Narrower Leaf Research Articles

Historical increases of maize leaf area index in the US Corn Belt due primarily to plant density increases

ContextLeaf area index (LAI) and leaf area distribution within the maize plant are important traits used to explain and predict light interception and thus crop productivity. ObjectivesHere we investigate breeding and plant density effects of leaf area traits. Our objectives are to 1) quantify maize breeding impacts on leaf area distribution and determine bell-shape coefficients used in crop modeling, 2) dissect the contribution of breeding from plant density, and 3) explore the relationship between LAI and crop yields. MethodsWe studied 18 hybrids released between 1983 and 2017 at two density treatments: current (8.5 pl m−2) and historical increasing density (from 4.6 to 8.5 pl m−2) in Iowa, USA. ResultsResults indicated that concurrent changes in hybrids and increases in plant density have increased LAI from 3.4 (in 1983) to 5.9 m2 m−2 (in 2017), with the highest LAI increases (>50 %) to be realized in the middle canopy. At historical increasing in plant density treatment, the LAI increased by 1.6 % year−1, but the individual plant leaf area decreased by 0.33 % year−1 from 1983 to 2017. This trade-off indicates that new hybrids are more tolerant to higher plant populations than old hybrids. At current plant density treatment, the year of hybrid release did not affect LAI or individual plant leaf area. New hybrids had 5 % narrower leaf area distributions, 23 % higher optimum LAI values (5.2 vs 4.2 m2 m−2) and 19 % higher grain yields compared to old hybrids. ConclusionsThe main reason for the increase in maize LAI in the US Corn Belt is plant density. However, an increase in LAI does not necessarily translate to higher grain yields as new hybrids had significantly higher grain yields than older hybrids at similar LAI values. Present results contribute to our understanding of maize canopy architecture and allow us to better calibrate crop models to accurately estimate LAI and grain yield.

Lysimachiaailaoshanensis (Primulaceae), a new species from Yunnan, China.

A new species, Lysimachiaailaoshanensis is described and illustrated. In gross morphology it is evidently allied to subgen. Palladiasect.Chenopodiopsis and is most similar to L.chenopodioides and L.remotiflora, but is distinguished from L.chenopodioides by narrower lanceolate leaf blade and longer pedicel, and longer stamens and styles, and from L.remotiflora by narrower leaf blade and longer stamens.

Genetic variation in growth and leaf traits associated with local adaptation to climate in yellow birch (Betula alleghaniensis Britton)

Understanding patterns of variation in functional traits of hardwood trees is crucial for conserving and managing North American temperate forests under climate change. This study examined provenance variation of yellow birch ( Betula alleghaniensis Britton) in growth, biomass allocation, leaf morphology, and stable carbon isotope composition. Trees were grown from 10 seed sources originating from across Canada and the northern USA. Height and diameter were not significantly related to climate at seed origin, suggesting that variation may be better explained by site factors, such as soil pH and soil moisture. In contrast, carbon isotope composition and leaf morphological traits were significantly correlated to climate variables including temperature, precipitation, and solar radiation. Provenances from warmer, drier localities tended to have higher stable carbon isotope ratio (δ13C), greater specific leaf area, and narrower leaf width than their counterparts from cooler, wetter climates. Thus, variation in leaf morphological traits appears to be involved in adaptation of yellow birch to variation in temperature and moisture availability across the species’ range. Our results suggest that there may exist potential for selection and breeding of drought-resistant yellow birch genotypes to aid in reforestation under climate change.

PpSCARECROW1 (PpSCR1) regulates leaf blade and mid-vein development in Physcomitrium patens.

