Utilizing Chromosome Segment Substitution Lines (CSSLs) for Evaluation of Root Responses to Transient Moisture Stresses in Rice

Alleles Affecting 30 Traits for Productivity in Two Japonica Rice Varieties, Koshihikari and Nipponbare (Oryza sativaL.)

“…A number of genetic materials such as backcross inbred lines and chromosome segment substitution lines (CSSLs) have been developed in rice. For the majority of them, indica varieties have been crossed with japonica varieties (Wan et al, 2004;Ebitani et al, 2005;Takai et al, 2007;Suralta et al, 2008). Using these materials, much genetic information on productivity has been stocked (e.g., Li et al, 1997;Ishimaru et al, 2001;Yue et al, 2006;Madoka et al, 2008;Takai et al, 2010;Ujiie et al, 2012;Ujiie and Ishimaru, 2013).…”

Roles of Root Aerenchyma Development and Its Associated QTL in Dry Matter Production under Transient Moisture Stress in Rice

“…These stresses are transiently recurring in the field due to the intermittent rainfall patterns and inefficient irrigation systems (Zeigler and Puckridge, 1995;Wade et al, 1998;Boling et al, 2004). The inability of the plants to acclimate to drought and oxygen (O 2 ) deficiency brought about by fluctuating soil moistures have been shown to reduce the dry matter production and yield in rice (Suralta and Yamauchi, 2008;Suralta et al, 2008aSuralta et al, , 2008bSuralta et al, 2010;Niones et al, 2012). Since rice roots are at the forefront of acclimation to fluctuating moisture conditions, component root traits other than those contributing to drought tolerance are important for coping with the aerobic-anaerobic transitions at all growth stages of the plant.…”

“…Root plasticity response in terms of promoted lateral root development and aerenchyma formation is essential for rice adaptation under soil moisture fluctuation conditions (Niones et al, 2012). Consequently, the root plasticity or the ability of plants to alter root phenotypes developmentally and functionally in response to changing environmental conditions has been suggested (O'Toole and Bland, 1987) and validated to play significant roles in plant adaptation to such kind of environment (Yamauchi et al, 1996;Bañoc et al, 2000;Siopongco et al, 2005;Wang and Yamauchi, 2006;Suralta and Yamauchi, 2008;Suralta et al, 2008aSuralta et al, , 2008bSuralta et al, , 2010Niones et al, 2012).…”

“…In a series of studies, we demonstrated that the plasticity in the developmental responses of LRs to different intensities of drought stress (Yamauchi et al, , 1996Wang and Yamauchi, 2006;Kano-Nakata et al, 2011), rewatering after drought (Bañoc et al, 2000;Siopongco et al, 2005), transient drought after waterlogging and vice versa (Suralta et al, 2008a(Suralta et al, , 2008b(Suralta et al, , 2010 and continuous cycles of alternate waterlogging and drought (Niones et al, 2012) contributed to the maintenance of dry matter production and yield in rice. Under fluctuating soil moisture stress (drought-to-waterlogged conditions), the plasticity in L-type LR formation was associated with higher aerenchyma development (Suralta et al, 2010;Niones et al, 2012) indicating that aerenchyma development under constant waterlogging and transient drought-to-waterlogged stress conditions is an essential trait for future varietal improvement for such kind of soil hydrologic conditions.…”

“…Available CSSLs such as the one derived from Nipponbare and Kasalath crosses have been successfully used for the precise quantification of the contribution of root plasticity to dry matter production and yield under fluctuating soil moisture environments in rice (Suralta et al, 2008a(Suralta et al, , 2008bNiones et al, 2012). In our previous studies, one CSSL (line 47) was selected because the growth of its shoots and roots is similar to that in Nipponbare parent under nonstressed conditions but plastic lateral root development and aerenchyma formation are promoted under shortduration transient moisture stresses (Suralta et al, 2008b(Suralta et al, , 2010 and continuous cycle of waterlogging and drought (Niones et al, 2012), which contributed to the maintenance of shoot dry matter production and yield. Genetically, we assumed that the segments from Kasalath allele introgressed into the Nipponbare genetic background in CSSL47 may regulate the formation of aerenchyma under fluctuating soil moisture at the vegetative stage.…”