Isolation, identification and biological characteristics of major pathogenic fungi in stiff fruits of <i>Torreya grandis</i>

LOU Kexun; LOU Jun; LAI Sisi; YE Haojie; YU Weiwu; FANG Nanshou; HU Yuanyuan

doi:10.11833/j.issn.2095-0756.20250575

Volume 43 Issue 2

Apr. 2026

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LOU Kexun, LOU Jun, LAI Sisi, et al. Isolation, identification and biological characteristics of major pathogenic fungi in stiff fruits of Torreya grandis[J]. Journal of Zhejiang A&F University, 2026, 43(2): 229−241 doi: 10.11833/j.issn.2095-0756.20250575

Citation:

LOU Kexun, LOU Jun, LAI Sisi, et al. Isolation, identification and biological characteristics of major pathogenic fungi in stiff fruits of Torreya grandis[J]. Journal of Zhejiang A&F University, 2026, 43(2): 229−241 doi: 10.11833/j.issn.2095-0756.20250575

Isolation, identification and biological characteristics of major pathogenic fungi in stiff fruits of Torreya grandis

DOI: 10.11833/j.issn.2095-0756.20250575

LOU Kexun^{1, 2, 3
,},
LOU Jun^{1, 2, 3},
LAI Sisi^{1, 2},
YE Haojie^{1, 2},
YU Weiwu^{1, 2},
FANG Nanshou⁴,
HU Yuanyuan^{1, 2
,
,}

1.
State Key Laboratory for Development and Utilization of Forest Food Resources, Zhejiang A&F University, Hangzhou 311300, Zhejiang, China
2.
Zhejiang Key Laboratory of Non-wood Forest Products Quality Regulation and Processing Utilization, Zhejiang A&F University, Hangzhou 311300, Zhejiang, China
3.
Agricultural Technology Extension Center in Fuyang District, Hangzhou 311400, Zhejiang, China
4.
Heqiao Torreya grandis Professional Cooperative of Lin’an District, Hangzhou 311321, Zhejiang, China

Received Date: 2025-11-11
Accepted Date: 2026-01-30
Rev Recd Date: 2026-01-26

Available Online: 2026-04-02

Publish Date: 2026-04-02

Abstract

Objective In April each year, 89% of the fruits on the bearing branches of Torreya grandis ‘Merrillii’ are stiff fruits characterized by unruptured arils and internal nucellus browning and shrinking. The aim of this study is to investigate the occurrence mechanism of stiff fruits, so as to provide a theoretical basis for developing effective prevention and control measures. Method The number of days after seed protrusion (D) was used as an indicator to record the developmental progression of T. grandis ‘Merrillii’ fruits, with the day of protrusion recorded as D=0. Nucellar tissue samples were collected at regular intervals. The tissue separation method was employed to isolate and purify pathogenic bacteria from the nucellar tissues at various developmental stages. By combining morphological analysis, multi-gene joint phylogenetic analysis and Koch’s postulates verification, the dominant pathogenic bacteria species of stiff fruits were identified and their biological characteristics were analyzed. Result (1) When D was within the range of −207 to 21 days, Cladosporium exhibited the highest isolation rate and frequency among the pathogens isolated from the nucellar tissues. Based on colony morphology, these Cladosporium isolates were classified into 5 types. Vaccination with representative strains and mixed strains of these 5 species of bacteria consistently induced browning of the T. grandis ‘Merrillii’ nucellus. The browning phenotype after inoculation with the mixed spore suspension was similar to that of stiff fruits. (2) Through morphological identification and multi-gene sequence analysis, the 5 major pathogenic strains of Cladosporium were identified as C. funiculosum TGZX1, C. oxysporum TGZX2, C. guizhouense TGZX3, C. tenuissimum TGZX4, and C. scabrellum TGZX5. (3) The optimal growth temperature for the 5 species of Cladosporium was 20−25 ℃. The optimal carbon sources for TGZX1-1, TGZX2-1, TGZX3-1, TGZX4-1, and TGZX5-1 were soluble starch, mannitol, glucose, maltose, and maltose, respectively. The optimal nitrogen source for all strains was tryptone. Moreover, these strains grew well under dark conditions. Conclusion The stiff fruits of T. grandis ‘Merrillii’ are caused by the combined infection of 5 species of Cladosporium, which is closely linked to the susceptibility of the female cone to Cladosporium infection during pollination. Therefore, the key to effectively preventing the formation of stiff fruits is to take control measures during the female flowering stage of T. grandis ‘Merrillii’. [Ch, 6 fig. 1 tab. 34 ref.]
- Torreya grandis ‘Merrillii’,
- stiff fruit,
- Cladosporium,
- biological characteristics

