Genome-wide identification and characterization of terpene synthase genes in Gossypium hirsutum.

Terpenoids are widely distributed in plants and play important roles in the regulation of plant growth and development and in the interactions between plants and both the environment and other organisms. However, terpene synthase (TPS) genes have not been systematically investigated in the tetraploid Gossypium hirsutum. In this study, whole genome identification and characterization of the TPS family from G. hirsutum were carried out. Eighty-five TPS genes, including 47 previously unidentified genes, were identified in the G. hirsutum genome and classified into 5 subfamilies according to protein sequence similarities, as follows: 43 GhTPS-a, 29 GhTPS-b, 4 GhTPS-c, 7 GhTPS-e/f, and 2 GhTPS-g members. These 85 TPS genes were mapped onto 19 chromosomes of the G. hirsutum genome. Segmental duplications and tandem duplications contributed greatly to the expansion of TPS genes in G. hirsutum and were followed by intense purifying selection during evolution. Indentification of cis-acting regulatory elements suggest that the expression of TPS genes is regulated by a variety of hormones. RNA sequencing (RNA-seq) expression profile analysis revealed that the TPS genes had distinct spatiotemporal expression patterns, and several genes were highly and preferentially expressed in the leaves of cotton with gossypol glands (glanded cotton) versus a glandless strain. Virus-induced gene silencing (VIGS) of three TPS genes yielded plants characterized by fewer, smaller, and lighter gossypol glands, which indicated that these three genes were responsible for gland activity. Taken together, our results provide a solid basis for further elucidation of the biological functions of TPS genes in relation to gland activity and gossypol biosynthesis to develop cotton cultivars with low cottonseed gossypol contents.

[Advance in quantitative traits from phenotypic variation to gene discovery].

With the rapid development of molecular biotechnology, many improved approaches have been provided for studying on the genetic bases of quantitative traits. Many studies paid attention to dissect the genetic bases using different emendatory approaches from phenotypic variation to gene discovery, mainly containing QTL mapping, chemical mutagenesis etc. Especially, QTL analysis was executed for a lot of important quantitative traits. This paper summarizes the development of quantitative genetics, the recent progress on QTL mapping populations and methods, the status of QTL locating and QTG identification, positional cloning, and QTL application in breeding.

Localization of QTLs for yield and fiber quality traits of tetraploid cotton cultivar.

Using SSR and RAPD as molecular markers, and the 69 F2 families from a cross between Handan208 (Gossypium hirsutum) and Pima90 (Gossypium barbadense) as a mapping population, a linkage map comprising 126 markers was constructed. With an average spacing 13.7 cM between markers, the linkage map spanned 1,717.0 cM, which covers approximately 34.34% of the total recombinational length of cotton genome. Based on the linkage map and the F2:3 phenotypic data, overall genome QTL screening was conducted by composite interval mapping method, then 29 QTLs related to cotton yield traits and fiber quality traits were found. There are 16 loci related to yield traits and 13 loci related to fiber quality. Particularly, two QTLs relevant to fiber strength were detected, which could explain phenotypic variance of 34.15% and 13.86%, respectively.