Physiological and genome-wide gene expression analyses of cold-induced leaf rolling at the seedling stage in rice (Oryza sativa L.)☆
Jingfang
Dong1, Junliang Zhao1, Shaohong Zhang, Tifeng Yang, Qing
Liu, Xingxue Mao,Hua Fu, Wu Yang, Bin Liu*
THE CROP JOURNAL
Abstract
Leaf
rolling and discoloration are two chilling-injury symptoms that are widely used
as indicators for the evaluation of cold tolerance at the seedling stage in
rice. However, the difference in cold-response mechanisms underlying these two
traits remains unknown. In the present study, a cold-tolerant rice cultivar,
Lijiangxintuanheigu, and a cold-sensitive cultivar, Sanhuangzhan-2, were
subjected to low-temperature treatments and physiolog[1]ical and genome-wide
gene expression analyses were conducted. Leaf rolling occurred at temperatures
lower than 11 °C, whereas discoloration appeared at moderately low temperatures
such as 13 °C. Chlorophyll contents in both cultivars were significantly decreased
at 13 °C, but not altered at 11 °C. In contrast, the relative water content and
relative electrolyte leakage of both cultivars decreased significantly at 11
°C, but did not change at 13 °C. Expression of genes associated with calcium
signaling and abscisic acid (ABA) degradation was significantly altered at 11
°C in comparison with 25 °C and 13 °C. Numerous genes in the DREB, MYB, bZIP,
NAC, Zinc finger, bHLH, and WRKY gene families were differentially expressed.
Many aquaporin genes and the key genes in trehalose and starch synthesis were
down regulated at 11 °C in comparison with 25 °C and 13 °C. These results
suggest that the two chilling injury symptoms are temperature-specific and are controlled
by different mechanisms. Cold-induced leaf rolling is associated with calcium and
ABA signaling pathways and is regulated by multiple transcriptional regulators.
The suppression of aquaporin genes and reduced accumulation of soluble sugars
under cold stress results in a reduction in cellular water potential and
consequently leaf rolling.
Keywords: Rice
(Oryza sativa L.) Cold-induced leaf
yellowing Cold-induced leaf rolling Physiological analysis Genome-wide expression profiling
