Inflorescence Meristem Research Articles

Unraveling the Genetic Mechanisms of Maize Ear Diameter Heterosis

Hybridization has long been a crucial strategy for breeders aiming to develop high-yield crops vital for global food security. However, the exact molecular mechanisms driving heterosis (hybrid vigor) remain a topic of debate. Maize (Zea mays), which demonstrates pronounced heterosis, serves as an ideal model for studying this phenomenon. In our study, we carefully measured phenotypic changes in ear diameter, tracing its development from the inflorescence meristem (IM) to the floral meristem (FM) stages. Our findings revealed a complex progression: the hybrid's ear diameter followed an additive pattern during the IM and spikelet pair meristem (SPM) stages, shifted to incomplete dominance at the spikelet meristem (SM) stage, and ultimately displayed over-dominance at the FM stage. Notably, significant phenotypic changes occurred during the SM stage with gene expression primarily showing non-additive patterns. Gene Ontology (GO) enrichment analysis highlighted the role of cell redox homeostasis genes, which exhibited over-dominant expression in hybrids, as key contributors to heterosis. Furthermore, we identified a distinct gene expression category - dominant maternal or paternal gene expression in F1 hybrids (DMP) - characterized by exclusive expression in the hybrid and one parent, while remaining inactive in the other. This category of DMP genes plays a pivotal role in shaping the diverse gene expression patterns observed in hybrids, distinguishing them from their parental lines. In conclusion, the widespread occurrence of non-additive expression seems to enhance the efficiency of biological processes and energy distribution in hybrids, ultimately driving the manifestation of heterosis.

The WOX9-WUS modules are indispensable for the maintenance of stem cell homeostasis in Arabidopsis thaliana.

The dynamic balance between the self-renewal and differentiation of stem cells in plants is precisely regulated by a series of developmental regulated genes that exhibit spatiotemporal-specific expression patterns. Several studies have demonstrated that the WOX family transcription factors play critical roles in maintaining the identity of stem cells in Arabidopsis thaliana. In this study, we obtained amiR-WOX9 transgenic plants, which displayed terminating prematurely of shoot apical meristem (SAM) development, along with alterations in inflorescence meristem and flower development. The phenotype of amiR-WOX9 plants exhibited similarities to that of wus-101 mutant, characterized by a stop-and-go growth pattern. It was also found that the expression of WUS in amiR-WOX9 lines was decreased significantly, while in UBQ10::WOX9-GFP transgenic plants, the WUS expression was increased significantly despite no substantial alteration in meristem size compared to Col. Therefore, these data substantiated the indispensable role of WOX9 in maintaining the proper expression of WUS. Further investigations unveiled the direct binding of WOX9 to the WUS promoter via the TAAT motif, thereby activating its expression. It was also found that WUS recognized identical the same TAAT motif cis-elements in its own promoter, thereby repress self-expression. Next, we successfully identified a physical interaction between WOX9 and WUS, and verified that it was harmful to the expression of WUS. Finally, our experimental findings demonstrate that WOX9 was responsible for the direct activating of WUS, which however was interfered by the ways of WUS binding its own promoter and the interaction of WUS and WOX9, thereby ensuring the appropriate expression pattern of WUS and then the stem cell stability. This study contributes to an enhanced comprehension of the regulatory network of the WOX9-WUS module in maintaining the equilibrium of the SAM.

Transcriptional corepressors in maize maintain meristem development.