In plants, asymmetric cell divisions result in distinct cell fates forming large and small daughter cells, adding to the cellular diversity in an organ. SCARECROW (SCR), a GRAS domain-containing transcription factor controls asymmetric periclinal cell divisions in flowering plants by governing radial patterning of ground tissue in roots and cell proliferation in leaves. Though SCR homologs are present across land plant lineages, the current understanding of their role in cellular patterning and leaf development is mostly limited to flowering plants. Our phylogenetic analysis identified three SCR homologs in moss Physcomitrium patens, amongst which PpSCR1 showed highest expression in gametophores and its promoter activity was prominent at the mid-vein and the flanking leaf blade cells pointing towards its role in leaf development. Notably, out of the three SCR homologs, only the ppscr1 knock-out lines developed slender leaves with four times narrower leaf blade and three times thicker mid-vein. Detailed histology studies revealed that slender leaf phenotype is either due to the loss of anticlinal cell divisions or failure of periclinal division suppression in the leaf blade. RNA-Seq analyses revealed that genes responsible for cell division and differentiation are expressed differentially in the mutant. PpSCR1 overexpression lines exhibited significantly wider leaf lamina, further reconfirming the role in leaf development. Together, our data suggests that PpSCR1 is involved in the leaf blade and mid-vein development of moss and that its role in the regulation of cell division and proliferation is ancient and conserved among flowering plants and mosses.

Interactions between beech and oak seedlings can modify the effects of hotter droughts and the onset of hydraulic failure.

Mixing species with contrasting resource use strategies could reduce forest vulnerability to extreme events. Yet, how species diversity affects seedling hydraulic responses to heat and drought, including mortality risk, is largely unknown. Using open-top chambers, we assessed how, over several years, species interactions (monocultures vs mixtures) modulate heat and drought impacts on the hydraulic traits of juvenile European beech and pubescent oak. Using modeling, we estimated species interaction effects on timing to drought-induced mortality and the underlying mechanisms driving these impacts. We show that mixtures mitigate adverse heat and drought impacts for oak (less negative leaf water potential, higher stomatal conductance, and delayed stomatal closure) but enhance them for beech (lower water potential and stomatal conductance, narrower leaf safety margins, faster tree mortality). Potential underlying mechanisms include oak's larger canopy and higher transpiration, allowing for quicker exhaustion of soil water in mixtures. Our findings highlight that diversity has the potential to alter the effects of extreme events, which would ensure that some species persist even if others remain sensitive. Among the many processes driving diversity effects, differences in canopy size and transpiration associated with the stomatal regulation strategy seem the primary mechanisms driving mortality vulnerability in mixed seedling plantations.

The RHW1-ZCN4 regulatory pathway confers natural variation of husk leaf width in maize.

Maize husk leaf - the outer leafy layers covering the ear - modulates kernel yield and quality. Despite its importance, however, the genetic controls underlying husk leaf development remain elusive. Our previous genome-wide association study identified a single nucleotide polymorphism located in the gene RHW1 (Regulator of Husk leaf Width) that is significantly associated with husk leaf-width diversity in maize. Here, we further demonstrate that a polymorphic 18-bp InDel (insertion/deletion) variant in the 3' untranslated region of RHW1 alters its protein abundance and accounts for husk leaf width variation. RHW1 encodes a putative MYB-like transcriptional repressor. Disruption of RHW1 altered cell proliferation and resulted in a narrower husk leaf, whereas RHW1 overexpression yielded a wider husk leaf. RHW1 positively regulated the expression of ZCN4, a well-known TFL1-like protein involved in maize ear development. Dysfunction of ZCN4 reduced husk leaf width even in the context of RHW1 overexpression. The InDel variant in RHW1 is subject to selection and is associated with maize husk leaf adaption from tropical to temperate regions. Overall, our results identify that RHW1-ZCN4 regulates a pathway conferring husk leaf width variation at a very early stage of husk leaf development in maize.

Geological Substrate Effects on Teucrium montanum L. (Lamiaceae) Morphological Traits: Geometric Morphometrics Approach.

The shape-environment relationship in plants refers to the ways in which the physical characteristics and structures of plants are influenced by their environment. Plants have evolved a remarkable ability to adapt to their specific habitats, and their shape and form play a crucial role in determining their survival and reproductive success. This study aimed to examine differences in size and shape between morphological traits in mountain germander (Teucrium montanum L.) from different geological substrates (calcareous and serpentinite). For this study, 400 individuals of T. montanum from 20 populations (ten populations from the serpentinite and ten from the calcareous substrate) were selected. Using the geometric morphometrics approach, it was shown that the degree of phenotypic variation in the size and shape of the corolla, leaf, and stem of T. montanum depends on the type of substrate. The main differences between the populations are the narrower part of the lower lip of the corolla, the narrower leaf, and the wider central part of the vascular system stem from serpentinite populations. The results of this study will contribute to a better understanding of the morphological variability of T. montanum in relation to edaphic conditions. In addition, the results confirm that certain morphological differences play an important role in the adaptive response in relation to substrate composition, especially for substrates with increased metal content, such as serpentinite. The shape-environment relationship in plants could define diversity and complexity in plant life, and underscores the importance of shape as a key factor in their survival and success in different habitats.

