Spatial and temporal distribution of mineral nutrients and sugars throughout the lifespan of Hibiscus rosa-sinensis L. flower

Abstract

Although the physiological and molecular mechanisms of flower development and senescence have been extensively investigated, a whole-flower partitioning study of mineral concentrations has not been carried out. In this work, the distribution of sucrose, total reducing sugars, dry and fresh weight and macro and micronutrients were analysed in Hibiscus rosa-sinensis L. petals, stylestigma including stamens and ovary at different developmental stages (bud, open and senescent flowers). Total reducing sugars showed the highest value in petals of bud flowers, then fell during the later stages of flower development whereas sucrose showed the highest value in petals of senescent flowers. In petals, nitrogen and phosphorus content increased during flower opening, then nitrogen level decreased in senescent flowers. The calcium, phosphorus and boron concentrations were highest in ovary tissues whatever the developmental stage. Overall, the data presented suggests that the high level of total reducing sugars prior the onset of flower opening contributes to support petal cells expansion, while the high amount of sucrose at the time of petal wilting may be viewed as a result of senescence. Furthermore, this study discusses how the accumulation of particular mineral nutrients can be considered in a tissue specific manner for the activation of processes directly connected with reproduction.

Spatial and temporal transcriptome changes occurring during flower opening and senescence of the ephemeral hibiscus flower,Hibiscus rosa-sinensis

“…Seven transcripts encoding autophagy genes ( ATG8c , ATG8f , and ATGg ; Supplementary Table S15) were strongly induced in senescing petals and S-S+S tissues. During hibiscus flower senescence, the nitrogen, phosphorus, potassium, and micro-nutrient content of petals and S-S+S is significantly reduced, supporting a possible role of autophagy in the degradation and remobilization of macromolecules during flower ageing (Trivellini et al , 2011 c ). These data support the previously documented role for autophagy in petal senescence (Yamada et al , 2009; Shibuya et al , 2013), pointing out also its role in senescing S-S+S as a major nutrient recycling mechanism in plants as suggested by Coll et al (2014).…”

“…This condition might be supported by the considerable differential regulation of aquaporin gene expression among different flower developmental stages. In hibiscus, it has been shown that flower senescence entrains circadian rhythms via endogenous oscillations in sugars (Trivellini et al , 2011 c ). This opens the possibility that variation in sugar may be important in entrainment of the clock in the flower petals and regulation of aquaporins.…”

Mineral nutrient remobilization during corolla senescence in ethylene-sensitive and -insensitive flowers

“…The changes in the nutrient profiles of senescing Hibiscus rosa-sinensis (hibiscus) are very similar to the pollination-induced changes in petunia corollas (Chapin and Jones 2007; Trivellini et al 2011). Hibiscus is an ethylene-sensitive, ephemeral flower that opens and wilts within 1 day.…”

“…The senescence of ephemeral flowers is generally not accelerated by pollination. Nutrient remobilization studies indicate that the senescence of these flowers may be more similar to pollination-induced senescence than developmental senescence in their longer-lived counterparts (Winkenbach 1970; Trivellini et al 2011). In Japanese morning glories, petal senescence starts before the flowers are even open (Winkenbach 1970).…”

“…Once the flower has been pollinated, or the stigma is no longer receptive to pollination, the corolla senesces (Jones 2002). Senescence is the last stage of flower development, during which nutrients are recycled to developing tissues (Bieleski 1995; Verlinden 2003; Chapin and Jones 2007; Trivellini et al 2011). A genetically controlled senescence programme allows the plant to systematically disassemble cellular organelles and macromolecules, and remobilize nutrients from the petals before cell death.…”