Phloem-feeding insects cause massive losses in agriculture and horticulture.Host plant resistance to phloem-feeding insects is often mediated by changes in phloem composition,which deter insect settling and feeding an...Phloem-feeding insects cause massive losses in agriculture and horticulture.Host plant resistance to phloem-feeding insects is often mediated by changes in phloem composition,which deter insect settling and feeding and decrease viability.Here,we report that rice plant resistance to the phloem-feeding brown planthopper(BPH)is associated with fortification of the sclerenchyma tissue,which is located just beneath the epidermis and a cell layer or two away from the vascular bundle in the rice leaf sheath.We found that BPHs prefer to feed on the smooth and soft region on the surface of rice leaf sheaths called the long-cell block.We identified Bph30 as a rice BPH resistance gene that prevents BPH stylets from reaching the phloem due to the fortified sclerenchyma.Bph30 is strongly expressed in sclerenchyma cells and enhances cellulose and hemicellulose synthesis,making the cell walls stiffer and sclerenchyma thicker.The structurally fortified sclerenchyma is a formidable barrier preventing BPH stylets from penetrating the leaf sheath tissues and arriving at the phloem to feed.Bph30 belongs to a novel gene family,encoding a protein with two leucine-rich domains.Another member of the family,Bph40,also conferred resistance to BPH.Collectively,the fortified sclerenchyma-mediated resistance mechanism revealed in this study expands our understanding of plant-insect interactions and opens a new path for controlling planthoppers in rice.展开更多
Equisetum(Equisetaceae)has long been a focus of attention for botanists and palaeontologists because,given its extensive and well-documented fossil record,it is considered the oldest extant vascular plant and a key el...Equisetum(Equisetaceae)has long been a focus of attention for botanists and palaeontologists because,given its extensive and well-documented fossil record,it is considered the oldest extant vascular plant and a key element in understanding vascular plant evolution.However,to date,no authentic fossil evidence of Equisetum has been found from the Indian Cenozoic.Here,we describe a new fossil species,namely,E.siwalikum sp.nov.,recovered from the middle Siwalik(Late Miocene)sediments of Himachal Pradesh,western Himalaya.We identified fossil specimens based on morphological and epidermal characters.In addition,X-Ray diffraction(XRD)analysis was used to determine the mineral composition of compressed stems of Equisetum.The close affinity of our recovered Siwalik fossils to Equisetum is supported by the presence of both macromorphological and epidermal characters.Because Equisetum generally grows in wet conditions around water reservoirs,our findings indicate that the fossil locality was humid and surrounded by swamp and lowland regions during deposition.Ample fossil evidence indicates that this sphenopsid once existed in the western Himalaya during the Siwalik period.However,at present Equisetum is confined to a particular area of our fossil locality,probably a consequence of severe environmental changes coupled with competition from opportunistic angiosperms.Our discovery of Equisetum fossils in appreciable numbers from the Siwalik sediments of the Himachal Himalayas is unique and constitutes the first reliable recognition of Equisetum from the Indian Cenozoic.展开更多
以超级杂交稻“两优培九”及其父本“9311”、母本“培矮64S”和三系杂交稻组合“汕优63”为研究材料，采用^14C同位素示踪等技术，研究了“两优培九”剑叶叶鞘的光合能力与叶鞘光合产物的分配。结果表明，两优培九剑叶叶鞘的净光合速...以超级杂交稻“两优培九”及其父本“9311”、母本“培矮64S”和三系杂交稻组合“汕优63”为研究材料，采用^14C同位素示踪等技术，研究了“两优培九”剑叶叶鞘的光合能力与叶鞘光合产物的分配。结果表明，两优培九剑叶叶鞘的净光合速率均值比汕优63高0．10μmol CO2 m^-2s^-2，尤以第3期，即灌浆关键时期，极显著高于汕优63，其他时期差异不显著；其叶鞘叶绿素含量的均值比汕优63高2．36SPAD值，各期均高于汕优63，其中，第1、3期显著高于汕优63；其剑叶叶鞘的Rubisco初始活性和总活性与汕优63差异不显著，但Rubisco活化率均值比汕优63高1．52％，具有平均优势，其中第3期显著高于汕优63；其叶鞘光合产物输送到穗部的量即转化为经济产量的量比汕优63高；与父母本相比，其剑叶叶鞘光合能力的均值具有平均优势或超亲优势；水稻叶鞘完全具有同叶片一样的光合能力，只有值的大小差异；水稻叶鞘的光合产物对产量的贡献一般为10％～20％。两优培九叶鞘及叶片光合功能都较强是其具有超高产特性的一个重要原因。展开更多
基金This work was supported by the Major Program of Guangdong Basic andApplied Research,China(2019B030302006)the National Program onResearch and Development of Transgenic Plants of China(2016ZX08009-003)+1 种基金grants from the National Natural Science Foundationof China(31630063)the National Key Research and DevelopmentProgram of China(2016YFD0100600 and 2016YFD0100900).
