High-Throughput Phenotyping of the Leaf Transpiration at the Primary Leaf in Soybean [Glycine max. (L.) Merr.]

High-throughput phenotyping of the leaf photosynthetic capacity will be a key to realize the enhanced photosynthesis in crop plants. We focused on the soybean primary leaf and found that there was a clear genotypic difference in the leaf transpiration rate by measuring the leaf temperature at this leaf position(TPL). The diversity in TPL correlated with the stomatal conductance and photosynthetic capacity measured in the field condition. Our study opens the possibility of the high-throughput phenotyping of the leaf transpiration and photosynthetic capacity at very early stage of the growth in soybean.

Yu Tanaka(1),(2), Yasuko Fukuda(1), Keiichiro Nakashima(1) and Tatsuhiko Shiraiwa(1) (1) Graduate School of Agriculture, Kyoto University (2) The Institute for Genomic Biology, UIUC

Materials and Methods

Fig. 2 The relationship between normalized TPL by the subtraction against the value of Tachinagaha (ΔTPL) and stomatal conductance (gs; a) and photosynthetic rate (Pn; b). Both gs and Pn were measured at the full pod stage in the field condition. **, †: significant at 1 % and 10 %, respectively. Bars indicate SE (n = 4).

Conclusion High throughput phenotyping of the transpiration characteristics is expected by measuring the leaf temperature at the primary leaf.

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2 weeks

1 shot / genotype

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land resources

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0.2

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Exp.1

Exp.2

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Exp.1 Exp.2

UA4805 ○

5002T ○

Fukuyutaka ○

Stressland ○ ○

Tachinagaha ○ ○

ST048 ○

ST053 ○ ○

ST068 ○

ST100 ○

ST128 ○

ST178 ○

ST203 ○

ST283 ○

5 soybean cultivars (3 from the US and 2 from Japan), and 8 recombinant inbred lines derived from a cross between Stressland and Tachinagaha were used in this study (Table 1).

Table 1. Genotypes used in the study

Leaf temperature measurements: Soybean were seeded in the plant density of 5x5cm in a planter sized for 65(L)x25(W)x20(H) cm filled with the vermiculite. Four soybean plants per genotype were grown under LED light (VEFA280WZ, ALTRADER, Japan) without sunlight. The day-length was set to 12 hr and the temperature were controlled between 25 and 28 ℃. At 14 days after sowing, leaf temperature at the primary leaf (TPL) were recorded using Thermo Gear G100 (Nippon Avionics, Japan). Leaf photosynthetic measurements: Soybean were seeded at the experimental field of Graduate School of Agriculture, Kyoto University on June 25th, 2013. The leaf photosynthetic rate (Pn) and stomatal conductance (gs) was measured by LI-6400 (Li-COR, USA). The measurement was conducted on August 13th, 2013 with the condition of PPFD = 2000μmol m-2 s-1 and [CO2] = 380 ppm.

photosynthetic measurement

in incubator feedback

thermal imaging

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23.0

23.5

24.0

24.5

25.0

T PL

(℃)

24.0

24.5

25.0

25.5

26.0

26.5

27.0

27.5

T PL

(℃）

Fig. 1 Variation of the temperature at the primary leaf (TPL). Bars indicate SE (n = 4).

Exp. 1 Exp. 2

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