Rice Sucrose Partitioning Mediated by a Putative Pectin Methyltransferase and Homogalacturonan Methylesterification

Plant Physiology
Yonghan XuXinchun Lin

Abstract

Homogalacturonan (HG) is the main component of pectins. HG methylesterification has recently emerged as a key determinant controlling cell attachment, organ formation, and phyllotaxy. However, whether and how HG methylesterification affects intercellular metabolite transport has rarely been reported. Here, we identified and characterized knockout mutants of the rice (Oryza sativa) OsQUA2 gene encoding a putative pectin methyltransferase. Osqua2 mutants exhibit a remarkable decrease in the degree of methylesterification of HG in the culm-sieve element cell wall and a markedly reduced grain yield. The culm of Osqua2 mutant plants contains excessive sucrose (Suc), and a 13CO2 feeding experiment showed that the Suc overaccumulation in the culm was caused by blocked Suc translocation. These and other findings demonstrate that OsQUA2 is essential for maintaining a high degree of methylesterification of HG in the rice culm-sieve element cell wall, which may be critical for efficient Suc partitioning and grain filling. In addition, our results suggest that the apoplastic pathway is involved in long-distance Suc transport in rice. The identification and characterization of the OsQUA2 gene and its functionality revealed a previously unkn...Continue Reading

Citations

Feb 23, 2020·Annual Review of Plant Biology·Charles T Anderson, Joseph J Kieber
May 7, 2020·Plants·Laura Bacete, Thorsten Hamann
Jul 30, 2021·Frontiers in Plant Science·Ke ChenMariusz Jaremko
Nov 10, 2021·The Plant Journal : for Cell and Molecular Biology·Yanwei WangTiegang Lu

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