Field-grown ictB tobacco transformants show no difference in photosynthetic efficiency for biomass relative to the wild type

Abstract

In this study, four tobacco transformants with the overexpression of inorganic carbon transporter B (ictB) were screened for photosynthetic performance relative to wild-type (WT) in field-based conditions. The WT and transgenic tobacco plants were evaluated for photosynthetic performance to determine the maximum rate of carboxylation (Vc,max), maximum rate of electron transport (Jmax), the photosynthetic compensation point (Γ*), quantum yield of photosystem II (ΦPSII), and mesophyll conductance (gm). Additionally, all plants were harvested to compare differences in above-ground biomass. Overall, transformants did not perform better than WT on photosynthesis, biomass, and leaf composition related traits. This is in contrast to previous studies that have suggested significant increases in photosynthesis and yield with the overexpression of ictB, although not widely evaluated under field conditions. These findings suggest that the benefit of ictB is not universal and may only be seen under certain growth conditions. While there is certainly still potential benefit to utilizing ictB in the future, further effort must be concentrated on understanding the underlying function of the gene and in which environmental conditions it offers the greatest benefit to crop performance. As of now, it is possible that ictB overexpression may be largely favorable in controlled environments, such as greenhouses.

Genomics and phenomics enabled prebreeding improved early-season chilling tolerance in Sorghum

“…1a and 6b ), to replicate relevant spatial and temporal stress variation endured in target environments, addressed the possible failure of controlled conditions genetics translating to TPE in previous studies ( Simmons et al . 2021 ; Ruiz-Vera et al . 2022 ).…”

Genomics and Phenomics Enabled Prebreeding Improved Early-Season Chilling Tolerance in Sorghum

“…Despite profound knowledge on the genetic architecture of complex traits, limited success stories exist on molecular breeding for complex traits due to the failure of genetics under controlled conditions translating to target population of environments (TPE), weak trait-to-marker associations, and the functioning of markers and QTL in diverse breeding programs (Blum, 2014; Cobb et al, 2018; Simmons et al, 2021; Ruiz-Vera et al, 2022). This sorghum chilling tolerance presents a case study demonstrating the utilization of genome-to-phenome approaches for complex trait improvement (Figures 6a and 6b).…”

“…This sorghum chilling tolerance presents a case study demonstrating the utilization of genome-to-phenome approaches for complex trait improvement (Figures 6a and 6b). Conducting sorghum CT research in natural chilling stress field trials (Figures 1a and 6b), to replicate relevant spatial and temporal stress variation endured in target environments, addressed the possible failure of controlled conditions genetics translating to TPE in previous studies (Simmons et al, 2021; Ruiz-Vera et al, 2022).…”

The Dynamic Assimilation Technique measures photosynthetic CO2 response curves with similar fidelity to steady-state approaches in half the time

“…For example, the CO 2 concentration is increased to saturating CO 2 concentration and then decreased to the low CO 2 concentration or, alternatively, CO 2 concentration is first decreased to low CO 2 concentration and then increased to saturating CO 2 concentration (split down–up) (e.g. Ainsworth et al , 2002 ; Long and Bernacchi, 2003 ; Manter and Kerrigan, 2004 ; Smith and Dukes, 2017 ; Dusenge et al , 2020 ; Ruiz-Vera et al , 2022 ). In other split protocols, the CO 2 concentration is then decreased or increased back to ambient CO 2 levels ( Walker et al , 2013 , 2016 ).…”