OsPEX1,a leucine-rich repeat extensin protein,functions in the regulation of caryopsis development and quality in rice

Rice caryopses are enclosed by outer glumes.The size and dimension of the outer glume are the main determinants of caryopsis size.However,it is unclear whether caryopsis development is completely dependent on the size of the glume,or whether it can grow and expand autonomously despite the constraint of glume enclosure.We report the identification of a mutant line that produces normal-sized glumes with smaller mature caryopses that do not fill the entire glume cavity.The caryopsis phenotype in the pex1 mutant is caused by a reduction in cell size.Os PEX1,a leucine-rich repeat extensin gene,was highly expressed in the developing caryopsis.Overexpression of Os PEX1 driven by a constitutive promoter recapitulated the mutant phenotype,showing that the small-caryopsis phenotype is caused by overexpression of the Os PEX1 gene.Free amino acids,including several essential amino acids,and crude protein were increased in pex1 relative to the wild type,endowing pex1 with improved nutritional quality.Our results suggest that caryopsis development can be genetically uncoupled from maternally controlled glume development and that Os PEX1 might be a new resource for improving nutritional quality of rice cultivars.

Effects of sowing methods on nitrogen compounds and protease activities of whole‐crop wheat silage

Background:Whole‐crop wheat(Triticum aestivum)has high nutritive value,and it has become one of the main sources of roughage for ruminants in some countries or regions.This study investigates the effects of no tillage on nitrogen compounds and protease activities of whole‐crop wheat silage.Methods:Wheat was planted on the 9th day(NB9)and 5th day(NB5)before rice harvest and on the first day after rice harvest.Sowing before harvest involved no tillage and sowing after rice harvest involved either no tillage(NA1)or conventional tillage(CK).Results:Compared to CK,the crude protein content of NB9 and NB5 decreased by 16.4%and 9.58%,respectively.With the delay of the sowing date,the contents of non‐protein nitrogen,rapidly degraded protein,and slowly degraded protein in whole‐plant wheat tended to increase.Compared to NA1 wheat silage,the NH_(3)‐N content of NB9 and NB5 silages decreased by 52.7%and 34.4%,respectively.The acid protease activity of NA1 was significantly higher than that of other treatments(p<0.05).Conclusions:There was no significant difference in the degree of protein degradation between NA1 and CK silages.Although the degree of protein degradation in early sowing was low,the degree of fermentation was also weak.