Figures (4)  Tables (1)

    • Figure 1. 

      Seed development in angiosperms. (a) Double fertilization (leftmost panels) initiates embryo and endosperm formation (right panels) across successive stages of seed development in Arabidopsis (dicot model) and rice (monocot model). (b) Different types of angiosperm endosperms. Dots denote endosperm nuclei, while ellipses denote the embryo sac before fertilization or the endosperm after fertilization. (c) Various maternal and paternal effects on the regulation of seed development. (a) & (c) Maternal and paternal components are indicated in red and blue, respectively. The seed coat is indicated in light brown. For the zygotic tissues, the endosperm and embryo are indicated in pink and purple, respectively.

    • Figure 2. 

      Maternal control of seed development. (a) Symbols of maternal and filial tissues appearing in this figure. (b) Scheme of typical maternal effects. The phenotype of developing or mature seeds is determined by the maternal genotype. (c) Scheme of on-site effects of the maternal tissue. The phenotype is restricted to the tissue inherited from the mother, and thus determined by the maternal genotype. (d) Characterization of gametophytic maternal effects by test crosses. As the phenotype of developing or mature seeds is determined by the genotype of the female gametophyte, phenotypic segregation is observable in F1 progenies of test crosses. (e) Characterization of sporophytic maternal effects by test crosses. As the phenotype of developing or mature seeds is determined by the genotype of the female sporophyte, phenotypic segregation is unobservable in F1 progenies of test crosses.

    • Figure 3. 

      Zygotic control of seed development. (a) A typical zygotic effect causes phenotype segregation among F1 siblings. (b) Scheme of Mendelian and non-Mendelian inheritance patterns of F1 progenies with zygotic effects. Left panels: possible phenotypes of F1 progenies with a recessive, semi-dominant, or dominant mutation. Right panels: possible phenotypes of F1 progenies with a non-mendelian mutation. Such patterns of non-mendelian inheritance are likely related to parental interactions. Ellipse indicates the quantified range of a phenotype. (c) Scheme of endospermic factors regulating F1 phenotypes in a parental-dependent manner. (d) Typical mechanisms underlying gene imprinting. MEG, maternally imprinted gene; PEG, paternally imprinted gene. (e) Phenotypic assumptions based on unbalanced parental dosage. The first four panels from the left show phenotypic patterns of reciprocal crosses between wild-type plants and plants with loss of function or overexpression of imprinted genes. The fifth panel shows phenotypic patterns of interploidy crosses in Arabidopsis, while the sixth panel shows a smilar phenotype between the paternal-excess cross (2nd column) and the cross with loss of MEG (meg) (4th column). Such phenotypes are suppressed by loss of PEG (peg) (3rd and 5th columns). Ellipse indicates the quantified range of a phenotype, while half ellipse indicates a possible abortive phenotype.

    • Figure 4. 

      Inter-tissue communication in seed development. (a) Inter-tissue communication at the beginning of seed development. Paternal SSP mRNA from the pollen affects the zygotic YDA pathway to determine zygote division. Paternal miR159 from the pollen quenches maternal MYB33/65 to initiate nascent endosperm division. Other contents in the pollen tube can also trigger ovule growth, which mimicks fertilization. (b) Inter-tissue communication in early seed development. Synergid nuclei affect the maternal-paternal genome ratio in the nascent endosperm, which is oppositely regulated by sporophytic and gametophytic EIN3. The communication between maternal antipodal cells and paternal cues in the nascent endosperm relies on the relative dosage of maternal and paternal TTG2, which is transcriptionally regulated by TOP1α and UPF1. Nascent endosperm-female gametophyte communication is also suggested, although the mechanisms are yet unknown. (c) Inter-tissue communication regulating endosperm and integument development. Chalazal-transcribed TFL1 functions in the peripheral endosperm to regulate endosperm cellularization. This module also infers a potential maternal-filial communication at the chalazal part. Endosperm regulators, AGLs, are regulated by maternal siRNAs from both the endosperm and maternal tissues. AGL62 in turn regulates maternal nucellus degradation via the maternal TT16 and integument growth via the maternal PcG complex. (d) Inter-tissue communication between endosperm and embryo. When the cuticle barrier between endosperm and embryo is not established, endosperm-expressed LEC1 relocates into the embryo to exert its function. The integrity of such a barrier is monitored by two-way communication, in which the precursor of the embryo-expressed TWS1 peptide (TWS1pre) is processed in the endosperm by ALE1 and the mature peptide signal moves back into the embryo to activate the GSO1/2-pathway. (e) Color legend shows different elements in this figure. Single- and double-headed arrows indicate one-way and reciprocal regulations, respectively. Dashed arrow indicates a putative regulation. Green single-headed arrow indicates protein movement, while green gradient single-headed arrow indicates protein movement along with the maturation process.

