Differences of starch granule distribution in grains from different spikelet positions in winter wheat

Significance of different milling methods on white proso millet flour physicochemical, rheological, and baking properties

Proso millet is a nutritious, sustainable, and gluten free food which is currently underutilized. They can be incorporated into the grain industry and provide much needed healthy alternatives. Efficient grinding method should be adopted for easy incorporation. This study aimed to investigate the effect of three different methods of grinding namely, roller milling (RM), pin milling (PM), and hammer milling (HM) on proso millet flour rheology and baking properties for food application. The milling flow sheet was developed toward the production of the quality whole grain flour. The particle size distribution of all the flours showed bi-modal distribution except for the RM flour. The PM produced the flour with the finest particles with geometric mean diameter of 82 μm. The study also revealed that starch damage in the PM flour (4.64%) was higher than RM (2.46%) and HM flour (2.51%). The nutritional composition was not significantly affected by different grinding methods. Pasting properties of the flour were also affected by the grinding method applied. Rapid Visco Analysis profile showed pin mill flour to have a higher peak viscosity (PV) (2,295 cP) compared to HM (2,065 cP) and RM flour (2,130 cP). Finally, this study demonstrated that the production of bread from proso millet flour with desirable quality and texture is possible. The grinding method did not affect the specific volume of bread loaves and C-cell characteristics. The specific volume of the breads ranged from 2.40 to 2.52 cm³ /g. This study will help in promoting and producing value-added proso millet food products with enhanced nutritional quality.

Programmed Degradation of Pericarp Cells in Wheat Grains Depends on Autophagy

Wheat is one of the most important food crops in the world, with development of the grains directly determining yield and quality. Understanding grain development and the underlying regulatory mechanisms is therefore essential in improving the yield and quality of wheat. In this study, the developmental characteristics of the pericarp was examined in developing wheat grains of the new variety Jimai 70. As a result, pericarp thickness was found to be thinnest in grains at the top of the spike, followed by those in the middle and thickest at the bottom. Moreover, this difference corresponded to the number of cell layers in the pericarp, which decreased as a result of programmed cell death (PCD). A number of autophagy-related genes (ATGs) are involved in the process of PCD in the pericarp, and in this study, an increase in ATG8-PE expression was observed followed by the appearance of autophagy structures. Meanwhile, following interference of the key autophagy gene ATG8, PCD was inhibited and the thickness of the pericarp increased, resulting in small premature grains. These findings suggest that autophagy and PCD coexist in the pericarp during early development of wheat grains, with both processes increasing from the bottom to the top of the spike. Moreover, PCD was also found to rely on ATG8-mediated autophagy. The results of this study therefore provide a theoretical basis for in-depth studies of the regulatory mechanisms of wheat grain development.

The Proportion of Superior Grains and the Sink Strength are the Main Yield Contributors in Modern Winter Wheat Varieties Grown in the Loess Plateau of China

Understanding the changes in phenotype resulting from the selection pressure and agronomic adaptation of grain yield provide an indication of the pathways for future increases in grain yield. Six dry land representative winter wheat cultivars (Triticum aestivum L.) released from 1942 to 2004 in the Loess Plateau of China were investigated to determine how the yield components of winter wheat were associated with grain yield at the Changwu Agricultural Research Station during the 2011–2012 and 2012–2013 seasons, using a completely randomized block design with three replicates. Plant height, aboveground biomass, grain yield, and yield components were measured, together with the traits of superior and inferior grains and the pre-anthesis stored dry matter remobilized to the grain was determined. In the relatively wet 2011–2012 season, there was a significant increase in grain yield and aboveground biomass with the year of release, but not in the dry 2012–2013 season. The harvest index (HI) and average grain weight (AGW) increased significantly with the year of release in both cropping seasons. HI and AGW are likely potential traits for improving grain yield of winter wheat in the Loess Plateau. The increase in HI mainly resulted from the decrease in plant height, and the increase in the use of pre-anthesis stored assimilates for grain filling. The increase in AGW mainly resulted from the increase in the proportion of superior grain (SG) and the decrease in the proportion of inferior grain (IG) in the whole spike in both cropping seasons. Depending on the climatic conditions, the different winter wheat cultivars showed different ability to use pre-anthesis stored assimilates. Modern wheat cultivars had higher yield under different rainfall conditions, and high ability to use pre-anthesis stored assimilates to fill the grain than earlier released cultivars. Both, the increase in sink capacity and source availability, should be considered as a strategy for increasing future grain yield in Loess Plateau of China.