The formation of the plant body proceeds in a sequential post-embryonic manner through the action of meristems. Tightly coordinated meristem regulation is required for development and reproductive success, eventually determining yield in crop species. In maize (Zea mays), the RAMOSA1 ENHANCER LOCUS2 (REL2) family of transcriptional corepressors includes four members, REL2, RELK1 (REL2-LIKE1), RELK2, and RELK3. In a screen for rel2 enhancers, we identified shorter double mutants with enlarged ear inflorescence meristems (IMs) carrying mutations in RELK1. Expression and genetic analysis indicated that REL2 and RELK1 cooperatively regulate ear IM development by controlling genes involved in redox balance, hormone homeostasis, and differentiation, ultimately tipping the meristem toward an environment favorable to expanded expression of the ZmWUSCHEL1 gene, which encodes a key stem-cell promoting transcription factor. We further demonstrated that RELK genes have partially redundant yet diverse functions in the maintenance of various meristem types during development. By exploiting subtle increases in ear IM size in rel2 heterozygous plants, we also showed that extra rows of kernels are formed across a diverse set of F1 hybrids. Our findings reveal that the REL2 family maintains development from embryonic initiation to reproductive growth and can potentially be harnessed for increasing seed yield in a major crop species.

A Functional Analysis of Inflorescence Architecture in Musa L. (Musaceae)

ABSTRACTInflorescence architecture underpins sexual reproduction in wild Musa species and productivity in edible banana cultivars. In a functional analysis, we identified the apical inflorescence and lateral ‘cushion’ meristems and the change in flower type as the three primary components that generate inflorescence architecture. Five genotypes of two clone sets of edible plantains (Musa AAB) were grown for four generations along an elevation gradient (1100–2200 m, 16°C–24°C) straddling the equator in the humid highlands of East Africa. The data consisted of reproductive peduncle length at harvest (Pr), fruit per hand (Fh) and hands per bunch (Hb). The activity of the apical inflorescence meristem drives peduncle length and generates lateral ‘cushion’ meristems which determine Fh. However, Hb is determined by a change in flower type—from fruit forming to non‐fruit forming. Site temperature affected Hb more than Fh, while the development of the genet (rhizome) changed the allocation of resources between Hb and Fh, independently of the effect of site temperature. Clone sets differed in their response to genet development. Cooler temperatures reduced the number of fruit‐forming flowers in an inflorescence and changed the balance away from female towards male flowers. In banana breeding schemes, manipulating inflorescence components independently raises options for producing genotypes better suited to markets, environments and cultural practices.

CLAVATA3 Signaling Buffers Arabidopsis Shoot Apical Meristem Activity in Response to Photoperiod.

Land plants grow throughout their life cycle via the continuous activity of stem cell reservoirs contained within their apical meristems. The shoot apical meristem (SAM) of Arabidopsis and other land plants responds to a variety of environmental cues, yet little is known about the response of meristems to seasonal changes in day length, or photoperiod. Here, the vegetative and reproductive growth of Arabidopsis wild-type and clavata3 (clv3) plants in different photoperiod conditions was analyzed. It was found that SAM size in wild-type Arabidopsis plants grown in long-day (LD) conditions gradually increased from embryonic to reproductive development. clv3 plants produced significantly more leaves as well as larger inflorescence meristems and more floral buds than wild-type plants in LD and short-day (SD) conditions, demonstrating that CLV3 signaling limits vegetative and inflorescence meristem activity in both photoperiods. The clv3 phenotypes were more severe in SDs, indicating a greater requirement for CLV3 restriction of SAM function when the days are short. In contrast, clv3 floral meristem size and carpel number were unchanged between LD and SD conditions, which shows that the photoperiod does not affect the regulation of floral meristem activity through the CLV3 pathway. This study reveals that CLV3 signaling specifically restricts vegetative and inflorescence meristem activity in both LD and SD photoperiods but plays a more prominent role during short days.

Genome-wide association study and selective sweep analysis uncover candidate genes controlling curd branch length in cauliflower.