Begoniaparvibracteata, a new species in Begonia sect. Platycentrum (Begoniaceae) from Guangxi of China, based on morphological and molecular evidence.

The previously reported begonias in a limestone forest of Guangxi mainly belong to Begoniasect.Coelocentrum Irmscher. In this article, we described and illustrated a new species in sect. Platycentrum (Klotzsch) A.DC., Begoniaparvibracteata X.X.Feng, R.K.Li & Z.X.Liu, which was discovered in a karst forest of south-western Guangxi. The begonia shows high morphological similarity to B.subhowii S.H. Huang and B.psilophylla Irmscher, but differs from the latter two in its narrower oblique-ovate asymmetric leaf blade, 4 (occasionally 6) tepals of pistillate flower and smaller membranous inflorescence bracts. Molecular phylogenetic analysis, based on ITS sequence data, supports the new species as monophyletic and distinct from B.subhowii and B.psilophylla. Considering its narrow distribution and the disturbance of human activities, the conservation status of new taxon is evaluated as "Vulnerable" (VU B1, B2 ab (i, iv, v), D2) according to the IUCN Red List Categories and Criteria.

Cestrum lozadai (Solanaceae), a new species from the state of Guerrero, Mexico

A new species from the cloud forest in the state of Guerrero, Mexico, is described and illustrated: Cestrum lozadai. This new entity is similar to C. laxum; however, it is distinguished from the latter by presenting narrower leaf blades, with up to 15 pairs of secondary veins, flowers with longer pedicels, up to 16 mm and articulated, the corolla tube longer, up to 21 mm and internally with retrorse trichomes in the portion attached to the filaments, with the fused part of the filaments up to 15 mm, and with a known distribution only in the state of Guerrero, Mexico.

Two New Species of Meiogyne (Annonaceae) from Vietnam, Based on Molecular Phylogeny and Morphology

Meiogyne rubra Jaikhamseub, Damth. & Chaowasku sp. nova and M. vietnamica Jaikhamseub, T.A. Le & Chaowasku sp. nova (Annonaceae) from Vietnam are described and illustrated. Molecular phylogenetic reconstructions based on up to eight plastid DNA regions (matK, ndhF, rbcL and ycf1 exons; trnL intron; ndhF-rpl32, rpl32-trnL and trnL-trnF intergenic spacers) and incorporating 33 accessions (31 species) of Meiogyne were performed. The two new species, as well as M. anomalocarpa, M. caudata, M. chiangraiensis and M. subsessilis are included in molecular phylogenetic analyses for the first time. Two major clades were retrieved within Meiogyne: a small clade consisting of M. anomalocarpa, M. hainanensis and M. kanthanensis, and a much larger clade comprising the remaining accessions. The phylogenetic position of the two new species in the latter clade is obscure. Meiogyne rubra appears to be morphologically most similar to M. monosperma. The former differs from the latter by having a narrower leaf blade, free (vs. basally connate) and longer sepals, longer outer petals and larger inner petals. Meigyne vietnamica is morphologically most similar to M. caudata, but differs from it by having an acute to acuminate (vs. usually distinctly caudate-acuminate) leaf apex, non-prominent (vs. prominent) secondary veins on lower leaf surface and higher number of secondary veins in the leaves. A key to the species of Meiogyne in Vietnam is also provided.

Frequency distribution and potence ratio of agronomic traits in F1 generation of intraspecific crosses of Robusta coffee.

