The objective of the current study is to investigate the effects of different stages of shading after anthesis on grain weight and quality of maize at cytology level. The shading experiments were conducted in the fiel...The objective of the current study is to investigate the effects of different stages of shading after anthesis on grain weight and quality of maize at cytology level. The shading experiments were conducted in the field from 2005 to 2006, with a common maize cultivar （TY2） as the experimental material. Plants were given stress using horizontal shading net and the light intensity was reduced by 55%. Field-grown maize plants were shaded at 1-14 d （S1）, 15-28 d （$2）, and 29-42 d （$3） after pollination, respectively. Control plants （SO） were grown under natural light. Grain weight, quality, endosperm cell proliferation, cob sugar content, and grain pedicel vascular bundle cross section area were measured. The ultrastructural changes of endosperm ceils and endosperm transfer cells were observed after pollination. The result indicated that the grain weight, starch content, endosperm cell number, and volume were declined after shading. On the contrary, the proportion of embryo and endosperm, protein content, and fat content in grain increased. Shading treatments significantly delayed the development of the starch granules and remarkably reduced the endosperm filling status. Among the three treatments, the number of the grain endosperm was the least under shading stress at 1-14 d after pollination. However, the volume of starch granules and the substantiation of endosperm under shading treatment at 15-28 d after pollination were the worst. Compared with the control （natural sunlight without shading）, the soluble sugar of maize cob increased significantly, while there was no obvious change in vascular structure of small cluster stalk. The number of protein body in maize endosperm was influenced markedly by low light at different stages after pollination. Low light decreased the volume of the grain endosperm transfer and the cell wall extensions of the basal transfer ceils became thinner and shorter under shading treatment than those of the control. Furthermore, the degree of connection and the capacity of the nutrient transport were decreased and the mitochondrion number of the transfer cell was reduced after shading. The change in grain quality after shading was observed due to increase in the proportion of embryo and endosperm. The morphology and functions in endosperm transfer cell and the shortage of energy restricted the nutrient transport greatly with shading at different stages, suggesting that an impeded flux may be one of the important reasons for the reduction of maize grain weight of maize grain at later growth stage under low light condition.展开更多
Basal endosperm transfer layer（BETL） cells are responsible for transferring apoplastic solutes from the maternal pedicel into the endosperm,supplying the grain with compounds required for embryo development and stor...Basal endosperm transfer layer（BETL） cells are responsible for transferring apoplastic solutes from the maternal pedicel into the endosperm,supplying the grain with compounds required for embryo development and storage reserve accumulation.Here,we analyze the maize（Zea mays L.） empty pericarp6（emp6） mutant,which causes early arrest in grain development.The Emp6 tgene function is required independently in both the embryo and endosperm.The emp6 mutant causes a notable effect on the differentiation of BETL cells;the extensive cell wall ingrowths that distinguish BETL cells are diminished and BETL marker gene expression is compromised in mutant kernels.Transposon tagging identified the emp6 locus as encoding a putative plant organelle RNA recognition（PORR） protein,1 of 15 PORR family members in maize.The emp6 transcript is widely detected in plant tissues with highest Researclevels in embryos and developing kernels.EMP6-green fluorescent protein（GFP） fusion proteins transiently expressed in Nicotiana benthamiana leaves were targeted specifically to mitochondria.These results suggest that BETL cell differentiation might be particularly energy intensive,or alternatively,that mitochondria might confer a developmental function.展开更多
基金supported by the National Basic Research Program of China (973 Program,2006CB101700)the National Natural Science Foundation of China (30871476)the Opening Foundation of State Key Laboratory of Crop Biology, and the Shandong Agricultural University (2009KF07)
文摘The objective of the current study is to investigate the effects of different stages of shading after anthesis on grain weight and quality of maize at cytology level. The shading experiments were conducted in the field from 2005 to 2006, with a common maize cultivar （TY2） as the experimental material. Plants were given stress using horizontal shading net and the light intensity was reduced by 55%. Field-grown maize plants were shaded at 1-14 d （S1）, 15-28 d （$2）, and 29-42 d （$3） after pollination, respectively. Control plants （SO） were grown under natural light. Grain weight, quality, endosperm cell proliferation, cob sugar content, and grain pedicel vascular bundle cross section area were measured. The ultrastructural changes of endosperm ceils and endosperm transfer cells were observed after pollination. The result indicated that the grain weight, starch content, endosperm cell number, and volume were declined after shading. On the contrary, the proportion of embryo and endosperm, protein content, and fat content in grain increased. Shading treatments significantly delayed the development of the starch granules and remarkably reduced the endosperm filling status. Among the three treatments, the number of the grain endosperm was the least under shading stress at 1-14 d after pollination. However, the volume of starch granules and the substantiation of endosperm under shading treatment at 15-28 d after pollination were the worst. Compared with the control （natural sunlight without shading）, the soluble sugar of maize cob increased significantly, while there was no obvious change in vascular structure of small cluster stalk. The number of protein body in maize endosperm was influenced markedly by low light at different stages after pollination. Low light decreased the volume of the grain endosperm transfer and the cell wall extensions of the basal transfer ceils became thinner and shorter under shading treatment than those of the control. Furthermore, the degree of connection and the capacity of the nutrient transport were decreased and the mitochondrion number of the transfer cell was reduced after shading. The change in grain quality after shading was observed due to increase in the proportion of embryo and endosperm. The morphology and functions in endosperm transfer cell and the shortage of energy restricted the nutrient transport greatly with shading at different stages, suggesting that an impeded flux may be one of the important reasons for the reduction of maize grain weight of maize grain at later growth stage under low light condition.
基金supported by grants from the US National Science Foundation (IOS-1121738) to PWBthe Spanish Ministerio de Ciencia e Innovacion (Grant BIO2009-11856) to GH
文摘Basal endosperm transfer layer（BETL） cells are responsible for transferring apoplastic solutes from the maternal pedicel into the endosperm,supplying the grain with compounds required for embryo development and storage reserve accumulation.Here,we analyze the maize（Zea mays L.） empty pericarp6（emp6） mutant,which causes early arrest in grain development.The Emp6 tgene function is required independently in both the embryo and endosperm.The emp6 mutant causes a notable effect on the differentiation of BETL cells;the extensive cell wall ingrowths that distinguish BETL cells are diminished and BETL marker gene expression is compromised in mutant kernels.Transposon tagging identified the emp6 locus as encoding a putative plant organelle RNA recognition（PORR） protein,1 of 15 PORR family members in maize.The emp6 transcript is widely detected in plant tissues with highest Researclevels in embryos and developing kernels.EMP6-green fluorescent protein（GFP） fusion proteins transiently expressed in Nicotiana benthamiana leaves were targeted specifically to mitochondria.These results suggest that BETL cell differentiation might be particularly energy intensive,or alternatively,that mitochondria might confer a developmental function.
