The pressing global issue of food insecurity due to population growth, diminishing land and variable climate can only be addressed in agriculture by improving both maximum crop yield potential and resilience. Genetic modification is one potential solution, but has yet to achieve worldwide acceptance, particularly for crops such as wheat. Trehalose-6-phosphate (T6P), a central sugar signal in plants, regulates sucrose use and allocation, underpinning crop growth and development. Here we show that application of a chemical intervention strategy directly modulates T6P levels in planta. Plant-permeable analogues of T6P were designed and constructed based on a 'signalling-precursor' concept for permeability, ready uptake and sunlight-triggered release of T6P in planta. We show that chemical intervention in a potent sugar signal increases grain yield, whereas application to vegetative tissue improves recovery and resurrection from drought. This technology offers a means to combine increases in yield with crop stress resilience. Given the generality of the T6P pathway in plants and other small-molecule signals in biology, these studies suggest that suitable synthetic exogenous small-molecule signal precursors can be used to directly enhance plant performance and perhaps other organism function.

One sentence summary: T6P can be targeted through genetic and chemical methods for crop yield 10 improvements in different environments through the effect of T6P on carbon allocation and 11 biosynthetic pathways 12Significant increases in global food security require improving crop yields in favourable and 13 poor conditions alike. However, it is challenging to increase both the crop yield potential and yield 14 resilience simultaneously, since the mechanisms that determine productivity and stress tolerance are 15 typically inversely related. Carbon allocation and use may be amenable to improving yields in a range 16 of conditions. The interaction between trehalose 6-phosphate (T6P) and SnRK1 (SNF1-related/AMPK 17 protein kinases) significantly affects the regulation of carbon allocation and utilisation in plants. 18Targeting T6P appropriately to certain cell types, tissue types, and developmental stages results in an 31 SUCROSE AND TREHALOSE: THE YIN AND YANG OF CROP IMPROVEMENT 32Plants are the only organisms that synthesise both non-reducing disaccharides, trehalose and 33 sucrose. The ubiquity of both pathways in plants has been known for less than 20 years and was a 34 major revelation for those working on carbon metabolism, as well as plant scientists in general, given 35 the range of processes affected by the trehalose pathway. Plant metabolism is highly regulated. Part 36 of this regulation is through trehalose 6-phosphate (T6P) signalling that regulates metabolism in the 37 light of carbon availability and reprograms metabolism between anabolic or catabolic pathways 38 depending on the carbohydrate status of the plant. This discovery is also significant for understanding 39 the regulation of growth and development by carbon supply. Furthermore, the trehalose pathway may 40 widely impact crop improvement. Crops are not yet optimised to maximize their biosynthetic pathways 41 for yield in sinks and growth recovery that are promoted by high T6P, and for mobilisation of reserves 42 and sugar transport which can enable resilience that are promoted by low T6P. 43Both the trehalose and sucrose biosynthesis pathways draw from a pool of core metabolites, 44 from which the carbon skeletons for all cellular components are also made (Paul et al. 2008 procedures to measure the abundance of T6P and trehalose (Lunn et al. 2006; Carillo et al. 2013; 51 Delatte et al. 2009;Mata et al. 2016). The capacity to synthesise trehalose in 52 plants began to become apparent as the associated plant genes were identified (Blazquez et al. 1998; 53 Vogel et al. 1998). Subsequent publication of the Arabidopsis genome showed an abundance of both 54 trehalose phosphate synthase (TPS) and trehalose phosphate phosphatase (TPP) gene families with 55 11 and 10 members respectively (Leyman et al. 2001). 56It is likely that T6P is a specific signal indicating sucrose abundance (Lunn et al. 2006; Nunes 57 et al. 2013a). T6P and sucrose levels are correlated in many tissues e.g. Arabidopsis and wheat 72TPSs have yet to be resolve...

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Little is known about how salt impacts primary metabolic pathways of C 4 plants, particularly related to kernel development and seed set. Osmotic stress was applied to maize (Zea mays) B73 by irrigation with increasing concentrations of NaCl from the initiation of floral organs until 3 d after pollination. At silking, photosynthesis was reduced to only 2% of control plants. Salt treatment was found to reduce spikelet growth, silk growth, and kernel set. Osmotic stress resulted in higher concentrations of sucrose (Suc) and hexose sugars in leaf, cob, and kernels at silking, pollination, and 3 d after pollination. Citric acid cycle intermediates were lower in salt-treated tissues, indicating that these sugars were unavailable for use in respiration. The sugar-signaling metabolite trehalose-6-phosphate was elevated in leaf, cob, and kernels at silking as a consequence of salt treatment but decreased thereafter even as Suc levels continued to rise. Interestingly, the transcripts of trehalose pathway genes were most affected by salt treatment in leaf tissue. On the other hand, transcripts of the SUCROSE NONFERMENTING-RELATED KINASE1 (SnRK1) marker genes were most affected in reproductive tissue. Overall, both source and sink strength are reduced by salt, and the data indicate that trehalose-6-phosphate and SnRK1 may have different roles in source and sink tissues. Kernel abortion resulting from osmotic stress is not from a lack of carbohydrate reserves but from the inability to utilize these energy reserves.