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沈阳化工大学材料科学与工程学院沈阳 110142

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香榧Torreya grandis ‘Merrillii’是红豆杉科Taxaceae榧树属Torreya中的优良栽培类型，其种仁风味香酥，余味浓郁，营养丰富，深受消费者喜爱，是干果中的珍品^[1]。香榧果实(实为裸露的种子。为了便于理解，本研究统称为果实)发育历时17个月，即每年4月上旬授粉，9月底完成受精，次年4月幼果突破种鳞开始膨大，9月成熟^[2]，但有部分幼果未能突破种鳞，内部珠心呈现褐化萎缩，称为僵果，比例高达89%^[3]。大量研究表明：植物僵果的形成常与病原微生物侵染密切相关。例如，佛罗里达炭疽菌Colletotrichum fioriniae侵染桃Prunus persica幼果或膨大果实，导致果实软腐、萎缩、硬化，并引发大量落果^[4]；伯氏镰刀菌Fusarium pernambucanum侵染荔枝Litchi chinensis幼果，抑制果实膨大并形成僵果^[5]。研究表明：苹果Malus pumila霉心病是由花期枝孢属Cladosporium spp.、链格孢菌属Alternaria spp.和粉红聚端孢Trichothecium roseum等病菌通过合生花柱顶缝—萼心间组织—萼窦路径侵染所致，在果实期显现症状，导致僵果、落果或果实腐烂^[6−8]。前期研究发现：在授粉期，香榧雌球花因珠孔裸露，枝孢属真菌可随花粉通过传粉滴进入储粉室，进而侵染珠心，严重时导致珠心褐腐、萎缩，雌球花脱落^[5]，表明授粉期是珠心这一核心部位面临病原侵染风险的关键时期^[9]。完成授粉后，雌球花需约24 d发育，使假种皮完全包被裸露珠孔^[9]，此后进入长达约11个月的缓生期，直至次年4月僵果病症显现^[1]。鉴于授粉期是珠心可被直接侵染的唯一阶段，且僵果的内部特征是珠心褐化、皱缩，由此推测，授粉期的病菌侵染及后续的潜伏性发展可能是导致香榧僵果的关键诱因。然而，在缓生期内，花期定殖的枝孢属等病原菌的动态变化及如何导致珠心褐化萎缩尚不清楚。因此，系统分析从缓生期至病症显现期香榧幼果珠心中的病原菌动态，对明确导致僵果的主要致病菌及致病机制至关重要。

组织分离法是果实病原菌鉴定的经典方法。通过病原菌分离纯化，结合形态学(如菌落特征)和分子生物学(如ITS、act、tef1多基因位点)分析，可精准鉴定病原菌种类^[9−11]。研究表明：枝孢属包含多个致病种，包括枝状枝孢菌C. cladosporioides、极细枝孢菌C. tenuissimum等^[12−15]。此外，病原菌生物学特性是研究其生长条件、预测流行趋势以及评估环境与宿主适应性的重要基础。这些研究结果可为制定有效的防控策略提供理论依据^[14−15]。

在过去几十年，香榧种植面积呈现指数型增长，但这种扩张主要依赖于毁坏现有林分，并将其转变为结构单一的人工林，因此，现有的香榧多以纯林形式存在，且栽培品种较为单一，导致其在面对病原菌侵袭时更为脆弱，容易受到病害影响。此外，从香榧缓生期(9月至翌年4月)至病症发生期(翌年4月至5月)历经8个多月，期间环境温度、光照时长等因子均发生了剧烈变化，表明病原菌需适应剧烈变化的环境条件才能完成侵染过程。本研究旨在明确导致香榧僵果形成的优势病原真菌，解析其从缓生期至显症期的动态，并探究其生物学特性，为致病机制研究和防控策略制定提供依据。

1. 材料与方法

1.1. 材料

1.1.1. 试验地概况及香榧僵果样本的采集

试验地点位于浙江省杭州市临安区太湖源镇潘母岗香榧基地(30°10′N，119°22′E)。该香榧林地于2012年采用“2+1”嫁接苗(砧木为2年生榧树T. grandis，穗条为1年生‘细榧’‘Xi Fei’)造林，2016年开始结实，林分密度为500株·hm⁻²。香榧果实发育成熟需历时17个月，其正常果实和僵果的主要外观区别在于果实是否突破种鳞，因此，为精确界定果实发育过程，本研究以距香榧果实突破种鳞的时间(D)作为记录发育进程的指标，突破种鳞当天记为D=0。

