Gene Regulatory Network Controlling Flower Development in Spinach (Spinacia oleracea L.).

Spinach (Spinacia oleracea L.) is a dioecious, diploid, wind-pollinated crop cultivated worldwide. Sex determination plays an important role in spinach breeding. Hence, this study aimed to understand the differences in sexual differentiation and floral organ development of dioecious flowers, as well as the differences in the regulatory mechanisms of floral organ development of dioecious and monoecious flowers. We compared transcriptional-level differences between different genders and identified differentially expressed genes (DEGs) related to spinach floral development, as well as sex-biased genes to investigate the flower development mechanisms in spinach. In this study, 9189 DEGs were identified among the different genders. DEG analysis showed the participation of four main transcription factor families, MIKC_MADS, MYB, NAC, and bHLH, in spinach flower development. In our key findings, abscisic acid (ABA) and gibberellic acid (GA) signal transduction pathways play major roles in male flower development, while auxin regulates both male and female flower development. By constructing a gene regulatory network (GRN) for floral organ development, core transcription factors (TFs) controlling organ initiation and growth were discovered. This analysis of the development of female, male, and monoecious flowers in spinach provides new insights into the molecular mechanisms of floral organ development and sexual differentiation in dioecious and monoecious plants in spinach.

Hermetic storage of okra seed maintains seed longevity under changing environment.

Okra seed is vulnerable to loss of germination and vigor in variable storage conditions. High seed moisture contents (SMC) accelerate seed deterioration during storage thus keeping low seed moisture contents by storing seed in hermetic bags may help to retain seed longevity. Okra seed was equilibrated to four initial moisture levels including 8,10, 12 and 14% SMC. Seed was then packed and stored in traditional storage bags (Paper, cloth, polypropylene and jute bag) and hermetic Super Bag for 12 months under ambient conditions. Seed stored in hermetic Super Bag at 8 and 10% moisture contents maintained higher germination due to low seed moisture contents. Moreover, activities of α-amylases and total soluble sugars were higher while electrical conductivity of seed leachates, malondialdehyde (MDA) and reducing sugar contents were less in the seeds stored in hermetic Super Bag at 8 and 10% SMC as compared to seed stored in traditional storage bags. Hermetic storage at 14% moisture negatively influenced the seed quality. Moisture adsorption isotherms of okra seeds were developed at constant temperature of 25°C and varying levels of relative humidity from 60 to 90%. Moisture isotherms indicated no significant increase in seed moisture contents at 60 and 70% relative humidity (RH) in hermetic bags whereas a minor increase in seed moisture at 80 and 90% RH has been observed for the seeds incubated in hermetic bags. SMC significantly increased in traditional storage bags particularly in jute bag at high RH. In conclusion, storage in hermetic bags, maintain low seed moisture and high seed quality. Okra seed storage in hermetic bags at 8 and 10% SMC maintains seed longevity under ambient storage conditions.