HbNIN2, a cytosolic alkaline/neutral‐invertase, is responsible for sucrose catabolism in rubber‐producing laticifers of Hevea brasiliensis (para rubber tree)

Abstract

Summary In Hevea brasiliensis, an alkaline/neutral invertase (A/N‐Inv) is responsible for sucrose catabolism in latex (essentially the cytoplasm of rubber‐producing laticifers, the source of natural rubber) and implicated in rubber yield. However, neither the gene encoding this enzyme nor its molecular and biochemical properties have been well documented. Three Hevea A/N‐Inv genes, namely HbNIN1, 2 and 3, were first cloned and characterized in planta and in Escherichia coli. Cellular localizations of HbNIN2 mRNA and protein were probed. From latex, active A/N‐Inv proteins were purified, identified, and explored for enzymatic properties. HbNIN2 was identified as the major A/N‐Inv gene functioning in latex based on its functionality in E. coli, its latex‐predominant expression, the conspicuous localization of its mRNA and protein in the laticifers, and its expressional correlation with rubber yield. An active A/N‐Inv protein was partially purified from latex, and determined as HbNIN2. The enhancement of HbNIN2 enzymatic activity by pyridoxal is peculiar to A/N‐Invs in other plants. We conclude that HbNIN2, a cytosolic A/N‐Inv, is responsible for sucrose catabolism in rubber laticifers. The results contribute to the studies of sucrose catabolism in plants as a whole and natural rubber synthesis in particular.

Suppression of extracellular invertase inhibitor gene expression improves seed weight in soybean (Glycine max)

“…The roles of VI in the major regulation of carbon metabolism, hexose distribution, cellular osmolarity, and oxidative stress defense have been extensively explored (Kohorn et al , 2006; Sergeeva et al , 2006; Nägele et al , 2010; Xiang et al , 2011; Liu et al , 2015). Suppression of VI activities alters soluble sugar conversion, thereby decreasing cold-induced sweetening in potato tubers (Bagnaresi et al , 2008; Bhaskar et al , 2010; Zhu et al , 2016) and affecting fruit size (Klann et al , 1996; Tang et al , 1999; Yu et al , 2008).…”

Characterization of the alkaline/neutral invertase gene in Dendrobium officinale and its relationship with polysaccharide accumulation

“…NI regulates sucrose metabolism in many plants, including Saccharum officinarum, Beta vulgaris, and Citrus reticulata (Hubbard et al, 1991), and plays an important role in monosaccharide-dependent biosynthesis (Nonis et al, 2007). In order to investigate the role of NI in polysaccharide-synthesis regulation, several NI cDNAs have been cloned from Solanum lycopersicum, Hevea brasiliensis, Saccharum officinarum, and Oryza sativa (Gallagher and Pollock, 1998;Murayama and Handa, 2007;Bocock et al, 2008;Liu et al, 2015), and differential NI expression has been reported in different plant tissues, e.g., in tomato, higher mRNA levels have been detected in the fruit and leaves than in the flowers and stems. In contrast, in Hevea brasiliensis, the highest mRNA levels were detected in the bark and leaves.…”

Validation of reference genes for quantitative real-time PCR during latex regeneration in rubber tree

“…At present, the development of molecular biology makes the studies of gene expression and regulation related to natural rubber biosynthesis become a hotspot in undressing the mechanisms of latex regeneration. For instance, several researchers have focused on the genes involved in the supply and utility of sucrose in the latex, using gene expression profile especially qPCR analysis (Dusotoit-Coucaud et al, 2010;Tang et al, 2010;Liu et al, 2015). To reveal the underlying molecular mechanism and regulatory network of latex regeneration, it is necessary and crucial to screen the suitable reference genes for normalization in relevant gene expression analysis.…”