Systemic regulation of sulfur homeostasis in Medicago truncatula.
Sulfur (S) is an essential macronutrient for plants, and deficiency in soil S availability limits plant growth. Adaptive strategies have been evolved by plants to respond to S deficiency by coordinating systemic regulatory mechanism. A split-root experiment using legume model plant Medicago truncatula Gaertn. was conducted to investigate the systemic response to S deficiency. Plant growth, root morphology and S contents under varying conditions of S supply were determined, and the expression of genes encoding sulfate transporter (MtSULTRs) and MtAPR1 encoding an enzyme involved in S assimilation was monitored. Our results demonstrated that there was an apparent systemic response of M. truncatula to heterogeneous S supply in terms of root length, S contents, and S uptake and assimilation at the transcriptional level. When exposed to heterogeneous S supply, M. truncatula plants showed proliferation of lateral roots in S-rich medium and reduction in investment to S-depleted roots. Growth was stimulated with half-part of roots exposed to S-deficient medium. There were different expression patterns of MtSULTRs and MtAPR1 in response to heterogeneous S supply both in roots and shoots of M. truncatula. Expression of MtSULTR1.1 and MtSULTR1.3 was systemically responsive to S deficiency, leading to an enhancement of S uptake in roots exposed to S-sufficient medium. In addition, the response of S-deprived seedlings to re-supply of sulfate and Cys was also analyzed. It was shown that sulfate, but not Cys, may serve as a systemic signal to regulate the expression of genes associated with S absorption and assimilation in M. truncatula. These findings provide a comprehensive picture of systemic responses to S deficiency in leguminous species.
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, People's Republic of China.
Yan
Y
Gao
Qiuying
Q
Tian
Wen-Hao
WH
Zhang
D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology; D003545:Cysteine / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D046913:Medicago truncatula / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D012987:Soil; D013431:Sulfates / Q000494:pharmacology; D013455:Sulfur / Q000378:metabolism* / Q000493:pharmacokinetics
D002352:Carrier Proteins; D003470:Culture Media; D010940:Plant Proteins; D012987:Soil; D013431:Sulfates; D013455:Sulfur; D050862:Oxidoreductases Acting on Sulfur Group Donors; D003545:Cysteine