title: Suppression of Photosynthetic Gene Expression in Roots Is Required for Sustained Root Growth under Phosphate Deficiency.
abstract: Plants cope with inorganic phosphate (Pi) deficiencies in their environment by adjusting their developmental programs and metabolic activities. For Arabidopsis (Arabidopsis thaliana), the developmental responses include the inhibition of primary root growth and the enhanced formation of lateral roots and root hairs. Pi deficiency also inhibits photosynthesis by suppressing the expression of photosynthetic genes. Early studies showed that photosynthetic gene expression was also suppressed in Pi-deficient roots, a nonphotosynthetic organ; however, the biological relevance of this phenomenon remains unknown. In this work, we characterized an Arabidopsis mutant, hypersensitive to Pi starvation7 (hps7), that is hypersensitive to Pi deficiency; the hypersensitivity includes an increased inhibition of root growth. HPS7 encodes a tyrosylprotein sulfotransferase. Accumulation of HPS7 proteins in root tips is enhanced by Pi deficiency. Comparative RNA sequencing analyses indicated that the expression of many photosynthetic genes is activated in roots of hps7. Under Pi deficiency, the expression of photosynthetic genes in hps7 is further increased, which leads to enhanced accumulation of chlorophyll, starch, and sucrose. Pi-deficient hps7 roots also produce a high level of reactive oxygen species. Previous research showed that the overexpression of GOLDEN-like (GLK) transcription factors in transgenic Arabidopsis activates photosynthesis in roots. The GLK overexpressing (GLK OX) lines also exhibit increased inhibition of root growth under Pi deficiency. The increased inhibition of root growth in hps7 and GLK OX lines by Pi deficiency was completely reversed by growing the plants in the dark. Based on these results, we propose that suppression of photosynthetic gene expression is required for sustained root growth under Pi deficiency.
authors.affiliation: Ministry of Education Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China (J.K., D.L.); andState Key Laboratory of Plant Genomics, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China (H.Y., C.T., W.Z., C.L., Y.J.).
authors.forename: Jun
authors.initials: J
authors.lastname: Kang
authors.affiliation: Ministry of Education Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China (J.K., D.L.); andState Key Laboratory of Plant Genomics, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China (H.Y., C.T., W.Z., C.L., Y.J.).
authors.forename: Haopeng
authors.initials: H
authors.lastname: Yu
authors.affiliation: Ministry of Education Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China (J.K., D.L.); andState Key Laboratory of Plant Genomics, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China (H.Y., C.T., W.Z., C.L., Y.J.).
authors.forename: Caihuan
authors.initials: C
authors.lastname: Tian
authors.affiliation: Ministry of Education Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China (J.K., D.L.); andState Key Laboratory of Plant Genomics, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China (H.Y., C.T., W.Z., C.L., Y.J.).
authors.forename: Wenkun
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Ministry of Education Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China (J.K., D.L.); andState Key Laboratory of Plant Genomics, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China (H.Y., C.T., W.Z., C.L., Y.J.).
authors.forename: Chuanyou
authors.initials: C
authors.lastname: Li
authors.affiliation: Ministry of Education Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China (J.K., D.L.); andState Key Laboratory of Plant Genomics, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China (H.Y., C.T., W.Z., C.L., Y.J.).
authors.forename: Yuling
authors.initials: Y
authors.lastname: Jiao
authors.affiliation: Ministry of Education Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China (J.K., D.L.); andState Key Laboratory of Plant Genomics, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China (H.Y., C.T., W.Z., C.L., Y.J.) liu-d@mail.tsinghua.edu.cn.
authors.forename: Dong
authors.initials: D
authors.lastname: Liu