Expression Level of<i>ABERRANT PANICLE ORGANIZATION1</i>Determines Rice Inflorescence Form through Control of Cell Proliferation in the Meristem

Ikeda-Kawakatsu, Kyoko; Yasuno, Nobuhiro; Oikawa, Tetsuo; Iida, Shigeru; Nagato, Yasuo; Maekawa, Masahiko; Kyozuka, Junko

doi:10.1104/pp.109.136739

Cited by 145 publications

(149 citation statements)

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“…In situ hybridization analysis of ABERRANT PANICLE ORGANI-ZATION1 (APO1) expression in V/R stage SAMs revealed a mixture of APO1-expressing and nonexpressing SAMs (see Supplemental Figure 2 online). Because induction of APO1 is concurrent with reproductive transition (Ikeda-Kawakatsu et al, 2009), this indicates that the V/R stage is a critical time in the transition of the SAM to the IM. Inflorescences at the primary branch initiation, secondary branch initiation, and spikelet initiation stages were collected as R2, R3, and R4 stages (Figures 2A and 2B).…”

Section: Pap2 Expression Is Induced In the Meristem Upon Reproductivementioning

confidence: 99%

“…To determine further the identity of meristems in the quadruple knockdown plants, we performed in situ hybridization analysis of APO1, which is normally expressed in the IM and the BM but not in the vegetative SAM (Ikeda-Kawakatsu et al, 2009). Absence of the APO1 signal in the quadruple knockdown plants confirmed that the axillary meristems retain the characteristics of the vegetative SAM ( Figures 4S and 4T).…”

Section: Inflorescence Development Was Severely Perturbed In the Madsmentioning

confidence: 99%

“…In situ hybridization of the APO1 and PAP2 genes was performed as previously described (Ikeda-Kawakatsu et al, 2009;Kobayashi et al, 2010).…”

Section: In Situ Hybridization Analysismentioning

confidence: 99%

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Inflorescence Meristem Identity in Rice Is Specified by Overlapping Functions of Three AP1/FUL-Like MADS Box Genes and PAP2, a SEPALLATA MADS Box Gene

et al. 2012

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In plants, the transition to reproductive growth is of particular importance for successful seed production. Transformation of the shoot apical meristem (SAM) to the inflorescence meristem (IM) is the crucial first step in this transition. Using laser microdissection and microarrays, we found that expression of PANICLE PHYTOMER2 (PAP2) and three APETALA1 (AP1)/ FRUITFULL (FUL)-like genes (MADS14, MADS15, and MADS18) is induced in the SAM during meristem phase transition in rice (Oryza sativa). PAP2 is a MADS box gene belonging to a grass-specific subclade of the SEPALLATA subfamily. Suppression of these three AP1/FUL-like genes by RNA interference caused a slight delay in reproductive transition. Further depletion of PAP2 function from these triple knockdown plants inhibited the transition of the meristem to the IM. In the quadruple knockdown lines, the meristem continued to generate leaves, rather than becoming an IM. Consequently, multiple shoots were formed instead of an inflorescence. PAP2 physically interacts with MAD14 and MADS15 in vivo. Furthermore, the precocious flowering phenotype caused by the overexpression of Hd3a, a rice florigen gene, was weakened in pap2-1 mutants. Based on these results, we propose that PAP2 and the three AP1/FUL-like genes coordinately act in the meristem to specify the identity of the IM downstream of the florigen signal.

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Section: Pap2 Expression Is Induced In the Meristem Upon Reproductivementioning

confidence: 99%

Section: Inflorescence Development Was Severely Perturbed In the Madsmentioning

confidence: 99%

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Inflorescence Meristem Identity in Rice Is Specified by Overlapping Functions of Three AP1/FUL-Like MADS Box Genes and PAP2, a SEPALLATA MADS Box Gene

et al. 2012

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“…Orthologs of RA2 and RA3 (but not RA1) are found in the rice genome, but their functions are unknown. The rice genes ABERRANT PANICLE1 (APO1) and APO2 are orthologs of the Arabidopsis genes UNUSUAL FLORAL ORGANS (UFO) and LEAFY (LFY), respectively, and they negatively regulate the shift to SM identity (10)(11)(12). In Arabidopsis and other eudicot species, UFO and LFY promote determinate floral meristem identity (10).…”

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confidence: 99%

TAWAWA1 , a regulator of rice inflorescence architecture, functions through the suppression of meristem phase transition