Cauliflower is a distinct subspecies of the Brassica oleracea plants due to its specialized and edible floral organ. Cauliflower curd is composed of enlarged inflorescence meristems that developed by a series of precise molecular regulations. Based solely on the curd solidity, cauliflower is generally classified into two groups (compact-curd and loose-curd), where curd branch length acts as a crucial parameter to determine the curd morphological difference. Herein, to understand the genetic basis of curd branch development, we utilized a total of 298 inbred lines representing two groups of cauliflower to comprehensively investigate the causal genes and regulatory mechanisms. Phylogenetic and population structure analyses revealed that two subgroups could be further categorized into the compact-curd and the loose-curd groups, respectively. Integrating the genotype and phenotype data, we conducted a genome-wide association study for the length of the outermost branch (LOB) and secondary branch (LSB) of the curd. Sixty-four significant loci were identified that are highly associated with curd branch development. Evidence from genome-wide selective sweep analysis (FST and XP-EHH) narrowed down the major signal on chromosome 8 into an approximately 79kb region which encodes eleven protein-coding genes. After further analysis of haplotypes, transcriptome profiling, and gene expression validation, we finally inferred that BOB08G028680, as a homologous counterpart of AtARR9, might be the causal gene for simultaneously regulating LOB and LSB traits in cauliflower. This result provides valuable information for improving curd solidity in future cauliflower breeding.

AGAMOUS-LIKE 24 senses continuous inductive photoperiod in the inflorescence meristem to promote anthesis in chrysanthemum.

During the floral transition, many plant species including chrysanthemum (Chrysanthemum morifolium) require continuous photoperiodic stimulation for successful anthesis. Insufficient photoperiodic stimulation results in flower bud arrest or even failure. The molecular mechanisms underlying how continuous photoperiodic stimulation promotes anthesis are not well understood. Here, we reveal that in wild chrysanthemum (Chrysanthemum indicum), an obligate short-day (SD) plant, floral evocation is not limited to SD conditions. However, SD signals generated locally in the inflorescence meristem (IM) play a vital role in ensuring anthesis after floral commitment. Genetic analyses indicate that the florigen FLOWERING LOCUS T-LIKE3 (CiFTL3) plays an important role in floral evocation, but a lesser role in anthesis. Importantly, our data demonstrate that AGAMOUS-LIKE 24 (CiAGL24) is a critical component of SD signal perception in the IM to promote successful anthesis, and that floral evocation and anthesis are two separate developmental events in chrysanthemum. We further reveal that the central circadian clock component PSEUDO-RESPONSE REGULATOR 7 (CiPRR7) in the IM activates CiAGL24 expression in response to SD conditions. Moreover, our findings elucidate a negative feedback loop in which CiAGL24 and SUPPRESSOR OF OVEREXPRESSION OF CO 1 (CiSOC1) modulate LEAFY (CiLFY) expression. Together, our results demonstrate that the CiPRR7-CiAGL24 module is vital for sustained SD signal perception in the IM to ensure successful anthesis in chrysanthemum.

Loss-of-function of LIGULELESS1 activates the jasmonate pathway and promotes maize resistance to corn leaf aphids.

Corn leaf aphids (Rhopalosiphum maidis) are highly destructive pests of maize (Zea mays) that threaten growth and seed yield, but resources for aphid resistance are scarce. Here, we identified an aphid-resistant maize mutant, resistance to aphids 1 (rta1), which is allelic to LIGULELESS1 (LG1). We confirmed LG1's role in aphid resistance using the independent allele lg1-2, allelism tests and LG1 overexpression lines. LG1 interacts with, and increases the stability of ZINC-FINGER PROTEIN EXPRESSED IN INFLORESCENCE MERISTEM (ZIM1), a central component of the jasmonic acid (JA) signalling pathway, by disturbing its interaction with the F-box protein CORONATINE INSENSITIVE 1a (COI1a). Natural variation in the LG1 promoter was associated with aphid resistance among inbred lines. Moreover, a loss-of-function mutant in the LG1-related gene SPL8 in the dicot Arabidopsis thaliana conferred aphid resistance. This study revealed the aphid resistance mechanism of lg1, providing a theoretical basis and germplasm for breeding aphid-resistant crops.

Cytokinin and reproductive shoot architecture: bigger and better?

