Page 172 - 《广西植物》2025年第10期
P. 172

1 9 0 2                                广  西  植  物                                         45 卷
                 Abstract: To study the gene abundance of carbohydrate ̄active enzymes (CAZymes) that degrade components from
                 different soil sources (plant and microorganisms) provides certain guidance for assessing the soil carbon storage potential
                 of plantation ecosystems for the response of forests after they are tranformed into broad ̄leaved or mixed coniferous ̄broad ̄
                 leaved plantations. In this studyꎬ metagenomic data of different soil depths (0-20 cmꎬ 20-40 cmꎬ 40-60 cm) of Pinus
                 massoniana forestꎬ Erythrophleum fordii forest and Pinus massoniana × Erythrophleum fordii mixed plantation in south
                 subtropical China were analyzedꎬ and combined with soil physicochemical propertiesꎬ the response of gene abundance of
                 CAZymes involved in degrading plant and microbial components to different stands and different soil depths was
                 investigated. Meanwhileꎬ the main regulatory factors were analyzed. The results were as follows: ( 1) After forest
                 conversionꎬ the gene abundance of CAZymes ( GH116ꎬ GH115ꎬ and AA5) that degraded plant components was
                 significantly increased and was strongly correlated with soil organic carbon (SOC)ꎬ C/ N ratioꎬ and microbial biomass
                 carbon (MBC) content. (2) The significant abundance of GH102 and GH25 genes in Pinus massoniana × Erythrophleum
                 fordii mixed plantations indicated that the ability to degrade microbial components in mixed coniferous ̄broad ̄leaved
                 plantations was stronger compared to the other two stands. The gene abundance of CAZymes that degraded plant and
                 microbial components in soils of the three stands generally decreased with increasing soil depthꎬ primarily due to the
                 significant positive effect of SOC content. (3) With the growth of the three stands to the later stageꎬ the contribution of
                 microbial ̄derived carbon to SOC may gradually exceed that of plant ̄derived carbonꎬ with bacterial ̄derived components
                 contributing the most. Overallꎬ the distribution of CAZymes genes is closely related to SOC content. Compared to pure
                 standsꎬ Pinus massoniana × Erythrophleum fordii mixed plantations show significant advantages in the gene abundance of
                 GH102 and GH25ꎬ potentially indicating higher carbon storage potential. The research results have certain guiding
                 significance for assessing the soil carbon storage pitential of plantations.
                 Key words: carbohydrate ̄active enzymes (CAZymes)ꎬ metagenomic sequencingꎬ carbon storageꎬ mixed coniferous ̄
                 broad ̄leaved plantationꎬ soil organic carbon



                碳水化合物是自然界广泛存在的重要有机物ꎬ                           首要任务ꎮ 随着高通量测序技术飞速发展ꎬ基于
            也是生物体的主要能量来源(Upadhyaya & Dubbuꎬ                    宏基因组学分析碳水化合物降解等方面的研究日
            2024)ꎬ依其复杂度可分为单糖、双糖、寡糖及多糖                          渐成熟ꎬ通过对碳水化合物活性酶( carbohydrate ̄
            (Dedhia et al.ꎬ 2022)ꎬ这些碳水化合物及其衍生物                 active enzymesꎬ CAZymes) 注释能够解析微生物碳
            共同构成全球碳库(Zaher et al.ꎬ 2020)ꎮ 土壤是一                 代谢过程ꎬ为碳资源利用及碳减排方案的实施提
            个巨 大 的 陆 地 碳 库ꎬ 土 壤 有 机 碳 ( soil organic           供理 论 支 撑 ( 刘 洋 荧 等ꎬ 2017 )ꎮ 目 前ꎬ 有 关
            carbonꎬSOC)储存量最多ꎬ对全球生态系统至关重                        CAZymes 基因的研究已逐渐成为科研热点ꎮ 孙翠
            要(郑发辉等ꎬ2024)ꎮ 土壤 SOC 源自植物凋落物、                      慈等(2023) 研究发现海洋沉积物 CAZymes 基因
            根茎沉积物及微生物坏死物质(Lehmann & Kleberꎬ                    组成与上层水体有机颗粒的沉降及水深相关ꎻ王
            2015)ꎬ其中植物生物质主要由纤维素、半纤维素和                          倩等(2023)研究发现免耕和秋翻处理比常规耕作
            木质素组成(Cotrufo et al.ꎬ 2013ꎻ López ̄Mondéjar et      更能提高 CAZymes 基因丰度ꎬ并通过影响土壤理
            al.ꎬ 2018)ꎬ而活微生物的生物量ꎬ如肽聚糖、几丁质                      化性质(如 SOC、土壤含水量等) 调节其组成以增
            等ꎬ构成另一个重要有机碳源(Ma et al.ꎬ 2018)ꎮ 近                  强土壤固碳潜力ꎮ 然而ꎬ当前有关 CAZymes 基因
            年提出的土壤微生物碳泵( microbial carbon pumpꎬ                的研究大多集中于海洋和农田ꎬ对人工林不同土
            MCP)概念强调微生物同化产物在稳定有机碳库中                            壤深度的 CAZymes 基因分布尚不明确ꎮ
            的重要贡献ꎮ 因此ꎬ微生物分解碳水化合物是土壤                                在我国森林资源中ꎬ人工林面积逐年扩大ꎬ占
            SOC 形成的关键ꎬ关乎碳储存与排放ꎬ对碳平衡至                           比超原始森林ꎬ面积居世界第一ꎬ这对碳循环至关
            关重要(Wu et al.ꎬ 2024)ꎮ                              重 要 ( 刘 世 荣 等ꎬ 2018 )ꎮ 马 尾 松 ( Pinus
                 气候变暖是人类当前面临的严峻挑战之一ꎮ                           massonianaꎬPM) 是南亚热带常见针叶造林树种ꎬ
            减排增汇是减缓气候变化、实现长期“ 碳中和” 的                           适应性强、生长迅速ꎬ具有较强的碳汇能力ꎬ尤其
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