Molecular Components that Drive Phosphorus‐Remobilisation during Leaf Senescence

Abstract

Senescence is a complex process of controlled degradation and nutrient recycling that is modulated by developmental and environmental cues. Beginning in the middle to late vegetative stage of growth, the remobilisation of phosphorus (P) from senescing leaves serves as the major source of P for sink tissues, such as young leaves, reproductive structures and storage organs. Although it is clear that plants are generally efficient at recycling P from senescing leaves, little is known regarding the molecular components involved in the process. Optimising P remobilisation during senescence will likely be a valuable contribution to future improvements in P‐use efficiency of crop species, which is urgently needed to minimise the use of unsustainable P fertilizers.

Seasonal Shifts in Bacterial and Fungal Microbiomes of Leaves and Associated Leaf-Mining Larvae Reveal Persistence of Core Taxa Regardless of Diet

“…For both bacterial and fungal components of the leaves, the composition of the April samples was the most distinct from the other time points, especially with respect to the bacterial component. Young leaves differ fundamentally from older ones with regard to general leaf traits, such as nutrients and chemistry ( 41 – 43 ). Leaf traits ( 26 , 47 ), environmental variables (i.e., climate), and changes in the local inoculum pool, combined with the host plant filtering, are fundamental drivers of leaf-associated communities ( 25 , 34 , 39 , 48 , 49 ), underlying the observed differences.…”

“…We investigated the factors determining the richness and composition of their microbiomes, with an emphasis on seasonal variation. Specifically, we expected changes in the composition and richness of the leaf microbiome resulting from the changes in leaf quality and plant secondary metabolites during senescence ( 41 – 43 ), as well as microbial community succession ( 30 ). Because the diet and host physiological environment predominantly shape the microbiomes of free-feeding caterpillars ( 44 – 46 ), we also expected changes in larval microbiota.…”

Potassium and Phosphorus Fertilizer Impacts on Alfalfa Taproot Carbon and Nitrogen Reserve Accumulation and Use During Fall Acclimation and Initial Growth in Spring

“…Ribosomal RNA contains approximately 50% of total cell P in vegetative tissues of plants, which is a far greater proportion than P accumulated in the inorganic-and phytate-P pools in alfalfa taproots (Campbell et al, 1991;Raven, 2012). In addition, specific RNAases are induced under P-limited conditions that are thought to liberate P from RNA that is subsequently mobilized to growing tissues (Bariola et al, 1994;Smith et al, 2018). Because we only quantified RNA in Year 2, additional research is needed to clarify the taproot P pools (inorganic P, phytate, RNA, and others) involved in providing P to regrowing alfalfa shoots.…”

Intracellular phosphate recycling systems for survival during phosphate starvation in plants

“…These facts, plus the following facts lead us to hypothesize that these RNases degrade apoplastic RNA and salvage Pi from apoplast under Pi starvation. First, most class I RNases are secreted to out of the cell ( Köck et al., 1995 ; Bariola et al., 1999 ; Smith et al., 2018 ). Also, Arabidopsis apoplastic fluid contains small RNAs and long noncoding RNAs, including circular RNAs ( Zand Karimi et al., 2022 ).…”