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The WUS (WUSCHEL) gene encodes a transcription factor that specifies the adjacent cells to be stem cell. The WUS dependent signal systems have been found in different tissues recent years. The feedback loop between the CLV and WUS genes maintains the stem cell self-renewal and apical dominance in shoot apical meristem. In the embryonic meristem, the expression of CLV3 depends on WUS only. During post-embryo development, both WUS and STM are needed for CLV3 expression and the triggering of organogenesis. The expression of AG in floral meristem is activated by co-existence of WUS and LFY, AG acts as a negative regulator of WUS expression to downregulate the WUS level. The signal system established by WUS is also involved in ovule development. The somatic embryogenesis can be promoted efficiently by WUS, especially in the presence of auxin. The results of prevoius works indicated that cell competence to WUS activity is related to microenvironment and the combination of WUS signal with different environmental factors could activate different downstream genes.

Allene oxide synthase (AOS) is the first enzyme in the lipoxygenase pathway which leads to the formation of jasmonic acid (JA). A full length cDNA of TaAOS was cloned in winter wheat (Triticum aestivum L. cv. Jinghua No.3) seedlings. The open reading frame encompassed 1410 bp encoding a polypeptide of 470 amino acids with calculated molecular mass of 51.9 kD. Southern blot analysis suggested there are three copies of the gene in wheat genome. The TaAOS mRNA could be strongly induced by exogenous JA, and the highest level JA was observed after a 10 h induction. In situ RNA hybridization of seedling indicated preferential gene expression in young leaves, especially in the parenchyma cells around the vascular bundles, and the hybridization also showed that exogenous La(3+) could not suppress the expression of TaAOS induced by JA.