A New Synthetic Amphiploid (AADDAA) between Gossypium hirsutum and G. arboreum Lays the Foundation for Transferring Resistances to Verticillium and Drought

Abstract

Gossypium arboreum, a cultivated cotton species (2n = 26, AA) native to Asia, possesses invaluable characteristics unavailable in the tetraploid cultivated cotton gene pool, such as resistance to pests and diseases and tolerance to abiotic stresses. However, it is quite difficult to transfer favorable traits into Upland cotton through conventional methods due to the cross-incompatibility of G. hirsutum (2n = 52, AADD) and G. arboreum. Here, we improved an embryo rescue technique to overcome the cross-incompatibility between these two parents for transferring favorable genes from G. arboreum into G. hirsutum. Our results indicate that MSB2K supplemented with 0.5 mgl-1 kinetin and 250 mg-1 casein hydrolysate is an efficient initial medium for rescuing early (3 d after pollination) hybrid embryos. Eight putative hybrids were successfully obtained, which were further verified and characterized by cytology, molecular markers and morphological analysis. The putative hybrids were subsequently treated with different concentrations of colchicine solution to double their chromosomes. The results demonstrate that four putative hybrid plants were successfully chromosome-doubled by treatment with 0.1% colchicine for 24 h and become amphiploid, which were confirmed by cytological observation, self-fertilization and backcrossing. Preliminary assessments of resistance at seedling stage indicate that the synthetic amphiploid showed highly resistant to Verticillium and drought. The synthetic amphiploid between G. hirsutum × G. arboreum would lay the foundation for developing G. arboreum-introgressed lines with the uniform genetic background of G. hirsutum acc TM-1, which would greatly enhance and simplify the mining, isolation, characterization, cloning and use of G. arboreum-specific desirable genes in future cotton breeding programs.

Genome-wide identification and functional analysis of the TIFY gene family in response to drought in cotton

“…Cotton is one of the most economically important crops worldwide (Kalivas et al 2011). Gossypium arboreum (diploid) is drought tolerant, and a better candidate for studying drought tolerance-related genes than G. hirsutum (tetraploid) (Chen et al 2015). Jasmonic acid regulates plant defense activities by inducing the expression of TIFY genes, which forms part of a negative feedback loop biosynthesis pathway and a signal transduction pathway that controls JAZ protein levels in response to JA and environmental stress (Song et al 2014).…”

Polyploidy: Pitfalls and paths to a paradigm

“…The comparison of synthetic and natural allopolyploids in cotton revealed that genome merger, rather than genome doubling or subsequent evolution, greatly alters expression levels due to cis‐ regulatory variation (Chaudhary et al, 2009); these results have been supported by both microarray and RNA‐sequencing analyses (Yoo et al, 2014). Finally, as an economically significant crop, novel synthetic allopolyploids are being developed rapidly to provide additional genetic materials for current breeding programs (Zhang et al, 2014b; Liu et al, 2015; Chen et al, 2015). Despite their lack of a natural counterpart, these novel synthetics can provide lineage‐specific biological replicates for understanding the impact of polyploidy in multiple genetic lines.…”

Inducement and identification of chromosome introgression and translocation of Gossypium australe on Gossypium hirsutum

“…Several obstacles exist in the process of cotton distant hybridization breeding using wild relatives, such as interspecific cross incompatibility, interspecific hybrid F 1 sterility, low rates of genetic recombination giving rise to linkage drag, and challenges in the reliable identification and characterization of the progenies of interspecific hybridization in mitotic and meiotic cells due to the small size of chromosomes in cotton (2n = 52). Our previous reports showed that the interspecific cross incompatibility can be alleviated via embryo rescue and F 1 sterility can be overcome by chromosome doubling through treatment with colchicines [ 28 ]. Identification and characterization of alien chromosomes in mitotic and meiotic cells of the progenies of interspecific hybridization can be easily achieved through a combination of GISH and molecular marker (SSR) analysis [ 5 , 29 , 30 ].…”