Cell wall invertase(CWIN)are known to play important roles in seed development.However,most reports to date have focused on a single gene family member,and have mainly investigated CWIN functions during the filling st...Cell wall invertase(CWIN)are known to play important roles in seed development.However,most reports to date have focused on a single gene family member,and have mainly investigated CWIN functions during the filling stage of seed development.In this study,we found significant lower levels of CWIN protein and activity associated with seed abortion in the Litchi chinensis cultivar“Nuomici.”We identified five litchi CWIN genes and observed that the expression of LcCWIN5 was limited to the flower tissues and decreased sharply with fruit development.Silencing of LcCWIN5 expression before 28 DAA(cell division stage)resulted in perturbed liquid endosperm development,smaller seeds,and higher seed abortion rate,while silencing after 28 DAA(filling stage)had no effect on seed development.In contrast,LcCWIN2 was mostly expressed in the funicle and seed coat,and increased with fruit development.Decreased LcCWIN2 expression and CWIN activity during early seed filling coincided with smaller seeds in the cultivar“Feizixiao.”Silencing of LcCWIN2 caused a reduction in the seed size without inducing seed abortion.We propose that CWIN activity in seed maternal tissues during cell division stage is likely due to LcCWIN5 expression,which regulates early seed development.On the other hand,CWIN activity during the filling stage is due to the expression of LcCWIN2,which may promote carbon import by creating a sucrose gradient.Comparable LcCWIN5 expression,but much lower CWIN activity,detected in the funicle of“Nuomici”is consistent with post-translational regulation.展开更多
Sugar composition not only affects fruit flavor but is also an important determinant of fruit taste and consumer preference.In this study,changes in the sugar content and sugar-metabolizing enzymes were investigated f...Sugar composition not only affects fruit flavor but is also an important determinant of fruit taste and consumer preference.In this study,changes in the sugar content and sugar-metabolizing enzymes were investigated from different sections of various fruit development phases of‘Hongshuijing’pitaya(Hylocereus monacanthus).Genes related to sugar metabolism were also screened by transcriptome analyses.The results indicated that glucose was the major sugar in mature pitaya fruit,and was mainly regulated by vacuolar acid invertase(VAI)and sucrose synthase(SS)(degradative direction).Sugar accumulation varied in pulp between different sections of the pitaya fruit.VAI,neutral invertase(NI)and SS(degradative direction)are crucial enzymes for sugar accumulation in pitaya.The expression of 17 genes related to sucrose metabolism obtained from seven databases[NCBI non-redundant protein database(Nr),NCBI non-redundant nucleotide sequence database(Nt),EuKaryotic Orthologous Groups(KOG),The Protein Families(Pfam),Kyoto Encyclopedia of Genes and Genomes(KEGG),Swiss-prot,and Gene Ontology(GO)]were analyzed in different pitaya pulp sections.HpVAI1 had the highest relative expression level on the 29th day after pollination(DAP).Positive correlations were found between HpVAI1 expression and VAI activity;HpNI4 and NI activity;HpSS2,HpSS5,and SS activity(synthetic direction),indicating that HpVAI1,HpNI4,and HpSS2 and HpSS5 were involved in the regulation of VAI,NI,and SS(synthetic direction),respectively.HpVAI1 and HpNI4 regulated sucrose degradation and the accumulation of glucose and fructose,while HpSS2 and HpSS5 regulated sucrose synthesis.These results suggest that HpVAI1 plays a key role in sugar metabolism during fruit development of‘Hongshuijing’pitaya.The results of this study provide new information about sugar metabolism in pitaya fruit that could help improve fruit quality and the breeding of new cultivars.展开更多
Sucrose synthase(SUS,EC 2.4.1.13)is widely considered as a key enzyme involved in plant sucrose metabolism,and the gene family encoding different SUS isozymes has been identified and characterized in several plant spe...Sucrose synthase(SUS,EC 2.4.1.13)is widely considered as a key enzyme involved in plant sucrose metabolism,and the gene family encoding different SUS isozymes has been identified and characterized in several plant species.However,to date scant information about the SUS genes is available in Litchi chinensis Sonn.Here,we identified five SUS genes in litchi.These Lc SUSs shared high levels of similarity in both nucleotide and amino acid sequences.Their gene structure,phylogenetic relationships,and expression profiles were characterized.Gene structure analysis indicated that the Lc SUSs have similar exon-intron structures.Phylogenetic analysis revealed that the five members could be classified into three groups(LcSUS1 and LcSUS2 in SUSⅡ,LcSUS4 and LcSUS5 in SUSⅢ,and LcSUS3 in SUSⅠ),demonstrating evolutionary conservation in the SUS family across litchi and other plant species.The expression levels of Lc SUSs were investigated via real-time PCR in various tissues and different developmental stages of aril.For tissues and organs,Lc SUSs exhibited distinct but partially redundant expression profiles in litchi,being predominantly expressed in young leaves(sink).During aril development,the expression pattern of LcSUS1 was consistent with the trend of sugar accumulation,indicating it may play important roles in determination of sink strength in aril.Moreover,transcript levels of LcSUS2,LcSUS4,and LcSUS5 varied between cultivars with different hexose/sucrose ratios,which may regulate the sugar composition in aril.Our results provide insights into physiological functions of SUS genes in litchi,especially roles in regulating sugar accumulation in aril.展开更多
基金This study was supported by the National Natural Science Fund of China(project No.31501734)the China Litchi and Longan Industry Technology Research System(project No.CARS-33-11).