本研究于2023年9月，选取15株生长状态和树冠形态较为一致的香榧树，平均地径和树高分别为10.2 cm和2.0 m。每5株树为1个重复，共设3个重复。参照历年香榧突破种鳞时间，于2023年9月15日(D≈−210 d)挂牌标记，并自此每间隔20 d采集香榧种实珠心样品。采样时间根据2024年香榧实际突破种鳞日期(4月20日)进行修正，分别在D=−207、−177、−147、−117、−92、−56、−35、0、21 d时采集样品。每次采样时，从每株样本树上采集1簇结果枝(每簇含12~14个果实)，每个重复5簇，3个重复共计15簇。样品采回后立即带回实验室，进行后续分离。

1.1.2. 供试培养基

马铃薯葡萄糖琼脂培养基(PDA)、马铃薯蔗糖琼脂培养基(PSA)、燕麦培养基(OMA)、麦芽汁琼脂培养基(MEA)和合成低营养琼脂(SNA)。

1.2. 方法

1.2.1. 香榧僵果主要病原菌的分离、纯化

采用组织分离法对所采集的样本进行病原菌分离。具体步骤：从每次采样获得的15簇结果枝中，每簇随机选取2个幼果，共30个幼果。去除种鳞后，取出内部小果(带假种皮)，用无菌水洗净并风干。随后进行表面消毒：将小果置于体积分数为75%乙醇中浸泡30 s，用无菌水冲洗3次；再转入质量分数为2%次氯酸钠溶液中浸泡3 min，最后无菌水冲洗3次。用无菌滤纸吸干表面水分后，风干备用。最后，用灭菌手术刀沿小果纵切，取内部珠心组织接种至PDA培养基上。每个平板接种3块组织，每个采样点接种10个平板，即每个采样点共接种30块组织。将所有平板置于25 ℃恒温避光培养。待菌丝长出后，用接种针挑取菌落边缘菌丝，在PDA培养基上培养，连续纯化3代。在最后纯化的PDA板上，加入5 mL无菌水，用涂布棒刮取菌丝和孢子制成菌悬液，再与等体积的体积分数为50%甘油混合，保存于−80 ℃冰箱中，用于后续实验。

结合菌落与孢子的形态特征(形态学鉴定)和使用核糖体DNA内转录间隔区(ITS)序列分析(分子鉴定)，对所有分离菌株进行初步属级鉴定。各真菌属的分离率和分离频率计算公式^[13]：分离率=(同一属的菌株数/鉴定出的菌株总数)×100%；分离频率=(某一属的菌株数/培养出菌落的组织块总数)×100%。

1.2.2. 香榧僵果主要病原菌致病性测定

基于不同发育时期果实珠心的分离率结果，枝孢属真菌是香榧幼果缓生期和病症显现期的优势菌群。为明确其致病性，本研究采用离体接种法，对5种主要枝孢属真菌(TGZX1、TGZX2、TGZX3、TGZX4、TGZX5)进行科赫法则验证。具体步骤如下：①枝孢属分生孢子悬浮液的制备。分别制备5种枝孢属的代表菌株(TGZX1-1、TGZX2-1、TGZX3-1、TGZX4-1、TGZX5-1)的分生孢子悬浮液。具体方法：刮取PDA平板上培养7 d的菌落，用无菌水悬浮后，经纱布过滤并离心，沉淀用无菌水重悬，最后用血球计数板将比例调整至1×10⁶个·mL⁻¹。同时，将等体积的上述5种悬浮液混合，配制成总孢子比例为1×10⁶个·mL⁻¹的混合孢子悬浮液(MIX，每种孢子的比例为2 × 10⁵个·mL⁻¹)。②采用分生孢子悬浮液进行离体接种。前期观察表明，缓生期(D=−207~−117 d)的果实珠心组织尚未褐变，因此，选取更早期的健康果实(D=−230 d)作为接种对象。采集21个结果枝组(每个枝组约含3簇结果枝)，依次用体积分数为75%乙醇浸泡30 s、质量分数为2%次氯酸钠溶液浸泡5 min进行表面消毒，随后用无菌水冲洗3次，风干备用。③使用1 mL注射器从香榧幼果顶部注入10 μL单一或混合孢子悬浮液，并以注射等量无菌水作为对照(ck)。每个菌种设置3个重复，每个重复包含3个结果枝组(共9个结果枝，108~126个果实)。接种后的结果枝组置于锥形瓶中，在25 ℃恒温培养箱中光暗交替培养并保持湿度。接种7 d后，通过体视荧光显微镜观察珠心组织发病情况。每个处理随机选取15个接种果实，利用ImageJ软件测量疾病面积与珠心组织面积，计算病害严重度=(病斑面积/珠心组织面积)×100%。同时，从典型病斑组织重新分离病原菌，纯化后观察其菌落和孢子形态特征，并与原接种菌株进行比对。