Yoshida

Sasao

Yasuno

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Inflorescence structures result from the activities of meristems, which coordinate both the renewal of stem cells in the center and organ formation at the periphery. The fate of a meristem is specified at its initiation and changes as the plant develops. During rice inflorescence development, newly formed meristems acquire a branch meristem (BM) identity, and can generate further meristems or terminate as spikelets. Thus, the form of rice inflorescence is determined by a reiterative pattern of decisions made at the meristems. In the dominant gain-of-function mutant tawawa1-D, the activity of the inflorescence meristem (IM) is extended and spikelet specification is delayed, resulting in prolonged branch formation and increased numbers of spikelets. In contrast, reductions in TAWAWA1 (TAW1) activity cause precocious IM abortion and spikelet formation, resulting in the generation of small inflorescences. TAW1 encodes a nuclear protein of unknown function and shows high levels of expression in the shoot apical meristem, the IM, and the BMs. TAW1 expression disappears from incipient spikelet meristems (SMs). We also demonstrate that members of the SHORT VEGETATIVE PHASE subfamily of MADS-box genes function downstream of TAW1. We thus propose that TAW1 is a unique regulator of meristem activity in rice and regulates inflorescence development through the promotion of IM activity and suppression of the phase change to SM identity.ALOG family | meristem identity | grain yield T he timing of each meristem phase change is crucial in the control of inflorescence architecture (1-3). In grass species, the basic architecture of inflorescence is defined by the spatial arrangement of spikelets, which are small branches containing a variable number of flowers. Among the meristems that are generated from the primary inflorescence meristem (IM) during inflorescence (panicle) development, early ones acquire an indeterminate branch meristem (BM) identity, whereas later ones are specified as determinate spikelet meristems (SMs) (Fig. 1A) (4, 5). The BMs themselves are eventually transformed into SMs after generating a certain number of branches and spikelets (Fig. 1B). Thus, the pattern of SM specification is a primary determinant of grass inflorescence form. Delays in SM specification lead to iterations of branching, resulting in larger panicles that could potentially produce more grain. Conversely, the acceleration of SM specification results in smaller panicles with fewer spikelets. Rice inflorescence development exhibits an additional unique feature in that the IM loses its activity after producing several BMs, leaving a vestige at the tip of the rachis, the inflorescence main stem (Fig. 1A). Therefore, the timing of IM abortion is also a critical factor determining the form of rice inflorescence.The competence of a meristem to become an SM gradually increases during inflorescence development; however, the molecular basis for the timing of SM specification is largely unknown.To date, several genes that control inflorescence form ...

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“…Several genes have been reported as positive (Huang et al 2009, Ikeda-Kawakatsu et al 2009, Jiao et al 2010, Komatsu et al 2001, Miura et al 2010, Rao et al 2008 or negative regulators (Kobayashi et al 2010, Takahashi et al 1998) of rachis mersitem activity or PB number in cultivars. However, for these genes, rachis meristem abortion still occurs in loss-of-function mutants or transformants.…”

Section: A Conical Panicle Is Ancestral In the Genus Oryzamentioning

confidence: 99%

Diversity of panicle branching patterns in wild relatives of rice

et al. 2010

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Panicle branchiness is one of the key characters specifying rice yield. To understand the potential of panicle branchiness, the diversity of panicle branching patterns was investigated in 43 accessions of 19 wild Oryza species and 27 accessions of O. rufipogon, which is the wild ancestor of the Asian cultivated species O. sativa. All these accessions were selected from a core collection of wild relatives of rice maintained at the National Institute of Genetics (NIG), Mishima, Japan. We found that panicles of wild Oryza species closely related to O. sativa generated primary branches with homogeneously large numbers of secondary branching organs, resulting in a truncated conical type of branching pattern. In contrast, panicles of distantly related wild species had primary branches with acropetally declining numbers of secondary organs toward the distal end of panicles, resulting in a conical type of branching pattern. The main axis meristem, which was aborted in closely related species, was converted into a terminal spikelet in distantly related species. Our data suggested that the panicle branching pattern evolved from conical to truncated conical in the genus Oryza. The possible advantage of a truncated-conical type of branching pattern for rice yield will be discussed.

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Expression Level ofABERRANT PANICLE ORGANIZATION1Determines Rice Inflorescence Form through Control of Cell Proliferation in the Meristem

Cited by 145 publications

References 58 publications

Inflorescence Meristem Identity in Rice Is Specified by Overlapping Functions of Three AP1/FUL-Like MADS Box Genes and PAP2, a SEPALLATA MADS Box Gene

Inflorescence Meristem Identity in Rice Is Specified by Overlapping Functions of Three AP1/FUL-Like MADS Box Genes and PAP2, a SEPALLATA MADS Box Gene

TAWAWA1 , a regulator of rice inflorescence architecture, functions through the suppression of meristem phase transition

Diversity of panicle branching patterns in wild relatives of rice

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