文摘Cell wall invertase(CWIN)are known to play important roles in seed development.However,most reports to date have focused on a single gene family member,and have mainly investigated CWIN functions during the filling stage of seed development.In this study,we found significant lower levels of CWIN protein and activity associated with seed abortion in the Litchi chinensis cultivar“Nuomici.”We identified five litchi CWIN genes and observed that the expression of LcCWIN5 was limited to the flower tissues and decreased sharply with fruit development.Silencing of LcCWIN5 expression before 28 DAA(cell division stage)resulted in perturbed liquid endosperm development,smaller seeds,and higher seed abortion rate,while silencing after 28 DAA(filling stage)had no effect on seed development.In contrast,LcCWIN2 was mostly expressed in the funicle and seed coat,and increased with fruit development.Decreased LcCWIN2 expression and CWIN activity during early seed filling coincided with smaller seeds in the cultivar“Feizixiao.”Silencing of LcCWIN2 caused a reduction in the seed size without inducing seed abortion.We propose that CWIN activity in seed maternal tissues during cell division stage is likely due to LcCWIN5 expression,which regulates early seed development.On the other hand,CWIN activity during the filling stage is due to the expression of LcCWIN2,which may promote carbon import by creating a sucrose gradient.Comparable LcCWIN5 expression,but much lower CWIN activity,detected in the funicle of“Nuomici”is consistent with post-translational regulation.
基金supported by grants from the Key Science and Technology Planning Project of Guangzhou (Grant No. 201904020015)Science and Technology Program of Zhanjiang (Grant No. 2019A01003)+1 种基金Key Realm R&D Program of Guangdong Province (Grant No. 2018B020202011)Science and Technology Program of Guangzhou (Grant Nos. 202002020060, 201704020003 and 2014Y2-00164)
文摘Sugar composition not only affects fruit flavor but is also an important determinant of fruit taste and consumer preference.In this study,changes in the sugar content and sugar-metabolizing enzymes were investigated from different sections of various fruit development phases of‘Hongshuijing’pitaya(Hylocereus monacanthus).Genes related to sugar metabolism were also screened by transcriptome analyses.The results indicated that glucose was the major sugar in mature pitaya fruit,and was mainly regulated by vacuolar acid invertase(VAI)and sucrose synthase(SS)(degradative direction).Sugar accumulation varied in pulp between different sections of the pitaya fruit.VAI,neutral invertase(NI)and SS(degradative direction)are crucial enzymes for sugar accumulation in pitaya.The expression of 17 genes related to sucrose metabolism obtained from seven databases[NCBI non-redundant protein database(Nr),NCBI non-redundant nucleotide sequence database(Nt),EuKaryotic Orthologous Groups(KOG),The Protein Families(Pfam),Kyoto Encyclopedia of Genes and Genomes(KEGG),Swiss-prot,and Gene Ontology(GO)]were analyzed in different pitaya pulp sections.HpVAI1 had the highest relative expression level on the 29th day after pollination(DAP).Positive correlations were found between HpVAI1 expression and VAI activity;HpNI4 and NI activity;HpSS2,HpSS5,and SS activity(synthetic direction),indicating that HpVAI1,HpNI4,and HpSS2 and HpSS5 were involved in the regulation of VAI,NI,and SS(synthetic direction),respectively.HpVAI1 and HpNI4 regulated sucrose degradation and the accumulation of glucose and fructose,while HpSS2 and HpSS5 regulated sucrose synthesis.These results suggest that HpVAI1 plays a key role in sugar metabolism during fruit development of‘Hongshuijing’pitaya.The results of this study provide new information about sugar metabolism in pitaya fruit that could help improve fruit quality and the breeding of new cultivars.
基金the Key-Area of Research and Development Program of Guangdong Province(Grant No.2018B020202011)the China Litchi and Longan Industry Technology Research System(Grant No.CARS-32-05)Yang Fan Innovative&Entrepreneurial Research Team Project(Grant No.2014YT02H013)。
文摘Sucrose synthase(SUS,EC 2.4.1.13)is widely considered as a key enzyme involved in plant sucrose metabolism,and the gene family encoding different SUS isozymes has been identified and characterized in several plant species.However,to date scant information about the SUS genes is available in Litchi chinensis Sonn.Here,we identified five SUS genes in litchi.These Lc SUSs shared high levels of similarity in both nucleotide and amino acid sequences.Their gene structure,phylogenetic relationships,and expression profiles were characterized.Gene structure analysis indicated that the Lc SUSs have similar exon-intron structures.Phylogenetic analysis revealed that the five members could be classified into three groups(LcSUS1 and LcSUS2 in SUSⅡ,LcSUS4 and LcSUS5 in SUSⅢ,and LcSUS3 in SUSⅠ),demonstrating evolutionary conservation in the SUS family across litchi and other plant species.The expression levels of Lc SUSs were investigated via real-time PCR in various tissues and different developmental stages of aril.For tissues and organs,Lc SUSs exhibited distinct but partially redundant expression profiles in litchi,being predominantly expressed in young leaves(sink).During aril development,the expression pattern of LcSUS1 was consistent with the trend of sugar accumulation,indicating it may play important roles in determination of sink strength in aril.Moreover,transcript levels of LcSUS2,LcSUS4,and LcSUS5 varied between cultivars with different hexose/sucrose ratios,which may regulate the sugar composition in aril.Our results provide insights into physiological functions of SUS genes in litchi,especially roles in regulating sugar accumulation in aril.
