Erratum: Overexpression of rice aquaporin OsPIP1;2 improves yield by enhancing mesophyll CO2 conductance and phloem sucrose transport.

Feiyun Xu,Ming Ding,Herbert J Kronzucker,Guanglei Chen,Rui Miao,Shuang Liu,Jianhua Zhang,Ke Wang,Wei Yuan,Maoxing Zhang,Lei Kai,Yiyong Zhu,Weifeng Xu,Liang Xiao

doi:10.1093/jxb/erz043

Abstract

Aquaporins are involved in CO2 transport from the leaf intercellular air space to the chloroplast, which contributes to CO2 assimilation. However, the mechanism of CO2 transport by rice (Oryza sativa L.) aquaporins is unknown. Here, we investigated the function of the aquaporin OsPIP1;2 in CO2 diffusion-associated photosynthesis and phloem sucrose transport. Moreover, the grain yield of rice lines overexpressing OsPIP1;2 was determined. OsPIP1;2 was localized to the plasma membrane and the relative expression of OsPIP1;2 was approximately 5-fold higher in leaves in the presence of an elevated CO2 concentration. Overexpression of OsPIP1;2 increased mesophyll conductance by approximately 150% compared with wild-type (WT) rice. The OsPIP1;2-overexpressing lines had higher biomass than the WT, possibly due to increased phloem sucrose transport. In addition, the grain yield of OsPIP1;2-overexpressing lines was approximately 25% higher than that of the WT in three-season field experiments, due to the increased numbers of effective tillers and spikelets per panicle. Our results suggest that OsPIP1;2 modulates rice growth and grain yield by facilitating leaf CO2 diffusion, which increases both the net CO2 assimilation rate and sucrose transport.

Highlights

The atmospheric CO2 concentration ([CO2]) has increased accelerate (Tripati et al, 2009), and is predicted to reach 550– significantly from 318 to >400 ppm since 1959 (Meinshausen 700 ppm by 2050 (Meinshausen et al, 2011)
Aquaporins are involved in CO2 transport from the leaf intercellular air space to the chloroplast, which contributes to CO2 assimilation
CO2 entering chloroplasts must pass through leaf stomata, plasma membranes, cytoplasm, and chloroplast membranes; these steps are collectively reflected by stomatal conductance and leaf mesophyll conductance to CO2 (Evans and Loreto, 2000; Evans et al, 2009)

Summary

Introduction

The atmospheric CO2 concentration ([CO2]) has increased accelerate (Tripati et al, 2009), and is predicted to reach 550– significantly from 318 to >400 ppm since 1959 (Meinshausen 700 ppm by 2050 (Meinshausen et al, 2011). Rice (Oryza sativa L.) is a major staple food crop for almost half the global population (Kurai et al, 2011).The yield of various rice cultivars is reportedly improved by an elevated [CO2], as indicated by increased growth, tiller number, and leaf area (Kimball, 2016; Hasegawa et al, 2013). An elevated [CO2] had a positive effect on leaf gas exchange and net photosynthetic rate (Norby et al, 2016), and is important for plant growth and development. Flexas et al (2008) reported that gm is an important determinant of the photosynthetic rate, indicating that CO2 diffusion from the leaf intercellular air space to the chloroplast is a limiting factor in photosynthesis.Aquaporin NtAQP1 from tobacco leaf facilitates CO2 transport across the plasma membrane in vivo, which in turn modulates membrane permeability to CO2 and mesophyll conductance (Uehlein et al, 2003).

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