Expansins expression is associated with grain size dynamics in wheat (Triticum aestivum L.)

Abstract

Grain weight is one of the most important components of cereal yield and quality. A clearer understanding of the physiological and molecular determinants of this complex trait would provide an insight into the potential benefits for plant breeding. In the present study, the dynamics of dry matter accumulation, water uptake, and grain size in parallel with the expression of expansins during grain growth in wheat were analysed. The stabilized water content of grains showed a strong association with final grain weight (r2=0.88, P <0.01). Grain length was found to be the trait that best correlated with final grain weight (r2=0.98, P <0.01) and volume (r2=0.94, P <0.01). The main events that defined final grain weight occurred during the first third of grain-filling when maternal tissues (the pericarp of grains) undergo considerable expansion. Eight expansin coding sequences were isolated from pericarp RNA and the temporal profiles of accumulation of these transcripts were monitored. Sequences showing high homology with TaExpA6 were notably abundant during early grain expansion and declined as maturity was reached. RNA in situ hybridization studies revealed that the transcript for TaExpA6 was principally found in the pericarp during early growth in grain development and, subsequently, in both the endosperm and pericarp. The signal in these images is likely to be the sum of the transcript levels of all three sequences with high similarity to the TaExpA6 gene. The early part of the expression profile of this putative expansin gene correlates well with the critical periods of early grain expansion, suggesting it as a possible factor in the final determination of grain size.

Differential expression analysis of transcripts related to oil metabolism in maturing seeds of Jatropha curcas L.

“…Expansins (Chen and Bradford 2000) and seed maturation proteins (Rosenberg and Rinne 1988) have been found to influence seed development and the progression of a seed to seedling stage. Higher levels of expansin transcript in JC3 in J. curcas seeds may be linked to cell expansion and increase in seed size because in wheat (Lizana et al 2010) expression of expansin genes correlated with grain size. Seed maturation protein transcript revealed two bands in the RT-PCR in JC3.…”

Dry matter and water dynamics of wheat grains in response to source reduction at different phases of grain filling

“…In addition, the relative individual grain weight (RIGW) was calculated as the ratio between dry weights of grains measured at time i and IGW at PM. The dynamic of grain water concentration (relative grain water content, RGWC) and the timing when water content stabilizes (SGWC) were calculated using a trilinear model similar to that described by Pepler et al (2006) and used by Lizana et al (2010). The hydric plateau duration (°C d, HPD) between the time when SGWC is reached and grain PM was derived from this model.…”

Regulation of Seed Germination in the Close Arabidopsis RelativeLepidium sativum: A Global Tissue-Specific Transcript Analysis

“…The a-expansins (EXPA) act with a pH optimum around 4. They have possible roles in developmental processes like organ size and elongation growth, fruit tissue softening, and seed germination (Sampedro and Cosgrove, 2005;Choi et al, 2006;Gaete-Eastman et al, 2009;Lizana et al, 2010). Transcripts of the tomato (Solanum lycopersicum) a-expansin SlEXPA4 and its putative ortholog in Datura ferox were specifically expressed in the micropylar endosperm in association with endosperm weakening (Chen and Bradford, 2000;Mella et al, 2004).…”