1.2.3. 香榧僵果主要病原菌的鉴定

①形态学鉴定。将纯化后的分离菌株接种在PDA平板上25 ℃黑暗培养7 d，观察菌落特征。在荧光显微镜(OLYMPUS BX53)下观察记录各菌株分生孢子的形态特征，并测量分生孢子大小。按BENSCH等^[11]的方法进行形态鉴定。②分子生物学鉴定。EF-728F(5′-CATCGAGAAGTTCGAGAAGG-3′)/EF-986R (5′-TACTTGAAGGAACCCTTAC-3′)、ACT-512F (5′-ATGTGCAAGGCCGGTTTCGC-3′)/ACT-512R (5′-TACGAGTCCTTCTGGCCCAT-3′)分别扩增菌株的翻译延伸因子 (tef1)和肌动蛋白 (act)基因片段，同时结合ITS rDNA区域(内转录间隔区)^[16−17]。扩增产物送至杭州有康生物技术有限公司进行测序。获得的菌株序列在美国生物技术信息中心(NCBI)的GenBank数据库 (https://www.ncbi.nlm.nih.gov/)中进行比对，将相似性较高的序列和模式菌株以FASTA的格式下载，相关序列见表1。以Cercospora beticola作为外群，使用MEGA 11.0软件对序列进行比对修剪，并使用PhyloSuite v 1.2.3软件对待测菌株和模式菌株ITS、tef1和act的序列进行最大似然法(ML)和贝叶斯推断(BI)系统发育树分析，确定菌株的具体分类地位。

病原菌	菌株	Genbank 登录号
病原菌	菌株	ITS	tef1	act
Cercospora beticola	CBS 116456*	AY840527	AY840494	AY840458
Cladosporium cladosporioides	CBS 101367	HM148002	HM148243	HM148489
Cladosporium cladosporioides	CBS 112388*	HM148003	HM148244	HM148490
Cladosporium cladosporioides	CBS 113738	HM148004	HM148245	HM148491
Cladosporium funiculosum	CBS 122129	HM148094	HM148338	HM148583
Cladosporium funiculosum	CBS 122128*	HM148093	HM148337	HM148582
Cladosporium funiculosum	CPC 22247	MF472980	MF473407	MF473830
Cladosporium guizhouense	GUCC 401.8*	ON334728	ON383470	ON383338
Cladosporium guizhouense	GUCC 21227.4	OP852663	OP859048	OP863100
Cladosporium maltirimosum	SFC20230103-M51*	OQ186147	OQ185155	OQ185195
Cladosporium maltirimosum	SFC20230103-M52	OQ186148	OQ185156	OQ185196
Cladosporium oxysporum	CBS 125991*	HM148118	HM148362	HM148607
Cladosporium pseudocladosporioides	CBS 117134	HM148156	HM148400	HM148645
Cladosporium pseudocladosporioides	CBS 125993*	HM148158	HM148402	HM148647
Cladosporium rectoides	CBS 125994*	HM148193	HM148438	HM148683
Cladosporium rectoides	CBS 126357	HM148194	HM148439	HM148684
Cladosporium scabrellum	CBS 126358*	HM148195	HM148440	HM148685
Cladosporium subuliforme	CBS 126500*	HM148196	HM148441	HM148686
Cladosporium subuliforme	DTO 130-H8	KP701938	KP701815	KP702060
Cladosporium tenuissimum	CBS 125995*	HM148197	HM148442	HM148687
Cladosporium tenuissimum	CBS 262.80	HM148201	HM148446	HM148691
Cladosporium tenuissimum	CPC 14196	HM148218	HM148463	HM148708
Cladosporium varians	CBS 126361	HM148223	HM148469	HM148714
Cladosporium varians	CBS 126362*	HM148224	HM148470	HM148715
说明：*为模式菌株。

