Heartwood formation progresses basipetally over years or decades in each conically shaped annual growth layer of Cryptomeria japonica stems

Nagai, Satoshi; Yazaki, K.; Utsumi, Yasuhiro

doi:10.1007/s00468-022-02333-w

Cited by 1 publication

(2 citation statements)

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“…Previous studies have shown that PCD initiation of xylem ray parenchyma cells may occur due to their aging [25,26] and/or this process may be influenced by their position relative to the cambial zone [27,28]. Nagai et al, in their study using the example of Cryptomeria japonica, showed that the aging of xylem ray parenchyma cells is not directly related to their death and heartwood formation, since it was shown that the number of sapwood growth rings decreased with the trunk height, i.e., radial parenchyma cells formed by the younger cambium undergo PCD earlier compared to cells formed by the older cambium [28]. Our study also showed a decrease in the number of sapwood rings with the increasing trunk height, while the percentage of heartwood in the total trunk area did not change with height (Figure 1B).…”

Section: Cambial Age and Pcd Of Xylem Ray Parenchyma Cellsmentioning

confidence: 99%

“…Measuring the radial distance from the heartwood boundary to the cambial zone also did not show significant differences in this indicator by height (Figure 1C), i.e., PCD initiation in xylem ray parenchyma cells in the trunk section with older and younger cambium occurred at approximately the same distance from the cambial zone. Nagai et al concluded that the death of xylem ray parenchyma cells at a certain distance from the cambial zone may be caused by a lack of oxygen in the inner sapwood [28].…”

Section: Cambial Age and Pcd Of Xylem Ray Parenchyma Cellsmentioning

confidence: 99%

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Cambial Age Influences PCD Gene Expression during Xylem Development and Heartwood Formation

Moshchenskaya,

Galibina,

Tarelkina

et al. 2023

Plants

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Heartwood formation is an important ontogenetic stage in Scots pine (Pinus sylvestris L.). The amount of heartwood determines the proportion of functionally active sapwood in the total trunk biomass as well as the quality of wood. The key criterion for heartwood formation is the death of xylem ray parenchyma cells. Previously, models that described the patterns of heartwood formation, depending on the cambial age, were derived from Scots pine trees of different ages. The cambial age is the number of annual xylem layers at the core sampling site at a certain trunk height. We studied the features of the occurrence of programmed cell death (PCD) processes during the xylem differentiation and heartwood formation of 80-year-old Scots pine trees, depending on the cambial age, under the lingonberry pine forest conditions in the transition area of the northern taiga subzone and tundra. We have shown that the distance from the cambial zone to the heartwood boundary does not change significantly with stem height. As the cambial age increases, the lifespan of the formed xylem ray parenchyma cells increases and the activity of PCD genes decreases during the formation of both (1) xylem (in the outer layers of sapwood) and (2) heartwood (in the inner layers of sapwood and transition zone). We hypothesized that the decisive factor in the PCD initiation during heartwood formation is the distance of the xylem ray parenchyma cells from the cambial zone. The younger cambium forms wider annual increments, and therefore the xylem ray parenchyma cells in these parts of the trunk reach the distance from the cambial zone earlier, which is necessary for PCD initiation.

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