Root-ABA1 QTL affects root lodging, grain yield, and other agronomic traits in maize grown under well-watered and water-stressed conditions

Abstract

A major QTL affecting root traits and leaf ABA concentration was identified in maize (Zea mays L.) and named root-ABA1. For this QTL, back-cross-derived lines (BDLs) homozygous either for the (+) or for the (-) allele increasing or decreasing, respectively, root size and leaf ABA concentration, were developed. This study was conducted to evaluate the QTL effects in various genetic backgrounds and at different water regimes. The (+/+) and (-/-) BDLs were crossed with five or 13 inbred tester lines of different origin, thus producing two sets of test-crosses that were evaluated in Italy and China, respectively. Testing was conducted under both well-watered and water-stressed conditions. In Italy, the test-crosses derived from (+/+) BDLs, as compared with those derived from (-/-) BDLs, showed, across both water regimes, higher leaf ABA concentration (on average 384 versus 351 ng g(-1) DW) and lower root lodging (28.0 versus 52.5%), and lower grain yield under water-stressed conditions (4.88 versus 6.27 Mg ha(-1)). In China, where root lodging did not occur, the test-crosses derived from (+/+) BDLs were less productive at both water regimes (on average, 6.83 versus 7.49 Mg ha(-1)). The lower grain yield of the test-crosses derived from (+/+) BDLs was due to a lower number of ears per plant and to lower kernel weight. The results indicate that the (+) root-ABA1 allele confers not only a consistently lower susceptibility to root lodging but also a lower grain yield, especially when root lodging does not occur.

Novel QTLs for growth angle of seminal roots in wheat (Triticum aestivum L.)

“…These results support the idea that deep rooting is beneficial to obtaining water from deep soil layers. In rice (Uga et al 2011;Steele et al 2006), sorghum (Tsuji et al 2005), and maize (Hund et al 2009;Landi et al 2007), several studies have reported positive associations between yield and root architecture under drought conditions. However, QTL analyses for drought tolerance in wheat have not revealed effective QTLs related to root system architecture.…”

Quantitative Trait Loci and Crop Performance under Abiotic Stress: Where Do We Stand?: Table I.

“…A number of studies have reported QTLs for root architecture and have investigated their effects on yield under varying moisture regimes in rice (MacMillan et al, 2006;Steele et al, 2006Steele et al, , 2007Yue et al, 2006) and maize (Tuberosa et al, 2002Landi et al, 2007). In rice, following the identification of four major QTLs influencing root traits (Courtois et al, 2000), markerassisted backcrossing (MABC) was used to introgress the alleles for greater root length from Azucena into Kalinga III, an upland variety (Steele et al, 2006(Steele et al, , 2007.…”

“…In rice, following the identification of four major QTLs influencing root traits (Courtois et al, 2000), markerassisted backcrossing (MABC) was used to introgress the alleles for greater root length from Azucena into Kalinga III, an upland variety (Steele et al, 2006(Steele et al, , 2007. In maize, a major QTL originally reported for leaf ABA concentration (Tuberosa et al, 1998) was later shown to affect root size and architecture (Giuliani et al, 2005b) and grain yield (Landi et al, 2007). Following its isogenization (Landi et al, 2005), the positional cloning of this QTL is under way at present (S. Salvi, unpublished data).…”

Genome-wide association analysis for lodging tolerance and plant height in a diverse European hexaploid oat collection

“…The rice gene ABERRANT PANICLE ORGANIZATION 1 (APO1), encoding for an F-box-protein involved in controlling rachis branch number of the panicle, has been shown to be responsible for increasing stem diameter (Ookawa et al 2010), providing a first clue of the genetic basis of stem strength in cereals. Root anchorage has been investigated more in maize than in other cereals, and several QTLs and candidate genes have been identified affecting root morphology and tolerance to root lodging (Bruce et al 2001;Landi et al 2007;Landi et al 2010). However, the physiological mechanisms and genetic factors affecting root lodging are still largely unclear.…”