Cytokinin (CK) is a key plant hormone, but one whose effects are often misunderstood, partly due to reliance on older data from before the molecular genetic age of plant science. In this mini-review, we examine the role of CK in controlling the reproductive shoot architecture of flowering plants. We begin with a long overdue re-examination of the role of CK in shoot branching, and discuss the relatively paucity of genetic evidence that CK does play a major role in this process. We then examine the role of CK in determining the number of inflorescences, flowers, fruit and seed that plants initiate during reproductive development, and how these are arranged in space and time. The genetic evidence for a major role of CK in controlling these processes is much clearer, and CK has profound effects in boosting the size and number of most reproductive structures. Conversely, the attenuation of CK levels during the reproductive phase likely contributes to reduced organ size seen later in flowering, and the ultimate arrest of inflorescence meristems during end-of-flowering. We finish by discussing how this information can potentially be used to improve crop yields.

LEAFY and WAPO1 jointly regulate spikelet number per spike and floret development in wheat.

In wheat, the transition of the inflorescence meristem to a terminal spikelet (IM→TS) determines the spikelet number per spike (SNS), an important yield component. In this study, we demonstrate that the plant-specific transcription factor LEAFY (LFY) physically and genetically interacts with WHEAT ORTHOLOG OF APO1 (WAPO1) to regulate SNS and floret development. Loss-of-function mutations in either or both genes result in significant and similar reductions in SNS, as a result of a reduction in the rate of spikelet meristem formation per day. SNS is also modulated by significant genetic interactions between LFY and the SQUAMOSA MADS-box genes VRN1 and FUL2, which promote the IM→TS transition. Single-molecule fluorescence in situ hybridization revealed a downregulation of LFY and upregulation of the SQUAMOSA MADS-box genes in the distal part of the developing spike during the IM→TS transition, supporting their opposite roles in the regulation of SNS in wheat. Concurrently, the overlap of LFY and WAPO1 transcription domains in the developing spikelets contributes to normal floret development. Understanding the genetic network regulating SNS is a necessary first step to engineer this important agronomic trait.

Epigenomic identification of vernalization cis-regulatory elements in winter wheat

BackgroundWinter wheat undergoes vernalization, a process activated by prolonged exposure to low temperatures. During this phase, flowering signals are generated and transported to the apical meristems, stimulating the transition to the inflorescence meristem while inhibiting tiller bud elongation. Although some vernalization genes have been identified, the key cis-regulatory elements and precise mechanisms governing this process in wheat remain largely unknown.ResultsIn this study, we construct extensive epigenomic and transcriptomic profiling across multiple tissues—leaf, axillary bud, and shoot apex—during the vernalization of winter wheat. Epigenetic modifications play a crucial role in eliciting tissue-specific responses and sub-genome-divergent expressions during vernalization. Notably, we observe that H3K27me3 primarily regulates vernalization-induced genes and has limited influence on vernalization-repressed genes. The integration of these datasets enables the identification of 10,600 putative vernalization-related regulatory elements including distal accessible chromatin regions (ACRs) situated 30Kb upstream of VRN3, contributing to the construction of a comprehensive regulatory network. Furthermore, we discover that TaSPL7/15, integral components of the aging-related flowering pathway, interact with the VRN1 promoter and VRN3 distal regulatory elements. These interactions finely regulate their expressions, consequently impacting the vernalization process and flowering.ConclusionsOur study offers critical insights into wheat vernalization’s epigenomic dynamics and identifies the putative regulatory elements crucial for developing wheat germplasm with varied vernalization characteristics. It also establishes a vernalization-related transcriptional network, and uncovers that TaSPL7/15 from the aging pathway participates in vernalization by directly binding to the VRN1 promoter and VRN3 distal regulatory elements.

Seed production determines the entrance to dormancy of the inflorescence meristem of Pisum sativum and the end of the flowering period.

