Quantitative trait locus mapping of yield and plant height in autotetraploid alfalfa (Medicago sativa L.)

Authors: HE, FEI - Chinese Academy Of Agricultural Sciences; LONG, RUICAI - Chinese Academy Of Agricultural Sciences; ZHANG, TIEJUN - Chinese Academy Of Agricultural Sciences; ZHANG, FAN - Chinese Academy Of Agricultural Sciences; WANG, ZHEN - Chinese Academy Of Agricultural Sciences; YANG, XIJIANG - Chinese Academy Of Agricultural Sciences; JIANG, XUEQIAN - Chinese Academy Of Agricultural Sciences; YANG, CHANGFU - Chinese Academy Of Agricultural Sciences; ZHI, XUXIN - Chinese Academy Of Agricultural Sciences; LI, MINGNA - Chinese Academy Of Agricultural Sciences; Yu, Long-Xi; KANG, JUNMEI - Chinese Academy Of Agricultural Sciences; YANG, QINGCHUAN - Chinese Academy Of Agricultural Sciences

Submitted to: The Crop Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2020
Publication Date: 6/19/2020
Citation: He, F., Long, R., Zhang, T., Zhang, F., Wang, Z., Yang, X., Jiang, X., Yang, C., Zhi, X., Li, M., Yu, L., Kang, J., Yang, Q. 2020. Quantitative trait locus mapping of yield and plant height in autotetraploid alfalfa (Medicago sativa L.). The Crop Journal. 8(5):812-818. https://doi.org/10.1016/j.cj.2020.05.003.
DOI: https://doi.org/10.1016/j.cj.2020.05.003

Interpretive Summary: Alfalfa is the most globally important forage legume and is grown in all 48 of the contiguous states in the US. Yield and plant height are important traits for alfalfa production. The importance of yield is obvious, while plant height is important because of its role in harvest and as an indicator of plant re-growth after harvest. These traits are controlled by genetic and environmental factors. This complex control makes it challenging to select plants for breeding because a plant may have high yields and tall plant height because of a good growing environment and not because it has good genes. In addition, while most plants have only two copies of each chromosome, alfalfa has four copies of each chromosome, which is referred to as “tetraploid”. The objective of this study was to identify DNA markers that are associated with yield and plant height in alfalfa. For three years we evaluated in the field 392 alfalfa plants derived from a cross between a low yield, early flowering plant and a high yield, late flowering plant. We also extracted DNA from all the plants and detected differences between plants in DNA sequences. We detected a total of 16 DNA markers associated with yield and plant height. Future studies will determine if these DNA markers can be used to select for plant height and yield in other alfalfa populations, which would make them especially useful for alfalfa breeding programs.

Technical Abstract: Alfalfa (Medicago sativa L.) is the most widely grown forage legume crop worldwide. Yield and plant height are important agronomic traits influenced by genetic and environmental factors. The objective of this study was to identify quantitative trait loci (QTL) and molecular markers associated with alfalfa yield and plant height. To understand the genetic basis of these traits, a full-sib F1 population composed of 392 individuals was developed by crossing a low-yielding precocious alfalfa genotype (male parent) with a high-yielding late maturing alfalfa cultivar (female parent). The linkage maps were constructed with 3818 single-nucleotide polymorphism (SNP) markers on 64 linkage groups. QTL for yield and plant height were mapped using phenotypic data for three years. Sixteen QTL associated with yield and plant height were identified on chromosomes 1 to 8. Six QTL explained more than 10% of phenotypic variation, representing major loci controlling yield and plant height. One locus on chromosome 1 controlling yield traits had not been identified in previous studies. Three QTL co-located with other QTL (qyield-1 and qheight-7, qheight-5 and qyield-4, qheight-6, and qyield-6). With further validation, the markers closely linked with these QTL may be used for marker-assisted selection in breeding new alfalfa varieties with high yield.