Cadmium(Cd)accumulation in rice grain is of health concern.Identifying genes involved in grain Cd accumulation and performing molecular breeding may reduce it.In this study,knockout of OsNRAMP2,a member of the NRAMP f...Cadmium(Cd)accumulation in rice grain is of health concern.Identifying genes involved in grain Cd accumulation and performing molecular breeding may reduce it.In this study,knockout of OsNRAMP2,a member of the NRAMP family,reduced grain Cd concentrations by more than 38%,and overexpressing OsNRAMP2 increased grain Cd concentrations by more than 50%.Physiological experiments showed that OsNRAMP2 facilitated Cd translocation from root to shoot by positively regulating Cd efflux from the vacuoles.At filling stage,OsNRAMP2 was highly expressed in all tissues except for husk,suggesting its role in Cd remobilization.Changes in OsNRAMP2 expression affected the concentrations of Fe,Mn,Zn,and Cu in grain and also affected rice growth.Phylogenetic analysis showed that the distribution of OsNRAMP2 haplotypes between japonica and indica was different.Among the four haplotypes of OsNRAMP2,Hap 1,with a 6-bp nucleotide insertion in exon 1,had grain Cd concentration at least 45.3%lower than any of the other three haplotypes.Almost all(99.3%)japonica accessions but rare indica accessions(4.44%)from the 3K sequenced rice genomes carry Hap 1 of OsNRAMP2.Our study sheds light on the molecular mechanism of grain Cd accumulation and provides a promising target for low-Cd rice breeding.展开更多
Leaf rolling and discoloration are two chilling-injury symptoms that are widely used as indicators for the evaluation of cold tolerance at the seedling stage in rice. However, the difference in cold-response mechanism...Leaf rolling and discoloration are two chilling-injury symptoms that are widely used as indicators for the evaluation of cold tolerance at the seedling stage in rice. However, the difference in cold-response mechanisms underlying these two traits remains unknown. In the present study, a cold-tolerant rice cultivar, Lijiangxintuanheigu, and a cold-sensitive cultivar, Sanhuangzhan-2, were subjected to low-temperature treatments and physiolog-ical and genome-wide gene expression analyses were conducted. Leaf rolling occurred at temperatures lower than 11℃, whereas discoloration appeared at moderately low temperatures such as 13℃. Chlorophyll contents in both cultivars were significantly decreased at 13℃, but not altered at 11℃. In contrast, the relative water content and relative electrolyte leakage of both cultivars decreased significantly at 11℃, but did not change at 13℃. Expression of genes associated with calcium signaling and abscisic acid (ABA) degradation was significantly altered at 11℃ in comparison with 25℃ and 13℃. Numerous genes in the DREB, MYB, bZIP, NAC, Zinc finger, bHLH, and WRKY gene families were differentially expressed. Many aquaporin genes and the key genes in trehalose and starch synthesis were down regulated at 11℃ in comparison with 25℃ and 13℃. These results suggest that the two chilling injury symptoms are temperature-specific and are controlled by different mechanisms. Cold-induced leaf rolling is associated with calcium and ABA signaling pathways and is regulated by multiple transcriptional regulators. The suppression of aquaporin genes and reduced accumulation of soluble sugars under cold stress results in a reduction in cellular water potential and consequently leaf rolling.展开更多
With rising living standards,there is an increasing demand for high-quality rice.Rice quality is mainly defined by milling quality,appearance quality,cooking and eating quality,and nutrition quality.Among them,chalkin...With rising living standards,there is an increasing demand for high-quality rice.Rice quality is mainly defined by milling quality,appearance quality,cooking and eating quality,and nutrition quality.Among them,chalkiness is a key trait for appearance quality,which adversely affects cooking and eating quality,head rice yield,and commercial value.Therefore,chalkiness is undesirable,and reducing chalkiness is a major goal in rice quality improvement.However,chalkiness is a complex trait jointly influenced by genetic and environmental factors,making its genetic study and precision improvement a huge challenge.With the rapid development of molecular techniques,much knowledge has been gained about the genes and molecular networks involved in chalkiness formation.The present review describes the major environmental factors affecting chalkiness and summarizes the quantitative trait loci(QTL)associated with chalkiness.More than 150 genes related to chalkiness formation have been reported.The functions of the genes regulating chalkiness,primarily those involved in starch synthesis,storage protein synthesis,transcription regulation,organelle development,grain shape regulation,and hightemperature response,are described.Finally,we identify the challenges associated with genetic improvement of chalkiness and suggest potential strategies.Thus,the review offers insight into the molecular dynamics of chalkiness and provides a strong basis for the future breeding of high-quality rice varieties.展开更多
基金supported by the National Natural Science Foundation of China(31901488)the Guangdong Basic and Applied Basic Research Foundation(2020A1515010193)+3 种基金the Innovation Team Project of Guangdong Modern Agricultural Industrial System(2021KJ106,2022KJ106)the Scientific and Technological Plan of Guangzhou(201804020078,202102021005)the Special fund for scientific innovation strategy-construction of high level Academy of Agriculture Science(R2021PY-QF002,202027,R2019-JX001,R2021PY-QF001)the Guangdong Key Laboratory of New Technology in Rice Breeding(2020B1212060047).
