Improvements in methods for determination of abscisic acid and indole-3-acetic acid by high-performance liquid chromatography

Overexpression of the Wheat TaPsb28 Gene Enhances Drought Tolerance in Transgenic Arabidopsis

Psb28 is a soluble protein in the photosystem II (PSII) complex, but its role in the drought stress response of wheat remains unclear. Here, we functionally characterized the TaPsb28 gene, which positively regulates drought tolerance in wheat. When the full-length 546-bp TaPsb28 cDNA was transferred into Arabidopsis thaliana, it was located in the guard cell chloroplast around the stroma. Overexpression of TaPsb28 conferred drought tolerance, as exhibited by the increases in the survival rate. Transgenic plants maintained lower MDA content and higher chlorophyll content by inducing chlorophyll synthase (ChlG) gene transcription. The content of abscisic acid (ABA) and zeatin increased significantly in wild-type (WT) plants under drought stress, and the transcriptional expression levels of RD22, dihydroflavonol 4-reductase (DFR) and anthocyanin reductase (ANR) genes were induced, thus enhancing the contents of endogenous cyanidin, delphinidin, and proanthocyanidins. However, in transgenic plants, although anthocyanins were further aggregated, the ABA increase was inhibited, zeatin was restored to the control level under drought stress, and stomatal closure was promoted. These findings indicate ABA and zeatin have opposite synergistic effects in the process of drought tolerance caused by TaPsb28 because only after the effect of zeatin is alleviated can ABA better play its role in promoting anthocyanin accumulation and stomatal closure, thus enhancing the drought tolerance of transgenic plants. The results suggest that overexpression of TaPsb28 exerts a positive role in the drought response by influencing the functional metabolism of endogenous hormones. The understanding acquired through the research laid a foundation for further in-depth investigation of the function of TaPsb28 in drought resistance in wheat, especially its relationship with anthocyanidin accumulation.

Naphthalic anhydride decreases persistence of alachlor and atrazine and elevates tolerance of maize

The present study aimed at alleviating the impacts of alachlor (Ala) or atrazine (Atr) on maize growth by seed-dressing with naphthalic anhydride (NA, 0.4% w/w by seed weight). The dressed and undressed seeds were germinated for 10 days and treated with Ala or Atr at 3.2 or 1.8 kg ha^-1, respectively, then the herbicide residues were determined in shoots one day after treatment. Atr residues were higher than Ala and remained in the same level for the 2^nd day then retracted consistently up to 12 days. Meanwhile, GSH and GST were significantly induced while growth parameters were reduced; the effect of Atr was higher than Ala. Nonetheless, ABA, phenolics and anthocyanins as well as PAL, TAL and CI were increased but IAA was decreased coincidently with enhanced IAA-O and peroxidase. The immediate detection of the herbicide residues could conclude that growth reduction as elucidated from the decreased IAA concomitant with elevating ABA, phenolics and anthocyanin contents and enzyme activities are consequences of the herbicide persistence. The drop of IAA was preceded by the stimulation of IAA-O and peroxidase while the increased phenolics and anthocyanins followed PAL, TAL and CI stimulation confirming the regulatory roles of these enzymes. The application of NA greatly lowered the herbicide residues concurrently with ameliorations in growth parameters, GSH, GST, and maintained the balancing of secondary metabolites and plant growth regulators. Lowering Ala and Atr residues by NA in synchronization with enhanced GSH and GST could conclude that NA encouraged the detoxification of the herbicide. Moreover, the balances of IAA, ABA, phenolics and anthocyanins were mostly maintained in normal levels concomitantly with growth ameliorations suggesting that phytohormones and secondary metabolites are involved in the elevation of maize tolerance to Ala and Atr.