Cell layer-specific expression of the B-class MADS-box gene PhDEF drives petal tube or limb development in petunia flowers

Floral homeotic MADS-box transcription factors ensure the correct development of floral organs with all their mature features, i.e. organ shape, size, colour and cellular identity. Furthermore, all plant organs develop from clonally-independent cell layers, deriving from the meristematic epidermal (L1) and internal (L2 and L3) layers. How cells from these distinct layers acquire their floral identities and coordinate their growth to ensure reproducible organ development is unclear. Here we study the development of the Petunia x hybrida (petunia) corolla, which consists of five fused petals forming a tube and pigmented limbs. We present petunia flowers expressing the B-class MADS-box gene PhDEF in the epidermis or in the mesophyll of the petal only, that we called wico and star respectively. Strikingly, the wico flowers form a very small tube while their limbs are almost normal, and the star flowers form a normal tube but very reduced and unpigmented limbs. Therefore, the star and wico phenotypes indicate that in the petunia petal, the epidermis mainly drives limb growth and pigmentation while the mesophyll mainly drives tube growth. As a first step towards the identification of candidate genes involved in specification of petal layer identities and tube/limb development, we sequenced the star and wico whole petal transcriptome at three developmental stages. Among downregulated genes in star petals, we found the major regulator of anthocyanin biosynthesis ANTHOCYANIN 1 (AN1), and we showed that, in vitro, PhDEF directly binds to its terminator sequence, suggesting that it might regulate its expression. Altogether this study shows that layer-specific expression of PhDEF drives petunia tube or limb development in a highly modular fashion, which adds an extra layer of complexity to the petal development process.

Seeing Red? The Role of Font Color, Size, and Sale Sign Location in Retail Garden Center Displays1

The goal of this study was to better understand consumers' likelihood to buy a plant when the word “sale” was presented in red font on a white sign, with a range of font sizes, showing an equivalent discounted price in three ways (dollar amount, 25% percent off, and buy-3-get-1-free), with the sale sign location either on the left or right side of the display. Researchers constructed a partial factorial design with three plant types producing 16 images for the study. They recruited 154 subjects from two states. Results of the rating-based conjoint study revealed that plant type comprised 45% of the purchase decision, which was consistent with prior research. Price (23.8%) was the next most important factor in likely to buy followed by sale font size. Sale sign location and sale font color were similar and third and fourth, respectively, in relative importance. The synergistic effect of sale font size and color indicate that when red fonts were used for the word “sale” they should be larger than other font sizes and placed to the right in the display. Consumer gaze appeared to move from left to right as though study participants “read” the display. Results showed the red font had greater attention-grabbing power on the right side of the display and when it appeared in a larger or smaller font size. Index words: consumer, eye-tracking, price, survey, signage. Species used in this study: Pepper [Capsicum annuum L. (C. frutescens)], parsley Petroselinum crispum J. Hill, petunia (Petunia x hybrida Juss.), rosemary Rosmarinus officinalis L., sage (Salvia officinalis L.), tomato (Solanum lycopersicum L.).

A Proposed Methodology to Analyze Plant Growth and Movement from Phenomics Data

Image analysis of developmental processes in plants reveals both growth and organ movement. This study proposes a methodology to study growth and movement. It includes the standard acquisition of internal and external reference points and coordinates, coordinates transformation, curve fitting and the corresponding statistical analysis. Several species with different growth habits were used including Antirrhinum majus, A. linkianum, Petunia x hybrida and Fragaria x ananassa. Complex growth patterns, including gated growth, could be identified using a generalized additive model. Movement, and in some cases, growth, could not be adjusted to curves due to drastic changes in position. The area under the curve was useful in order to identify the initial stage of growth of an organ, and its growth rate. Organs displayed either continuous movements during the day with gated day/night periods of maxima, or sharp changes in position coinciding with day/night shifts. The movement was dependent on light in petunia and independent in F. ananassa. Petunia showed organ movement in both growing and fully-grown organs, while A. majus and F. ananassa showed both leaf and flower movement patterns linked to growth. The results indicate that different mathematical fits may help quantify growth rate, growth duration and gating. While organ movement may complicate image and data analysis, it may be a surrogate method to determine organ growth potential.

