MIC-100, a new system for high-throughput phenotyping of instantaneous leaf photosynthetic rate in the field

Abstract

Photosynthesis occurs mainly in plant leaves and is a fundamental process in the global carbon cycle and in crop production. The exploitation of natural genetic variation in leaf photosynthetic capacity is a promising strategy to meet the increasing demand for crops. The present study reports the newly developed photosynthesis measurement system ‘MIC-100,’ with a higher throughput for measuring instantaneous photosynthetic rate in the field. MIC-100 is established based on the closed system and directly detects the CO2 absorption in the leaf chamber. The reproducibility, accuracy, and measurement throughput of MIC-100 were tested using soybean (Glycine max L. (Merr.)) and rice (Oryza sativa L.) grown under field conditions. In most cases, the coefficient of variance (CV) for repeated-measurements of the same leaf was less than 0.1. The photosynthetic rates measured with the MIC-100 model showed a significant correlation (R2 = 0.93–0.95) with rates measured by a widely used gas-exchange system. The measurement throughput of the MIC-100 is significantly greater than that of conventional open gas-exchange systems under field conditions. Although MIC-100 solely detects the instantaneous photosynthetic rate under a given environment, this study demonstrated that the MIC-100 enables the rough evaluation of leaf photosynthesis within the large-scale plant populations grown in the field.

Analysis of Physiological Variations and Genetic Architecture for Photosynthetic Capacity of Japanese Soybean Germplasm

“…We used a high-throughput portable close-chamber infrared gas analyzer, MIC-100 (MASA International Cooperation, Japan), to analyze light-saturated photosynthetic rates ( A sat ) in 2019 and 2020. This system requires less than 30 s per sample whereas a standard LI-6800 achieves stability in at least 45 s for the “Fast Survey Measurements.” MIC100 explains around 95% variations in A sat measured by a standard LI-6800 system (LI-COR, United States) therefore, making it a high-throughput efficient system ( LI-COR Biosciences, 2021 ; Tanaka et al, 2021 ). Moreover, our observations in the field revealed that MIC-100 can measure A sat up to sevenfold faster than LI-6800.…”

Identification and Characterization of an Early Leaf Senescence Gene ELS1 in Soybean

“…Chl a and Chl b contents were determined using the method described by Porra et al (1989) . The carbon assimilation rate was measured in sunlight using the Rapid Photosynthesis Measuring System MIC-100 (Masa International, Japan; Tanaka et al, 2021 ).…”

Applicability of a Closed and Rapid Gas-exchange System to Leaf Photosynthetic Measurements in Tropical Fruit Trees

“…Because a closed system requires a longer time for a single measurement under changes in gas concentration and temperature inside the chamber, the measurement accuracy becomes inferior to that of open systems in controlled environments (Bugbee, 1992;Hunt, 2003). However, a recently developed closed and rapid gas-exchange system can measure a single record in approximately 30 s, that is, several hundred records per day (Tanaka et al, 2022), making it feasible to measure and evaluate the assimilation capacity of numerous samples over a long cultivation period. Because tree species, including tropical fruit tree species, have long growing times and large plant sizes, photosynthetic phenotyping has the benefits of not only obtaining data with high accuracy but also of reducing labor by speeding up operations, that is, high-throughput phenotyping.…”

“…Trees generally have lower individual leaf photosynthetic rates than herbaceous plants (Evans, 1989;Hikosaka et al, 1998). Lower photosynthetic rates lead to longer periods for photosynthetic measurements when leaves are kept in closed chambers, which may affect the measured values owing to dew condensation and physical stress (Tanaka et al, 2022). In addition, data on photosynthetic rates are limited for tropical fruit trees compared to temperate fruit trees.…”