Sugarcane genes differentially expressed during water deficit

Abstract

To identify genes that are up and down-regulated by water deficit in sugarcane we used the macroarray methodology and the expression level of 3 575 independent sugarcane cDNAs was measured by hybridization with RNA extracted from plants submitted to mild, moderate and severe water deficit. We identified approximately 1 670 differentially expressed genes from which 62 % were up-regulated by different stress-conditions, whereas many repressed genes were exclusive for each time-point. Analysis of similarity showed that approximately 24 % of the differentially expressed genes shared homology with proteins involved in different processes such as signal transduction, hormone metabolism, photosynthesis, transcription and stress response. Transcripts with no known function accounted for approximately 39 % and those without similarity represented 36 % of the sequences. Five genes analyzed by RT-PCR confirmed the macroarray results.

Sugarcane Responses at Water Deficit Conditions

“…Eragrostris curvula submitted to water stress showed higher photosynthetic rate and RWC than the ones observed in tolerant cultivar (Colom & Vazzana, 2003). In sugarcane under dehydration conditions low photosynthetic rates at moderate (8 days) and severe stress (10 days) were observed (Rodrigues et al, 2009(Rodrigues et al, , 2011. Submitting the same sugarcane cultivars to other waterlimited regime where irrigation was completely suppressed, produced low photosynthetic rates under a moderate stress.…”

“…Therefore, the abscisic acid (ABA) (Kholová et al, 2010), the pH (Schachtman & Goodger, 2008) and the ionic distribution (Bahrun et al, 2002) seem to play an important role on signaling throughout the plant under water stress. Molecular studies have identified a wide range of genes expressed by sugarcane plants under water stress conditions (Iskandar et al, 2011;Prabu et al, 2010;Rodrigues et al, 2011). Regarding the responses to stress, signaling pathways regulated by hormones are highly drought-responsive, mainly those associated with the increased ABA synthesis (Pinheiro & Chaves, 2011).…”

“…Under drought stress condition, the level of endogenous ABA was increased and its function upon the stomatal closure can protect plants against immediate desiccation (Yoshida et al, 2006). In sugarcane cultivars some genes showed similarity to ABA-regulated proteins and genes directly or indirectly involved in its biosynthesis in plants submitted to water deficit, as well as a reduction in stomatal conductance (Rodrigues et al, 2011). Soil water content seems to be more influent in stomatal conductance than plant water content (Davies et al, 2002;Taiz & Zeiger, 2006).…”

“…Soil water content seems to be more influent in stomatal conductance than plant water content (Davies et al, 2002;Taiz & Zeiger, 2006). Sugarcane plants also presented a decreased soil water content under moderate (42%) and severe stress (22%) which produced changes in all photosynthetic apparatus, such as stomatal closure, reduction of transpiration and photosynthetic rate, as well as in RWC, photochemical efficiency of photosystem II (PS II), and increase in leaf temperature in plants submitted to water deficit (Rodrigues et al, 2009(Rodrigues et al, , 2011. Different methods have been applied in plant genetic breeding programs, and considering the drought tolerance, programs have focused mainly on the characterization of genotypes under water stress conditions (Condon et al, 2004).…”

“…Data obtained from this project was used to support studies of biotic (Barsalobres-Cavallari et al, 2006) and abiotic stresses (Kurama et al, 2002;Nogueira et al, 2003), as well as other researches with sugarcane (Camargo et al, 2007;Papini-Terzi et al, 2005;Rocha et al, 2007;Rosa et al, 2005). To perform a collection of ESTs from Brazilian sugarcane cultivars expressed specifically under water deficit conditions, the data provided by www.intechopen.com Sucest project was also applied in a large scale gene expression study using sugarcane cultivars with different tolerance to drought (Rocha et al, 2007;Rodrigues et al, 2009Rodrigues et al, , 2011. After the advent of sequencing projects and the consequent establishment of databases, the use of some molecular techniques became a valuable tool in identifying genes involved in plant responses to stress.…”