Leaf morphological traits and internode length significantly affect the adapt-ability and production of coffee plants, respectively. Therefore, genetic studies of these two characters can support the effectiveness of Robusta coffee breeding program for obtaining superior planting materials. This study aimed to determine the diversity and frequency distribution of F1 generation on internode length and leaf size of Robusta coffee crosses. The study involved six groups of F1 progeny and their reciprocals (F1R) resulted from a cross of three parents, namely BP 961, Q 121, and BP 409. Each cross combination was planted with 41–49 progenies singly side by side in Kaliwining Experimental Station, Jember, Indonesia. The observed traits were internode length and leaf size. Analysis results of progeny variation distribution showed that most of the F1 and F1R progenies from intraspecific Robusta crosses had shorter branches than both parents in all combinations of crosses, even in BP 961 × BP 409 crosses. In addition, all F1 and F1R progenies had shorter internodes than both parents. More than 50% of the progeny of Q 121 × BP 409 and BP 961 × BP 409 crosses showed leaf length trait between parents. This indicates the absence of dominance of one parent in the progeny. Less than 20.9% of the progeny had a narrower leaf size than Q 121 parent. Most of the F1 and F1R crosses had a leaf width between both parents. The leaf length and leaf width traits were incomplete dominance or recessive, while the internodelength was overdominant.

WOX family transcriptional regulators modulate cytokinin homeostasis during leaf blade development in Medicago truncatula and Nicotiana sylvestris.

The plant-specific family of WUSCHEL (WUS)-related homeobox (WOX) transcription factors is key regulators of embryogenesis, meristem maintenance, and lateral organ development in flowering plants. The modern/WUS clade transcriptional repressor STENOFOLIA/LAMINA1(LAM1), and the intermediate/WOX9 clade transcriptional activator MtWOX9/NsWOX9 antagonistically regulate leaf blade expansion, but the molecular mechanism is unknown. Using transcriptome profiling and biochemical methods, we determined that NsCKX3 is the common target of LAM1 and NsWOX9 in Nicotiana sylvestris. LAM1 and NsWOX9 directly recognize and bind to the same cis-elements in the NsCKX3 promoter to repress and activate its expression, respectively, thus controlling the levels of active cytokinins in vivo. Disruption of NsCKX3 in the lam1 background yielded a phenotype similar to the knockdown of NsWOX9 in lam1, while overexpressing NsCKX3 resulted in narrower and shorter lam1 leaf blades reminiscent of NsWOX9 overexpression in the lam1 mutant. Moreover, we established that LAM1 physically interacts with NsWOX9, and this interaction is required to regulate NsCKX3 transcription. Taken together, our results indicate that repressor and activator WOX members oppositely regulate a common downstream target to function in leaf blade outgrowth, offering a novel insight into the role of local cytokinins in balancing cell proliferation and differentiation during lateral organ development.

Overexpression of PvWOX3a in switchgrass promotes stem development and increases plant height

Switchgrass (Panicum virgatum L.) is an important perennial, noninvasive, tall ornamental grass that adds color and texture to gardens and landscapes. Moreover, switchgrass has been considered a forage and bioenergy crop because of its vigorous growth, low-input requirements, and broad geography. Here, we identified PvWOX3a from switchgrass, which encodes a WUSCHEL-related homeobox transcription factor. Transgenic overexpression of PvWOX3a in switchgrass increased stem length, internode diameter, and leaf blade length and width, all of which contributed to a 95% average increase in dry weight biomass compared with control plants. Yeast one-hybrid and transient dual-luciferase assays showed that PvWOX3a can repress the expression of gibberellin 2-oxidase and cytokinin oxidase/dehydrogenase through apparently direct interaction with their promoter sequences. These results suggested that overexpression of PvWOX3a could increase gibberellin and cytokinin levels in transgenic switchgrass plants, which promotes cell division, elongation, and vascular bundle development. We also overexpressed PvWOX3a in a transgenic miR156-overexpressing switchgrass line that characteristically exhibited more tillers, thinner internodes, and narrower leaf blades. Double transgenic switchgrass plants displayed significant increases in internode length and diameter, leaf blade width, and plant height but retained a tiller number comparable to that of plants expressing miR156 alone. Ultimately, the double transgenic switchgrass plants produced 174% more dry-weight biomass and 162% more solubilized sugars on average than control plants. These findings indicated that PvWOX3a is a viable potential genetic target for engineering improved shoot architecture and biomass yield of horticulture, fodder, and biofuel crops.

Dissection of physiological, transcriptional, and metabolic traits in two tall fescue genotypes with contrasting drought tolerance.

