Effects of Different NH_4^+/NO_3^- Ratio and Water Condition on Physiological Characteristics of Rice Seedlings

[Objective] This study aimed to further explore the dynamics of related physiological indexes of rice seedlings under different NH4＋ /NO3- ratio and different water condition. [Method] Under the hydroponic condition in laboratory, 3 NH4＋/NO3- ratios （0/100, 50/50 and 100/0） and 2 water conditions （＋PEG,-PEG） were designed for Fengliangyou 7203. [Result] The root-canopy ratio of rice seedlings increased under any of the NH4＋/NO3- ratios and water conditions. Under water stress, the root-canopy ratio of rice seedlings changed most greatly at the NH4＋/NO3- ratio of 0/ 100; the overall water potential of rice seedlings reached the lowest at the NH4＋/ NO3- ratio of 100/0; and the changes of water potential and xylem flow pH were relatively stable at the NH4＋/NO3- ratio of 50/50. Under the condition of no water stress, the growth of rice seedlings was best at the NH4＋/NO3- ratio of 50/50, followed by the NH4＋/NO3- ratios of 0/100 and 100/0. [Conclusion] This study will pro- vide a basis for understanding the relationship between water potential and xylem flow.

Improvement in bioconversion efficiency and reduction of ammonia emission by introduction of fruit fermentation broth in a black soldier fly larvae and kitchen waste conversion system

The black soldier fly(BSF),Hermetia illucens(Diptera:Stratiomyidae),is an insect commonly used for the bioconversion of various organic wastes.Not only can the BSF convert organic waste into macromolecular organic substances,such as insect pro-teins,but it can also lessen the pollution associated with these waste products by reducing ammonia emissions,for example.In this study,we measured the effects of adding fruit fermentation broth(Fer)and commercial lactic acid bacteria fermentation broth(Em)to kitchen waste(KW),as deodorizing auxiliary substances,on the growth performance of black soldier fly larvae(BSFL),the intestinal flora structure of BSFL,the ammonia emis-sion from the KW substrate,and the microbial community structure of the KW substrate.We found that the addition of Fer or Em increased the body weight of BSFL after 6 d of culture,increasing the growth rate by 9.96%and 7.96%,respectively.The addition of Fer not only reduced the pH of the KW substrate but also increased the relative abundance of probiotics,such as Lactobacillus,Lysinibacillus,and Vagococcus,which inhibited the growth of ammonifiers such as Bacillus,Oligella,Paenalcaligenes,Paenibacillus,Pseu-dogracilibacillus,and Pseudomonas,resulting in the reduction of ammonia emission in the KW substrate.Moreover,the addition of Fer or Em significantly increased the rela-tive abundances of Bacteroides,Campylobacter,Dysgonomonas,Enterococcus,and Ig-natzschineria in the gut of BSFL and increased the species diversity and richness in the K W substrate.Our findings provide a novel way to improve the conversion rate of organic waste and reduce the environmental pollution caused by BSF.

Coexpression network analysis reveals an MYB transcriptional activator involved in capsaicinoid biosynthesis in hot peppers

Plant biosynthesis involves numerous specialized metabolites with diverse chemical natures and biological activities.The biosynthesis of metabolites often exclusively occurs in response to tissue-specific combinatorial developmental cues that are controlled at the transcriptional level.Capsaicinoids are a group of specialized metabolites that confer a pungent flavor to pepper fruits.Capsaicinoid biosynthesis occurs in the fruit placenta and combines its developmental cues.Although the capsaicinoid biosynthetic pathway has been largely characterized,the regulatory mechanisms that control capsaicinoid metabolism have not been fully elucidated.In this study,we combined fruit placenta transcriptome data with weighted gene coexpression network analysis(WGCNA)to generate coexpression networks.A capsaicinoid-related gene module was identified in which the MYB transcription factor CaMYB48 plays a critical role in regulating capsaicinoid in pepper.Capsaicinoid biosynthetic gene(CBG)and CaMYB48 expression primarily occurs in the placenta and is consistent with capsaicinoid biosynthesis.CaMYB48 encodes a nucleus-localized protein that primarily functions as a transcriptional activator through its C-terminal activation motif.CaMYB48 regulates capsaicinoid biosynthesis by directly regulating the expression of CBGs,including AT3a and KasIa.Taken together,the results of this study indicate ways to generate robust networks optimized for the mining of CBG-related regulators,establishing a foundation for future research elucidating capsaicinoid regulation.