Analysis of Soluble Sugar Content in Minute Quantities of Rice Tissues by GC-MS.

Soluble sugars play key roles in plant growth, development, and adaption to the environment. Characterizing sugar content profiling of plant tissues promotes our understanding of the mechanisms underlying these plant processes. Several technologies have been developed to quantitate soluble sugar content in plant tissues; however, it is difficult with only minute quantities of plant tissues available. Here, we provide a detailed protocol for gas chromatography mass spectrometry (GC-MS)-based soluble sugar profiling of rice tissues that offers a good balance of sensitivity and reliability, and is considerably more sensitive and accurate than other reported methods. We summarize all the steps from sample collection and soluble sugar extraction to derivatization procedures of the soluble extracted sugars, instrumentation settings, and data analysis.

Plasmodesmata play pivotal role in sucrose supply to Meloidogyne graminicola-caused giant cells in rice.

On infection, plant-parasitic nematodes establish feeding sites in roots from which they take up carbohydrates among other nutrients. Knowledge on how carbohydrates are supplied to the nematodes' feeding sites is limited. Here, gene expression analyses showed that RNA levels of OsSWEET11 to OsSWEET15 were extremely low in both Meloidogyne graminicola (Mg)-caused galls and noninoculated roots. All the rice sucrose transporter genes, OsSUT1 to OsSUT5, were either down-regulated in Mg-caused galls compared with noninoculated rice roots or had very low transcript abundance. OsSUT1 was the only gene up-regulated in galls, at 14 days postinoculation (dpi), after being highly down-regulated at 3 and 7 dpi. OsSUT4 was down-regulated at 3 dpi. No noticeable OsSUTs promoter activities were detected in Mg-caused galls of pOsSUT1 to -5::GUS rice lines. Loading experiments with carboxyfluorescein diacetate (CFDA) demonstrated that symplastic connections exist between phloem and Mg-caused giant cells (GCs). According to data from OsGNS5- and OsGSL2-overexpressing rice plants that had decreased and increased callose deposition, respectively, callose negatively affected Mg parasitism and sucrose supply to Mg-caused GCs. Our results suggest that plasmodesmata-mediated sucrose transport plays a pivotal role in sucrose supply from rice root phloem to Mg-caused GCs, and OsSWEET11 to -15 and OsSUTs are not major players in it, although further functional analysis is needed for OsSUT1 and OsSUT4.