Tall fescue (Festuca arundinacea) is an important cool-season perennial forage grass that forms mutualistic symbioses with fungal endophytes. Physiological, biochemical and transcriptional comparisons were made between two tall fescue genotypes with contrasting drought tolerance (tolerant, T400, and sensitive, S279), either with or without endophyte (Epichloë coenophiala). Drought stress was applied by withholding watering until plants reached mild, moderate and severe stresses. Physiological characterization showed that T400 had narrower, thicker leaves, and lower leaf conductance under well-watered conditions, compared to S279. After severe drought and recovery, endophytic T400 had greater shoot and root biomass than other plant types. Under drought, leaf osmotic pressure increased much more in T400 than S279, consistent with accumulation of metabolites/osmolytes, especially proline. Gene Ontology enrichment analysis indicated that T400 had more active organic acid metabolism than S279 under drought, and implicated the role of endophyte in stimulating protein metabolism in both genotypes. Overall T400 and S279 responded to endophyte differently in aspects of physiology, gene transcription and metabolites, indicating plant genotype-specific reactions to endophyte infection.

Dendrobium ormerodii (Orchidaceae, Dendrobieae), a new Dendrobium species from Central Kalimantan, Indonesia

A species new to science, Dendrobium ormerodii Handoyo, Naive & J.Champ. from Kalimantan, Borneo is herein described and illustrated. The species is superficially similar to D. fulminicaule but differs in having shorter stem, narrower leaf, dorsal sepal with acute apex, labellum without sidelobes or without the broadening at the base, labellum apex obtuse-truncate, and shorter column. Detailed description, a colour plate, line drawing, notes on phenology, distribution, and a conservation assessment are provided below.

<p><strong>Taxonomic review of the expanded <em>Plocama</em> (Rubiaceae, Putorieae) from flora of Iran, with a new species and a new combination</strong></p>

Plocama ehrendorferi is described as a new species from southeast of Iran that can be easily distinguished from the related species P. bruguieri and P. kandaharensis by its compact leaves on the stem and shorter internodes, the bright green color of the plant, shorter and narrower leaf segments and the length of corolla. This study provides new information on the taxonomic state and geographical distribution of Plocama species from the flora of Iran. It is concluded that P. macrantha has been reported wrongly from Iran such that the reports of P. kandaharensis and P. olivieri cannot be confirmed.

14-3-3 proteins contribute to leaf and root development via brassinosteroid insensitive 1 in Arabidopsis thaliana.

Brassinosteroids (BR) are essential growth hormone in plants. Various components involved in signal transduction pathway have been identified as targets of 14-3-3 phospho-binding proteins. Previously, we showed that 14-3-3 proteins directly interact with the Brassinosteroid Insensitive 1 (BRI1), the BR receptor kinase, and are also subject to phosphorylation in a BR-dependent manner. In this study, we aimed to examine a potential interplay between 14-3-3 proteins and BRI1 in plant growth. Morphological phenotypes of a T-DNA insertion mutant line, 14-3-3ψφε, defective in three 14-3-3 isoforms, psi, phi and epsilon, were characterized and compared with bri1-5 and two transgenic lines for BRI1, BRI1-Flag and BRI1-Flag (14-3-3ψφε). We also generated complementation lines carrying each of the three 14-3-3 genes and determined their differences in rosette growth. No significant differences between the wild-type and 14-3-3ψφε seedlings were observed regardless of BR applications. However, BRI1-Flag (14-3-3ψφε) showed a significantly reduced cold tolerance and BR sensitivity in hypocotyl and root development when compared to BRI1-Flag. In addition, narrower leaf shape and smaller rosette size were observed in BRI1-Flag (14-3-3ψφε), while the mutant phenotypes were partially restored in the complementation lines, two of which with 14-3-3φ and 14-3-3ε showed the rosette growth comparable to BRI1-Flag. Taken together, our results suggested that 14-3-3 proteins might positively regulate BRI1 activity and showed that 14-3-3 isoforms have different functional impacts in BR signaling.

