Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/26/1997
Publication Date: N/A
Interpretive Summary: Plant mutants are forms that deviate from the normal. While most mutations are undesirable, as evidenced by the connotation of the word, they are key to identifying genes and understanding gene function and location. For many crops, mutant forms are studied, published, maintained in collections, and distributed to researchers. Sugarcane has a relatively high number of chromosomes compared to many crop plants. No sugarcane mutants have been registered, and this deficiency has further complicated studies of its genetic makeup. Sugarcane farmers normally plant whole stalks or stalk pieces, and shoots develop from a shoot bud located at each node along the length of the stalk. We studied field performance traits of seven mutant plants of sugarcane that possess more than one bud at each node (called multiple bud mutants). We found that the mutants produced substantial numbers of nodes having multiple buds, and that this trait was stable. Shoot production of mutants in the field tended to be lower than in commercial types even though mutants produced about 2 shoots per node in greenhouse tests. This was probably because commercial types, unlike the mutants, were selected for high shoot number and vigor. We also found that the multiple bud trait was only weakly transmitted to offspring. Other researchers had shown that expression of the multiple bud gene(s) was unstable. Thus, it would be difficult to transfer the multiple bud trait to commercial types of sugar cane. We plan to register these mutants so that they may be distributed to researchers for genetic, breeding, physiological studies of sugarcane.
Technical Abstract: Few morphological mutations have been identified in sugarcane (Saccharum spp. Hybrids), a clonally propagated grass with complex, polyploid genetics. The objective of this study was to measure yield components, multiple bud frequency, bud germination, and genetic transmission of the multiple bud trait. Seven multiple bud mutants, including one gall-forming mutant (US 94-12, were tested in comparison to two check cultivars. Entries were evaluated in plant cane crops for 2 years in a randomized complete block design with four replications. Transmission was measured for 1 year in progeny of 19 populations having at least one multiple bud parent. None of the mutant genotypes was considered suitable for commercial release due to one or more measured or observed faults. Most multiple bud genotypes produced about 2 shoots per node in vitro, but US 94-12 produced 4.5 shoots per node. Contrary to expectation, shoot, stalk, and stool production tended to be low in genotypes with high multiple bud frequency, even though most multiple buds generated in vitro. We found that the multiple bud trait was genetically transmitted to only 2% of progeny, lower than previously reported. This may have been due to higher stringency screening. However, intermittent gene expression also may account for the disparate inheritance findings. While these multiple bud mutants were phenotypically stable, it seems unlikely that the multiple bud trait will be easily transmitted to sugarcane populations given the low rate of transmission, the difficulty in screening for the trait, and its intermittent expression.