Expression of trehalose-6-phosphate phosphatase in maize ears improves yield in well-watered and drought conditions

Abstract

Maize, the highest-yielding cereal crop worldwide, is particularly susceptible to drought during its 2- to 3-week flowering period. Many genetic engineering strategies for drought tolerance impinge on plant development, reduce maximum yield potential or do not translate from laboratory conditions to the field. We overexpressed a gene encoding a rice trehalose-6-phosphate phosphatase (TPP) in developing maize ears using a floral promoter. This reduced the concentration of trehalose-6-phosphate (T6P), a sugar signal that regulates growth and development, and increased the concentration of sucrose in ear spikelets. Overexpression of TPP increased both kernel set and harvest index. Field data at several sites and over multiple seasons showed that the engineered trait improved yields from 9% to 49% under non-drought or mild drought conditions, and from 31% to 123% under more severe drought conditions, relative to yields from nontransgenic controls.

A Tale of Two Sugars: Trehalose 6-Phosphate and Sucrose

“…Tre6P levels were decreased by about half in the ear spikelets under both drought stressed and nonstressed conditions, while Suc was increased under nonstressed conditions. In a commentary on the work of Nuccio et al (2015), the simultaneous increase in Suc and decrease in Tre6P, presumably signaling low Suc, was considered to be puzzling (Guan and Koch, 2015). However, these reciprocal changes are exactly what would be predicted from the Suc-Tre6P nexus model, i.e.…”

“…This landmark example of how to improve stress tolerance in a major crop species, with no yield penalty under nonstressed conditions, highlights both the potential of engineering trehalose metabolism for crop improvement and the likely need for spatio-temporally targeted interventions for a successful outcome (Nuccio et al, 2015). It also throws a spotlight on TPP.…”

“…Recently, expression of a rice TPP in developing maize ears was shown to improve yields under wellwatered as well as drought conditions by preventing kernel abortion (Nuccio et al, 2015). The rice OsTPP1 gene was expressed under the control of the rice OsMADS6 gene promoter.…”

The Energy-Signaling Hub SnRK1 Is Important for Sucrose-Induced Hypocotyl Elongation

“…Therefore, it has been suggested that control of KIN10/11 by [Tre6P] may prime the regulation of growth-related genes to capitalize upon increased energy availability, rather than by inducing growth directly (Nunes et al, 2013a(Nunes et al, , 2013b. Remarkably, the impact of this pathway is sufficiently global that its manipulation can increase maize (Zea mays) yields by almost 50% (Nuccio et al, 2015) and increase the yield and drought tolerance of wheat (Triticum aestivum; Griffiths et al, 2016).…”

The Dynamic Plant: Capture, Transformation, and Management of Energy

“…Already, spatial regulation of T6P metabolism has been shown to improve the allocation of leaf photosynthate to developing kernels of maize (Zea mays) in varied environments (Nuccio et al, 2015). Advances based on computational modeling, precision monitoring, genotype characterization, gene manipulation, and metabolic engineering will accelerate progress toward these goals.…”