The levels of endogenous plant hormones regulate floret development and degeneration, and thus grain set in flower crops. This study was undertaken to characterize the changes of endogenous hormone levels during flor...The levels of endogenous plant hormones regulate floret development and degeneration, and thus grain set in flower crops. This study was undertaken to characterize the changes of endogenous hormone levels during floret development in three wheat ( Triticum aestivum L.) genotypes: “97J1' with the highest grain set and fertile florets per spike, “H8679' with the lowest grain set and fertile florets per spike, and a medium, “YM158'. The results showed that the peak level of ABA appeared between stamen and pistil differentiation and antherlobe formation of floret development, and the timing delayed with the size of spike (earliest in “H8679” and latest in “97J1”). From antherlobe formation to meiosis, the levels of ABA and GA 1+3 decreased sharply in the ears of “97J1”, while in the ears of “H8679” there was only a slight decrease in ABA, and even an increase in GA 1+3 . The ratio of isopentenyladenosine (iPA)/ABA and IAA/ABA in the ears of “97J1” increased sharply from antherlobe formation to meiosis, but changed only slightly in the ears of “H8679”. At antherlobe formation, IAA and GA 1+3 levels were higher in the ears of “97J1”, but lower in the ears of “H8679” than in the leaves. At meiosis, ABA, GA 1+3 and IAA levels in the “97J1” ears were much lower than in the leaves, but similar in “H8679”. These results indicated that the sharp decreases of ABA and GA 1+3 in ears from antherlobe formation to meiosis and the lowest maintenance at meiosis may be favorable for development of fertile florets and enhancement of grain set in wheat.展开更多
A breeding strategy for widening the germplasm of Brassica napus was proposed by introgression of the A^r subgenome of B. rapa （A^rA^r） and C^c of B. carinata （B^cB^cC^cC^c） into natural B. napus （AnAncncn）. The...A breeding strategy for widening the germplasm of Brassica napus was proposed by introgression of the A^r subgenome of B. rapa （A^rA^r） and C^c of B. carinata （B^cB^cC^cC^c） into natural B. napus （AnAncncn）. The progenies with 38 chromosomes that were derived from the self-pollinated seeds of pentaploid hybrids （A^rA^nB^cC^cC^n） were used for further research. Some of the partial new-typed B. napus showed normal meiotic behavior, high portion of germinated pollen and normal embryological development. This indicates that the selected new-typed B. napus had a balanced genetic base. Molecular analysis showed that about 50% of the genome in the new-typed B. napus was replaced by A^r and C^c subgenome from B. rapa and B. carinata. Considering the genetic diversity among different lines of new-typed B. napus, it was deduced that the introgression of the genomic components from B, rapa and B. carinata could widen the genetic diversity of rapeseed.展开更多
Magnesium （Mg^2＋） is abundant in plant cells and plays a critical role in many physiological processes. A 10-member gene family AtMGT （also known as AtMRS2） was identified in Arabidopsis, which belongs to a eukar...Magnesium （Mg^2＋） is abundant in plant cells and plays a critical role in many physiological processes. A 10-member gene family AtMGT （also known as AtMRS2） was identified in Arabidopsis, which belongs to a eukaryote subset of the CorA superfamily, functioning as Mg^2＋ transporters. Some family members （AtMGT1 and AtMGT10） function as high-affinity Mg^2＋ transporter and could complement bacterial mutant or yeast mutant lacking Mg^2＋ transport capability. Here we report an AtMGT family member, AtMGT9, that functions as a low-affinity Mg^2＋ transporter, and is essential for pollen development. The functional complementation assay in Salmonella mutant strain MM281 showed that AtMGT9 is capable of mediating Mg^2＋ uptake in the sub-millimolar range of Mg^2＋. The AtMGT9 gene was expressed most strongly in mature anthers and was also detectable in vascular tissues of the leaves, and in young roots. Disruption of AtMGT9 gene expression resulted in abortion of half of the mature pollen grains in heterozygous mutant ＋/mgt9, and no homozygous mutant plant was obtained in the progeny of selfed ＋/mgt9 plants. Transgenic plants expressing AtMGT9 in these heterozygous plants can recover the pollen phenotype to the wild type. In addition, At- MGT9 RNAi transgenic plants also showed similar abortive pollen phenotype to mutant ＋/mgt9. Together, our results demonstrate that AtMGT9 functions as a low-affinity Mg^2＋ transporter that plays a crucial role in male gametophyte development and male fertility.展开更多
The plant phospholipase D （PLD） plays versatile functions in multiple aspects of plant growth, development, and stress re- sponses. However, until now, our knowledge concerning the PLD gene family members and their ...The plant phospholipase D （PLD） plays versatile functions in multiple aspects of plant growth, development, and stress re- sponses. However, until now, our knowledge concerning the PLD gene family members and their expression patterns in cotton has been limited. In this study, we performed for the first time the genome-wide analysis and expression profiling of PLD gene family in Gossypium arboretum, and finally, a total of 19 non-redundant PLD genes （GaPLDs） were identified. Based on the phylogenetic analysis, they were divided into six well-supported clades （tx, 13/？, 8, ~, ~ and q~）. Most of the GaPLD genes with- in the same clade showed the similar exon-intron organization and highly conserved motif structures. Additionally, the chro- mosomal distribution pattern revealed that GaPLD genes were unevenly distributed across 10 of the 13 cotton chromosomes. Segmental duplication is the major contributor to the expansion of GaPLD gene family and estimated to have occurred from 19.61 to 20.44 million years ago when a recent large-scale genome duplication occurred in cotton. Moreover, the expression profiling provides the functional divergence of GaPLD genes in cotton and provides some new light on the molecular mecha- nisms of GaPLDcd and GaPLD62 in fiber development.展开更多
文摘The levels of endogenous plant hormones regulate floret development and degeneration, and thus grain set in flower crops. This study was undertaken to characterize the changes of endogenous hormone levels during floret development in three wheat ( Triticum aestivum L.) genotypes: “97J1' with the highest grain set and fertile florets per spike, “H8679' with the lowest grain set and fertile florets per spike, and a medium, “YM158'. The results showed that the peak level of ABA appeared between stamen and pistil differentiation and antherlobe formation of floret development, and the timing delayed with the size of spike (earliest in “H8679” and latest in “97J1”). From antherlobe formation to meiosis, the levels of ABA and GA 1+3 decreased sharply in the ears of “97J1”, while in the ears of “H8679” there was only a slight decrease in ABA, and even an increase in GA 1+3 . The ratio of isopentenyladenosine (iPA)/ABA and IAA/ABA in the ears of “97J1” increased sharply from antherlobe formation to meiosis, but changed only slightly in the ears of “H8679”. At antherlobe formation, IAA and GA 1+3 levels were higher in the ears of “97J1”, but lower in the ears of “H8679” than in the leaves. At meiosis, ABA, GA 1+3 and IAA levels in the “97J1” ears were much lower than in the leaves, but similar in “H8679”. These results indicated that the sharp decreases of ABA and GA 1+3 in ears from antherlobe formation to meiosis and the lowest maintenance at meiosis may be favorable for development of fertile florets and enhancement of grain set in wheat.