Flowering plants adjust their reproductive period to maximize the success of the offspring. Monocarpic plants, those with a single reproductive cycle that precedes plant senescence and death, tightly regulate both flowering initiation and flowering cessation. The end of the flowering period involves the arrest of the inflorescence meristem activity, known as proliferative arrest, in what has been interpreted as an evolutionary adaptation to maximize the allocation of resources to seed production and the viability of the progeny. Factors influencing proliferative arrest were described for several monocarpic plant species many decades ago, but only in the last few years studies performed in Arabidopsis have allowed to approach proliferative arrest regulation in a comprehensive manner by studying the physiology, hormone dynamics, and genetic factors involved in its regulation. However, these studies remain restricted to Arabidopsis and there is a need to expand our knowledge to other monocarpic species to propose general mechanisms controlling the process. In this work, we have characterized proliferative arrest in Pisum sativum, trying to parallel available studies in Arabidopsis to maximize this comparative framework. We have assessed quantitatively the role of fruits/seeds in the process, the influence of the positional effect of these fruits/seeds in the behavior of the inflorescence meristem, and the transcriptomic changes in the inflorescence associated with the arrested state of the meristem. Our results support a high conservation of the factors triggering arrest in pea and Arabidopsis, but also reveal differences reinforcing the need to perform similar studies in other species.

The receptor kinase OsANX limits precocious flowering and inflorescence over-branching and maintains pollen tube integrity in rice

CrRLK1L subfamily members are involved in diverse growth- and development-related processes in Arabidopsis. However, the functions of their counterparts in rice are unknown. Here, OsANX expression was detected in developing inflorescences, mature pollen grains, and growing pollen tubes, and it was localized to the plasma membrane in pollen grains and tobacco epidermal cells. Homozygous osanx progeny could not be segregated from the CRISPR/Cas9-edited mutants osanx-c1+/- and osanx-c2+/-, and such progeny were segregated only occasionally from osanx-c3+/-. Further, all three alleles showed osanx male but not female gamete transmission defects, in line with premature pollen tube rupture in osanx-c3. Additionally, osanx-c3 exhibited precocious flowering, excessively branched inflorescences, and an extremely low seed setting rate of 1.4 %, while osanx-c2+/- and osanx-c3+/- had no obvious defects in inflorescence development or the seed setting rate compared to wild-type Nipponbare (Nip). Consistent with this, the complemented line pPS1:OsANX-GFP/osanx-c2 (PSC), in which the lack of OsANX expression was inflorescence-specific, showed slightly earlier flowering and overly-branched panicles. Multiple inflorescence meristem transition-related and inflorescence architecture-related genes were expressed at higher levels in osanx-c3 than in Nip; thus, they may partially account for the aforementioned mutant phenotypes. Our findings broaden our understanding of the biological functions of OsANX in rice.

Progressive meristem and single-cell transcriptomes reveal the regulatory mechanisms underlying maize inflorescence development and sex differentiation

Maize develops separate ear and tassel inflorescences with initially similar morphology but ultimately different architecture and sexuality. The detailed regulatory mechanisms underlying these changes still remain largely unclear. In this study, through analyzing the time-course meristem transcriptomes and floret single-cell transcriptomes of ear and tassel, we revealed the regulatory dynamics and pathways underlying inflorescence development and sex differentiation. We identified 16 diverse gene clusters with differential spatiotemporal expression patterns and revealed biased regulation of redox, programmed cell death, and hormone signals during meristem differentiation between ear and tassel. Notably, based on their dynamic expression patterns, we revealed the roles of two RNA-binding proteins in regulating inflorescence meristem activity and axillary meristem formation. Moreover, using the transcriptional profiles of 53 910 single cells, we uncovered the cellular heterogeneity between ear and tassel florets. We found that multiple signals associated with either enhanced cell death or reduced growth are responsible for tassel pistil suppression, while part of the gibberellic acid signal may act non-cell-autonomously to regulate ear stamen arrest during sex differentiation. We further showed that the pistil-protection gene SILKLESS 1 (SK1) functions antagonistically to the known pistil-suppression genes through regulating common molecular pathways, and constructed a regulatory network for pistil-fate determination. Collectively, our study provides a deep understanding of the regulatory mechanisms underlying inflorescence development and sex differentiation in maize, laying the foundation for identifying new regulators and pathways for maize hybrid breeding and improvement.

