Leaf senescence and nutrient remobilisation in barley and wheat

Abstract

Extensive studies have been undertaken on senescence processes in barley and wheat and their importance for the nitrogen use efficiency of these crop plants. During the senescence processes, proteins are degraded and nutrients are re‐mobilised from senescing leaves to other organs, especially the developing grain. Most of the proteins degraded reside in the chloroplasts, with Rubisco constituting the most dominant protein fraction. Despite intensive studies, the proteases responsible for Rubisco degradation have not yet been identified. Evidence for degradation of stromal proteins outside of chloroplasts is summarised. Rubisco is thought to be released from chloroplasts into vesicles containing stroma material (RCB = Rubisco‐containing bodies). These vesicles may then take different routes for their degradation. Transcriptome analyses on barley and wheat senescence have identified genes involved in degradative, metabolic and regulatory processes that could be used in future strategies aimed at modifying the senescence process. The breeding of crops for characters related to senescence processes, e.g. higher yields and better nutrient use efficiency, is complex. Such breeding has to cope with the dilemma that delayed senescence, which could lead to higher yields, is correlated with a decrease in nutrient use efficiency. Pinpointing regulatory genes involved in senescence might lead to tools that could effectively overcome this dilemma.

Mapping QTL for stay-green and agronomic traits in wheat under diverse water regimes

“…Although there are many reports on stay-green (Gregersen et al 2008;Verma et al 2004;Xie et al 2016;Pinto et al 2016;Montazeaud et al 2016), the underlying genetic mechanisms of stay-green and the relationship between stay-green and agronomic traits are not well understood. This might be due to fewer known genes and QTL.…”

Overexpression of a NAC transcription factor delays leaf senescence and increases grain nitrogen concentration in wheat

“…2008). The proportion of grain N in wheat that originates from remobilisation of N taken up before anthesis is estimated as >70% (Kichey et al .…”

PvNAC1 and PvNAC2 Are Associated with Leaf Senescence and Nitrogen Use Efficiency in Switchgrass

“…For annual plants including many crop species, leaf senescence mobilizes nutrients for seed production. Small-grain cereals like rice, wheat, and barley mobilize up to 90 % of the nitrogen in vegetative organs to the grain [9,10]. In perennial grasses like switchgrass, nutrients in leaves are remobilized during yearly senescence not only to the inflorescence for seed production but also to the root system for storage and later reuse.…”