A Novel Endo-β-Mannanase Gene in Tomato LeMAN5 Is Associated with Anther and Pollen Development

Abstract

Endo-β-mannanase (EC 3.2.1.78) is involved in cell wall disassembly and the weakening of plant tissues by degrading mannan polymers in the cell walls. Endo-β-mannanase genes are expressed in tomato (Lycopersicon esculentum) seeds (LeMAN1 and LeMAN2) and fruits (LeMAN3 and LeMAN4). A novel endo-β-mannanase gene (termed LeMAN5) was found in the tomato genome by genome-walking PCR and bacterial artificial chromosome library screening. The 5′-upstream region of this endo-β-mannanase gene contained four copies of the pollen-specific cis-acting elements POLLEN1LELAT52 (AGAAA). A GUS-reporter gene driven with the putative LeMAN5 promoter (-543 to +38) was activated in anthers and pollen of transgenic Arabidopsis, with the highest β-glucuronidase activity detected in pollen. β-Glucuronidase expression was detected in mature pollen retained in sporangia, discharged pollen, and elongating pollen tubes in transgenic Arabidopsis. Consistently, expression of LeMAN5 mRNA and endo-β-mannnanase activity was detected in tomato anthers and pollen. In anthers, the highest mRNA expression and endo-β-mannanase activity were detected during late stages of anther development, when pollen maturation occurred. Endo-β-mannanase activity was present in discharged pollen, which was easily eluted in a buffer, indicating that the enzyme proteins are probably secreted from, and deposited on, the surface of pollen. These data suggest that the LeMAN5 endo-β-mannanase is associated with anther and pollen development.

Genome-wide identification and characterization of the Dof gene family in Medicago truncatula

“…The results of the ciselements analysis confirmed that the functional diversities of the MtDof genes are mainly involved in tissue development, response to environmental stress, and interactions with other TFs. For example, motifs related to tissue development, including CAATBOX1 related to tissue-specific promoter activity (Shirsat et al, 1989), ROOTMOTIFTAPOX1 related to root development (Elmayan and Tepfer, 1995), POLLEN1LELAT52 and GTGANTG10 related to flower development (Rogers et al, 2001;Filichkin et al, 2004), and CACTFTPPCA1 related to leaf development (Gowik et al, 2004), were extensively present in the MtDof genes, and thus, most of these were highly expressed in roots, blades, buds, flowers, and seedpods. In addition, light responsive elements were also identified, such as GT1CONSENSUS (Terzaghi and Cashmore, 1995), and these were widely represented in the MtDof genes.…”

Properties and Physiological Functions of UDP-Sugar Pyrophosphorylase inArabidopsis

“…As is the case in other tissues, several cell-wall glycosidases have been identified in pollen development. 22,23) Monosaccharides released from cell-wall polysaccharides by glycosidases are perhaps converted to UDP-sugars by the action of several monosaccharide kinases and AtUSP, and then serve as substrates for glycosyltransferases in developing pollens. Recently, Schnurr et al found by scanning and transmission electron microscopy that usp mutations (usp-1 and usp-2) prevent the synthesis of the pectocellulosic inner wall of pollens.…”

Functional Genomic Analysis Supports Conservation of Function Among Cellulose Synthase-Like A Gene Family Members and Suggests Diverse Roles of Mannans in Plants

“…In tomato (Lycopersicon esculentum), mannan metabolic enzymes, including endo-b-mannanase and mannan transglycosylase, are present in a variety of tissues. Endob-mannanase activity is observed in tomato fruits, anthers, and pollen grains (Filichkin et al, 2004). Mannan transglycosylase activity, potentially involved in reorganization of mannan polysaccharides, is present in tissues from a variety of plants (Schroder et al, 2004), and organs/tissues.…”