ASHS 2024 Conference: Full Schedule

2:15pm HST

EcoPhys/HPRB/PGR - Molecular Assessment of Heat Sensitivity in Broccoli Flowering

Wednesday September 25, 2024 2:15pm - 2:25pm HST

In the warm growing season on the East Coast, broccoli crown development is often disrupted because insufficient cold accumulation for flower bud initiation and enlargement. As part of an effort to breed for adaptation to higher growing temperatures, we investigated whether the sensitivity is due to expression of one or more of the central genes involved in flower initiation. Broccoli transitions from vegetative to reproductive phase normally, it is the transition from reproductive meristem to floral meristem and flower bud that is arrested or delayed in warm temperatures. We compared the heat response of a highly sensitive genotype, ‘Clara’ and the most resistant available genotype ‘P13xP19’ (P. Griffiths, Cornell). Plants that had just entered the reproductive phase were exposed to temperatures that were either permissive (16/12°C Day/Night) or restrictive (28/22°C Day/Night) for three days, then RNA was isolated from the meristem. The RNA was sequenced, transcripts were identified and relative abundance of each transcript was determined. Transcripts were available corresponding to the genes of interest. The model is that various developmental and environmental cues affect expression of the integrator gene SOC. The expression level of SOC then influences a gene that maintains meristem (TFL1) and one that promotes flower development (LFY). The interplay between those genes in time and space is believed to control how big the meristem will get and when the meristem will start to make flowers. When LFY expression dominates, it promotes expression of AP1 (and paralogs) inducing floral primordia. A gene responsible for the heat sensitivity would have differential expression in heat only in the sensitive genotype. That was the case for TFL1 and one copy of SOC1, but not for the other genes. Therefore, heat sensitivity is caused by genes associated with meristem transition, not with the classic flower-initiation genes.

Speakers

Thomas Bjorkman

Professor, CALS Horticulture

Co-authors

Zachary Stansell

USDA-ARS

Wednesday September 25, 2024 2:15pm - 2:25pm HST
South Pacific 3

Poster presentation (individual talk), Horticultural Plant Reproductive Biology Temp

SUBJECT Horticultural Plant Reproductive Biology

5:05pm HST

NUTS/HPRB - Identifying the association between self-fertility and floral reproductive morphology in macadamia

Thursday September 26, 2024 5:05pm - 5:15pm HST

South Pacific 3

Self-fertility, the ability of a plant to set fruits with self-pollen, is an important commercial trait in many crops. Self-fertility has the potential to set fruits in the absence of pollinators and pollenisers. Most macadamia cultivars are self-infertile but a few exhibit degrees of self-fertility. The potential morphological factors underpinning variability in this trait have not been previously investigated in macadamia. Therefore, this study aimed to determine whether floral reproductive morphology differs among self-fertile and self-infertile cultivars. Pistil length (PL), stamen length (SmL) and stigma-anther distance (SAD) were measured from cultivars within a self-fertile and a self-infertile group for two flowering seasons. The analysed self-fertile cultivars were ‘HAES 741’, ‘HAES 791’, ‘A38’, ‘Q’, ‘K’ and ‘UQM40’, while the self-infertile cultivars were ‘HAES 344’, ‘A16’, ‘Daddow’, ‘D4’ and ‘A268’. There was no significant difference between years for any of the traits (P>0.05). However, significant differences were found between the self-fertile/self-infertile groups and among cultivars within groups for the three examined traits (P

Speakers

Palakdeep Kaur

Queensland Alliance for Agriculture and Food Innovation (QAAFI), The University of Queensland (UQ)

I am pursuing Ph.D. from the University of Queensland, Australia. I started in October 2022 and have successfully finished my candidature confirmation. I did my Bachelors in Agriculture specialisation in Plant Breeding, Genetics and Biotechnology from India. I did my Masters in Agriculture... Read More →

Co-authors

Poster presentation (individual talk), Horticultural Plant Reproductive Biology Temp

SUBJECT Horticultural Plant Reproductive Biology, Temperate Tree Nut Crops

ASHS 2024 Conference

2:15pm HST

Thomas Bjorkman

Zachary Stansell

5:05pm HST

Palakdeep Kaur

Bruce Topp

Ky Mathews

Max Cowan

Mobashwer Alam