Biology subjects

Oluwasanya, D. N.

Publications and source records attributed to Oluwasanya, D. N..

3 recordsLinked to original sources

bioRxiv2021

Environmental responsiveness of flowering time in cassava genotypes and associated transcriptome changes

Cassava is an important food security crop in tropical regions of the world. Cassava improvement by breeding is limited by its delayed and poor production of flowers, such that cassava flowering under field conditions indirectly lengthens the breeding cycle. By studying genotype and environment interaction under two Nigerian field conditions (Ubiaja and Ibadan) and three controlled temperature conditions (22{degrees}C/18{degrees}C, 28/24{degrees}C and 34/30{degrees}C (day/night)), we found that while early flowering genotypes flowered at similar times and rates under all growing conditions (unfavorable and favorable field and controlled-temperature environments), late flowering genotypes were environmentally sensitive such that they were substantially delayed in unfavorable environments. Flowering times of late genotypes approached the flowering time of early flowering genotypes under relatively cool Ubiaja field conditions and in growth chambers at 22{degrees}C, whereas warmer temperatures elicited a delaying effect. Analysis of field and controlled temperature transcriptomes in leaves revealed that conditions that promote early flowering in cassava have low expression of the flowering repressor gene TEMPRANILLO 1 (TEM1), before and after flowering, among others. Field transcriptomes showed that the balance between flower promoting and inhibitory signaling, appeared to correlate with flowering time across the environments and genotypes.

plant biology↗

bioRxiv2020

Enhancing cassava reproductive development does not negatively impact shoot to root ratio and dry matter content in storage roots

From previous studies we developed treatments that significantly improved cassava female flower and fruit development, using a combination of the anti-ethylene, silver thiosulfate (STS), and the cytokinin, benzyladenine (BA); collectively referred to as plant growth regulators (PGR). In this study, we investigated whether the benefit derived from this treatment altered partitioning of photosynthate to other sinks and general vegetative growth of cassava in the first six months of plants growth, when reproductive growth initiates and peaks. Our flower enhancing treatment did not significantly alter shoot and storage root fresh weight, partitioning index on a fresh weight basis and percent dry matter content of storage roots between Months 2 and 5. With the onset of the dry season in Month 6, PGR treated plants had higher shoot and storage root fresh weight than controls but these plant parts responded proportionally and so partitioning index between controls and treated plants was not significantly different. The nighttime starch export under PGR treatments was reduced at Months 2, 4 and 5 but this was not correlated with flower development at these months. The survival of PGR treated plants until harvest was however reduced owing to increased mortality arising from phytotoxicity and increased susceptibility to disease. We therefore conclude that PGRs have effects more directly on flower and fruit reproductive signaling and regulatory pathways rather than on an indirect effect on resource partitioning.

plant biology↗

bioRxiv2020

Silver thiosulfate and Benzyladenine in combination with pruning additively feminizes cassava flowers and modulates transcriptome

Cassava, a tropical storage-root crop, is a major source of food security for millions in the tropics. Cassava breeding however is hindered by the poor development of flowers and female flowers in particular, since flower development is strongly skewed towards male flowers. Our objectives were to test plant growth regulator and pruning treatments for their effectiveness in field conditions in improving flower production and fruit set in cassava. Pruning the fork type branches that arise at the shoot apex immediately below newly formed inflorescences stimulated inflorescence and floral development. The anti-ethylene silver thiosulfate (STS) also increased flower abundance. Both pruning and STS increased flower numbers without influencing sex ratios. In contrast, the cytokinin benzyladenine (BA) feminized flowers without increasing flower abundance. Combining pruning and STS treatments led to an additive increase in flower abundance; with the addition of BA, over 80% of flowers were females. This three-way treatment combination of pruning+STS+BA also led to an increase in fruit development. Transcriptomic analysis of gene expression in tissues of the apical region and developing inflorescence revealed that the enhancement of female flower development by STS+BA was accompanied by the downregulation in of several genes associated with repression of flowering, including Tempranillo 1 (TEM1), GA receptor GID1b, and ABA signaling genes ABI1 and PP2CA. We conclude that treatments with pruning, STS and BA create widespread changes on the network of hormone signaling and regulatory factors beyond ethylene and cytokinin.

plant biology↗