cDNA Microarray Analysis of Transcriptional Responses to Foliar Methanol Application on Tamba Black Soybean Plants Grown on Acidic Soil.

A foliar spray of 5 % (v/v) methanol had better effects on the growth of the Tamba black soybean (TBS) in an acidic soil (pH 4.6) than in a neutral soil (pH 7.1). To better understand the molecular mechanisms behind the methanol-enhanced growth of the TBS under acidic soil conditions, the Affymetrix GeneChip Soybean Genome was used to identify methanol-responsive genes in TBS leaves sprayed with 5 % methanol for 24 h. The results showed that a total of 516 transcripts (including 190 upregulated genes and 326 downregulated genes) were significantly regulated (at least two fold) by methanol. RT-PCR analysis verified that the microarray data were reliable and reproducible. The expression of six POD and other antioxidant-related genes was upregulated in methanol-treated TBS leaves. This might be an important molecular mechanism through which methanol application ameliorated the effects of acidic soil stress on TBS growth. Methanol also induced the expression of three CaMs, which might be involved in the regulation of TBS growth and development through interactions with various clients. The expression of two gibberellin-related genes and two auxin-related genes was also upregulated by methanol. Changes in the expression of these genes might alter the distribution and content of gibberellin and auxin in TBS plants, thereby enhancing the growth of stem and leaves. RT-PCR analysis confirmed that the expressions of the selected photosynthesis-associated genes were all upregulated during the methanol treatment period. Consistent with these results, the photosynthesis rate was also obviously elevated in methanol-treated TBS leaves. These data suggested that methanol enhanced the photosynthesis and expression of photosynthesis-associated genes, thereby increasing the biomass accumulation of TBS leaves. [ABSTRACT FROM AUTHOR]