A chromosome-level genome assembly of Agave hybrid NO.11648 provides insights into the CAM photosynthesis.

The subfamily Agavoideae comprises crassulacean acid metabolism (CAM), C3, and C4 plants with a young age of speciation and slower mutation accumulation, making it a model crop for studying CAM evolution. However, the genetic mechanism underlying CAM evolution remains unclear because of lacking genomic information. This study assembled the genome of Agave hybrid NO.11648, a constitutive CAM plant belonging to subfamily Agavoideae, at the chromosome level using data generated from high-throughput chromosome conformation capture, Nanopore, and Illumina techniques, resulting in 30 pseudo-chromosomes with a size of 4.87 Gb and scaffold N50 of 186.42 Mb. The genome annotation revealed 58 841 protein-coding genes and 76.91% repetitive sequences, with the dominant repetitive sequences being the I-type repeats (Copia and Gypsy accounting for 18.34% and 13.5% of the genome, respectively). Our findings also provide support for a whole genome duplication event in the lineage leading to A. hybrid, which occurred after its divergence from subfamily Asparagoideae. Moreover, we identified a gene duplication event in the phosphoenolpyruvate carboxylase kinase (PEPCK) gene family and revealed that three PEPCK genes (PEPCK3, PEPCK5, and PEPCK12) were involved in the CAM pathway. More importantly, we identified transcription factors enriched in the circadian rhythm, MAPK signaling, and plant hormone signal pathway that regulate the PEPCK3 expression by analysing the transcriptome and using yeast one-hybrid assays. Our results shed light on CAM evolution and offer an essential resource for the molecular breeding program of Agave spp.

Two Short-Wave UV Antimony(III) Sulfates Exhibiting Large Birefringence.

In the present work, we have successfully obtained two new UV antimony-based sulfates, NH4Sb(SO4)2 and Ca2Sb2O(SO4)4, by a conventional hydrothermal method. Interestingly, both compounds share similar structural building blocks, such as SbO4 seesaws and SO4 tetrahedra, yet they endow discrepant birefringence values measured at 546 nm with values of 0.150 and 0.114, respectively, owing to the different distortions of the SbO4 groups with SCALP electrons. Moreover, both compounds display large band gaps (4.32 and 4.43 eV, respectively), so they can be used as short-wavelength UV birefringent materials. Moreover, NH4Sb(SO4)2 is a noncentrosymmetric compound, showing a frequency doubling effect of 0.2 × KDP. Detailed structural analyses and calculations confirm the source of superior optical performance and the reasons for the different birefringence of the two compounds. This work provides ideas for the following discovery of antimony-based optical materials with excellent properties.

Genome-Wide Investigation of BAM Gene Family in Annona atemoya: Evolution and Expression Network Profiles during Fruit Ripening.

ß-amylase proteins (BAM) are important to many aspects of physiological process such as starch degradation. However, little information was available about the BAM genes in Annona atemoya, an important tropical fruit. Seven BAM genes containing the conservative domain of glycoside hydrolase family 14 (PF01373) were identified with Annona atemoya genome, and these BAM genes can be divided into four groups. Subcellular localization analysis revealed that AaBAM3 and AaBAM9 were located in the chloroplast, and AaBAM1.2 was located in the cell membrane and the chloroplast. The AaBAMs belonging to Subfamily I contribute to starch degradation have the higher expression than those belonging to Subfamily II. The analysis of the expression showed that AaBAM3 may function in the whole fruit ripening process, and AaBAM1.2 may be important to starch degradation in other organs. Temperature and ethylene affect the expression of major AaBAM genes in Subfamily I during fruit ripening. These expressions and subcellular localization results indicating ß-amylase play an important role in starch degradation.

A GmSIN1/GmNCED3s/GmRbohBs Feed-Forward Loop Acts as a Signal Amplifier That Regulates Root Growth in Soybean Exposed to Salt Stress.

Abscisic acid (ABA) and reactive oxygen species (ROS) act as key signaling molecules in the plant response to salt stress; however, how these signals are transduced and amplified remains unclear. Here, a soybean (Glycine max) salinity-induced NAM/ATAF1/2/CUC2 (NAC) transcription factor encoded by SALT INDUCED NAC1 (GmSIN1) was shown to be a key component of this process. Overexpression of GmSIN1 in soybean promoted root growth and salt tolerance and increased yield under salt stress; RNA interference-mediated knockdown of GmSIN1 had the opposite effect. The rapid induction of GmSIN1 in response to salinity required ABA and ROS, and the effect of GmSIN1 on root elongation and salt tolerance was achieved by boosting cellular ABA and ROS contents. GmSIN1 upregulated 9-cis-epoxycarotenoid dioxygenase coding genes in soybean (GmNCED3s, associated with ABA synthesis) and Respiratory burst oxidase homolog B genes in soybean (GmRbohBs, associated with ROS generation) by binding to their promoters at a site that has not been described to date. Together, GmSIN1, GmNCED3s, and GmRbohBs constitute a positive feed-forward system that enables the rapid accumulation of ABA and ROS, effectively amplifying the initial salt stress signal. These findings suggest that the combined modulation of ABA and ROS contents enhances soybean salt tolerance.