    • Gene nameAbbreviationGene IDFunction noteReference
      ABERRANT TESTA SHAPEATSAT5G42630KANADI family transcription factor[30,31]
      ABNORMAL LEAF-SHAPE 1ALE1AT1G62340Subtilisin-like serine protease[126−129]
      ABSCISIC ACID INSENSITIVE 3ABI3AT3G24650B3 domain transcription factor[48−50]
      ADMETOSADMAT4G11940J-domain chaperone[99]
      ADRENODOXIN 1ADX1AT4G05450Adrenodoxin[47]
      ADRENODOXIN 2ADX2AT4G21090Adrenodoxin[47]
      ADRENODOXIN REDUCTASEADXRAT4G32360Adrenodoxin reductase[47]
      AGAMOUS-LIKE 40AGL40AT4G36590MADS-box family transcription factor[32]
      AGAMOUS-LIKE 62AGL62AT5G60440MADS-box family transcription factor[122]
      AGAMOUS-LIKE 91AGL91AT3G66656MADS-box family transcription factor[32]
      AINTEGUMENTAANTAT4G37750AP2 family transcription factor[22, 23]
      APETALA2AP2AT4G36920AP2 family transcription factor[29]
      BABY BOOMBBMAT5G17430AP2 family transcription factor[51−53]
      CYTOCHROME P450 FAMILY 78 A7CYP78A7AT5G09970Cytochrome p450 family[36,37]
      CYTOCHROME P450 FAMILY 78 A9CYP78A9AT3G61880Cytochrome p450 family[36,37]
      DA1DA1AT1G19270Ubiquitin-activated peptidase[26,27]
      DA2DA2AT1G78420RING-type E3 ubiquitin ligase[26]
      DEMETERDMEAT5G04560DNA glycosylase[65,66,68,
      69,78,80]
      DOSAGEEFFECT DEFECTIVE 1DED1Zm00001eb050770MYB family transcription factor[93]
      ENDOSPERM BREAKDOWN1ENB1Zm00001eb061800Cellulose synthase 5[62]
      ENHANCER OF da1-1 3EOD3 (CYP78A6)AT2G46660Cytochrome p450 family[36]
      ETHYLENE INSENSITIVE 3EIN3AT3G20770Transcription regulator[114]
      FERTILIZATION INDEPENDENT SEED 2FIS2AT2G35670PRC2 component[72,89]
      FLOWERING WAGENINGENFWAAT4G25530Homeodomain-containing transcription factor[73]
      FUSCA3FUS3AT3G26790B3 domains transcription factor[48−50]
      GASSHO1GSO1AT4G20140Leucine rich repeat (LRR) receptor-like kinase[126,127]
      GASSHO2GSO2AT5G44700Leucine rich repeat (LRR) receptor-like kinase[126,127]
      GIANT EMBRYOGE (OsCYP78A13)LOC_Os07g41240Cytochrome p450 family[45,46]
      GLABRA2GL2AT1G79840Homeodomain-containing transcription factor[17]
      GRAIN WEIGHT 2GW2LOC_Os02g14720RING-type E3 ubiquitin ligase[41]
      HAIKU1IKU1AT1G55600Plant-specific VQ motif-containing protein[5,6,8]
      HAIKU2IKU2AT3G19700Leucine rich repeat (LRR) kinase[5−7]
      HOMEDOMAIN GLABROUS 3HDG3AT2G32370Homeodomain-containing transcription factor[92]
      INDUCER OF CBF EXPRESSIONICE 1ICE1AT3G26744bHLH family transcription factor[128, 129]
      INNER NO OUTERINOAT1G23420YABBY family transcription factor[24]
      KERBEROSKRSAT1G50650STIG1 family of peptide[130]
      KLUHKLU (CYP78A5)AT1G13710Cytochrome p450 family[35]
      LEAFY COTYLEDON 1LEC1AT1G21970Nuclear factor Y transcription factor[48−50]
