Two gene clusters and their positive regulator SlMYB13 that have undergone domestication-associated negative selection control phenolamide accumulation and drought tolerance in tomato.

Among plant metabolites, phenolamides, which are conjugates of hydroxycinnamic acid derivatives and polyamines, play important roles in plant adaptation to abiotic and biotic stresses. However, the molecular mechanisms underlying phenolamide metabolism and regulation as well as the effects of domestication and breeding on phenolamide diversity in tomato remain largely unclear. In this study, we performed a metabolite-based genome-wide association study and identified two biosynthetic gene clusters (BGC7 and BGC11) containing 12 genes involved in phenolamide metabolism, including four biosynthesis genes (two 4CL genes, one C3H gene, and one CPA gene), seven decoration genes (five AT genes and two UGT genes), and one transport protein gene (DTX29). Using gene co-expression network analysis we further discovered that SlMYB13 positively regulates the expression of two gene clusters, thereby promoting phenolamide accumulation. Genetic and physiological analyses showed that BGC7, BGC11 and SlMYB13 enhance drought tolerance by enhancing scavenging of reactive oxygen species and increasing abscisic acid content in tomato. Natural variation analysis suggested that BGC7, BGC11 and SlMYB13 were negatively selected during tomato domestication and improvement, leading to reduced phenolamide content and drought tolerance of cultivated tomato. Collectively, our study discovers a key mechanism of phenolamide biosynthesis and regulation in tomato and reveals that crop domestication and improvement shapes metabolic diversity to affect plant environmental adaptation.

Receiver performance characteristics of single-photon lidar in a strong background environment.

The detection performance of the single-photon lidar (SPL) receiver is investigated as a function of optical attenuation and superconducting nanowire single-photon detector (SNSPD) parameters (detection efficiency and dead time) in a strong background environment. With detection theory, it is found that there is optimal attenuation to make detection probability the highest at a given false alarm probability, namely, optimal working conditions. Optical attenuation is proved to be required only when the background photon number is higher than a certain value; otherwise, it is not necessary. Furthermore, the performance of a Geiger-mode avalanche photodiode (GMAPD) is compared. Under optimized working conditions, the SNSPD-based receiver exhibits higher detection performance in a strong background environment than that of the GMAPD-based receiver due to shorter dead time, while in a low-noise environment, attenuation is not essential, and detection efficiency becomes the dominant factor. The theoretical result gives a reference for the SPL receiver system design to achieve optimal detection performance.