The additive function of YIGE2 and YIGE1 in regulating maize ear length.

Ear length (EL) is a key trait that greatly contributes to yield in maize. Although dozens of EL quantitative trait loci have been mapped, very few causal genes have been cloned, and the molecular mechanisms remain largely unknown. Our previous study showed that YIGE1 is involved in sugar and auxin pathways to regulate ear inflorescence meristem (IM) development and thus affects EL in maize. Here, we reveal that YIGE2, the paralog of YIGE1, regulates maize ear development and EL through auxin pathway. Knockout of YIGE2 causes a significant decrease of auxin level, IM length, floret number, EL, and grain yield. yige1 yige2 double mutants had even shorter IM and ears implying that these two genes redundantly regulate IM development and EL. The genes controlling auxin levels are differential expressed in yige1 yige2 double mutants, leading to lower auxin level. These results elucidated the critical role of YIGE2 and the redundancy between YIGE2 and YIGE1 in maize ear development, providing a new genetic resource for maize yield improvement.

COI1 F-box proteins regulate DELLA protein levels, growth, and photosynthetic efficiency in maize.

The F-box protein Coronatine Insensitive (COI) is a receptor for the jasmonic acid signaling pathway in plants. To investigate the functions of the 6 maize (Zea mays) COI proteins (COI1a, COI1b, COI1c, COI1d, COI2a, and COI2b), we generated single, double, and quadruple loss-of-function mutants. The pollen of the coi2a coi2b double mutant was inviable. The coi1 quadruple mutant (coi1-4x) exhibited shorter internodes, decreased photosynthesis, leaf discoloration, microelement deficiencies, and accumulation of DWARF8 and/or DWARF9, 2 DELLA family proteins that repress the gibberellic acid (GA) signaling pathway. Coexpression of COI and DELLA in Nicotiana benthamiana showed that the COI proteins trigger proteasome-dependent DELLA degradation. Many genes that are downregulated in the coi1-4x mutant are GA-inducible. In addition, most of the proteins encoded by the downregulated genes are predicted to be bundle sheath- or mesophyll-enriched, including those encoding C4-specific photosynthetic enzymes. Heterologous expression of maize Coi genes in N. benthamiana showed that COI2a is nucleus-localized and interacts with maize jasmonate zinc-finger inflorescence meristem domain (JAZ) proteins, the canonical COI repressor partners. However, maize COI1a and COI1c showed only partial nuclear localization and reduced binding efficiency to the tested JAZ proteins. Together, these results show the divergent functions of the 6 COI proteins in regulating maize growth and defense pathways.

Beyond floral initiation: the role of flower bud dormancy in flowering time control of annual plants.

The phenology of temperate perennials, including the timing of vegetative growth and flowering, is well known to be controlled by seasonal dormancy cycles. Dormant structures are known as buds and have specialized covering structures, symplastic isolation from the plant, and often autonomous stores of carbon and nitrogen reserves. In contrast, in annual plants, our current understanding of the control of the timing of flowering focuses on the mechanisms affecting floral initiation, the transition from a vegetative apical meristem to a inflorescence meristem producing flower primordia in place of leaves. Recently we revealed that annual crops in Brassicaceae exhibit chilling-responsive growth control in a manner closely resembling bud dormancy breakage in perennial species. Here I discuss evidence that vernalization in autumn is widespread and further discuss its role in inducing flower bud set prior to winter. I also review evidence that flower bud dormancy has a more widespread role in annual plant flowering time control than previously appreciated.

A SEPALLATA MADS-Box Transcription Factor, SlMBP21, Functions as a Negative Regulator of Flower Number and Fruit Yields in Tomato.