      LEAFY COTYLEDON 2LEC2AT1G28300B3 domains transcription factor[48−50]
      MATERNAL DEREPRESSION OF r1MDR1 (DNG101)Zm00001eb202980DNA glycosylase[81]
      MATERNAL EFFECT EMBRYO ARREST45MEE45AT4G00260B3 domains transcription factor[38]
      MATERNALLY EXPRESSED PAB C-TERMINALMPCAT3G19350C-terminal domain of poly(A) binding protein[71]
      MEDEAMEAAT1G02580PRC2 component[69,72,74,75,
      83,84,89]
      METHYLTRANSFERASE 1MET1AT5G49160Methyltransferase 1[70, 83,84,
      86,106]
      MINISEED3MINI3AT1G55600WRKY family transcription factor, WRKY10[6,7]
      MIR159aMIR159aAT1G73687MicroRNA[112]
      MIR159bMIR159bAT1G18075MicroRNA[112]
      MIR159cMIR159cAT2G46255MicroRNA[112]
      MYB33MYB33AT5G06100MYB family transcription factor[112]
      MYB65MYB65AT3G11440MYB family transcription factor[112]
      PHERES 1PHE1(AGL37)AT1G65330MADS-box family transcription factor[83−85]
      PHOSPHATE 1PHO1AT3G23430Phosphate transporter[19]
      PICKLE RELATED 2PKR2AT4G31900Chromatin remodeling factor[104]
      OsBBM1OsBBM1LOC_Os11g19060AP2 family transcription factor[110,111]
      SHAGGY-LIKE KINASE 11SK11AT5G26751GSK3 family/SHAGGY-like protein kinase[16, 18]
      SHAGGY-LIKE KINASE 12SK12AT3G05840GSK3 family/SHAGGY-like protein kinase[16,18]
      SHORT HYPOCOTYL UNDER BLUE1SHB1AT4G25350homologous with SYG1 protein family members, transcription regulator[9]
      SHORT SUSPENSORSSPAT2G17090Receptor-like cytoplasmic protein kinase[108,109]
      SmD1bSmD1bAT4G02840Smith protein[18]
      TERMINAL FLOWER1TFL1AT5G03840Phosphatidylethanolamine binding protein (PEBP) family member[121]
      TOPOISOMERASE IαTOP1αAT5G55300DNA topoisomerase[117]
      TRANSPARENT TESTA 16TT16 (AGL32)AT5G23260MADS-box family transcription factor[123]
      TRANSPARENT TESTA 2TT2AT5G35550MYB family transcription factor[13]
      TRANSPARENT TESTA 8TT8AT4G09820bHLH family transcription factor[14]
      TRANSPARENT TESTA GLABRA 1TTG1AT5G24520WD40-motif containing transcription regulator[15, 16]
      TRANSPARENT TESTA GLABRA 2TTG2AT2G37260WRKY family transcription factor, WRKY44[28,117]
      TWISTED SEED 1TWS1AT5G01075Signaling peptide precursor[126, 127]
      UBIQUITIN-SPECIFIC PROTEASE 12UBP12AT5G06600Deubiquitination enzyme[27]
      UBIQUITIN-SPECIFIC PROTEASE 13UBP13AT3G11910Deubiquitination enzyme[27]
      UP-FRAMESHIFT SUPPRESSOR 1UPF1AT5G47010RNA helicase[117]
      YODAYDAAT1G63700Member of MEKK subfamily, involved in MAPK cascade[108,109]
      ZHOUPIZOUAT1G49770bHLH family transcription factor[128, 129]
      ZmGW2-CHR4ZmGW2-CHR4Zm00001eb204560RING-type E3 ubiquitin ligase[43]
      ZmGW2-CHR5ZmGW2-CHR5Zm00001eb238650RING-type E3 ubiquitin ligase[43]
      ZmSWEET4cZmSWEET4cZm00001eb236820Sugar transporter[20]

      Table 1. 

      Information on the genes discussed in this review.