Effects of Insect-resistant and Insect-susceptible Cassava Varieties on the Expression of Wax Biosynthesis Genes in Phenacoccus manihoti

doi:10.13560/j.cnki.biotech.bull.1985.2025-1190

Abstract

Abstract:

Objective Phenacoccus manihoti is a major pest of cassava, and its cuticular wax layer serves as a critical barrier against external stresses. Identifying key genes involved in wax biosynthesis in P. manihoti and elucidating their expression patterns under the stress of insect-resistant versus insect-susceptible cassava varieties will provide a theoretical basis for pest control strategies targeting wax synthesis disruption. Method Based on annotations from the NR database and established knowledge of the insect wax biosynthesis pathway, wax synthesis candidate genes were initially screened from lipid metabolism-related genes. The expression profiles of these candidate genes were systematically analyzed by RT-qPCR in P. manihoti reared on a highly resistant cassava variety (C1115) versus a highly susceptible one (KU50). Subsequently, for those candidate genes whose expression peaks closely coincided with the critical wax secretion period of the mealybug and exhibited significant differential expression between insect-resistant and insect-susceptible hosts, their expression dynamics were further examined in insects reared on six cassava varieties with varying levels of resistance. The correlation between their expression levels and host resistance was assessed to identify key candidate genes. Finally, enzyme activity assays were performed focusing on these key candidates, and their association with host resistance was analyzed. Result A total of nine wax biosynthesis candidate genes were identified (FAR1/2, FAD1/2, ACC, FAS1/2, and ELO1/2). Among them, the expression peaks of FAR2, FAD1, ACC, and FAS1 closely coincided with the key wax secretion period of P. manihoti, and their expressions were significantly higher in insects reared on insect-susceptible cassava varieties than in those reared on insect-resistant ones. Furthermore, the expressions of FAR2, FAD1, and ACC showed significant negative correlations with host resistance. However, only total FAR enzyme activity showed a significant negative correlation with cassava resistance. Conclusion FAR2, FAD1, and ACC are three key genes that respond to host resistance and regulate wax biosynthesis. The suppression of FAR2 expression and total FAR enzyme activity in insects feeding on resistant cassava varieties likely represents a crucial mechanism limiting the adaptability of P. manihoti.

Key words: insect-resistant cassava variety, insect-susceptible cassava variety, Phenacoccus manihoti, wax biosynthesis genes, gene expression

GUO Wei, GENG Yue, LIANG Xiao, LIU Ying, WU Chun-ling, CHEN Qing. Effects of Insect-resistant and Insect-susceptible Cassava Varieties on the Expression of Wax Biosynthesis Genes in Phenacoccus manihoti[J]. Biotechnology Bulletin, 2026, 42(6): 128-138.

Figures/Tables 7

References 35

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基因 Gene	目标序列ID Subject_id	相似性 Identity（%）	得分 Score	期望值 E_value
FAR1	ANN23959.1	90.7	989.2	1.2E-285
FAR2	ANN23960.1	90.9	933.7	5.1E-269
FAD1	QBM20313.1	98.9	758.1	4.7E-216
FAD2	QBM20314.1	90.3	678.3	2.8E-192
ACC	QGZ00537.1	80.0	3 805.4	0.00E+00
FAS1	UEV87819.1	67.9	3 359.3	0.00E+00
FAS2	XP_025208386.1	66.8	2 933.3	0.00E+00
ELO1	QAX90474.1	74.6	444.5	9E-122
ELO2	XP_018327719.1	74.7	436.4	1.6E-119

基因 Gene	目标序列ID Subject_id	相似性 Identity（%）	得分 Score	期望值 E_value
FAR1	ANN23959.1	90.7	989.2	1.2E-285
FAR2	ANN23960.1	90.9	933.7	5.1E-269
FAD1	QBM20313.1	98.9	758.1	4.7E-216
FAD2	QBM20314.1	90.3	678.3	2.8E-192
ACC	QGZ00537.1	80.0	3 805.4	0.00E+00
FAS1	UEV87819.1	67.9	3 359.3	0.00E+00
FAS2	XP_025208386.1	66.8	2 933.3	0.00E+00
ELO1	QAX90474.1	74.6	444.5	9E-122
ELO2	XP_018327719.1	74.7	436.4	1.6E-119