping insect seasonal polyphenism

by Zhang,Z., Li... at www.biorxiv.org 04-09-2024

https://www.biorxiv.org/content/10.1101/2024.04.06.588405v1

Deeper Inquiries

How do other neuroendocrine hormones, such as insulin and ecdysone, interact with the Bursicon signaling pathway to regulate seasonal polyphenism in C. chinensis

In C. chinensis, other neuroendocrine hormones, such as insulin and ecdysone, likely interact with the Bursicon signaling pathway to regulate seasonal polyphenism. Insulin, known for its role in metabolism and growth, may influence the energy allocation and resource utilization required for the physiological changes associated with transitioning between summer-form and winter-form. Ecdysone, a key hormone in insect molting and development, could potentially coordinate the timing and progression of the phenotypic shifts by regulating gene expression and physiological processes. These hormones may act in concert with Bursicon to orchestrate the complex molecular and physiological changes underlying seasonal polyphenism in C. chinensis.

What are the potential evolutionary advantages and ecological implications of the seasonal polyphenism mediated by Bursicon signaling in C. chinensis and other insect species

The seasonal polyphenism mediated by Bursicon signaling in C. chinensis and other insect species offers several evolutionary advantages and ecological implications. From an evolutionary perspective, seasonal polyphenism allows organisms to adapt to changing environmental conditions, enhancing their survival and reproductive success. In the case of C. chinensis, the ability to transition between summer-form and winter-form enables the insect to optimize its phenotype for different seasonal challenges, such as temperature fluctuations and resource availability. This phenotypic plasticity may confer a selective advantage, increasing the fitness of the population as a whole.
Ecologically, seasonal polyphenism can impact various aspects of the ecosystem. For example, the different phenotypes of C. chinensis may influence interactions with host plants, predators, and competitors, shaping community dynamics. The ability to switch between phenotypes in response to environmental cues can also impact population dynamics, distribution patterns, and overall ecosystem stability. Understanding the ecological implications of seasonal polyphenism mediated by Bursicon signaling is crucial for comprehending the broader ecological context in which these insects operate.

Could the insights gained from studying the Bursicon-mediated seasonal polyphenism in C. chinensis be applied to understand similar phenomena in other organisms, such as plants or vertebrates, that exhibit phenotypic plasticity in response to environmental cues

The insights gained from studying the Bursicon-mediated seasonal polyphenism in C. chinensis have the potential to be applied to understand similar phenomena in other organisms that exhibit phenotypic plasticity in response to environmental cues. While the specific mechanisms and signaling pathways may vary across different species, the fundamental principles of how organisms adapt and respond to changing environmental conditions are likely to be conserved.
For example, in plants, the study of hormone signaling pathways and genetic regulation of developmental plasticity in response to environmental factors could benefit from the insights gained from insect seasonal polyphenism. Understanding how plants adjust their growth, flowering, and defense mechanisms in different seasons could be enhanced by exploring the parallels with insect polyphenism.
Similarly, in vertebrates, such as fish and reptiles, where temperature-dependent sex determination and seasonal color changes are common, investigating the molecular mechanisms underlying phenotypic plasticity could draw inspiration from the research on insect polyphenism. By elucidating the role of neuroendocrine hormones, miRNAs, and signaling pathways in shaping seasonal phenotypes, researchers can uncover shared principles of phenotypic plasticity across diverse organisms.