Each major step leading to the classical yellow, orange and red constituents of Monascus azaphilone pigments was defined.

Anther cuticle and pollen exine act as protective envelopes for the male gametophyte or pollen grain, but the mechanism underlying the synthesis of these lipidic polymers remains unclear. Previously, a tapetum-expressed CYP703A3, a putative cytochrome P450 fatty acid hydroxylase, was shown to be essential for male fertility in rice (Oryza sativa L.). However, the biochemical and biological roles of CYP703A3 has not been characterized. Here, we observed that cyp703a3-2 caused by one base insertion in CYP703A3 displays defective pollen exine and anther epicuticular layer, which differs from Arabidopsis cyp703a2 in which only defective pollen exine occurs. Consistently, chemical composition assay showed that levels of cutin monomers and wax components were dramatically reduced in cyp703a3-2 anthers. Unlike the wide range of substrates of Arabidopsis CYP703A2, CYP703A3 functions as an in-chain hydroxylase only for a specific substrate, lauric acid, preferably generating 7-hydroxylated lauric acid. Moreover, chromatin immunoprecipitation and expression analyses revealed that the expression of CYP703A3 is directly regulated by Tapetum Degeneration Retardation, a known regulator of tapetum PCD and pollen exine formation. Collectively, our results suggest that CYP703A3 represents a conserved and diversified biochemical pathway for in-chain hydroxylation of lauric acid required for the development of male organ in higher plants.

Monascus spp. are filamentous fungi famous for their fermented products, especially red mold rice (RMR), a traditional fermented food in East Asian areas with a very long edible history documented back to the Han dynasty (BC 202-AD 220) in China. Nowadays, RMR and its related products involve a very large industry from artisanal traditional fermentations to food companies to medicine manufacturers, which are distributed worldwide. Modern studies have shown that Monascus spp. are able to produce abundant beneficial secondary metabolites, such as monacolins (cholesterollowering agents), γ -amino butyric acid (an antihypertensive substance), dimerumic acid (an antioxidant), and pigments (food-grade colorants), and some strains can also secrete citrinin, a nephrotoxic metabolite. Monascus-related studies have received much attention because of their wide applications. However, to our knowledge, no systematic review on the progress of Monascus research has ever been published. In this review, the progress of research on Monascus is summarized into 3 stages: Monascus fermentation, Monascus molecular biology, and Monascus genomics. This review covers the past history, current status, and future direction of Monascus research, contributing to a comprehensive understanding of Monascus research progress.

Heterologous expression of the citrinin polyketide synthase, CitS, plus the tailoring enzymes CitA–CitE from Monascus ruber has fully elucidated the biosynthetic pathway to citrinin for the first time, showing relationships to tropolone, azaphilone and sorbicillinoid biosynthetic pathways in fungi.