Evolutionary Conservation and Expression Patterns of Neutral/Alkaline Invertases in Solanum

Abstract

The invertase gene family in plants is composed of two subfamilies of enzymes, namely, acid-and neutral/alkaline invertases (cytosolic invertase, CIN). Both can irreversibly cleave sucrose into fructose and glucose, which are thought to play key roles in carbon metabolism and plant growth. CINs are widely found in plants, but little is reported about this family. In this paper, a comparative genomic approach was used to analyze the CIN gene family in Solanum, including Solanum tuberosum, Solanum lycopersicum, Solanum pennellii, Solanum pimpinellifolium, and Solanum melongena. A total of 40 CINs were identified in five Solanum plants, and sequence features, phylogenetic relationships, motif compositions, gene structure, collinear relationship, and expression profile were further analyzed. Sequence analysis revealed a remarkable conservation of CINs in sequence length, gene number, and molecular weight. The previously verified four amino acid residues (D188, E414, Arg430, and Ser547) were also observed in 39 out of 40 CINs in our study, showing to be deeply conserved. The CIN gene family could be distinguished into groups α and β, and α is further subdivided into subgroups α1 and α2 in our phylogenetic tree. More remarkably, each species has an average of four CINs in the α and β groups. Marked interspecies conservation and collinearity of CINs were also further revealed by chromosome mapping. Exon-intron configuration and conserved motifs were consistent in each of these α and β groups on the basis of in silico analysis. Expression analysis indicated that CINs were constitutively expressed and share similar expression profiles in all tested samples from S. tuberosum and S. lycopersicum. In addition, in CIN genes of the tomato and potato in response to abiotic and biotic stresses, phytohormones also performed. Overall, CINs in Solanum were encoded by a small and highly conserved gene family, possibly reflecting structural and functional conservation in Solanum. These results lay the foundation for further expounding the functional characterization of CIN genes and are also significant for understanding the evolutionary profiling of the CIN gene family in Solanum.

Structure and Expression Analysis of Sucrose Phosphate Synthase, Sucrose Synthase and Invertase Gene Families in Solanum lycopersicum

“…However, there was an exception in SlINVAN1 , which contained seven exons ( Figure S1D ). It should be pointed out that the exon numbers of SlINVAN1 and SlINVAN6 found in this study were inconsistent with the study of Pan et al [ 2 ]. The differences may be related to the differences in the genomic annotations, which remain to be further explored.…”

“…With the development of sequencing technology and bioinformatics, the family genes encoding these enzymes have been identified and the structure characteristics have also been analyzed in some plants, such as Arabidopsis and rice [ 6 , 7 , 11 , 14 ]. In tomato, although some genes of SPS , SUS and INV families have been identified [ 2 , 5 , 11 , 17 ], a comprehensive analysis of the structure characteristics and evolution of these genes is still lacking. Moreover, the expression responses of these genes to environmental stimuli are largely unknown.…”

“…Sucrose plays an important role in plant growth and development. On the one hand, it provides energy and structural components of plants; on the other hand, sucrose and its hydrolysis products may function as signaling molecules, which regulate the expression of genes involved in important physiological processes [ 2 , 3 ]. Sucrose also functions in osmotic adjustment [ 3 ] and thus plays an important role in stress adaption.…”

“…Invertases can be classified as acid invertase and alkaline/neutral (A/N) invertase based on their optimum pH [ 5 ]. Acid invertases are usually localized in the cell wall or vacuole, and alkaline/neutral invertases are localized in the cytosol, mitochondria or plastid [ 2 ]. SUS proteins are mainly localized in the cytosol or plasma membrane, and some are localized in the vacuole, cell wall or mitochondria [ 1 ].…”

“…There are eight acid invertase genes and six A/N invertase genes in sugarcane [ 15 ], and these corresponding numbers in soybean are nineteen and thirteen, respectively [ 16 ]. In tomato ( Solanum lycopersicum ), an important vegetable crop, four SPS genes [ 17 ], six SUS genes [ 11 ], eleven acid invertase genes [ 5 ] and eight alkaline/neutral invertase encoding genes [ 2 ] have also been identified. However, the structure characteristics of the genes have not been comprehensively analyzed, except those of one type of invertase—A/N invertase [ 2 ].…”