文摘Cadmium(Cd)accumulation in rice grain is of health concern.Identifying genes involved in grain Cd accumulation and performing molecular breeding may reduce it.In this study,knockout of OsNRAMP2,a member of the NRAMP family,reduced grain Cd concentrations by more than 38%,and overexpressing OsNRAMP2 increased grain Cd concentrations by more than 50%.Physiological experiments showed that OsNRAMP2 facilitated Cd translocation from root to shoot by positively regulating Cd efflux from the vacuoles.At filling stage,OsNRAMP2 was highly expressed in all tissues except for husk,suggesting its role in Cd remobilization.Changes in OsNRAMP2 expression affected the concentrations of Fe,Mn,Zn,and Cu in grain and also affected rice growth.Phylogenetic analysis showed that the distribution of OsNRAMP2 haplotypes between japonica and indica was different.Among the four haplotypes of OsNRAMP2,Hap 1,with a 6-bp nucleotide insertion in exon 1,had grain Cd concentration at least 45.3%lower than any of the other three haplotypes.Almost all(99.3%)japonica accessions but rare indica accessions(4.44%)from the 3K sequenced rice genomes carry Hap 1 of OsNRAMP2.Our study sheds light on the molecular mechanism of grain Cd accumulation and provides a promising target for low-Cd rice breeding.
基金supported in part by the Ph.D. Start-up Fund of Natural Science Foundation of Guangdong Province, China (2015A030310419)the Guangdong Scientific and Technological Plan (2015B020231002, 2017A070702006, 2017A020208022)+3 种基金the Guangzhou Scientific and Technological Plan (201804020078)the Guangdong-Hong Kong joint project (2017A050506035)the Development Project of Guangdong Provincial Key Lab (2017B030314173)the Special Fund of Central Government Guided Local Scientific Development
文摘Leaf rolling and discoloration are two chilling-injury symptoms that are widely used as indicators for the evaluation of cold tolerance at the seedling stage in rice. However, the difference in cold-response mechanisms underlying these two traits remains unknown. In the present study, a cold-tolerant rice cultivar, Lijiangxintuanheigu, and a cold-sensitive cultivar, Sanhuangzhan-2, were subjected to low-temperature treatments and physiolog-ical and genome-wide gene expression analyses were conducted. Leaf rolling occurred at temperatures lower than 11℃, whereas discoloration appeared at moderately low temperatures such as 13℃. Chlorophyll contents in both cultivars were significantly decreased at 13℃, but not altered at 11℃. In contrast, the relative water content and relative electrolyte leakage of both cultivars decreased significantly at 11℃, but did not change at 13℃. Expression of genes associated with calcium signaling and abscisic acid (ABA) degradation was significantly altered at 11℃ in comparison with 25℃ and 13℃. Numerous genes in the DREB, MYB, bZIP, NAC, Zinc finger, bHLH, and WRKY gene families were differentially expressed. Many aquaporin genes and the key genes in trehalose and starch synthesis were down regulated at 11℃ in comparison with 25℃ and 13℃. These results suggest that the two chilling injury symptoms are temperature-specific and are controlled by different mechanisms. Cold-induced leaf rolling is associated with calcium and ABA signaling pathways and is regulated by multiple transcriptional regulators. The suppression of aquaporin genes and reduced accumulation of soluble sugars under cold stress results in a reduction in cellular water potential and consequently leaf rolling.
基金supported by the Guangdong Basic and Applied Basic Research Foundation(2023A1515010400,2023A1515030023)the Discipline Team of Agricultural Competitive Industries in Guangdong Academy of Agricultural Sciences(202101TD)+1 种基金the Special Fund for Scientific Innovation Strategyconstruction of High-level Academy of Agriculture Science(R2023PY-JX001)the Guangdong Key Laboratory of New Technology in Rice Breeding(2023B1212060042).
文摘With rising living standards,there is an increasing demand for high-quality rice.Rice quality is mainly defined by milling quality,appearance quality,cooking and eating quality,and nutrition quality.Among them,chalkiness is a key trait for appearance quality,which adversely affects cooking and eating quality,head rice yield,and commercial value.Therefore,chalkiness is undesirable,and reducing chalkiness is a major goal in rice quality improvement.However,chalkiness is a complex trait jointly influenced by genetic and environmental factors,making its genetic study and precision improvement a huge challenge.With the rapid development of molecular techniques,much knowledge has been gained about the genes and molecular networks involved in chalkiness formation.The present review describes the major environmental factors affecting chalkiness and summarizes the quantitative trait loci(QTL)associated with chalkiness.More than 150 genes related to chalkiness formation have been reported.The functions of the genes regulating chalkiness,primarily those involved in starch synthesis,storage protein synthesis,transcription regulation,organelle development,grain shape regulation,and hightemperature response,are described.Finally,we identify the challenges associated with genetic improvement of chalkiness and suggest potential strategies.Thus,the review offers insight into the molecular dynamics of chalkiness and provides a strong basis for the future breeding of high-quality rice varieties.
