The Crucial Roles of Phloem Companion Cells in Response to Phosphorus Deficiency

• Published in: Plant, cell and environment Vol. 48; no. 6; pp. 4327 - 4340
• Main Authors: Xia, Chao, Huang, Jing, Zhou, Xiangjun, Payyavula, Raja S., Lan, Hai, Chen, Li‐Qing, Turgeon, Robert, Zhang, Cankui
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.06.2025; John Wiley and Sons Inc
• Subjects: Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - physiology; companion cell; environment; food transport; Gene expression; Gene Expression Regulation, Plant; herbaceous plants; Leaves; nutrient deficiencies; Original; Phloem; Phloem - cytology; Phloem - metabolism; Phloem - physiology; phosphates; Phosphorus; Phosphorus - deficiency; Phosphorus - metabolism; Plant growth; Plant Leaves - metabolism; Plant Roots - growth & development; Plant Roots - metabolism; Plant Shoots - metabolism; Plant tissues; root development; root growth; Shoots; Signal Transduction; systemic signaling; translatome; phloem; companion cell; root development; translatome; systemic signaling; phosphorus
• ISSN: 0140-7791; 1365-3040; 1365-3040
• DOI: 10.1111/pce.15421

ABSTRACT Mineral deficiency is a major problem in agriculture. Plant adaption to low mineral environments involves signaling between shoots and roots, via the food transport cells, the sieve elements. However, due to the sequestered position of the sieve elements in the vascular bundles, identifying shoot‐to‐root mobile signals is challenging. In herbaceous species, sieve elements and companion cells (CCs) are isolated from other leaf tissues. We hypothesize that phloem CCs play an essential role by synthesizing shoot‐to‐root signals in response to mineral deficiency. To test this hypothesis, we analyzed gene expression responses in Arabidopsis CCs under phosphorus deficiency using TRAP‐Seq. Phosphorus was chosen for its importance in plant growth and the known role of shoot‐to‐root signaling in regulating root phosphate transporters during deficiency. Our findings revealed that CCs exhibit more dramatic molecular responses than other leaf cells. We also found that many genes altered in CCs have potential functions in regulating root growth. This is unexpected because it has been widely believed that shoot‐to‐root signaling is not involved in root growth regulation under P deficiency. The importance of CCs in regulating mineral deficiency may extend beyond phosphorus because shoot‐to‐root signaling is a common response to the deficiency of various minerals. Summary statement TRAP‐Seq was used to elucidate the importance of the phloem companion cells (CCs) in regulation of mineral deficiency responses in Arabidopsis. Traditional methods utilizing whole leaves do not capture most CC expressed genes under phosphorus deficiency.