INVESTIGATION OF MORPHOLOGICAL, PHYSIOLOGICAL, AND MOLECULAR MARKERS OF SENESCENCE IN PINE TREES (PINUS SYLVESTRIS) FROM THE NATIONAL PARK OF BURABAY REGION

Abstract

Senescence, or aging happens in all living organisms, including long-lived trees like Pinus sylvestris. These trees are especially interesting for studying aging because they live for such a long time, offering a unique window into how aging process over decades or even centuries. Knowing how tree aging works is also important for forest management, especially in Kazakhstan, where conservation and wildfire risks are big concerns. In this research, Pinus sylvestris trees growing in Burabay National Park were studied. The work was focused on four age groups and looked at aging through three areas: morphology, physiology, and molecular biology. When it came to morphological markers like height, trunk diameter, and needle length, some clear changes among the age groups were observed. Older trees typically had thicker, longer trunks and longer needles, although there was a lot of variation, probably due to environmental factors. On the physiological side, such markers as, chlorophyll content, relative water content (RWC), reactive oxygen species (ROS), and chemical elements content were measured. Chlorophyll levels dropped in older trees, which likely means their ability to photosynthesize is reduced. Heavy metal analysis using ICP-MS (iCAP RQ Inductively Coupled Plasma Mass Spectrometer) revealed that younger trees had higher levels of Potassium (K), while middle age trees have high Aluminum (Al) concentration. On the other hand, RWC measurement showed no changes across the age groups, as well as ROS level. However, there were found correlations between these markers and bio-climatic variables, as annual temperature and precipitations rate. For the molecular part, gene expression in meristem tissues using RT-qPCR (Quantitative Reverse Transcriptase Polymerase Chain Reaction) was analyzed. The study was focused on putative senescence genes, as PsORE1 (Osenescence-Related Gene 1) and PsHSP90 (Heat Shock Protein 90). PsHSP90, which is involved in stress responses, was clearly actively expressed in over 100 years old trees, while PsORE1 expression showed no differences across distinct age groups. Overall, this study identified several potential indicators of aging in Pinus sylvestris in Burabay Region. By looking at changes in morphological, physiological markers, and gene expression, the "senescence passport" can be built to understand aging in pines. This may be helpful for managing forests and decreasing fire risk, especially in Kazakhstan where ecosystems are vulnerable and long-term planning is essential.