Transcriptional Structure of Petunia Clock in Leaves and Petals

The plant circadian clock coordinates environmental signals with internal processes including secondary metabolism, growth, flowering, and volatile emission. Plant tissues are specialized in different functions, and petals conceal the sexual organs while attracting pollinators. Here we analyzed the transcriptional structure of the petunia (Petunia x hybrida) circadian clock in leaves and petals. We recorded the expression of 13 clock genes in petunia under light:dark (LD) and constant darkness (DD). Under light:dark conditions, clock genes reached maximum expression during the light phase in leaves and the dark period in petals. Under free running conditions of constant darkness, maximum expression was delayed, especially in petals. Interestingly, the rhythmic expression pattern of PhLHY persisted in leaves and petals in LD and DD. Gene expression variability differed among leaves and petals, time of day and photoperiod. The transcriptional noise was higher especially in leaves under constant darkness. We found that PhPRR7, PhPRR5, and PhGI paralogs showed changes in gene structure including exon number and deletions of CCT domain of the PRR family. Our results revealed that petunia petals presented a specialized clock.

Tipos de compatibilidad A1 y A2 de Phytophthora capsici y P. drechsleri coexisten en plantas ornamentales de vivero

<p>No se ha reportado la presencia de ambos tipos de compatibilidad de especies de Phytophthora en plantas hospedantes sembradas en una misma maceta en viveros comerciales de México. En 2015, se colectaron aislados de <em>Phytophthora</em> en viveros comerciales en la Ciudad de México y en el estado de Morelos. Se detectaron los tipos de compatibilidad A1 y A2 de <em>Phytophthora capsici</em> y <em>P. drechsleri</em> en plantas marchitas de <em>Capsicum annuum</em> (tallos) y <em>Petunia x hybrida</em> (rizósfera), respectivamente. Los aislados de <em>Phytophthora</em> coinoculados <em>in planta</em> formaron oosporas en condiciones de invernadero. <em>Phytophthora</em> fue re-aislada de plantas inoculadas e identificada mediante herramientas morfológicas y moleculares. Los tipos de compatibilidad A1 y A2 de <em>Phytophthora capsici</em> y <em>P. drechsleri</em> se presentan simultáneamente en plantas de invernadero, lo cual sugiere que están ocurriendo recombinación sexual y variación genética. Los tipos de compatibilidad A1 y A2 de <em>Phytophthora capsici</em> y <em>Phytophtora dechsleri</em> fueron detectados por primera vez en <em>Capsicum annuum</em> y <em>Petunia x hybrida</em> respectivamente, en viveros mexicanos.</p>

Tipos de compatibilidad A1 y A2 de Phytophthora capsici y P. drechsleri coexisten en plantas ornamentales de vivero

<p>No se ha reportado la presencia de ambos tipos de compatibilidad de especies de Phytophthora en plantas hospedantes sembradas en una misma maceta en viveros comerciales de México. En 2015, se colectaron aislados de <em>Phytophthora</em> en viveros comerciales en la Ciudad de México y en el estado de Morelos. Se detectaron los tipos de compatibilidad A1 y A2 de <em>Phytophthora capsici</em> y <em>P. drechsleri</em> en plantas marchitas de <em>Capsicum annuum</em> (tallos) y <em>Petunia x hybrida</em> (rizósfera), respectivamente. Los aislados de <em>Phytophthora</em> coinoculados <em>in planta</em> formaron oosporas en condiciones de invernadero. <em>Phytophthora</em> fue re-aislada de plantas inoculadas e identificada mediante herramientas morfológicas y moleculares. Los tipos de compatibilidad A1 y A2 de <em>Phytophthora capsici</em> y <em>P. drechsleri</em> se presentan simultáneamente en plantas de invernadero, lo cual sugiere que están ocurriendo recombinación sexual y variación genética. Los tipos de compatibilidad A1 y A2 de <em>Phytophthora capsici</em> y <em>Phytophtora dechsleri</em> fueron detectados por primera vez en <em>Capsicum annuum</em> y <em>Petunia x hybrida</em> respectivamente, en viveros mexicanos.</p>