MADS-box transcription factors act as the crucial regulators in plant organ differentiation. Crop yields are highly influenced by the flower number and fruit growth. However, flower identification is a very complex biological process, which involves many cascade regulations. The molecular mechanisms underlying the genetic regulation of flower identification in cultivated plants, such as tomato, are intricate and require further exploration. In this study, we investigated the vital function of a SEPALLATA (SEP) MADS-box gene, SlMBP21, in tomato sympodial inflorescence meristem (SIM) development for the conversion from SIMs to floral meristems (FMs). SlMBP21 transcripts were primarily accumulated in young inflorescence meristem, flowers, sepals, and abscission zones. The Ailsa Craig (AC++) tomato plants with suppressed SlMBP21 mRNA levels using RNAi exhibited a large increase in flower number and fruit yields in addition to enlarged sepals and inhibited abscission zone development. Scanning electron microscopy (SEM) revealed that the maturation of inflorescence meristems (IMs) was repressed in SlMBP21-RNAi lines. RNA-seq and qRT-PCR analyses showed that numerous genes related to the flower development, plant hormone signal transduction, cell cycle, and cell proliferation et al. were dramatically changed in SlMBP21-RNAi lines. Yeast two-hybrid assay exhibited that SlMBP21 can respectively interact with SlCMB1, SFT, JOINTLESS, and MC, which play key roles in inflorescence meristems or FM development. In summary, our data demonstrate that SlMBP21 functions as a key regulator in SIM development and the conversion from SIMs to FMs, through interacting with other regulatory proteins to control the expression of related genes.

Genome-Wide Identification and Expression Pattern Analysis of TIFY Family Genes Reveal Their Potential Roles in Phalaenopsis aphrodite Flower Opening.

The TIFY gene family (formerly known as the zinc finger proteins expressed in inflorescence meristem (ZIM) family) not only functions in plant defense responses but also are widely involved in regulating plant growth and development. However, the identification and functional analysis of TIFY proteins remain unexplored in Orchidaceae. Here, we identified 19 putative TIFY genes in the Phalaenopsis aphrodite genome. The phylogenetic tree classified them into four subfamilies: 14 members from JAZ, 3 members from ZML, and 1 each from PPD and TIFY. Sequence analysis revealed that all Phalaenopsis TIFY proteins contained a TIFY domain. Exon-intron analysis showed that the intron number and length of Phalaenopsis TIFY genes varied, whereas the same subfamily and subgroup genes had similar exon or intron numbers and distributions. The most abundant cis-elements in the promoter regions of the 19 TIFY genes were associated with light responsiveness, followed by MeJA and ABA, indicating their potential regulation by light and phytohormones. The 13 candidate TIFY genes screened from the transcriptome data exhibited two types of expression trends, suggesting their different roles in cell proliferation and cell expansion of floral organ growth during Phalaenopsis flower opening. Overall, this study serves as a background for investigating the underlying roles of TIFY genes in floral organ growth in Phalaenopsis.

A spatial transcriptome map of the developing maize ear.

A comprehensive understanding of inflorescence development is crucial for crop genetic improvement, as inflorescence meristems give rise to reproductive organs and determine grain yield. However, dissecting inflorescence development at the cellular level has been challenging owing to a lack of specific marker genes to distinguish among cell types, particularly in different types of meristems that are vital for organ formation. In this study, we used spatial enhanced resolution omics-sequencing (Stereo-seq) to construct a precise spatial transcriptome map of the developing maize ear primordium, identifying 12 cell types, including 4 newly defined cell types found mainly in the inflorescence meristem. By extracting the meristem components for detailed clustering, we identified three subtypes of meristem and validated two MADS-box genes that were specifically expressed at the apex of determinate meristems and involved in stem cell determinacy. Furthermore, by integrating single-cell RNA transcriptomes, we identified a series of spatially specific networks and hub genes that may provide new insights into the formation of different tissues. In summary, this study provides a valuable resource for research on cereal inflorescence development, offering new clues for yield improvement.