Trait components of whole plant water use efficiency are defined by unique, environmentally responsive genetic signatures in the model C₄grassSetaria

Abstract

One sentence summary: Regulation of plant growth can be partitioned into water 15 dependent and water independent processes controlled by unique genetic 16 components. 17 18 ABSTRACT 19Plant growth and water use are interrelated processes influenced by the 20 genetic control of both plant morphological and biochemical characteristics. 21Improving plant water use efficiency (WUE) to sustain growth in different 22 environments is an important breeding objective that can improve crop yields and 23 enhance agricultural sustainability. However, genetic improvements of WUE using 24 traditional methods have proven difficult due to low throughput and environmental 25 heterogeneity encountered in field settings. To overcome these limitations the study 26 presented here utilizes a high-throughput phenotyping platform to quantify plant 27 size and water use of an interspecific Setaria italica x Setaria viridis recombinant 28 inbred line population at daily intervals in both well-watered and water-limited 29 conditions. Our findings indicate that measurements of plant size and water use in 30 this system are strongly correlated; therefore, a linear modeling approach was used 31 . CC-BY-ND 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.

A genetic link between whole-plant water use efficiency and leaf carbon isotope composition in the C4 grass Setaria

“…Bellwether Foundation Phenotyping Facility at the Danforth Center(Feldman et al, 221 2017;Feldman et al, 2018). After two days, the potting medium in the water-limited222 treatment was not watered until water content dropped to 40 % PC, at which point 223 watering resumed.…”

“…Two to three replicates per 208 genotype, including the A10 and B10 parental accessions, per treatment (1138 209 individuals) were transferred to the Bellwether Phenotyping System at 8 days after 210 sowing. The experiment continued for 25 days with a photoperiod of 16 h light / 8 h 211 night, light intensity of 500 μmol/m 2 /s, a temperature regime of 31 °C day/21 °C night 212and relative humidity was maintained between 40 -80 %(Feldman et al, 2018). For…”

“…Measurements of biomass and transpiration234 RGB images of individual plants were acquired using a side view camera at four 235 different angular rotations (0°, 90° 180°, 270°) every other day, which was used to 236 calculate biomass dry weight(Fahlgren et al, 2015;Feldman et al, 2018). Optical zoom 237 was adjusted during the experiment to ensure optimal images for plant size 238 measurements.…”

“…Scaling factors relating pixel area to ground truth measurements were used to translate pixels to relative area (pixels/cm 2 ). The sensitivity of the measurements limited reliable measurements of plant size and transpiration to a period from day 17 to 241 33 when plants were sufficiently large for accurate image analysis and measurements of 242 transpiration(Feldman et al, 2018). After the experiment concluded, 176 individual243 plants (91 plants from the 100 % FC and 85 from the 40 % FC) were randomly harvested 244 and weighed for fresh aboveground biomass.…”

“…The plants on275 day 27 were in vegetative phase and growing rapidly, typical of when physiological 276 and gas exchange measurements would be made. Additionally, day 27 was 277 representative in terms of QTL and other analyses conducted throughout the 278 experiment(Feldman et al, 2018). To not interrupt the experiment, the δ 13 Cleaf had to be 279 collected from a harvested leaf at the end of the experiment (day 34).…”