Plant-specific type III polyketide synthase (PKS) produces a variety of plant secondary metabolites with notable structural diversity and biological activity. So far 14 plant-specific type III PKS have been identified according to their enzymatic products, and the corresponding genes have been cloned and characterized. The differences among the various PKS are mainly in their substrate specificities, the number of their condensation reactions, and the type of ring closure of their products. However, numerous studies have revealed the common features among the plant-specific type III PKS, which include sequence homology, similar gene structure, conserved amino acid residues in the reaction center, enzymatic characteristics and reaction mechanism. We briefly reviewed 14 plant-specific type III PKS to better understand genetic and metabolic engineering of plant-specific type III PKS.
Acyltransferases ; genetics ; metabolism ; physiology ; Genes, Plant ; Genetic Engineering ; Metabolic Engineering ; Plants ; enzymology ; genetics ; Substrate Specificity

Simmering method is one of the traditional processing methods of Chinese materia medica， which has been documented in the herbal literature and medical books of the past dynasties and has a great variety， but at present， there are not many specific varieties of Chinese materia medica involved， and there are few related researches. By reviewing the ancient and modern related information， the authors have organized and analyzed the historical evolution， processing purpose， modern representative Chinese materia medica（processing technology， quality evaluation， pharmacological research） of simmering method. After sorting out， it was found that the simmering method was widely used in ancient times， which was first seen in Huashi Zhongzangjing of the Eastern Han dynasty， and was enriched and developed through the Tang， Song， Jin， Yuan， Ming and Qing dynasties， and entered its heyday in Ming and Qing dynasties along with the economic prosperity and development of the Ming dynasty， involving as many as 159 varieties of Chinese materia medica， and gradually perfecting the processing theory of the simmering method. However， the number of varieties that still use the simmering method in modern times significantly decreased. The main purposes of using simmering method in modern Chinese materia medica are to reduce adverse reactions， moderate medicinal properties， enhance therapeutic effects， remove non-medicinal parts， and facilitate further processing， etc. This paper combed the key information of simmering methods for Chinese materia medica from ancient to modern times， which can provide a literature basis for the clinical application and modern research of simmered products of Chinese materia medica.