Defective mitochondrial function by mutation in THICK ALEURONE 1 encoding a mitochondrion-targeted single-stranded DNA-binding protein leads to increased aleurone cell layers and improved nutrition in rice

Cereal endosperm comprises an outer aleurone and an inner starchy endosperm.Although these two tissues have the same developmental origin,they differ in morphology,cell fate,and storage product accumulation,with the mechanism largely unknown.Here,we report the identification and characterization of rice thick aleurone 1(ta1)mutant that shows an increased number of aleurone cell layers and increased contents of nutritional factors including proteins,lipids,vitamins,dietary fibers,and micronutrients.We identified that the TA1 gene,which is expressed in embryo,aleurone,and subaleurone in caryopses,encodes a mitochondrion-targeted protein with single-stranded DNA-binding activity named OsmtSSB1.Cytological analyses revealed that the increased aleurone cell layers in ta1 originate from a developmental switch of subaleurone toward aleurone instead of starchy endosperm in the wild type.We found that TA1/OsmtSSB1 interacts with mitochondrial DNA recombinase RECA3 and DNA helicase TWINKLE,and downregulation of REC A3 or TWINKLE also leads to ta1-like phenotypes.We further showed that mutation in TA1/OsmtSSB1 causes elevated illegitimate recombinations in the mitochondrial genome,altered mitochondrial morphology,and compromised energy supply,suggesting that the OsmtSSB1-mediated mitochondrial function plays a critical role in subaleur one cell-fate determination in rice.

Inclusion of wheat aleurone in gestation diets improves postprandial satiety,stress status and stillbirth rate of sows

This study investigated the effects of different amounts of wheat aleurone(WA)(0,15%,30%)inclusion in gestation diets on the reproductive performance,postprandial satiety,stress status and stereotypic be-haviors of sows.A total of 84 Landrace×Yorkshire sows(parity 4.87±1.32)at breeding were randomly allotted to one of the three isoenergetic and isonitrogenous dietary treatments based on parity and body weight.The results showed that,compared with the control(0),sows fed the WA diet had a higher serum concentration of peptide YY(PYY)(P<0.05)and glucagon like peptide-1(GLP-1)(P<0.05)and a lower concentration of saliva cortisol(P<0.01).Importantly,compared with the control group,only the 15%WA group had a higher concentration of the total antioxidant capacity(T-AOC)(P<0.05),lower pro-portions of sitting(P=0.05)and stillbirth rates(P<0.01).Accordingly,the production cost per piglet born alive($6.9 vs.$7.6)or per piglet born healthy($7.4 vs.$7.9)declined in the 15%WA group versus the control group.Overall,15%WA inclusion in gestation diets contributed to enhancing postprandial satiety,alleviating stress status and decreasing stillbirth rate of sows.This study provides a reference for the application of WA as a partial substitute for conventional feed ingredients to improve sows'repro-ductive performance.

Investigating seed mineral composition in Korean landrace maize(Zea mays L.) and its kernel texture specificity

Mineral malnutrition affects billions of people all over the world and biofortification of staple crops provides a potential way to alleviate dietary mineral deficiencies.For example,nutritional quality is an important breeding target for fresh waxy maize(Zea mays L.),which is widely consumed in Asian countries.Successful improvement of mineral composition will require comprehensive profiling of the mineral composition of maize varieties and an understanding of the capacity for maize grains to accumulate minerals.Here,using inductively coupled plasma absorption emission spectrometry,we quantified 12 minerals from the seeds of 47 maize varieties,including 25 Korean landraces.We also compared the mineral contents in varieties with different seed starch profiles:waxy maize(which contains 100%amylopectin),dent maize(roughly 75%amylopectin and 25%amylose),and flint maize(similar to dent maize).The amounts of potassium,phosphorus,and sulfur were correlated with seed texture,waxy maize having higher amounts of phosphorus and potassium than dent maize and lower amounts of sulfur than flint maize or dent maize.In addition,a positive relationship was detected between the amount of phosphorus and that of potassium,magnesium,and manganese.These results provide information on maize seed mineral composition and indicate that it could be affected by starch composition.Furthermore,the landraces that exhibit high mineral contents could be used as germplasm materials for breeding programs aimed at producing biofortified maize cultivars.

Rice FLOURY ENDOSPERM 18 encodes a pentatricopeptide repeat protein required for 5′ processing of mitochondrial nad5 messenger RNA and endosperm development

Pentatricopeptide repeat(PPR) proteins, composing one of the largest protein families in plants,are involved in RNA binding and regulation of organelle RNA metabolism at the posttranscriptional level. Although several PPR proteins have been implicated in endosperm development in rice(Oryza sativa), the molecular functions of many PPRs remain obscure. Here, we identified a rice endosperm mutant named floury endosperm 18(flo18) with pleiotropic defects in both reproductive and vegetative development.Map-based cloning and complementation tests showed that FLO18 encodes a mitochondriontargeted P-type PPR protein with 15 PPR motifs.Mitochondrial function was disrupted in the flo18 mutant, as evidenced by decreased assembly of Complex I in the mitochondrial electron transport chain and altered mitochondrial morphology. Loss of FLO18 function resulted in defective 5′-end processing of mitochondrial nad5 transcripts encoding subunit 5 of nicotinamide adenine dinucleotide hydrogenase. These results suggested that FLO18 is involved in 5′-end processing of nad5 messenger RNA and plays an important role in mitochondrial function and endosperm development.

Molecular cloning, sequence analysis and expression studies of a novel GAmyb homologous gene, hvmyb

Using a known GAmyb gene as the probe, two fully identical clones were isolated from a barley aleurone cDNA library. Sequence analysis showed that their 5′ termini are highly homologous to the 3′ termini of GAmyb (97%) and their 3′ termini share no significant homology with any myb genes. Therefore, the deduced protein may hold intact putative GAmyb activation domain but lack the normal DNA binding domain. Northern blot reveals that hvmyb expression in barley aleurone layers is strongly up regulated by gibberellin (GA) and down regulated by abscisic acid (ABA). The tissue and developmental stage specificity of hvmyb was also found, which was only expressed in barley aleurone cells and dropped to non detectable level soon after germination.