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Flowering in angiosperms is a crucial event that marks the transition from the vegetative to the reproductive phase. In many perennials, pruning is an important horticultural practice that induces synchronized and profuse flowering. In pomegranate, vegetative growth immediately after pruning is associated with activation of PgCENa, a flowering suppressor of the phosphatidyl ethanolamine binding protein (PEBP) family, while a reduction is associated with synchronous flowering. We show that flowering in pomegranate is activated by expression of another PEBP family member, PgFT1, a homolog of the FLOWERING LOCUS T (FT) gene that promotes flowering. PgFT1 shows a rapid reduction in expression during the extensive vegetative growth immediately after pruning but shows robust expression during synchronous flowering post-pruning, in flower-bearing shoots but not in branches that do not bear flowers. A continuous low-level flowering in the absence of pruning is associated with continuous but reduced expression of PgFT1. Flowering by heterologous expression of PgFT1 in Arabidopsis is affected by a single amino acid change in the C-terminal region of PgFT1, which upon correction, promotes flowering in Arabidopsis. Our study provides insights into the molecular mechanisms by which pruning affects flowering pathways in tropical perennial fruit plants such as pomegranate., (© 2022 Scandinavian Plant Physiology Society.)

In tropics, combined stresses of drought and heat often reduce crop productivity in plants like Musa acuminata L. We compared responses of two contrasting banana genotypes, namely the drought-sensitive Grand Nain (GN; AAA genome) and drought tolerant Hill banana (HB; AAB genome) to individual drought, heat and their combination under controlled and field conditions. Drought and combined drought and heat treatments caused greater reduction in leaf relative water content and greater increase in ion leakage and H 2 O 2 content in GN plants, especially in early stages, while the responses were more pronounced in HB at later stages. A combination of drought and heat increased the severity of responses. Real-time expression patterns of the A-1 and A-2 group DEHYDRATION-RESPONSIVE ELEMENT BINDING (DREB) genes revealed greater changes in expression in leaves of HB plants for both the individual stresses under controlled conditions compared to GN plants. A combination of heat and drought, however, activated most DREB genes in GN but surprisingly suppressed their expression in HB in controlled and field conditions. Its response seems correlated to a better stomatal control over transpiration in HB and a DREB-independent pathway for the more severe combined stresses unlike in GN. Most of the DREB genes had abscisic acid (ABA)-responsive elements in their promoters and were also activated by ABA suggesting at least partial dependence on ABA. This study provides valuable information on physiological and molecular responses of the two genotypes to individual and combined drought and heat stresses., (© 2018 Scandinavian Plant Physiology Society.)