Coordination of spring vascular and organ phenology in deciduous angiosperms growing in seasonally cold climates

Abstract

In seasonally cold climates, many woody plants tolerate chilling and freezing temperatures by ceasing growth, shedding leaves and entering dormancy. At the same time, transport within these plants often decreases as the vascular system exhibits reduced functionality. As spring growth requires water and nutrients, we ask the question: how much does bud, leaf and flower development depend on the vasculature in spring? In this review, we present what is known about leaf, flower and vascular phenology to sort out this question. In early stages of bud development, buds rely on internal resources and do not appear to require vascular support. The situation changes during organ expansion, after leaves and flowers reconnect to the stem vascular system. However, there are major gaps in our understanding of the timing of vascular development, especially regarding the phloem, as well as the synchronization among leaves, flowers, stem and root vasculature. We believe these gaps are mainly the outcome of research completed in silo and urge future work to take a more integrative approach. We highlight current challenges and propose future directions to make rapid progress on this important topic in upcoming years.

ABA and Bud Dormancy in Perennials: Current Knowledge and Future Perspective

“…During the stage of winter rest, there are many metabolic and developmental activities happening in the dormant buds including respiration, photosynthesis, slow cell division, enzyme synthesis, production of growth stimulators, and dissipation of growth inhibitors. In buds, callose disrupts the symplastic pathway in all vascular cells, including sieve elements, by blocking the plasmodesmata, resulting in decreased flow of water, nutrients and other molecules in buds [23]. Phytohormones including abscisic acid (ABA), gibberellin (GA), ethylene (ET), auxin and cytokinins (CKs) are involved in bud dormancy, of which ABA plays an essential role in this process [24].…”

“…For many deciduous plants, e.g., Malus pumila, the growth cassation occurs in summer, with long photoperiod and high temperature, while the endodormancy happens in autumn, during SD and low temperature [49]. In most deciduous angiosperms, bud dormancy is followed by blockage of vessels with accumulated callose, which results in decreased metabolic function and transport between buds and branches [23]. In autumn, short-term cold exposure increases endogenous ABA content in perennial buds by CBF, which binds and activates DAM/SVL transcription, thus increasing ABA levels and inducing bud endodormancy [50,51].…”

“…After exposure to chilling temperatures, there is an increase in cell connectivity in buds when endodormancy is releasing [23]. Many studies have shown that long terms of cold treatment decrease ABA content by inhibiting ABA biosynthesis while activating ABA catabolism in dormant organs, including tree's buds and geophytes, like poplar, pear, Gladiolus hybridus and Leafy spurge [21,29,34,53].…”

Changes in ploidy affect vascular allometry and hydraulic function in Mangifera indica trees

“…Hydraulically conductive cells (tube elements of the xylem or the phloem) vary in size spatially (in an organ‐dependent fashion), and temporally (during ontogeny), in a manner thought to integrate plant growth and adaptation to environmental conditions. This is particularly relevant in woody plants, which exhibit long lifespans, seasonally renovating conduits for maintaining long‐distance hydraulic transport (Savage, 2019; Savage and Chuine, 2021). Largely, the anatomy and hydraulics of the aerial organs have been studied in isolation, limiting our understanding of the continuous transport of water and photoassimilates in woody angiosperms.…”

Changes In Ploidy Affect Vascular Allometry And Hydraulic Function In Trees

“…Hydraulically conductive cells (tube elements of the xylem or the phloem) vary in size spatially (in an organ dependent fashion), and temporally (during ontogeny), in a manner thought to integrate plant growth and adaptation to environmental conditions. This is particularly relevant in woody plants, which exhibit long life spans, seasonally renovating conduits for maintaining long distance hydraulic transport (Savage, 2019;Savage & Chuine, 2021). Largely, the anatomy and hydraulics of the aerial organs have been studied in isolation, limiting our understanding of the continuous water and photoassimilate transport in woody angiosperms.…”