Table 1. Strains and gene sequences used for phylogenetic analysis

1.2.4. 病原菌的生物学特性研究

将培养7 d的7 mm病原菌菌饼接种在PDA平板中央，分别置于5、10、15、20、25、30和35 ℃的培养箱中黑暗培养7 d。随后采用十字交叉法使用钢直尺测量菌落直径，并观察病原菌在培养基上的菌落特征。采用相同接种方法将菌饼接种至PDA培养基，分别置于全光照(光照24 h)、光暗交替(光照和黑暗各12 h)和完全黑暗(光照0 h)等3种光照条件下培养7 d (28 ℃)，以分析病原菌的最适光照条件。此外，将菌饼分别接种至PSA、PDA、SNA、OMA和MEA培养基，在25 ℃黑暗条件下培养7 d，通过十字交叉法测量菌落直径，筛选最适病原菌生长的培养基。以察氏培养基为基础培养基，分别用等摩尔碳质量的可溶性淀粉、乳糖、麦芽糖、甘露醇、山梨醇、葡萄糖、蔗糖和果糖替代其中的蔗糖，并用等摩尔氮质量的氯化铵、牛肉浸粉、硫酸铵、硝酸钠、甘氨酸、胰蛋白胨、丙氨酸和酵母提取物替代其中的硝酸钠。同时设置无碳无氮源作为对照，在28 ℃黑暗条件下培养7 d后，采用十字交叉法测量菌落直径并观察菌落特征。

1.3. 数据处理

采用Excel 2021和SPSS 27.0软件进行统计分析。利用PhyloSuite_v1.2.3进行系统发育树分析。图表中数据以平均值±标准误表示，并利用GraphPad Prism 8.0绘图。

3. 讨论

果实的主要病原菌会因不同发育时期而发生改变^{[6, 18]}。本研究结果显示：从缓生期至僵果发病期(D=−207~21 d)，枝孢属始终是香榧幼果珠心中的优势菌属。由于枝孢属真菌种类丰富，且部分种在形态上极其相似，难以分辨，通常需结合分子生物学手段才能确认具体种类^[11−13]。本研究基于act和tef1基因序列构建多基因系统发育树，鉴定出5种枝孢属真菌，包括绳状枝孢菌TGZX1-1、尖孢枝孢菌TGZX2-1、贵州枝孢菌TGZX3-1、极细枝孢菌TGZX4-1和微糙枝孢菌TGZX5-1。其中，贵州枝孢菌TGZX3-1的分离率最高。研究表明：这5种枝孢属真菌可导致多种植物病害，例如，尖孢枝孢菌能引起辣椒Capsicum annuum叶片和果实病斑发霉^[19]及尼泊尔李Prunus nepalensis叶斑病^[20]；贵州枝孢菌可导致蓝莓Eucommia ulmoides幼果发霉腐烂^[21]；极细枝孢菌与绣球Hydrangea macrophylla花叶斑病^[22]和醋栗Physalis pruinosa黑斑病^[23]相关；微糙枝孢菌可引起羊肚菌Morchella importuna子实体腐烂^[24]。为排除外界环境干扰，本研究采用离体接种法测定致病性。结果显示：5类枝孢属真菌代表株及混合株的孢子液均可诱发香榧珠心褐化。其中，接种5种菌株混合孢子液的香榧珠心表现出明显皱缩褐化的表型，与香榧僵果的珠心症状最为相似，表明香榧僵果是由多种枝孢属真菌复合侵染所致。本研究还发现：在漫长的缓生期中，除了枝孢属优势菌外，还分离到其他3个菌属(链格孢属、镰刀菌属和Zasmidium)。研究表明：这些菌属同样具有致病性，如链格孢属菌A. alternata和A. arborescens可引起柑橘Citrus落果^[25]；尖孢镰刀菌Fusarium oxysporum和链格孢菌会导致核桃Juglans regia顶端坏死^[26]；Z. mangiferae则能引发芒果Mangifera indica叶锈病^[27]。本研究仅明确了优势病原菌枝孢属对香榧珠心的致病性，后续研究需进一步验证不同菌属之间是否存在协同互作关系。

