Identification of Pathogen Causing Loquat Root Rot in Zhejiang and Characteristics of Host Endogenous Hormone Response

doi:10.16420/j.issn.0513-353x.2026-0323

Acta Horticulturae Sinica ›› 2026, Vol. 53 ›› Issue (7): 2200-2212.doi: 10.16420/j.issn.0513-353x.2026-0323

• Plant Protection • Previous Articles

Identification of Pathogen Causing Loquat Root Rot in Zhejiang and Characteristics of Host Endogenous Hormone Response

GOU Xiuhong¹, WEI Yue¹, QIN Yi¹, CHEN Junwei², GUO Qigao¹, LIANG Guolu¹, ZHOU Can³, WU Di¹^,^*()

¹ Key Laboratory of Agricultural Biosafety and Green Production of Upper Yangtze River（Ministry of Education）;Chongqing Key Laboratory of Forest Ecological Restoration and Utilization in the Three Gorges Reservoir Area;College of Horticulture and Landscape Architecture， Southwest University， Chongqing 400715， China
² Institute of Horticulture， Zhejiang Academy of Agricultural Sciences， Hangzhou 310021， China
³ Agricultural and Rural Development and Financial Services Center of Zhicun Town， Mengzi City，Mengzi， Yunnan 661102， China

Received:2026-04-08 Revised:2026-06-12 Online:2026-07-25 Published:2026-07-23
Contact: WU Di

Abstract

Abstract:

The pathogens causing loquat root rot exhibit high diversity and regional specificity，making the identification and pathogenicity characterization essential for precise disease management. Through tissue isolation，morphological observation，molecular identification，and pathogenicity assays，Fusarium oxysporum was identified as an important pathogen causing loquat root rot in Zhejiang Province. Biological characterization of the representative isolate（R1）revealed that the optimal culture conditions for mycelial growth of F. oxysporum were 30 ℃ and pH 7-8，with soluble starch as the optimal carbon source，and yeast extract and potassium nitrate as the optimal nitrogen sources. To elucidate the host-pathogen interaction，the spatiotemporal dynamics of endogenous hormones in loquat following F. oxysporum infection were profiled using liquid chromatography-tandem mass spectrometry（LC-MS/MS）and real-time quantitative PCR（qRT-PCR）. The results showed that during the early stage of infection（1 day post-inoculation，1 dpi），the jasmonic acid（JA）content in roots decreased，followed by an increase in the middle（7 dpi）and late（14 dpi）stages. Correspondingly，the expression of jasmonic acid carboxyl methyltransferase 5（JMT5）was initially up-regulated and subsequently down-regulated. Conversely，salicylic acid（SA）and its inactive glucoside form，SA 2-O-β-D-glucoside（SAG），accumulated significantly during the middle stage before declining rapidly in the late stage. In the stems，the SA content showed no significant change，whereas SAG and JA accumulated substantially in the late stage. The expression of defense-related genes，such as chitinase（CHI）and pathogenesis-related 1（PR1），was up-regulated initially；however，PR1 was suppressed in the late stage. In contrast，the JA synthesis-related lipoxygenase 22（Lox22）was up-regulated during the late stage. In conclusion，F. oxysporum facilitates colonization by regulating loquat endogenous hormone signaling networks. In the early stage，it disrupts JA metabolic homeostasis to weaken local defense；in the middle stage，it induces SA accumulation to antagonize JA signaling；and in the late stage，it further facilitates infection by suppressing SA-mediated systemic acquired resistance（SAR）.

Key words: loquat, root rot, Fusarium oxysporum, biological characteristics, jasmonic acid, salicylic acid

GOU Xiuhong, WEI Yue, QIN Yi, CHEN Junwei, GUO Qigao, LIANG Guolu, ZHOU Can, WU Di. Identification of Pathogen Causing Loquat Root Rot in Zhejiang and Characteristics of Host Endogenous Hormone Response[J]. Acta Horticulturae Sinica, 2026, 53(7): 2200-2212.

Figures/Tables 8

Table 1 Primer sequences used for RT-qPCR

目的基因 Target	引物名称 Primer name	引物序列（5′-3′） Sequence	用途 Purpose
CHI	CHI-F	TGGAGGATGGGAAAGTGC	SA信号通路基因 SA signal pathway
CHI	CHI-R	GGGTGAGTTGGATGGGTC
PR1	PR1-F	GCAGCAGTAGGCGTTGGTCCCT
PR1	PR1-R	CCAGTGCTCATGGCAAGGTTTT
Lox22	Lox22-F	GAAGGGGTATGGGCACAA	JA信号通路基因 JA signal pathway
Lox22	Lox22-R	ACATTAACAGTGCCGTTTGG
JMT5	JMT5-F	AGGACCATACTTCCTCCG
JMT5	JMT5-R	CCAAGGAAGGAGAGGGAC

Fig. 1 Natural field symptoms of loquat root rot disease A：Above-ground symptoms；B：Root rot symptom；C：Dissection section symptom of an infected root

Fig. 2 Morphological characteristics of the loquat root rot pathogen A：Colony morphology of strain R1；B：Macroconidium；C：Microconidium

Fig. 3 Phylogenetic tree based on ITS-TEF1-RPB2 combined gene sequences

Fig. 4 Pathogenicity test of loquat root rot pathogen

Fig. 5 Biological characteristics of Fusarium oxysporum R1 A：Carbon source；B：Nitrogen source；C：pH；D：Temperature. The lowercase letters indicate the significant difference among different treatments（P < 0.05）

Fig. 6 Effects of Fusarium oxysporum R1 infection on endogenous hormone contents in loquat A：Changes in hormone contents in roots and stems upon F. oxysporum R1 infection. The analyzed hormones include：salicylic acids（SA and SAG），jasmonates（JA，H2JA，MeJA，OPC-4，OPC-6，OPDA，JA-Val，and JA-Ile），gibberellins（GA4 and GA24），and abscisic acids （ABA and ABA-GE）. B：Contents of JA，SA and SAG in the roots and stems at different time post-inoculation. Asterisks indicate significant differences between the R1 treatment and the control group at the same time（* P < 0.05，** P < 0.01，*** P < 0.001）

Fig. 7 Expression patterns of genes related to SA and JA signaling pathways in loquat roorts and stems A：Roots；B：Stems. The asterisks indicate the significant difference between different groups at the same time（*P < 0.05，**P < 0.01，***P < 0.001）

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Identification of Pathogen Causing Loquat Root Rot in Zhejiang and Characteristics of Host Endogenous Hormone Response

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