Inheritance of Compact Growth Habit, and Investigation of Linkage to Weeping Architecture and Purple Leaf Color in Eastern Redbud (Cercis canadensis L.)

Eastern redbud (Cercis canadensis L.) is a commonly used small landscape tree. Compact growth, purple leaf color, and weeping architecture are three popular ornamental phenotypes. Inheritances of weeping architecture and purple leaves have been reported previously. Inheritance of compact growth habit and its genetic linkage with the weeping and purple leaf genes have not been reported. In the present research, the inheritance of compact growth derived from ‘Ace of Hearts’ was explored in the F1, F2, and reciprocal backcross families resulting from the controlled hybridization of ‘Ruby Falls’ (normal growth/weeping architecture/purple leaf) × ‘Ace of Hearts’ (compact growth/nonweeping architecture/green leaf). All 27 F1 individuals were nonweeping, green-leaved, and noncompact. A total of 572 F2 progeny were obtained, and subsequent analysis of segregation revealed a single recessive gene controlled compact growth habit. Analysis of reciprocal backcross families confirmed this result as well. Weeping architecture and purple leaf color were also controlled by single recessive genes, confirming findings presented in previous studies in another redbud family. No linkage between the three genes was detected. This research is the first to report the inheritance of compact growth in eastern redbud and confirms independent assortment between the compact, purple leaf, and weeping genes.

Comparative Ecosystem Benefits of Common Urban Trees and Palms in South Florida

This new 2-page factsheet was written to support urban forestry Extension clientele queries for information guiding Florida HOA and property owner decisions on whether to replace hardwood trees with palms, due to palms’ compact growth habit and lower leaf-shed volume, compared to hardwood trees. Written by Marguerite Beckford and Gary W. Knox, and published by the UF/IFAS Environmental Horticulture Department.

A temperature regime that disrupts clock-controlled starch mobilization induces transient carbohydrate starvation, resulting in compact growth

In nature plants are usually subjected to a light/temperature regime of warm day and cold night (referred to as +DIF). Compared to growth under +DIF, Arabidopsis plants show compact growth under the same photoperiod, but with an inverse temperature regime (cold day and warm night: -DIF). Here we show that -DIF differentially affects the phase and amplitude of core clock gene expression. Under -DIF the phase of the morning clock gene CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) is delayed, similar to that of plants grown on low sucrose. Indeed, under -DIF carbohydrate (CHO) starvation marker genes are specifically upregulated at the End of the Night (EN) in Arabidopsis rosettes. However, only in inner-rosette tissue (small sink leaves and petioles of older leaves) sucrose levels are lower under -DIF compared to under +DIF, suggesting that sucrose in source leaf blades is not sensed for CHO status and that sucrose transport from source to sink may be impaired at EN. CHO-starvation under -DIF correlated with increased starch breakdown during the night and decreased starch accumulation during the day. Moreover, we demonstrate that different ways of inducing CHO-starvation all link to reduced growth of sink leaves. Practical implications for control of plant growth in horticulture are discussed.

Architectural Components of Compact Growth Habits in Diploid Roses

Criteria to determine the horticultural quality of ornamental plants include plant architecture, flower characteristics, and resistance to biotic and abiotic stresses. The architecture of a rose (Rosa sp.) bush is linked to flower yield and ornamental value. The Texas A&M University (TAMU) Rose Breeding and Genetics program has the objective of developing garden rose cultivars that flower heavily and exhibit a compact full shape. To determine which architectural traits are key for the development of this desired shape, five rose seedlings with a desirable compact growth habit and five with an undesirable growth habit were selected from TAMU diploid rose breeding germplasm. This comparison indicated that the key traits for the selection of compact growth habit are the number of primary shoots followed by the number of secondary and tertiary shoots produced.

Accelerating Soybean Breeding in a CO2-Supplemented Growth Chamber

Soybean (Glycine max) is the most important dicot crop worldwide, and is increasingly used as a model legume due to the wide availability of genomic soybean resources; however, the slow generation times of soybean plants are currently a major hindrance to research. Here, we demonstrate a method for accelerating soybean breeding in compact growth chambers, which greatly shortens the generation time of the plants and accelerates breeding and research projects. Our breeding method utilizes commonly used fluorescent lamps (220 �mol m–2 s–1 at the canopy level), a 14 h light (30�C)/10 h dark (25�C) cycle and carbon dioxide (CO2) supplementation at >400 p.p.m. Using this approach, the generation time of the best-characterized elite Japanese soybean cultivar, Enrei, was shortened from 102–132 d reported in the field to just 70 d, thereby allowing up to 5 generations per year instead of the 1–2 generations currently possible in the field and/or greenhouse. The method also facilitates the highly efficient and controlled crossing of soybean plants. Our method uses CO2 supplementation to promote the growth and yield of plants, appropriate light and temperature conditions to reduce the days to flowering, and the reaping and sowing of immature seeds to shorten the reproductive period greatly. Thus, the appropriate parameters enable acceleration of soybean breeding in the compact growth chambers commonly used for laboratory research. The parameters used in our method could therefore be optimized for other species, cultivars, accessions and experimental designs to facilitate rapid breeding in a wide range of crops.