QTL Analysis Of Plant Height And Yield Component Traits In Barley

Barley (Hordeum vulgare L.) is the fourth largest crop in China, and it is important for the development of national economy. The development of society and the increase of life level need to breed barley varieties with higher yield, better quanlity, stronger disease-resistance and wider adaptability, which requires to strengthen the genetic study of germplasm, and it is an efficient method to map QTLs for important agronomic traits. Nowadays, the development of QTL mapping in barley is slower than in rice, wheat and maize, and fewer researches were made in China, which will hinder the development of barley breeding and production. Therefore, it is of great significance to map QTLs for plant height and yield component traits such as 1000-grain weight, grain number per ear, spike length and spikelet density.In this study, correlation analysis was made between plant height, spike length, 1000-grain weight, grain number per ear and spikelet density for the five backcross populations from the crosses between 91G318, Hu 95-2639, Zhepi 1, India Aisheng, Baiqingke and Dalimai. The BC populations were detected with SSR markers, and then their genetic linkage maps were constructed with Kosambi function and software MapMaker/EXP3.0. Four qualitative genes were located for ligule color, rowed type, awn type and naked-grain. QTLs were mapped for plant height, 1000-grain weight, grain number per ear, spike length and spikelet density. The main results and conclusions are summarized as following:1. Plant height showed a positive correlation with spike length, 1000-grain weight and grain number per ear, while a negative correlation with spikelet density; spike length showed a positive correlation with grain number per ear and 1000-grain weight, while a negative correlation with spikelet density; a negative correlation was found between 1000-grain weight and grain number per ear, spikelet density.2. Five framework linkage maps were constructed for the BC populations based on SSR data. White ligule gene Wl was located on the 3H chromosome, and flanked SSR makers were detected for awn type gene K on 4H, naked-grain gene n on 7H and six-rowed gene vsrn on 2H.3. Thirty-three QTLs with a LOD threshold of 1.5 were determined using Composite Interval Mapping for the 5 agronomic traits, of which 10 reached more than 30% genetic contribution rate, including 3 for plant height on the 3H, 4H and 5H chromosomes. Among 6 QTLs with more than 30% genetic contribution rate and LOD>3.0, two were related to plant height, one to grain number per ear, two to 1000-grain weight and one to spikelet density.