文摘Phloem-feeding insects cause massive losses in agriculture and horticulture.Host plant resistance to phloem-feeding insects is often mediated by changes in phloem composition,which deter insect settling and feeding and decrease viability.Here,we report that rice plant resistance to the phloem-feeding brown planthopper(BPH)is associated with fortification of the sclerenchyma tissue,which is located just beneath the epidermis and a cell layer or two away from the vascular bundle in the rice leaf sheath.We found that BPHs prefer to feed on the smooth and soft region on the surface of rice leaf sheaths called the long-cell block.We identified Bph30 as a rice BPH resistance gene that prevents BPH stylets from reaching the phloem due to the fortified sclerenchyma.Bph30 is strongly expressed in sclerenchyma cells and enhances cellulose and hemicellulose synthesis,making the cell walls stiffer and sclerenchyma thicker.The structurally fortified sclerenchyma is a formidable barrier preventing BPH stylets from penetrating the leaf sheath tissues and arriving at the phloem to feed.Bph30 belongs to a novel gene family,encoding a protein with two leucine-rich domains.Another member of the family,Bph40,also conferred resistance to BPH.Collectively,the fortified sclerenchyma-mediated resistance mechanism revealed in this study expands our understanding of plant-insect interactions and opens a new path for controlling planthoppers in rice.
基金DST-SERB,GOI,New Delhi,India(File no.CRG/2020/001303)for their financial assistance。
文摘Equisetum(Equisetaceae)has long been a focus of attention for botanists and palaeontologists because,given its extensive and well-documented fossil record,it is considered the oldest extant vascular plant and a key element in understanding vascular plant evolution.However,to date,no authentic fossil evidence of Equisetum has been found from the Indian Cenozoic.Here,we describe a new fossil species,namely,E.siwalikum sp.nov.,recovered from the middle Siwalik(Late Miocene)sediments of Himachal Pradesh,western Himalaya.We identified fossil specimens based on morphological and epidermal characters.In addition,X-Ray diffraction(XRD)analysis was used to determine the mineral composition of compressed stems of Equisetum.The close affinity of our recovered Siwalik fossils to Equisetum is supported by the presence of both macromorphological and epidermal characters.Because Equisetum generally grows in wet conditions around water reservoirs,our findings indicate that the fossil locality was humid and surrounded by swamp and lowland regions during deposition.Ample fossil evidence indicates that this sphenopsid once existed in the western Himalaya during the Siwalik period.However,at present Equisetum is confined to a particular area of our fossil locality,probably a consequence of severe environmental changes coupled with competition from opportunistic angiosperms.Our discovery of Equisetum fossils in appreciable numbers from the Siwalik sediments of the Himachal Himalayas is unique and constitutes the first reliable recognition of Equisetum from the Indian Cenozoic.
文摘以超级杂交稻“两优培九”及其父本“9311”、母本“培矮64S”和三系杂交稻组合“汕优63”为研究材料，采用^14C同位素示踪等技术，研究了“两优培九”剑叶叶鞘的光合能力与叶鞘光合产物的分配。结果表明，两优培九剑叶叶鞘的净光合速率均值比汕优63高0．10μmol CO2 m^-2s^-2，尤以第3期，即灌浆关键时期，极显著高于汕优63，其他时期差异不显著；其叶鞘叶绿素含量的均值比汕优63高2．36SPAD值，各期均高于汕优63，其中，第1、3期显著高于汕优63；其剑叶叶鞘的Rubisco初始活性和总活性与汕优63差异不显著，但Rubisco活化率均值比汕优63高1．52％，具有平均优势，其中第3期显著高于汕优63；其叶鞘光合产物输送到穗部的量即转化为经济产量的量比汕优63高；与父母本相比，其剑叶叶鞘光合能力的均值具有平均优势或超亲优势；水稻叶鞘完全具有同叶片一样的光合能力，只有值的大小差异；水稻叶鞘的光合产物对产量的贡献一般为10％～20％。两优培九叶鞘及叶片光合功能都较强是其具有超高产特性的一个重要原因。