Registration of ‘DALZ 1308’ zoysiagrass

Abstract‘DALZ 1308’ (Reg. no. CV‐285, PI 691612) is a first‐generation interspecific hybrid developed in 2004 by crossing a genotype of Zoysia minima (Colenso) Zotov and Z. matrella (L.) Merr. ‘Diamond.’ After field evaluations in Dallas, TX (2004–2009) and Gainesville, FL (2006–2008), DALZ 1308 was selected for advancement to the 2013 Warm‐season Putting Greens National Turfgrass Evaluation Program (NTEP). DALZ 1308 was evaluated at 10 NTEP locations (2013–2018) as well as in Dallas, TX (2014–2017) and Gainesville, FL (2013–2017). DALZ 1308 exhibited a diminutive growth habit with narrower and shorter leaf blades and dwarf canopy height as compared to Diamond and L1F; shorter internode length, smaller node, and smaller internode diameter as compared to L1F; superior ball roll as compared to Diamond and L1F in Arizona, Kentucky, and Texas; resistance to tawny mole crickets; and reduced seedhead incidence and density during the growing season. As compared to Diamond and L1F, DALZ 1308 has shown to have reduced winter injury with fabric cover in Bloomington, IN. Although characteristics varied by location, DALZ 1308 exhibits good turfgrass quality, high shoot density, medium‐green genetic color, and extended fall and winter color retention. Initial greenhouse experimentation under moderate shade shows that DALZ 1308 has a greater percent green cover as compared to ‘Palisades’, Diamond, and ‘Zorro’. Overall, DALZ 1308 is an ultradwarf zoysiagrass suitable for golf course putting greens in a wide range of environments across the United States.

Revision of the genus Cordaites UNGER from the Permian of the Intrasudetic Basin (Broumov Formation, Olivětín Member, Czech Republic)

Cordaitalean remains are not very common in the Permian of the Intrasudetic Basin (Czech Republic and Poland) and have usually been classified simply as Cordaites sp. Based on leaf morphology, venation and cuticles (where possible), five cordaitalean species are recognised: Cordaites cf. beinertianus, C. cf. affinis, C. cf. roesslerianus, C. cf. foliolatus and Cordaites sp. A. The determination of Cordaites leaves is difficult because of the variability and similarities between several species. The biggest leaf was determined as Cordaites cf. beinertianus. The cuticles of Cordaites cf. affinis resemble the cuticles of C. palmaeformis and C. radvanicensis,however, the latter is known only in a fragmentary state. Cordaites beinertianus and C. palmaeformis are very similar and are considered as conspecific by some authors. Cordaites affinis has generally smaller leaves. Cordaites cf. roesslerianus is comparable with C. principalis with which it is sometimes synonymised. C. cf. foliolatus is represented by a much narrower leaf than is typical for cordaitalean leaves from France. Cordaites sp. A is a relatively small leaf-form and differs from all other forms previously described.

Evaluation of validity and limitations of the soybean canopy height‐to‐row spacing ratio as an onsite index to control weeds using diverse soybean accessions

A canopy height‐to‐row spacing ratio (CHRSR) of 1.0 is expected to be a simple and practical onsite index for soybean growers to determine when further weed control is no longer necessary. This is decided when relative photosynthetic photon flux density (PPFD) reaches 50% under the soybean canopy. To evaluate the validity of this index, a 2‐year field experiment was conducted to compare days after sowing (DAS) to reach a relative PPFD of 50% (defined as PPFD50) and DAS to reach a CHRSR of 1.0 (defined as CHRSR1.0) in 190 accessions with different canopy architectures from a soybean core collection. A total of 104 accessions, for which final relative PPFD reached <10% in 2014, were examined for the differences between CHRSR1.0 and PPFD50. The mean and median values of the difference in 2014 were 0.02 and 2.2, respectively. Similarly, the mean and median values in 2015 were 2.8 and 2.6, respectively. Thus, CHRSR1.0 tended to be achieved slightly later than PPFD50, so a consideration was made that there would be a negligible risk of failure if growers used CHRSR1.0 to determine the termination time for weed control in the most of accessions. Although there were some accessions with a standing type of morphological characteristics or with a smaller or narrower leaf, showing negative differences between CHRSR1.0 and PPFD50 larger than 1 week, a CHRSR of 1.0 could be used to estimate PPFD50 in most of accessions without risk of failure to control weeds.