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

Takayuki Yabiku,Osamu Ueno

doi:10.1080/1343943x.2017.1398050

Abstract

C4 plants show higher photosynthetic capacity and resource use efficiency than C3 plants. However, the genetic variations of these traits and their regulatory factors in C4 plants still remain to be resolved. We investigated physiological, biochemical, and structural traits involved in photosynthesis and photosynthetic water and nitrogen use efficiencies (PWUE and PNUE) in 22 maize lines and four teosinte lines from various regions of the world. Net photosynthetic rate (PN) ranged from 32.1 to 46.5 μmol m−2 s−1. PN was positively correlated with stomatal conductance, transpiration rate, and chlorophyll, nitrogen and soluble protein contents of leaves, but not with specific leaf weight. PN was positively correlated with the activities of ribulose-1,5-bisphosphate carboxylase/oxygenase and the C4-acid decarboxylases, NADP-malic enzyme and phosphoenolpyruvate carboxykinase, but not with the activity of phosphoenolpyruvate carboxylase. Leaf structural traits (stomatal parameters, leaf thickness, and interveinal distance) were not correlated with PN. These data suggest that physiological and biochemical traits are involved in the genetic variation of PN, but structural traits are not directly involved. PWUE is in the lower class of values reported for C4 plants, whereas PNUE is in the highest class of values reported for C4 plants. PNUE was negatively correlated with leaf nitrogen content but not significantly correlated with PN. PWUE was not correlated with δ13C values of leaves, indicating difficulty in using δ13C values as an indicator of PWUE of maize. In general, teosinte lines showed lower PN but higher PWUE than maize lines.

Highlights

Photosynthetic traits of leaves are one of the most important physiological factors responsible for plant productivity
This study investigated the genetic variations in photosynthetic rate and resource use efficiency in maize and teosinte lines and the regulatory factors involving in these variations
photosynthetic rate (PN) was positively correlated with activities of NADP-malic enzyme (NADP-ME), phosphoenolpyruvate carboxykinase (PCK), and Rubisco, but not with that of phosphoenolpyruvate carboxylase (PEPC)

Summary

Introduction

Photosynthetic traits of leaves are one of the most important physiological factors responsible for plant productivity. The improvement of photosynthetic traits promises further increases in plant productivity (Evans, 2013; Zhu et al, 2010). The genetic variation in photosynthetic traits found in both crop and wild species includes a potential to improve crop photosynthesis and productivity but is largely unexplored (McCouch, 2004; Flood et al, 2011). Photosynthesis is complicatedly regulated by biophysical, biochemical, physiological, and structural traits of leaves. Our understanding of the regulatory processes is still insufficient (Evans, 2013). The factors that cause the genetic variation in photosynthesis remain largely unknown (Flood et al, 2011)

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