Kentaro Kawaguchi

Analysis of Proteins in Aerenchymatous Seminal Roots of Wheat Grown in Hypoxic Soils Under Waterlogged Conditions (supplementary Material)

Hypoxia caused by waterlogging results in a severe loss of crop production. At the primary stage of wheat development, the seminal roots have strategies to survive under hypoxia through alternative metabolism coupling root anatomical modification. The present study used a model system of lysigenous aerenchymatous seminal roots from a representative seedling stage of wheat to elucidate the root physiology in response to soil hypoxia. Seminal roots characteristic with lysigenous aerenchyma tissues were developed in pot cultures for 7 days under two hypoxic conditions, water depths of 15 cm below and 3 cm above the soil surface. Proteins from the roots were separated using two-dimensional polyacrylamide gel electrophoresis and identified using mass spectrometry. The results showed that approximately 345 distinct protein spots were detected by 2-DE, 29 spots changed in the expression levels between the control and two hypoxic plants, and 10 spots exhibited a reproducible up- or down regulated fluctuation. The up-regulated proteins were thought to be involved in alteration in energy and redox status, defense responses and cell wall turnover. These results suggest the effects of soil hypoxia on the activity of the identified up-regulated proteins and their roles in alternative respiration and cell degeneration in wheat in order to gain metabolic adjustment under hypoxia stress.

Characterization of Arabinogalactan-Proteins and a Related Oligosaccharide in Developing Rice Anthers

Male sterility induced by chilling temperature (12–18°C) at the booting stage causes serious loss of grain yield in rice, one of the most serious problems for Asian agriculture. To resolve this problem, it is important to understand the physiological mechanisms of chilling injury during pollen development. Male gametogenesis is a very important step in plant reproduction and is known to be very sensitive to various forms of environmental stress, including chilling. Meiosis and mitosis are important events in gametogenesis, as are rapid turnovers of pollen walls that occur through interactions between microspores and tapetal cells. Although many anther-specific genes have been identified, the physiological or biochemical basis of male gametogenesis is not well understood. Thus, the physiological and biochemical characterization of these processes is essential for understanding agronomically important phenomena such as chilling injury in rice.

Quantitative Proteomics of the Root of Transgenic Wheat Expressing TaBWPR-1.2 Genes in Response to Waterlogging

Once candidate genes are available, the application of genetic transformation plays a major part to study their function in plants for adaptation to respective environmental stresses, including waterlogging (WL). The introduction of stress-inducible genes into wheat remains difficult because of low transformation and plant regeneration efficiencies and expression variability and instability. Earlier, we found two cDNAs encoding WL stress-responsive wheat pathogenesis-related proteins 1.2 (TaBWPR-1.2), TaBWPR-1.2#2 and TaBWPR-1.2#13. Using microprojectile bombardment, both cDNAs were introduced into “Bobwhite”. Despite low transformation efficiency, four independent T2 homozygous lines for each gene were isolated, where transgenes were ubiquitously and variously expressed. The highest transgene expression was obtained in Ubi:TaBWPR-1.2#2 L#11a and Ubi:TaBWPR-1.2#13 L#4a. Using quantitative proteomics, the root proteins of L#11a were analyzed to explore possible physiological pathways regulated by TaBWPR-1.2 under normal and waterlogged conditions. In L#11a, the abundance of proteasome subunit alpha type-3 decreased under normal conditions, whereas that of ferredoxin precursor and elongation factor-2 increased under waterlogged conditions in comparison with normal plants. Proteomic results suggest that L#11a is one of the engineered wheat plants where TaBWPR-1.2#2 is most probably involved in proteolysis, protein synthesis and alteration in the energy pathway in root tissues via the above proteins in order to gain metabolic adjustment to WL.