Post-anthesis development of inferior and superior spikelets in rice in relation to abscisic acid and ethylene

Abstract

The purpose of this study was to test the hypothesis that the interaction between abscisic acid (ABA) and ethylene may be involved in mediating the post-anthesis development of spikelets in rice (Oryza sativa L.). Two rice genotypes were field-grown, and the changes of ABA, ethylene, and 1-aminocylopropane-1-carboxylic acid (ACC) levels in spikelets during grain filling and their relationships with endosperm-division and grain-filling rates were investigated. The results showed that earlier-flowering superior spikelets exerted dominance over later-flowering inferior spikelets in endosperm cell-division and grain-filling rates. The two genotypes behaved the same. Later-flowering spikelets had higher levels of ethylene and ACC than earlier-flowering spikelets. The ethylene evolution rate was significantly and negatively correlated with the cell division and grain filling rates. By contrast to ethylene, later-flowering spikelets contained a lower ABA content/concentration and showed a low content ratio of ABA to ACC than earlier-flowering ones. The cell-division and grain-filling rates were significantly and positively correlated with both ABA contents and the ratio of ABA to ACC. Application of cobalt ion (inhibitor of ethylene synthesis) or ABA at an early grain-filling stage significantly increased endosperm cell division rate and cell number, grain-filling rate, and grain weight of inferior spikelets. Application of ethephon (an ethylene-releasing agent) or fluridone (an inhibitor of carotenoid synthesis) had the opposite effect. The results suggest that antagonistic interactions between ABA and ethylene mediate endosperm cell-division and grain-filling in rice. A higher ratio of ABA to ethylene in rice spikelets is required to maintain a faster grain-filling rate.

The Ethylene Receptor ETR2 Delays Floral Transition and Affects Starch Accumulation in Rice

“…This process of starch metabolism was also regulated by the ERF-type transcription factor Sub1C (Fukao et al, 2006). Ethylene, together with abscisic acid, also had an influence on grain filling (Yang et al, 2006). These studies imply that ethylene and receptor signaling can regulate carbohydrate metabolism, sugar translocation, and grain filling in rice.…”

Effects of Salt Stress after Late Booting Stage on Yield and Antioxidant Capacity in Pigmented Rice Grains and Alleviation of the Salt-Induced Yield Reduction by Exogenous Spermidine

“…Reduction in grain weight could be due to limited soluble carbohydrate translocation from leaves to spikelets and inhibition of starch synthetase activity in developing rice grains (Abdullah et al, 2001). Final grain weight is also determined by grain filling rate which has been associated with ratio between ABA and ethylene in developing grains (Yang et al, 2006) and activity of sucrose synthase (Tang et al, 2009). In contrast to this study, when rice plants were exposed to salinity earlier in the vegetative stages, the reduction in tiller number per plant and total spikelet number per panicle were the major causes of yield loss (Zeng and Shannon, 2000;Zeng et al, 2001;Zeng et al, 2002).…”

“…Endogenous PAs which are induced by abiotic stresses play multifaceted roles in protecting plant cells against environmental stresses (Shabala et al, 2007;Farooq et al, 2009;Hussain et al, 2011). Synthesis of PAs during reproductive development has been demonstrated to be essential for normal seed development (Liang and Lur, 2002;Urano et al, 2005) and their actions are antagonized by ethylene (Yang et al, 2006). Exogenous PAs have been shown to reduce salinity stress-induced damages in several plants including rice.…”

Transcriptome Analysis of Proliferating Arabidopsis Endosperm Reveals Biological Implications for the Control of Syncytial Division, Cytokinin Signaling, and Gene Expression Regulation

“…The varied distributions of phytohormones and their well-documented ability to regulate growth and development of the seed make them obvious candidates for identifying important components in the control of early endosperm development (Lur and Setter, 1993;Yang et al, 2002Yang et al, , 2006. A recent study by Nemhauser et al (2006) used the AtGenExpress hormone series to identify genes that were only expressed in response to particular hormones, suggesting that these genes can be used as markers for hormone action.…”

“…In a recent study, Yang et al (2006) made direct comparisons of both ethylene and ABA levels with endosperm cell division in spikelets of rice. They concluded that cell division and grain-filling rates were positively associated with ABA and negatively associated with ethylene.…”