Comprehensive analysis of JAZ family members in Ginkgo biloba reveals the regulatory role of the GbCOI1/GbJAZs/GbMYC2 module in ginkgolide biosynthesis.

Ginkgo biloba L., an ancient relict plant known as a 'living fossil', has a high medicinal and nutritional value in its kernels and leaves. Ginkgolides are unique diterpene lactone compounds in G. biloba, with favorable therapeutic effects on cardiovascular and cerebrovascular diseases. Thus, it is essential to study the biosynthesis and regulatory mechanism of ginkgolide, which will contribute to quality improvement and medication requirements. In this study, the regulatory roles of the JAZ gene family and GbCOI1/GbJAZs/GbMYC2 module in ginkgolide biosynthesis were explored based on genome and methyl jasmonate-induced transcriptome. Firstly, 18 JAZ proteins were identified from G. biloba, and the gene characteristics and expansion patterns along with evolutionary relationships of these GbJAZs were analyzed systematically. Expression patterns analysis indicated that most GbJAZs expressed highly in the fibrous root and were induced significantly by methyl jasmonate. Mechanistically, yeast two-hybrid assays suggested that GbJAZ3/11 interacted with both GbMYC2 and GbCOI1, and several GbJAZ proteins could form homodimers or heterodimers between the GbJAZ family. Moreover, GbMYC2 is directly bound to the G-box element in the promoter of GbLPS, to regulate the biosynthesis of ginkgolide. Collectively, these results systematically characterized the JAZ gene family in G. biloba and demonstrated that the GbCOI1/GbJAZs/GbMYC2 module could regulate ginkgolides biosynthesis, which provides a novel insight for studying the mechanism of JA regulating ginkgolide biosynthesis.

[Allelopathic effects of Artemisia frigida on three Poaceae plants seed germination and seedling growth].

Aqueous extracts of Artemisia frigida leaf and stem and soils beneath A. frigida were used to test their allelopathic effects on the seed germination and seedling growth of three Poaceae plants (Leymus chinensis, Stipa krylovii, and Cleistogenes squarrosa) on Leymus chinensis grassland. The aqueous extracts of A. frigida leaf and stem decreased the seed germination index of test plants and prolonged their seed germination time, and inhibited the shoot growth of the three plants and the root growth of S. krylovii. The aqueous extracts at concentration > or = 0.075 g x ml(-1) presented a strong inhibition on the root growth of L. chinensis, while those at concentration < or = 0.05 g x ml(-1) had less effects. For the root growth of C. squarrosa, the aqueous extracts showed a "low-promotion and high-inhibition effect". Under the effects of A. frigida soil, the seedling growth of test plants was inhibited. The sensitivity of test plants to the allelopathic effects of A. frigida was in the order of S. krylovii > L. chinense > C. squarrosa, with a higher sensitivity of root growth than shoot growth.