Insights into the relations between cell wall integrity and in vitro digestion properties of granular starches in pulse cotyledon cells after dry heat treatment

Natural foods,such as whole pulses,are recommended in the dietary guidelines of the US and China.The plant cell wall structure in whole pulses has important implications for the nutritional functionalities of starch.In this study,garbanzo bean cells with varying degrees of cell wall integrity were subjected to dry heat treatment(DHT)and used to elucidate the food structure-starch digestion properties of pulse food.The morphological features suggested that all cell samples do not exhibit remarkable changes after being subjected to DHT.Molecular rearrangement and the crystallite disruption of starch granules entrapped in cells occurred during DHT as assessed by the crystal structure and thermal properties.DHT decreased the inhibitory effects of enzymes of both the soluble and insoluble components,but the digestion rate and extent of slightly and highly damaged cell samples did not exhibit significant differences compared with their native counterparts.We concluded that the starch digestion of pulse cotyledon cells is primarily determined by the intactness of the cellular structure.This study reveals the role of food structure on the ability to retain the desirable nutritional properties of starch after subjection to physical modification.

Cell Wall, Cytoskeleton, and Cell Expansion in Higher Plants

To accommodate two seemingly contradictory biological roles in plant physiology, providing both the rigid structural support of plant cells and the adjustable elasticity needed for cell expansion, the composition of the plant cell wall has evolved to become an intricate network of cellulosic, hemicellulosic, and pectic polysaccharides and protein. Due to its complexity, many aspects of the cell wall influence plant cell expansion, and many new and insightful observations and technologies are forthcoming. The biosynthesis of cell wall polymers and the roles of the variety of proteins involved in polysaccharide synthesis continue to be characterized. The interactions within the cell wall polymer network and the modification of these interactions provide insight into how the plant cell wall provides its dual function. The complex cell wall architecture is controlled and organized in part by the dynamic intracellular cytoskeleton and by diverse trafficking pathways of the cell wall polymers and cell wall-related machinery. Meanwhile, the cell wall is continually influenced by hormonal and integrity sensing stimuli that are perceived by the cell. These many processes cooperate to construct, maintain, and manipulate the intricate plant cell wall--an essential structure for the sustaining of the plant stature, growth, and life.

Arabidopsis pollen-specific glycerophosphodiester phosphodiesterase-like genes are essential for pollen tube tip growth

In angiosperms,pollen tube growth is critical for double fertilization and seed formation.Many of the factors involved in pollen tube tip growth are unknown.Here,we report the roles of pollenspecific GLYCEROPHOSPHODIESTER PHOSPHO DIESTERASE-LIKE(GDPD-LIKE)genes in pollen tube tip growth.Arabidopsis thaliana GDPD-LIKE6(At GDPDL6)and At GDPDL7 were specifically expressed in mature pollen grains and pollen tubes and green fluorescent protein(GFP)-At GDPDL6 and GFP-At GDPDL7 fusion proteins were enriched at the plasma membrane at the apex of forming pollen tubes.Atgdpdl6 Atgdpdl7 double mutants displayed severe sterility that was rescued by genetic complementation with At GDPDL6 or At GDPDL7.This sterility was associated with defective male gametophytic transmission.Atgdpdl6 Atgdpdl7 pollen tubes burst immediately after initiation of pollen germination in vitro and in vivo,consistent with the thin and fragile walls in their tips.Cellulose deposition was greatly reduced along the mutant pollen tube tip walls,and the localization of pollen-specific CELLULOSE SYNTHASE-LIKE D1(CSLD1)and CSLD4 was impaired to the apex of mutant pollen tubes.A rice pollen-specific GDPD-LIKE protein also contributed to pollen tube tip growth,suggesting that members of this family have conserved functions in angiosperms.Thus,pollen-specific GDPDLIKEs mediate pollen tube tip growth,possibly by modulating cellulose deposition in pollen tube walls.

The regeneration factors ERF114 and ERF115 regulate auxin-mediated lateral root development in response to mechanical cues

Plants show an unparalleled regenerative capacity,allowing them to survive severe stress conditions,such as injury,herbivory attack,and harsh weather conditions.This potential not only replenishes tissues and restores damaged organs but can also give rise to whole plant bodies.Despite the intertwined nature of development and regeneration,common upstream cues and signaling mechanisms are largely unknown.Here,we demonstrate that in addition to being activators of regeneration,ETHYLENE RESPONSE FACTOR 114(ERF114)and ERF115 govern developmental growth in the absence of wounding or injury.Increased ERF114 and ERF115 activity enhances auxin sensitivity,which is correlated with enhanced xylem maturation and lateral root formation,whereas their knockout results in a decrease in lateral roots.Moreover,we provide evidence that mechanical cues contribute to ERF114 and ERF115 expression in correlation with BZR1-mediated brassinosteroid signaling under both regenerative and developmental conditions.Antagonistically,cell wall integrity surveillance via mechanosensory FERONIA signaling suppresses their expression under both conditions.Taken together,our data suggest a molecular framework in which cell wall signals and mechanical strains regulate organ development and regenerative responses via ERF114-and ERF115-mediated auxin signaling.