Laboratory of Plant Physiology, Wageningen University and Research, Wageningen, The Netherlands.
Business Unit Bioscience, Wageningen University & Research, Wageningen, The Netherlands.
Physiol Plant. 2023 Nov-Dec;175(6):e14109. doi: 10.1111/ppl.14109.
Vegetative desiccation tolerance (VDT), the ability of such tissues to survive the near complete loss of cellular water, is a rare but polyphyletic phenotype. It is a complex multifactorial trait, typified by universal (core) factors but with many and varied adaptations due to plant architecture, biochemistry and biotic/abiotic dynamics of particular ecological niches. The ability to enter into a quiescent biophysically stable state is what ultimately determines desiccation tolerance. Thus, understanding the metabolomic complement of plants with VDT gives insight into the nature of survival as well as evolutionary aspects of VDT. In this study, we measured the soluble carbohydrate profiles and the polar, TMS-derivatisable metabolomes of 7 phylogenetically diverse species with VDT, in contrast with two desiccation sensitive (DS) species, under conditions of full hydration, severe water deficit stress, and desiccation. Our study confirmed the existence of core mechanisms of VDT systems associated with either constitutively abundant trehalose or the accumulation of raffinose family oligosaccharides and sucrose, with threshold ratios conditioned by other features of the metabolome. DS systems did not meet these ratios. Considerable chemical variations among VDT species suggest that co-occurring but distinct stresses (e.g., photooxidative stress) are dealt with using different chemical regimes. Furthermore, differences in the timing of metabolic shifts suggest there is not a single "desiccation programme" but that subprocesses are coordinated differently at different drying phases. There are likely to be constraints on the composition of a viable dry state and how different adaptive strategies interact with the biophysical constraints of VDT.
营养性脱水耐性（VDT），即这些组织在几乎完全失去细胞水分的情况下存活的能力，是一种罕见但多系的表型。它是一种复杂的多因素性状，以普遍存在的（核心）因素为特征，但由于植物结构、生物化学和特定生态位的生物/非生物动态，存在许多不同的适应性。能够进入休眠的生物物理稳定状态是决定脱水耐性的最终因素。因此，了解具有 VDT 的植物的代谢组学特征可以深入了解生存的本质以及 VDT 的进化方面。在这项研究中，我们测量了 7 种具有 VDT 的具有不同系统发育的物种的可溶性碳水化合物谱和极性、TMS 衍生代谢组学，以及 2 种脱水敏感（DS）物种，在充分水合、严重水分胁迫和脱水的条件下。我们的研究证实了与组成型丰富的海藻糖或 raffinose 家族寡糖和蔗糖积累相关的 VDT 系统的核心机制的存在，这些机制受到代谢组其他特征的条件限制。DS 系统不符合这些比例。VDT 物种之间存在相当大的化学变化表明，同时存在但不同的胁迫（例如，光氧化胁迫）使用不同的化学体系来处理。此外，代谢变化的时间差异表明，不存在单一的“脱水程序”，而是不同的干燥阶段以不同的方式协调亚过程。可能存在可行的干燥状态的组成限制以及不同的适应策略如何与 VDT 的生物物理限制相互作用。
