II.1.5 Phenotyping pearl millet for adaptation to drought.
Bottom Line: The DTI is closely associated to the panicle harvest index (PNHI), a trait that relates to a better grain setting and grain filling capacity.However, there is no contribution of root traits in this QTL.Current work is taking place to map these water saving traits, understand their genetic interactions, and design ideotypes having specific genetic make-up toward adaptation to specific rainfall environments.
Affiliation: GT-1 Biotechnology, ICRISAT Patancheru, India.
Pearl millet is highly resilient to some of the driest areas of the world, like the Sahel area or fringes of the Thar desert in India. Despite this, there is a wealth of variation in pearl millet genotypes for their adaptation to drought and the object of this paper was to review some related work in the past 25 years to harness these capacities toward the breeding of better adapted cultivars. Work on short duration cultivars has been a major effort. Pearl millet has also some development plasticity thanks to a high tillering ability, which allows compensating for possible drought-related failure of the main culm under intermittent drought. The development of molecular tools for breeding has made great progress in the last 10-15 years and markers, maps, EST libraries, BACs are now available and a number of quantitative trait loci (QTLs) for different traits, including drought, have been identified. Most of the work on drought has focused on the drought tolerance index (DTI), an index that reflect the genetic differences in drought adaptation that are independent of flowering time and yield potential. The DTI is closely associated to the panicle harvest index (PNHI), a trait that relates to a better grain setting and grain filling capacity. Initial work on the DTI involved empirical breeding and selection based on PNHI. A QTL for PNHI has then been identified and introgressed by marker-assisted backcrossing. More recently, a thorough dissection of that QTL has been carried out and shows that high PNHI is related to the constitutive ability of tolerant lines to save water (lower leaf conductance and sensitivity of transpiration to high vapor pressure deficit) at a vegetative stage and use it for the grain filling period. However, there is no contribution of root traits in this QTL. Current work is taking place to map these water saving traits, understand their genetic interactions, and design ideotypes having specific genetic make-up toward adaptation to specific rainfall environments.
No MeSH data available.
Related in: MedlinePlus
Mentions: For terminal drought tolerance, contrasting parents PRLT 2/89-33 (tolerant) and H77/833-2 (sensitive) were identified and crossed. Then, selfing was done for two generations. Test crossing was done on F4:F2 derived progenies, using several pollinators, and measuring the GCA for PNHI (Figure 2). In doing this, two parents and 19 product lines all combined to five different testers were used, giving 105 Drought Tolerance QTL-near isogenic line (NIL) testcross hybrids. These materials were evaluated during the summers of 2003 and 2004 in the drought nursery at ICRISAT-Patancheru under three moisture regimes (fully irrigated conditions; early stress imposed by stopping irrigation at booting; late stress imposed by stopping irrigation at flowering). The experimental design is an alpha design with two-row plots and 4 m rows, into three replications. Usually, many QTLs are identified, each differing in the percentage of the variation in phenotypic data that they explain. QTLs can be identified for many different traits, some of these collocating at the same portion of the chromosome (Figure 3).
No MeSH data available.