Copper-induced alteration in sucrose partitioning and its relationship to the root growth of two Elsholtzia haichowensis Sun populations

Modification of Sugar Profile and Ripening in Atemoya (Annona × atemoya Mabb.) Fruits through Copper Hydroxide Application

Atemoya (Annona × atemoya Mabb.), a climacteric fruit of the Annonaceae family, is becoming increasingly popular due to its organoleptic and nutritional properties. Anthracnose, a fungus of the Colletotrichum genus, is one of the most serious diseases in orchards, causing significant damage if not controlled, so producers use phytosanitary products. The current study sought to investigate the quality of atemoya fruits after harvest in an orchard with anthracnose controlled by Cu(OH)² application: T1-no Cu(OH)², T2-7.8 mL Cu(OH)² L1 divided into two applications, T3-15.6 mL Cu(OH)² L1 divided into four, T4-8.0 mL Cu(OH)² L1 divided into eight, and T5-13.0 mL Cu(OH)² L1 divided into thirteen applications. The sugar profile of fruits was examined, as well as MDA, H₂O₂, and quality parameters such as pH, mass, soluble solids, titratable acidity, and maturation index. MDA, such as H₂O₂, can function as a signal molecule. Eight applications of 1.0 mL L-1 Cu(OH)² resulted in increased concentrations of H₂O₂ and MDA, signal molecules involved in sugar modification profiles such as glucose, fructose, and trehalose. It also had a high titratable acidity, a lower maturation index, better fruit quality, and a longer shelf life.

Cloning and functional analysis of soluble acid invertase 2 gene (SbSAI-2) in sorghum

The sorghum soluble acid invertase gene SbSAI-2 was cloned and the function verified in Pichia pastoris and rice, showing the SbSAI-2 affects composition and content of sugar in stem juice. Sugar metabolism is one of the most important metabolic processes in plants, in which soluble acid invertase plays a key role. However, the structure and function of the soluble acid transferase gene in sorghum are still fully unclear. In this study, SbSAI-2 was cloned from the sorghum variety BTx623, and two transcripts were found through sequence analysis, with only one transcript translated into an active protein. There is 72% homology between SbSAI-2 and OsVIN2. The construction of Osvin2 mutant lines and SbSAI-2-1 overexpression lines in Oryza sativa L. japonica. cv. Nipponbare were produced to clarify the invertase functionality. While the invertase activity in the stem of the Osvin2 mutant line was reduced, with no significant difference (P  > 0.05), and the contents of fructose and glucose in stem tissue did not change significantly (P  > 0.05), and the content of sucrose increased by 38.89% (P  < 0.01). In SbSAI-2-1 overexpression lines, the invertase activity in stem was increased by more than 20 times (P  < 0.01). The contents of glucose and fructose in stem tissues were increased by two and three times, respectively (P  < 0.01), while the content of sucrose was significantly decreased, which was below the detection limit (P  < 0.01). This study indicated that SbSAI-2 is a key enzyme related to sucrose metabolism and affects the composition and content of sugar in stems. The result provided further the gene function verification and laid a foundation for the development of molecular markers.

Comparison and Characterization of a Cell Wall Invertase Promoter from Cu-Tolerant and Non-Tolerant Populations of Elsholtzia haichowensis

Cell wall invertase (CWIN) activity and the expression of the corresponding gene were previously observed to be significantly elevated in a Cu-tolerant population of Elsholtzia haichowensis relative to a non-tolerant population under copper stress. To understand the differences in CWIN gene regulation between the two populations, their CWIN promoter β-glucuronidase (GUS) reporter vectors were constructed. GUS activity was measured in transgenic Arabidopsis in response to copper, sugar, and phytohormone treatments. Under the copper treatment, only the activity of the CWIN promoter from the Cu-tolerant population was slightly increased. Glucose and fructose significantly induced the activity of CWIN promoters from both populations. Among the phytohormone treatments, only salicylic acid induced significantly higher (p < 0.05) activity of the Cu-tolerant CWIN promoter relative to the non-tolerant promoters. Analysis of 5′-deletion constructs revealed that a 270-bp promoter fragment was required for SA induction of the promoter from the Cu-tolerant population. Comparison of this region in the two CWIN promoters revealed that it had 10 mutation sites and contained CAAT-box and W-box cis-elements in the Cu-tolerant promoter only. This work provides insights into the regulatory role of SA in CWIN gene expression and offers an explanation for differences in CWIN expression between E. haichowensis populations.