Differential expression of isoflavone biosynthetic genes in soybean during water deficits

Juan J. Gutierrez-Gonzalez, Satish K. Guttikonda, Lam Son Phan Tran, Donavan L. Aldrich, Rui Zhong, Oliver Yu, Henry T. Nguyen, David A. Sleper

Research output: Contribution to journalArticlepeer-review

105 Scopus citations

Abstract

Numerous environmental factors influence isoflavone accumulation and have long hampered their genetic dissection. Temperature and water regimes are two of the most significant abiotic factors. However, while the effects of temperature have been widely studied, little is known about how water scarcity might affect isoflavone concentration in seeds. Studies have shown that accumulation of isoflavones is promoted by well-watered conditions, but the molecular basis remains elusive. The length and severity of the water stress required to induce changes are also still unknown. In the present work, several intensities of water stress were evaluated at various critical stages for soybean [Glycine max (L.) Merr.] seed development, in both field and controlled environments. The results suggested that only long-term progressive drought, spanning most of the seed developmental stages, significantly decreased isoflavone content in seeds. The reduction is proportional to the intensity of the stress and appears to occur in a genotype-dependent manner. However, regardless of water regime, isoflavone compounds were mainly accumulated in the later seed developmental stages. Transcripts of the most important genes for isoflavone biosynthesis were also quantified from samples collected at key seed developmental stages under well-watered and long-term water deficit conditions. Expression of CHS7, CHS8 and IFS2 correlated with isoflavone accumulation under well-watered conditions. Interestingly, we found that the two isoflavone synthase genes in soybean (IFS1 and IFS2) showed different patterns of expression. The abundance of IFS1 transcripts was maintained at a constant rate, whereas IFS2 was down-regulated and highly correlated with isoflavone accumulation under both water deficit and well-watered conditions, suggesting IFS2 as a main contributor to isoflavone diminution under drought.

Original languageEnglish (US)
Pages (from-to)936-948
Number of pages13
JournalPlant and Cell Physiology
Volume51
Issue number6
DOIs
StatePublished - Jun 2010
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported the National Science Foundation (NSF) [grant No. MCB0519634]; US Department of Agriculture (USDA) [grant No. NRI2005-05190 to O.Y.]; USDA-CSREES [award No. 2006-34555-17010 for the National Center for Soybean Biotechnology] and NSF-MRI [Major Research Instrumentation grant No. 0526687].

Keywords

  • Daidzein
  • Drought
  • Genistein
  • Isoflavone
  • Isoflavone synthase
  • Phenylpropanoid transcripts

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