Chlorophyll (Chl) content, especially Chl b content, and stomatal conductance (G_s) are key factors that greatly affect net photosynthetic rate (P_n).  Setaria italica, a diploid C₄ panicoid species with a simple genome and high transformation efficiency, has been widely accepted as a model in photosynthesis and drought-tolerance research.  In the current study, Chl content, G_s, and P_n of 48 Setaria mutants induced by ethyl methanesulfonate were characterized.  A total of 24, 34 and 35 mutants had significant variations in Chl content, G_s, and P_n, respectively. Correlation analysis showed that positive correlation exists between increased G_s and increased Pn, and a weak correlation between decreased Chl b content and decreased P_n was also found. Remarkably, two mutants behaved significantly decreased Chl b content but increased P_n when compared that of Yugu 1. Seven mutants behaved significantly decreased G_s but non-decreasing P_n when compared that of Yugu 1.  The current study thus identified various genetic lines, further exploration of which would be beneficial to elucidate the relationship between Chl content, G_s and P_n and the mechanism underlying why C₄ species are efficient at photosynthesis and water saving.

    Quorum sensing (QS) is a type of microbe-microbe communication system that is widespread among the microbial world, particularly among microorganisms that are symbiotic with plants and animals. Thereby, the cell-cell signalling is likely to occur in an anaerobic rumen environment, which is a complex microbial ecosystem. In this study, using six ruminally fistulated Liuyang black goats as experimental animals, we aimed to detect the activity of quorum sensing autoinducers (AI) both in vivo and in vitro and to clone the luxS gene that encoded autoinducer-2 (AI-2) synthase of microbial samples that were collected from the rumen of goats. Neutral detergent fiber (NDF) and soluble starch were the two types of substrates that were used for in vitro fermentation. The fermented fluid samples were collected at 0, 2, 4, 6, 8, 12, 24, 36, and 48 h of incubation. The acyl-homoserine lactones (AHLs) activity was determined using gas chromatography-mass spectrometer (GC-MS) analysis. However, none of the rumen fluid extracts that were collected from the goat rumen showed the same or similar fragmentation pattern to AHLs standards. Meanwhile, the AI-2 activity, assayed using a Vibrio harveyi BB170 bioassay, was negative in all samples that were collected from the goat rumen and from in vitro fermentation fluids. Our results indicated that the activities of AHLs and AI-2 were not detected in the ruminal contents from six goats and in ruminal fluids obtained from in vitro fermentation at different sampling time-points. However, the homologues of luxS in Prevotella ruminicola were cloned from in vivo and in vitro ruminal fluids. We concluded that AHLs and AI-2 could not be detected in in vivo and in vitro ruminal fluids of goats using the current detection techniques under current dietary conditions. However, the microbes that inhabited the goat rumen had the potential ability to secrete AI-2 signaling molecules and to communicate with each other via AI-2-mediated QS because of the presence of luxS.