Variations in physiological, biochemical, and structural traits of photosynthesis and resource use efficiency in maize and teosintes (NADP-ME-type C₄)

Figures & data

Table 1. Maize and teosinte lines examined in this study.

Species	Line	Country
Zea mays ssp. mays	B73	Iowa, USA
	HP301	Indiana, USA
	IL14H	Illinois, USA
	Ky21	Kentucky, USA
	Mo18W	Missouri, USA
	OH7B	Ohio, USA
	P39	Indiana, USA
	WF9	Indiana, USA
	CM109	Canada
	CML69	Mexico
	Pipoca 4	Brazil
	Pisinga Purpura	Peru
	CB44	Netherlands
	Kuma Mais	Netherlands
	F575	France
	I.C.A.R. 54	Romania
	TZI3	Nigeria
	PI 195114	Ethiopia
	Homedale	South Africa
	Geargian local 1	USSR
	Pakistan	Pakistan
	Ki3	Thailand
Z. mays. ssp. mexicana	Ames 8083	Mexico
Z. diploperennis	PI 441930	Mexico
Z. perennis	Ames 21875	Mexico
Z. nicaraguensis	PI 615697	Nicaragua

Figure 1. Variations in (A) net photosynthetic rate (P_N), (B) photosynthetic water use efficiency (PWUE), and (C) photosynthetic nitrogen use efficiency (PNUE) in leaves of maize and teosinte lines.

Notes: Means ± SD (n = 3–5). Dashed lines show mean values. Black, maize (Z. mays ssp. mays); gray, Z. mays ssp. mexicana; white, Z. diploperennis, Z. perennis, and Z. nicaraguensis.

Figure 2. Relationships between P_N and (A) stomatal conductance (g_s), (B) transpiration rate (T_r), (C) chlorophyll (Chl) content, (D) leaf soluble protein (LSP) content, (E) leaf N content, and (F) specific leaf weight (SLW) in leaves of maize and teosinte lines.

Notes: Circles are the mean values of each line (n = 3–5): black, maize (Z. mays ssp. mays); gray, Z. mays ssp. mexicana; white, Z. diploperennis, Z. perennis, and Z. nicaraguensis. Significant at P: **< .01; *** < .001. ^NSnot significant.

Table 2. Correlation coefficients (r) from linear regression analysis and statistical significance of the relationships between physiological and biochemical traits in maize and teosinte lines. P_N, net photosynthetic rate; g_s, stomatal conductance; T_r, transpiration rate; C_i/C_a, intercellular CO₂ to ambient CO₂ concentration; PWUE, photosynthetic water use efficiency; LSP, leaf soluble protein; Chl, chlorophyll; SLW, specific leaf weight; PNUE, photosynthetic nitrogen use efficiency; δ¹³C, carbon isotope ratio; PEPC, phosphoenolpyruvate carboxylase; ME, malic enzyme; PCK, phosphoenolpyruvate carboxykinase; DC, capacity for C₄ acid decarboxylation (=NADP−ME activity + PCK activity); PCK ratio, [=PCK activity/(NADP−ME activity + PCK activity)].

	PN	gs	Tr	Ci/Ca	PWUE	LSP content	Chl content	Leaf N content	SLW	PNUE	δ^13C	Rubisco activity	PEPC activity	NADP-ME activity	PCK activity	DC	PCK ratio
PN	1
gs	.813***	1
Tr	.878***	.961***	1
Ci/Ca	.169^NS	.632***	.557**	1
PWUE	−.510**	−.805***	−.819***	−.835***	1
LSP content	.718***	.671***	.724***	.276^NS	−.592**	1
Chl content	.726***	.558**	.671***	.129^NS	−.433*	.809***	1
Leaf N content	.581**	.372^NS	.487*	.080^NS	−.342^NS	.576**	.614***	1
SLW	−.095^NS	−.092^NS	−.102^NS	−.076^NS	.069^NS	−.233^NS	−.279^NS	−.030^NS	1
PNUE	−.098^NS	.040^NS	−.056^NS	−.010^NS	.135^NS	−.287^NS	−.311^NS	−.832***	−.161^NS	1
δ^13C	−.034^NS	.095^NS	.037^NS	.045^NS	.022^NS	−.026^NS	−.268^NS	−.247^NS	.252^NS	.214^NS	1
Rubisco activity	.610***	.652***	.692***	.419*	−.615***	.668***	.667***	.301^NS	−.003^NS	−.070^NS	.176^NS	1
PEPC activity	−.059^NS	.013^NS	−.055^NS	.051^NS	.018^NS	−.099^NS	−.234^NS	.114^NS	.205^NS	−.129^NS	−.008^NS	−.211^NS	1
NADP-ME activity	.501**	.492*	.519**	.223^NS	−.440*	.541**	.389*	.344^NS	.212^NS	−.141^NS	.039^NS	.519**	.368^NS	1
PCK activity	.521**	.439*	.469*	.117^NS	−.225^NS	.438*	.423*	.633***	−.104^NS	−.382^NS	−.149^NS	.188^NS	.396*	.437*	1
DC	.457*	.491*	.509**	.267^NS	−.438*	.467*	.326^NS	.385^NS	.150^NS	−.182^NS	.012^NS	.414*	.486*	.958***	.597**	1
PCK ratio	.387^NS	.186^NS	.225^NS	−.107^NS	.001^NS	.344^NS	.319^NS	.560**	−.088^NS	−.400*	−.100^NS	.119^NS	.313^NS	.175^NS	.860***	.288^NS	1

* Significant at P: < .05

** < .01

*** < .001

^NS not significant.

Figure 3. Relationship between photosynthetic water use efficiency (PWUE) and δ¹³C in leaves of maize and teosinte lines.

Notes: Circles are the mean values of each line (n = 3–5). Circle shading is as in Figure 2. ^NSnot significant.

Figure 4. Relationships between P_N and activities of (A) PEP carboxylase (PEPC), (B) NADP-malic enzyme (NADP-ME), (C) PEP carboxykinase (PCK), and (D) Rubisco in leaves of maize and teosinte lines.

Notes: Circles are the mean values of each line (n = 3–5). Circle shading is as in Figure 2. Significant at P: ** < .01; *** < .001. ^NSnot significant. Broken lines (y = x) show enzyme activities that would be required for equal P_N.

Table 3. Correlation coefficients (r) from linear regression analysis and statistical significance of the relationships between structural traits of maize and teosinte lines. IVD, interveinal distance; SD, stomatal density; GL, guard cell length.

	Leaf thickness	IVD	SD	GL	SD×GL
Leaf thickness	1
IVD	.645***	1
SD	−.371^NS	−.487*	1
GL	.257^NS	.225^NS	−.686***	1
SD×GL	−.352^NS	−.526	.953***	−.439*	1

* Significant at P: < .05

** < .01

*** < .001

^NS not significant.