Xie Zhou

Involvement of endogenous plant hormones in the effect of mixed nitrogen source on growth and tillering of wheat

Abstract A Chinese spring wheat (Triticum aestivum L. cv. Yang Mai 158) was grown hydroponically with nitrogen (N) supplied as all ammonium (NH4 +), all nitrate (NC3 ‐), and a mixture (NH4 +‐N:NO3 ‐‐N=30:70) of each form. Wheat plants produced more tiller and more dry matter, and showed a higher shoot/root dry matter ratio when grown with mixed N than with either N form alone. In addition, all‐NH4 +‐grown plants produced more tillers and dry matter as compared to all‐NO3 ‐‐grown plants. Subsequently, endogenous levels of isopentenyladenine and isopentenyladenosine, zeatin and zeatin riboside, dihydrozeatin and dihydrozeatin riboside, indole‐3‐acetic acid (IAA), gibberellin A, and gibberellin A3 (GA1+3) and abscisic acid (ABA) in the shoot and the root was determined by enzyme‐linked immunosorbent assays. It was found that the levels of cytokinin in both the shoot and the root of mixed‐N‐grown plants were higher than those of all‐NO3 ‐‐grown and all‐NH4 +‐grown plant, whereas ABA level was similar among pl...

Lateral root formation in rice (Oryza sativa L.): differential effects of indole-3-acetic acid and indole-3-butyric acid

Comparative effects of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) on lateral root (LR) formation were studied using 2-day-old seedlings of IR8 rice (Oryza sativa L.). Results showed that IBA at all concentrations (0.8–500 nmol/L) increased the number of LRs in the seminal root. However exogenous IAA, failed to increase the number of LRs. On the other hand, both IBA and IAA caused inhibition of seminal root elongation and promotion of LR elongation, but IAA can only reach to the same degree of that of IBA at a more than 20-fold concentration. Exogenous IBA had no effect on endogenous IAA content. We conclude from the results that IBA could act directly as a distinct auxin, promoting LR formation in rice, and that the signal transduction pathway for IBA is at least partially different from that for IAA.

Effect of yeast elicitor and salicylic acid on the fluctuation of phytohormone contents in Ti-transformed Salvia miltiorrhiza cell cultures

When Ti transformed Salvia miltiorrhiza cells werecultured in a MS-NH4 medium (MS without ammonium nitrate, containing30 g/L sucrose) at 25 °C in darkness for 18d, the total tanshinone (cryptotanshinone and tashinone IIA)contents in cultures were 12.23 mg/L and 15.07 mg/Lfor yeast elicitor (4 g/L), and yeast elicitor plus 200μmol/L salicylic acid (SA) treated cultures, respectively,whereas only trace amounts of tanshinone were detected in the control or SAtreated cells. To explore the hormonal background concerning these phenomena,endogenous phytohormones were determined using ELISA kits. We found that ABA andiPAs contents in yeast elicitor plus SA treated cell cultures were increased 2.8to 9.8-fold and 3.6 to 5.8-fold respectively, while contents of GA1and IAA were decreased by 13.2%–56.9% and 34.8%–74.6% respectively.This suggests that higher levels of ABA and iPAs combined with lower levels ofGA1 and IAA inhibit the growth of cells, then probably stimulate thetanshinone production.

Methyl jasmonate inhibits lamina joint inclination by repressing brassinosteroid biosynthesis and signaling in rice.

Lamina joint inclination or leaf angle (the angle between the leaf blade and vertical culm) is a major trait of rice plant architecture. The plant hormone brassinosteroid (BR) is the main regulator of this trait, while other plant hormones, including ethylene, gibberellin, and auxin, also influence leaf angle. In this study, we found that methyl jasmonate (MeJA) also participates in regulating lamina joint inclination. MeJA decreased lamina joint inclination and inhibited the BR-induced increase in lamina joint inclination. Furthermore, addition of a BR synthesis inhibitor increased the extent of change in lamina joint inclination in response to treatment with a low concentration of MeJA (0.05 or 0.5mgL(-1)), but it did not alter the lamina joint inclination of plants treated with a high concentration of MeJA (5mgL(-1)). Further studies showed that MeJA treatment significantly repressed the expression of BR biosynthesis-related genes and decreased endogenous BRs levels. In addition, the lamina joint inclination in the OsBRI1 mutant d61-1 was less sensitive to MeJA compared with its wild type counterpart, and lithium chloride-induced inactivation of GSK3-like kinase, a negative regulator of BR signaling, partly rescued the MeJA-induced reduction in lamina joint inclination. Further studies showed that MeJA treatment reduced the mRNA levels of BR signaling and target genes. These results indicate that MeJA-inhibition of lamina joint inclination may depend on BR biosynthesis and the BR signaling pathway.

An ELISA for the determination of salicylic acid in plants using a monoclonal antibody

Abstract A mouse monoclonal antibody (McAb) against salicylic acid (SA) was produced and characterized for the first time. The McAb, based on the study of immuno-response of rabbit to immunogens conjugated SA to carrier proteins through different methods, and effect of changing conjugation bridge between hapten and carrier proteins on the specialty of salicylate polyclonal antibodies (PAbs), was derived from an immunogen in which 5-aminosalicylic acid (5-ASA) was conjugated to KLH (hemocyanin from keyhole limpet) through its (C 5 )-NH 2 group. The antibody shows high specificity to SA and even more high specificity to 5-ASA (the cross-reaction is 144.8%), but show very little cross-reactivity with 5-sulfosalicylic acid (0.9%) and 4-aminosalicylic acid (0.3%). Other compounds structurally similar to SA, such as 4-hydroxybenzoic acid, 4-aminobenzoic acid and salicylaldoxime, were not found to exhibit any cross-reactivity. Based on this antibody, a direct enzyme-linked immunosorbent assay (ELISA) with high sensitivity and precision was developed which displays a linear range from 0.0195 to 20 nmol of SA. Using this ELISA, the fluctuation of endogenous SA levels of cucumber after infected with Pseudomonas syringae pv. syringae were examined.

Gibberellin-responding and non-responding dwarf mutants in foxtail millet

The sensitivity of foxtail millet (Setaria italica Beauv.) dwarf mutants to GA was studied. Seedlings of dwarf mutants, Aininghuang (ANH) and CH84113 were treated with GAs (GA1, GA4, GA9, GA19 and GA20) using the micro-drop method, or by soaking in GA3 solution. Plants were also sprayed with GA3 solution at the jointing stage. It was found that ANH was a GA-responding dwarf mutant, whose leaf blade, leaf sheath and internode length increased significantly after GA application, whereas CH84113 was a non-GA-responding dwarf mutant. However, the mesocotyl in etiolated seedlings of both ANH and CH84113 responded to exogenous GA3 in a similar way. With the help of an enzyme-linked immunosorbent assay, it was found that the endogenous GA1+3 level in leaves was lower in the GA-responding dwarf mutant ANH, but higher in the non-GA-responding dwarf mutant CH84113, compared with levels in normal cultivars.