枝孢属真菌属于弱寄生菌或腐生菌，需通过自然开口或伤口侵入宿主^{[14, 16]}。本研究结果显示：香榧僵果症状仅表现为内部珠心皱缩褐化，假种皮未见破损病征，表明病害并非由外部侵入，而是从内部开始发病。前人研究表明：在授粉等待期，香榧雌球花的珠心因珠孔裸露而易受枝孢属侵染，导致雌球花黄化、皱缩和脱落^[9]。值得注意的是，本研究中从缓生期香榧幼果珠心分离出的优势菌属(枝孢属)及其他常见菌属(链格孢菌和Zasmidium)，与叶浩杰^[9]在香榧雌球花中分离出的菌属高度相似，表明花期可能是一个重要的共同侵染窗口期。因其珠孔裸露，授粉期可能是珠心受外部病原菌侵染的关键时期，结合僵果珠心具有顶端褐化、皱缩的特征，推测枝孢属菌对香榧僵果的侵染过程可能始于花期，部分病原菌在珠心中长期存活，直至条件适宜时引发症状。这与苹果霉心病相似，其实质是病原菌在花期侵染心室^[7]。此外，戴蓬博^[8]通过绿色荧光蛋白(GFP)标记菌株证实花期受粉时红聚端孢Trichothecium roseum侵染会导致苹果霉心病的发生。本研究已证实枝孢属菌从授粉期至缓生期持续存在于香榧幼果中，这在一定程度上可说明枝孢属真菌侵染具有连续性。后续研究可结合荧光标记菌株进一步明确具体的侵染与潜伏时期。

温度、光照和养分等环境条件对病原菌的侵染具有重要影响^[14−15]，明确病原菌的生物学特性对探索病原菌致病机制具有关键意义^[28]。研究表明：枝孢属真菌对温度响应存在种间差异。例如，尖孢枝孢菌菌丝的最适生长温度为20~25 ℃^[19]，而极细枝孢菌菌丝的适宜生长温度为20 ℃^[29]。本研究结果与之相符，5种枝孢属菌丝的适宜生长温度均为20~25 ℃，3—5月气温的快速上升(12.8~22.4 ℃)为幼果中枝孢属的定殖提供了适宜的环境温度。此外，研究发现光照对TGZX1-1和TGZX2-1菌丝生长无显著影响，而其他3种菌株(TGZX3-1、TGZX5-1和TGZX4-1)在半光照和黑暗条件下的菌丝生长优于全光照条件，表明这5种枝孢属真菌均能在黑暗条件下正常生长，这与香榧珠孔等组织长期被假种皮包被形成的低光照微环境高度契合，进一步解释了病原菌在宿主体内的定殖优势。

碳源和氮源等养分是影响病原菌菌丝生长和侵染能力的关键因素^[30−31]。研究表明：尖孢枝孢菌菌丝生长的最适碳源和氮源分别为山梨醇和麦芽浸膏，以V8果汁为菌丝最适宜生长的培养基^[19]。此外，研究发现极细枝孢菌菌丝生长的最适碳源为葡萄糖和木糖，最适氮源为天门冬素和蛋白胨^[29]。前人研究表明：枝孢属真菌具有丰富的碳水化合物酶和植物细胞壁降解酶，可增强对碳水化合物的降解和利用的能力^[32]。香榧雌球花及果实内部组织均含有丰富的淀粉和葡萄糖等碳水化合物^[33−34]。本研究结果显示：TGZX1-1、TGZX2-1、TGZX3-1、TGZX4-1和TGZX5-1的最适碳源分别为可溶性淀粉、甘露醇、葡萄糖、麦芽糖和麦芽糖，而5种枝孢属真菌的最适氮源均为胰蛋白胨，表明香榧幼果内部组织可为枝孢属真菌提供充足的碳源，从而增强其侵染和定殖能力。

由于香榧雌球花裸露的珠孔在授粉期易受枝孢属真菌侵染，因此，应将传统保果期的防治重心前移至授粉期，未来需评估内吸性杀菌剂或针对枝孢属真菌的生防菌剂在花期的精准防控效果。此外，病原菌适宜在黑暗湿润环境中生长，可通过合理修剪以增强通风透光。

4. 结论

引起香榧僵果病害的病原菌为枝孢属菌，包括绳状枝孢菌、尖孢枝孢菌、贵州枝孢菌、极细枝孢菌和微糙枝孢菌；这些枝孢属真菌的最适宜生长温度为20~25 ℃，能够在黑暗条件下生长，它们的最佳碳源分别为可溶性淀粉、甘露醇、葡萄糖、麦芽糖和麦芽糖，最佳氮源为胰蛋白胨。

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