The reduction in maize leaf growth under mild drought affects the transition between cell division and cell expansion and cannot be restored by elevated gibberellic acid levels

AbstractGrowth of plant organs results from the combined activity of cell division and cell expansion. The coordination of these two processes depends on the interplay between multiple hormones that determine final organ size. Using the semidominant Hairy Sheath Frayed1 (Hsf1) maize mutant, that hypersignals the perception of cytokinin (CK), we show that CK can reduce leaf size and growth rate by decreasing cell division. Linked to CK hypersignaling, the Hsf1 mutant has increased jasmonic acid (JA) content, a hormone that can inhibit cell division. Treatment of wild type seedlings with exogenous JA reduces maize leaf size and growth rate, while JA deficient maize mutants have increased leaf size and growth rate. Expression analysis revealed increased transcript accumulation of several JA pathway genes in the Hsf1 leaf growth zone. A transient treatment of growing wild type maize shoots with exogenous CK also induced JA pathway gene expression, although this effect was blocked by co-treatment with cycloheximide. Together our results suggest that CK can promote JA accumulation possibly through increased expression of specific JA pathway genes.One sentence summaryCytokinin-signaling upregulates the jasmonate biosynthesis pathway, resulting in jasmonate accumulation and influences on maize leaf growth.

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From Cell Growth to Leaf Growth: I. Coupling Cell Division and Cell Expansion

Agronomy Journal ◽

10.2134/agronj1995.00021962008700010018x ◽

1995 ◽

Vol 87 (1) ◽

pp. 99-105 ◽

Cited By ~ 12

Author(s):

Timothy J. Arkebauer ◽

John M. Norman

Keyword(s):

Cell Division ◽

Cell Growth ◽

Cell Expansion ◽

Leaf Growth ◽

Coupling Cell

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Identification of new leaf intrinsic yield genes using cross-species network analysis in plants

10.1101/2021.10.25.465753 ◽

2021 ◽

Author(s):

Pasquale Luca Curci ◽

Jie Zhang ◽

Niklas Mähler ◽

Carolin Seyfferth ◽

Chanaka Mannapperuma ◽

...

Keyword(s):

Cell Division ◽

Cell Expansion ◽

Leaf Growth ◽

Defense Responses ◽

Phenotypic Characterization ◽

Transcriptional Networks ◽

Loss Of Function ◽

Plant Defense Responses ◽

Leaf Phenotype ◽

Brassinosteroid Signaling

Plant leaves differ in their size, form and structure, and the processes of cell division and cell expansion contribute to this diversity. Leaf transcriptional networks covering cell division and cell expansion in Arabidopsis thaliana, maize (Zea mays) and aspen (Populus tremula) were compared to identify candidate genes that are conserved in plant growth and ultimately have the potential to increase biomass (intrinsic yield, IY). Our approach revealed that genes showing strongly conserved co-expression were mainly involved in fundamental leaf developmental processes such as photosynthesis, translation, and cell proliferation. Next, known intrinsic yield genes (IYGs) together with cross-species conserved networks were used to predict novel potential Arabidopsis leaf IYGs. Using an in-depth literature screening, 34 out of 100 top predicted IYGs were confirmed to affect leaf phenotype if mutated or overexpressed and thus represent novel potential IYGs. Globally, these new IYGs were involved in processes mostly covering cell cycle, plant defense responses, gibberellin, auxin and brassinosteroid signaling. Application of loss-of-function lines and phenotypic characterization confirmed two newly predicted IYGs to be involved in leaf growth (NPF6.4 and LATE MERISTEM IDENTITY2). In conclusion, the presented network approach offers an integrative cross-species strategy to identify new yield genes and to accelerate plant breeding.

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Developmental stages of delayed-greening leaves inferred from measurements of chlorophyll content and leaf growth

Functional Plant Biology ◽

10.1071/fp09035 ◽

2009 ◽

Vol 36 (7) ◽

pp. 654 ◽

Cited By ~ 5

Author(s):

Andrzej Stefan Czech ◽

Kazimierz Strzałka ◽

Ulrich Schurr ◽

Shizue Matsubara

Keyword(s):

Cell Division ◽

Cell Expansion ◽

Developmental Stages ◽

Leaf Growth ◽

Co2 Assimilation ◽

Leaf Expansion ◽

Leaf Structure ◽

Phase Iii ◽

Clear Correlation ◽

Delayed Greening

Chlorophyll (Chl) accumulation and leaf growth were analysed in delayed-greening leaves of Theobroma cacao (L.) to examine whether these parameters are correlated during leaf development and can be used as non-destructive indicators of leaf developmental stages. There was a clear correlation between Chl content and leaf relative growth rate (RGR) and between Chl content and percentage of full leaf expansion (%FLE) under different growth conditions. Five distinct developmental phases were defined according to the correlation between these parameters and corroborated by data from the analyses of leaf growth (epidermal cell size and specific leaf area) or photosynthetic properties (maximal PSII efficiency, CO2 assimilation and non-structural carbohydrate contents). The five phases were characterised by rapid leaf expansion by cell division (I), pronounced cell expansion (II), development of photosynthetic capacity concomitant with reinforcement of leaf structure (III), and maturation (IV and V). The transition from cell division to cell expansion happened uniformly across the leaf lamina between phase I and II; the sink-to-source transition was found between phase III and IV. These results demonstrate coordinated development of photosynthetic machinery and leaf structure in delayed-greening leaves and provide a simple and non-invasive method for estimation of leaf developmental stages in T. cacao.

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Distinct Cellular Strategies Determine Sensitivity to Mild Drought of Arabidopsis Natural Accessions

10.1101/2020.08.24.265041 ◽

2020 ◽

Author(s):

Ying Chen ◽

Marieke Dubois ◽

Mattias Vermeersch ◽

Dirk Inzé ◽

Hannes Vanhaeren

Keyword(s):

Drought Stress ◽

Stress Responses ◽

Cell Expansion ◽

Leaf Growth ◽

Stomatal Closure ◽

Wide Distribution ◽

Abiotic Stress Response ◽

Transcriptional Responses ◽

Drought Tolerant ◽

Mild Drought

AbstractThe world-wide distribution of Arabidopsis thaliana (Arabidopsis) accessions imposes different types of evolutionary pressures, which contributes to various responses of these accessions to environmental stresses. Drought stress responses have been well studied, particularly in Columbia, a common Arabidopsis accession. However, the reactions to drought stress are complex and our understanding of which of these responses contribute to the plant’s tolerance to mild drought is very limited. Here, we studied the mechanisms by which natural accessions react to mild drought at a physiological and molecular level during early leaf development. We documented variations in mild drought tolerance among natural accessions and used transcriptome sequencing of a drought-sensitive accession, ICE163, and a drought-tolerant accession, Yeg-1, to get insights into the mechanisms underlying this tolerance. This revealed that ICE163 preferentially induces jasmonates and anthocyanin-related pathways, which are beneficial in biotic stress defense, while Yeg-1 has a more pronounced activation of abscisic acid signaling, the classical abiotic stress response. Related physiological traits, including content of proline, anthocyanins and ROS, stomatal closure and cellular leaf parameters, were investigated and linked to the transcriptional responses. We conclude that most of these processes constitute general drought response mechanisms that are regulated similarly in drought-tolerant and -sensitive accessions. However, the capacity to close stomata and maintain cell expansion under mild drought appeared to be major factors that contribute to a better leaf growth under mild drought.One-sentence summaryThis paper demonstrates that an efficient closure of stomata and maintenance of cell expansion during drought conditions are crucial to maximally preserve plant growth during water deficit.

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