RESUMO
Magnesium (Mg) plays an irreplaceable role in plant growth and development. Mg transporters, especially CorA/MGT/MRS2 family proteins, played a vital role in regulating Mg content in plant cells. Although extensive work has been conducted in model crops, such as Arabidopsis, rice, and maize, the relevant information is scarce in tropical crops. In this study, 10 MaMRS2 genes in banana (Musa acuminata) were isolated from its genome and classified into five distinct clades. The putative physiochemical properties, chromosome location, gene structure, cis-acting elements, and duplication relationships in between these members were analyzed. Complementary experiments revealed that three MaMRS2 gene members (MaMRS2-1, MaMRS2-4, MaMRS2-7), from three distinct phylogenetic branches, were capable of restoring the function of Mg transport in Salmonella typhimurium mutants. Semi-quantitative RT-PCR showed that MaMRS2 genes were differentially expressed in banana cultivar 'Baxijiao' (Musa spp. AAA Cavendish) seedlings. The result was confirmed by real-time PCR analysis, in addition to tissue specific expression, expression differences among MaMRS2 members were also observed under Mg deficiency conditions. These results showed that Mg transporters may play a versatile role in banana growth and development, and our work will shed light on the functional analysis of Mg transporters in banana.
Assuntos
Proteínas de Transporte de Cátions/metabolismo , Magnésio/metabolismo , Musa/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Transporte de Cátions/genética , Mapeamento Cromossômico , Galactolipídeos/genética , Duplicação Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Teste de Complementação Genética , Família Multigênica , Musa/genética , Musa/crescimento & desenvolvimento , Oryza/genética , Filogenia , Proteínas de Plantas/genética , Regiões Promotoras Genéticas , Leveduras/genética , Zea mays/genéticaRESUMO
Cyanobacterial monoglucosyldiacylglycerol (MGlcDG) not only serves as a precursor for monogalactosyldiacylglycerol (MGDG) synthesis, but also participates in stress acclimation. Two genes (mgdA and mgdE) related to MGDG synthesis of Synechococcus sp. PCC 7942 were identified. The mgdE-suppressed mutant (AE) accumulated MGlcDG (4.2%) and showed better growth and photosynthetic activities compared with WT and other mutants (mgdA/mgdE-overexpressed and mgdA-suppressed strains), which suggested that MGlcDG was involved in phosphate stress adaptation for Synechococcus sp. PCC 7942. A notable increase in contents of 18:1 fatty acid (FA) of MGDG (127%), DGDG (68%), and SQDG (105%) in AE were found under phosphate starvation. However, the expression of â³9 desaturase (desC) was not higher in AE than that in WT during phosphate-starved period. These results suggested that MGlcDG might be involved in the process of FA desaturation, which contributed to membrane fluidity and cell basic metabolism for stress acclimation in cyanobacteria. In complementary experiments of E. coli, although the expression of mgdA and desC in the mgdA and desC coexpressed strain (OEAC) reduced by 22% and 35% compared with that of the strains only overexpressing mgdA (OEA) or desC (OEC), the content of unsaturated FA in OEAC was the highest. This further implied that the accumulation of MGlcDG could prompt FA desaturation in E. coli. Therefore, we propose that an overproduction of MGlcDG is responsible for FA desaturation and participates in phosphate stress adaptation in cyanobacteria.
Assuntos
Galactolipídeos/metabolismo , Fosfatos/metabolismo , Synechococcus/fisiologia , Adaptação Fisiológica , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Galactolipídeos/genética , Genes Bacterianos , Estresse Fisiológico , Synechococcus/genéticaRESUMO
During evolution, the male gametophyte of Angiosperms has been severely reduced to the pollen grain, consisting of a vegetative cell containing two sperm cells. This vegetative cell has to deliver the sperm cells from the stigma through the style to the ovule. It does so by producing a pollen tube and elongating it to many centimeters in length in some species, requiring vast amounts of fatty acid and membrane lipid synthesis. In order to optimize this polar tip growth, a unique lipid composition in the pollen has evolved. Pollen tubes produce extraplastidial galactolipids and store triacylglycerols in lipid droplets, probably needed as precursors of glycerolipids or for acyl editing. They also possess special sterol and sphingolipid moieties that might together form microdomains in the membranes. The individual lipid classes, the proteins involved in their synthesis as well as the corresponding Arabidopsis knockout mutant phenotypes are discussed in this review. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.