Mycorrhiza stimulates root-hair growth and IAA synthesis and transport in trifoliate orange under drought stress

• Published in: Scientific reports Vol. 8; no. 1; pp. 1978 - 9
• Main Authors: Liu, Chun-Yan, Zhang, Fei, Zhang, De-Jian, Srivastava, AK, Wu, Qiang-Sheng, Zou, Ying-Ning
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 31-01-2018; Nature Publishing Group
• Subjects: 631/449/2661/2146; 631/449/2676/2061; Arbuscular mycorrhizas; Biological Transport; Biosynthesis; Colony Count, Microbial; Drought resistance; Droughts; Fungi; Gene Expression Regulation, Plant; Genes, Plant; Glomeromycota - growth & development; Glomeromycota - physiology; Host plants; Humanities and Social Sciences; Indoleacetic acid; Indoleacetic Acids - metabolism; Inoculation; multidisciplinary; Mycorrhizae - growth & development; Mycorrhizae - physiology; Plant growth; Plant Proteins - genetics; Plant Proteins - metabolism; Poncirus - genetics; Poncirus - growth & development; Poncirus - microbiology; Poncirus - physiology; RNA, Messenger - genetics; RNA, Messenger - metabolism; Root hairs; Science; Science (multidisciplinary); Seedlings; Soil microorganisms; Soil moisture; Stress, Physiological; Transcription; Water stress
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-20456-4

Root-hair growth and development regulated by soil microbes is associated with auxin. In this background, we hypothesized that mycorrhizal fungal inoculation induces greater root-hair growth through stimulated auxin synthesis and transport under water stress conditions. Trifoliate orange (
Poncirus trifoliata
) was inoculated with an arbuscular mycorrhizal (AM) fungus (
Funneliformis mosseae
) under well-watered (WW) and drought stress (DS) for 9 weeks. Compared with non-AM seedlings, AM seedlings displayed significantly higher density, length, and diameter of root hairs and root indoleacetic acid (IAA) level, whereas lower total root IAA efflux, regardless of soil moisture status. Root
PtYUC3
and
PtYUC8
involved in IAA biosynthesis were up-regulated by mycorrhization under WW and DS, whereas AM-modulated expression in
PtTAA1
,
PtTAR2
,
PtYUC4
, and
PtYUC6
depended on status of soil moisture. Mycorrhizal inoculation down-regulated the transcript level of root auxin efflux carriers like
PtPIN1
and
PtPIN3
, whereas significantly up-regulated the expression of root auxin-species influx carriers like
PtABCB19
and
PtLAX2
under DS. These results indicated that AMF-stimulated greater root-hair growth of trifoliate orange under DS that is independent on AMF species is related with mycorrhiza-modulated auxin synthesis and transport, which benefits the host plant to enhance drought tolerance.