biologia plantarum

Biologia plantarum 2016, 60:532-542 | DOI: 10.1007/s10535-016-0606-6

Growth characteristics and endosperm structure of superior and inferior spikelets of indica rice under high-temperature stress

Y. Y. Cao^1,2, Y. H. Chen¹, M. X. Chen², Z. Q. Wang³, C. F. Wu⁴, X. C. Bian⁴, J. C. Yang^3,*, J. H. Zhang^2,*

¹ College of Life Science, Nantong University, Nantong, P.R. China

² School of Life Sciences and State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Hong Kong, P.R. China

³ Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Yangzhou University, Yangzhou, P.R. China

⁴ Jiangsu Yanjiang Institute of Agricultural Sciences, Rugao, P.R. China

Heat stress severely reduces rice yield and quality; however, differences between the superior, early-flowering and inferior, later-flowering spikelets of indica rice in response to high-temperature stress during grain filling remain unclear. This study investigated the effects of high temperature (HT, 33.6/20.7 °C day/night) on growth, endosperm structure, and hormone and polyamine content of superior and inferior spikelets of heat-sensitive (SG-1) and heat-tolerant (HHZ) indica cultivars. The HT decreased fertilization rate, caused earlier grain filling, and reduced duration of grain filling, thus resulting in decreased grain mass and a poor endosperm structure. In addition, soluble sugar and sucrose content increased, and starch synthesis decreased by HT at the early stage of grain filling. The HT increased polyamine [spermidine (Spd) and spermine (Spm)] and abscisic acid (ABA) content, but reduced zeatin (Z) + zeatin riboside (ZR) and indole-3-acetic acid (IAA) content in the grains. Such effects were more apparent in the inferior than superior spikelets; however, the inferior spikelets of SG-1 were more affected than those of HHZ. At the middle grain filling stage, HT produced little difference between the two cultivars. Our results suggest that the poor development of inferior spikelets of SG-1 under the HT could be attributed, at least in part, to the changed content and ratios of free polyamines [putrescine (Put), Spd, and Spm] and phytohormones (Z+ZR, IAA, and ABA) and the conversion efficiency of sucrose into starch.

Keywords: abscisic acid; auxin; cytokinin; Oryza sativa; polyamines; starch; sugars

Subjects: endosperm; temperture - high; abscisic acid; auxin; cytokinin; polyamines; starch; sugars; rice; grain development

Species: Oryza sativa

Received: August 18, 2015; Revised: November 19, 2015; Accepted: December 1, 2015; Published: September 1, 2016Show citation