基金This study was supported by High Project of Science and Technology in China (No. 2001AA21110103)Doctoral Foundation of Education Department in China (No. 20020504009).
文摘A breeding strategy for widening the germplasm of Brassica napus was proposed by introgression of the A^r subgenome of B. rapa （A^rA^r） and C^c of B. carinata （B^cB^cC^cC^c） into natural B. napus （AnAncncn）. The progenies with 38 chromosomes that were derived from the self-pollinated seeds of pentaploid hybrids （A^rA^nB^cC^cC^n） were used for further research. Some of the partial new-typed B. napus showed normal meiotic behavior, high portion of germinated pollen and normal embryological development. This indicates that the selected new-typed B. napus had a balanced genetic base. Molecular analysis showed that about 50% of the genome in the new-typed B. napus was replaced by A^r and C^c subgenome from B. rapa and B. carinata. Considering the genetic diversity among different lines of new-typed B. napus, it was deduced that the introgression of the genomic components from B, rapa and B. carinata could widen the genetic diversity of rapeseed.
基金Acknowledgments We are grateful to Dr Michael E Maguire （Case Western Reserve University, USA） for providing the Salmonella mutant strain MM281 and advice on tracer uptake. This work was supported by grants from National Natural Science Foundation of China （30370794）, Hunan Young Scientist Program （03JJY1003）, and Hunan Provincial NSFC （08JJ3088）.
文摘Magnesium （Mg^2＋） is abundant in plant cells and plays a critical role in many physiological processes. A 10-member gene family AtMGT （also known as AtMRS2） was identified in Arabidopsis, which belongs to a eukaryote subset of the CorA superfamily, functioning as Mg^2＋ transporters. Some family members （AtMGT1 and AtMGT10） function as high-affinity Mg^2＋ transporter and could complement bacterial mutant or yeast mutant lacking Mg^2＋ transport capability. Here we report an AtMGT family member, AtMGT9, that functions as a low-affinity Mg^2＋ transporter, and is essential for pollen development. The functional complementation assay in Salmonella mutant strain MM281 showed that AtMGT9 is capable of mediating Mg^2＋ uptake in the sub-millimolar range of Mg^2＋. The AtMGT9 gene was expressed most strongly in mature anthers and was also detectable in vascular tissues of the leaves, and in young roots. Disruption of AtMGT9 gene expression resulted in abortion of half of the mature pollen grains in heterozygous mutant ＋/mgt9, and no homozygous mutant plant was obtained in the progeny of selfed ＋/mgt9 plants. Transgenic plants expressing AtMGT9 in these heterozygous plants can recover the pollen phenotype to the wild type. In addition, At- MGT9 RNAi transgenic plants also showed similar abortive pollen phenotype to mutant ＋/mgt9. Together, our results demonstrate that AtMGT9 functions as a low-affinity Mg^2＋ transporter that plays a crucial role in male gametophyte development and male fertility.
基金the State Key Basic Research and Development Plan (2010CB126003)the National Transgenic Animals and Plants Research Project (2011ZX08005-003, 2011ZX08009-003)
文摘The plant phospholipase D （PLD） plays versatile functions in multiple aspects of plant growth, development, and stress re- sponses. However, until now, our knowledge concerning the PLD gene family members and their expression patterns in cotton has been limited. In this study, we performed for the first time the genome-wide analysis and expression profiling of PLD gene family in Gossypium arboretum, and finally, a total of 19 non-redundant PLD genes （GaPLDs） were identified. Based on the phylogenetic analysis, they were divided into six well-supported clades （tx, 13/？, 8, ~, ~ and q~）. Most of the GaPLD genes with- in the same clade showed the similar exon-intron organization and highly conserved motif structures. Additionally, the chro- mosomal distribution pattern revealed that GaPLD genes were unevenly distributed across 10 of the 13 cotton chromosomes. Segmental duplication is the major contributor to the expansion of GaPLD gene family and estimated to have occurred from 19.61 to 20.44 million years ago when a recent large-scale genome duplication occurred in cotton. Moreover, the expression profiling provides the functional divergence of GaPLD genes in cotton and provides some new light on the molecular mecha- nisms of GaPLDcd and GaPLD62 in fiber development.
