Untitled

Abstract

Carbon assimilation in maize follows the C(4) mechanism. This requires the tissue-specific and light-induced expression of a set of different genes involved in CO(2) fixation as well as adaptations in the leaf anatomy including a reduced distance between vascular bundles compared to C(3) plants. However, several maize tissues exist with larger bundle distances and there is significant evidence that CO(2) fixation follows the C(3) mechanism in these tissues. We isolated maize C(3) and C(4) tissues and quantified the accumulation of mRNAs encoding PEPC, ME, the small subunit of Rubisco, and PPDK. For this, primer systems for the specific and sensitive detection by real-time PCR were established. The observed patterns show the expected distribution for foliar leaf tissues. Also in total husk leaves, all transcripts under investigation were detected, albeit at a lower level. When mesophyll cells which are located distant from bundles were isolated from husk leaves, only accumulation of RbcS was observed. Comparing the expression of two genes encoding for isoenzymes of the small subunit of RbcS in the different tissues differential patterns of relative transcript abundance were observed. Transcripts for the DOF1 transcription factor involved in the activation of photosynthetic genes in maize were found in leaf tissues performing both C(4) and C(3) photosynthesis with highest accumulation levels in C(4) mesophyll cells, whereas the homologous DOF2 gene was not expressed in any of the investigated samples. The results provide novel insights into the regulation of C(3) and C(4) carbon fixation pathways in maize.

RBCS1A and RBCS3B, two major members within the Arabidopsis RBCS multigene family, function to yield sufficient Rubisco content for leaf photosynthetic capacity

“…The RBCS multigene family consists of 2–22 members, depending on the species (Sasanuma, 2001; Spreitzer, 2003). The number of expressing members and transcript abundance within the RBCS multigene family have been investigated in different tissues, under different environments, and/or during tissue development in some plant species including tomato (Wanner and Gruissem, 1991; Meier et al , 1995), Lemna gibba (Silverthorne and Tobin, 1990; Silverthorne et al , 1990), Arabidopsis (Dedonder et al , 1993; Cheng et al , 1998; Yoon et al , 2001), French bean (Knight and Jenkins, 1992; Sawbridge et al , 1996), maize (Ewing et al , 1998; Hahnen et al , 2003), wheat (Galili et al , 1998), rice (Suzuki et al , 2009 b ), and Eucalyptus (Suzuki et al , 2010). In rice, it has been demonstrated that four out of the five RBCS genes are highly expressed in leaf blades and that the total RBCS mRNA level is highly correlated with Rubisco content at their maxima irrespective of tissues and growth stages (Suzuki et al , 2009 a , b ).…”

Polyethylenimine-Functionalized Corn Bract, an Agricultural Waste Material, for Efficient Removal and Recovery of Cr(VI) from Aqueous Solution

“…For corn bract (CB), as a typical agricultural waste, open burning is a usual disposal method and occurs more frequently in grain-producing regions, with increasing crop yields in China . However, the burning has been considered as an important source of carbonaceous species.…”