Griffin Kevin L, Anderson O Roger, Tissue David T, Turnbull Matthew H, Whitehead David
Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.
Tree Physiol. 2004 Mar;24(3):347-53. doi: 10.1093/treephys/24.3.347.
Within-leaf variations in cell size, mitochondrial numbers and dark respiration rates were compared in the most recently expanded tip, the mid-section and base of needles of Pinus radiata D. Don trees grown for 4 years in open-top chambers at ambient (36 Pa) or elevated (65 Pa) carbon dioxide partial pressure (p(CO2)a). Mitochondrial numbers and respiratory activity varied along the length of the needle, with the highest number of mitochondria per unit cytoplasm and the highest rate of respiration per unit leaf area at the base of the needle. Regardless of the location of the cells (tip, middle or basal sections), needles collected from trees grown in elevated p(CO2)a had nearly twice the number of mitochondria per unit cytoplasm as those grown in ambient p(CO2)a. This stimulation of mitochondrial density by growth at elevated p(CO2)a was greater at the tip of the needle (2.7 times more mitochondria than in needles grown in ambient CO2) than at the base of the needle (1.7 times). The mean size of individual mitochondria was unaffected either by growth at elevated p(CO2)a or by position along the needle. Tree growth at elevated p(CO2)a had a variable effect on respiration per unit leaf area, significantly increasing respiration in the tip of the needles (+25%) and decreasing respiration at the mid-section and base of the needles (-14% and -25%, respectively). Although a simple relationship between respiration per unit leaf area and mitochondrial number per unit cytoplasm was found within each CO2 treatment, the variable effect of growth at elevated p(CO2)a on respiration along the length of the needles indicates that a more complex relationship must determine the association between structure and function in these needles.
对辐射松(Pinus radiata D. Don)树在开顶式气室中于环境二氧化碳分压(36帕)或升高的二氧化碳分压(65帕)下生长4年后,其针叶的最顶端、中部和基部的细胞大小、线粒体数量及暗呼吸速率的叶内变化进行了比较。线粒体数量和呼吸活性沿针叶长度变化,单位细胞质中线粒体数量最多以及单位叶面积呼吸速率最高的部位在针叶基部。无论细胞位于何处(顶端、中部或基部),从生长在升高的二氧化碳分压环境中的树木上采集的针叶,其单位细胞质中线粒体数量几乎是生长在环境二氧化碳分压下的两倍。在升高的二氧化碳分压环境中生长对线粒体密度的这种刺激作用,在针叶顶端(比生长在环境二氧化碳中的针叶线粒体多2.7倍)比在针叶基部(多1.7倍)更大。单个线粒体的平均大小不受升高的二氧化碳分压环境下生长的影响,也不受沿针叶位置的影响。在升高的二氧化碳分压环境中树木生长对单位叶面积呼吸有不同影响,显著增加了针叶顶端的呼吸(+25%),而降低了针叶中部和基部的呼吸(分别为-14%和-25%)。尽管在每种二氧化碳处理中发现单位叶面积呼吸与单位细胞质中线粒体数量之间存在简单关系,但在升高的二氧化碳分压环境中生长对沿针叶长度呼吸的不同影响表明,必定存在更复杂的关系来决定这些针叶中结构与功能之间的关联。