Intergeneric chromosome-specific painting reveals differential chromosomal transmission from Tripidium arundinaceum in sugarcane progeny

Sugarcane has recently attracted increasing attention for its potential as a source of sugar and bioethanol,so increasing its yield is essential to ensure the sugar security and bioenergy production.Intergeneric hybridization is a highly efficient method to produce new genetic variants of crop plants,particularly those species with high ploidy such as sugarcane(Saccharum spp.).Tripidium arundinaceum exhibits many desirable agronomic traits,and has been widely studied to produce hybrids with improved stress tolerance and other characteristics in sugarcane breeding.However,the genetic relationship between T.arundinaceum and Saccharum species,and the individual T.arundinaceum chromosomal compositions in sugarcane hybrids are still elusive.Here we used whole-genome single-nucleotide polymorphisms(SNPs)to ascertain the phylogenetic relationships between these species and found that T.arundinaceum is more closely related to Saccharum than Sorghum,in contrast to the previous narrow genetic analyses using chloroplast DNA.Additionally,oligonucleotide(oligo)-based chromosome-specific painting derived from Saccharum officinarum was able to distinctly identify the chromosomes of T.arundinaceum.We developed the oligo-genomic in situ hybridization(GISH)system for the first time,to unveil the novel chromosome translocations and the transmission of individual T.arundinaceum chromosomes in sugarcane progeny.Notably,we discovered that the chromosomal transmission of T.arundinaceum exhibited several different inheritance modes,including n,2n,and over 2n in the BC1 progenies.Such inheritance patterns may have resulted from first division restitution(FDR)or FDR+nondisjunction of a chromosome with the sister chromatids in the second meiosis division/second division restitution(FDR+NSC/SDR)model during meiosis.These results will be of substantial benefit for the further selection of T.arundinaceum chromosomes for sugarcane genetic improvement.

Genetic Research and Utilization Reference of Saccharum spontaneum L.

[Objectives]The genetic characteristics of wild germplasm resources of Saccharum spontaneum L.were further investigated to provide a scientific theoretical basis for the improved hybridization of sugarcane varieties.[Methods]The first flowering date data of 112 wild resources were statistically analyzed by broad heritability for 3 consecutive years,and pollen quantity and yield were investigated to provide reference for hybridization.[Results]The broad heritability of the first flowering date of S.spontaneum was 0.079.The differences in the first flowering date between the S.spontaneum resources were in the range of 4-49 d,with an average of 13.65 d.The inter-annual changes within 20 d accounted for 90 %,and only 4.5% exceeded 30 d.The first flowering dates of some S.spontaneum resources were obviously postponed after being treated.[Conclusions]In the hybridization season,the hybridization plan must be adjusted according to the actual situation of the flowering period to make full use of it.

Past and recent advances in sugarcane cytogenetics

The Saccharum genus comprises species with large and variable chromosome numbers, leading to challenges in genomic studies and breeding improvement. Cytogenetics, including classical and molecular approaches, has played a central role in deciphering the genome structure, classification, and evolution of the genus Saccharum. The application of fluorescence in situ hybridization using oligonucleotide probes significantly improved our understanding of the complex genomes of Saccharum species. This paper reviews the application and progress of cytogenetic techniques in Saccharum. Future applications of cytogenetics are discussed, as they could benefit both genomic studies and breeding of sugarcane as well as other plants with complex genomes.